How to Perform Roof Inspections
The goal of this book is to teach inspectors how to perform a visual inspection of a roof system. It covers common roof terms, gutters and drainage, framing and trim, roof coverings, roof !ashing, roof ventilation, and a brief section on inspecting chimneys. Upon successful completion of this course, the student will be able to inspect dierent types of residential roofs, identify the systems and components of roof systems, understand how the components of a roof system function and perform, and describe to clients the defects observed.
This guide also serves as a handy on-the-job reference manual for home inspectors, as well as a study aid for InterNACHI’s “How to Perform Roof Inspections” online course and exam.
Table of Contents
Roof Inspection Safety 5
Safety, Standards, and Walking the Roof 5 Safety First 5 Standards of Practice 5 Some Roofs Should Not Be Walked On 5
Types of Ladders and Safety Guidelines 6
Common Types of Household Ladders 6 Ladders Defined 6
Here are some basic rules regarding ladder placement: 7
Guidelines for Safe Ladder Set-Up and Use 7 Three-Point Control for Climbing Ladders 8 Conclusion 10
From a Ladder 11
Ladder Set-Up Tips 11
Overview & Requirements 12
International Standards of Practice 12
The Basics 13
Roof Slope and Pitch 13
Geometry 14 Slope 14 Slope Ratio 14 Pitch 14 Pitch Fraction 14 Asphalt Shingles 15 Roof Slopes 16 Summary 16
Roof Styles and Features 17
Gable 17 Hip 17 Mansard 17 Flat 18
Shed 18 Gambrel 18 Bonnet 18 Butterfly Roof 18 Roof Features 19 Clerestory 19 Cupola 19 Conical Roofs 20 Other Roof Combinations and Styles 21
Life Expectancy 22
Weather 23 Impact Damage 23 Environmental Conditions 23 Orientation 23 Ventilation 23 Insulation 23 Structural Issues 24 Installation Defects 24 Quiz #1 25
Gutters and Drainage 27
Roof Drainage 27 Effective Roof Drainage 27 Guttering Types and Materials 28 Common Gutter Inspection Issues 29
Downspouts and Terminations 30
Downspouts 30 Internal Drainage 30
Underground Systems 31 Quiz #2 32
Roof Framing from the Exterior 33
Ridge Issues 33 Rafter Issues 33
Sheathing Issues 33 General Structural Inspection 34
Conventional Roof Framing 35
Conventional Roofs 35
Roof Trusses 40
Roof Panel Sheathing 44 Trim 47 StructuralIssuesDisguisedasCosmeticOnes 50
Collar Ties vs. Rafter Ties 52
Tension Tie 52 Collar Ties 52 Rafter Ties 53 Tension Forces 54 Outward Thrust 54 Ceiling Joists 54 Cathedral Ceilings 55 Bottom Chord of a Truss 55 Lower One-Third 55 Tension 55 Compression 56 Bending Moment 56 Summary 56 Quiz #3 57
Introduction to Roof Coverings 59
Square 59 Asphalt Shingles, Part I 60 Asphalt Shingles, Part II 62 Asphalt Shingles, Part III 64 Slate Tile Roofing 65 Slate Roofs 65 Clay and Concrete Tiles 66 Asbestos Cement Tiles 69 Wood Shingles and Shakes, Part I 70
Wood Shingles and Shakes, Part II 73 Quiz #4 76
Flat Roofs: Roll Roofing 79
Flat Roofs: Built-Up Roofing 80 Flat Roofs: Membrane 83 Flat Roofs: EPDM 83 Metal Roofing 87
Roofing Oddities 90
Quiz #5 91
Roof Flashing 93
Edge and Ridge Flashings 93 Roof-to-Roof Flashings 96 Roof-to-Wall Flashings 96 Vents and Other Penetrations 101 Quiz #6 102
Roof Ventilation 104
Basic Ventilation 104 Unvented Roof Systems/Attic Assemblies 105 Quiz #7 107
Inspecting Chimneys 108
Masonry Chimneys 108 Manufactured Chimneys 110 Quiz #8 112
Appendix I: Answer Keys 114
Answer Key for Quiz #1 114 Answer Key for Quiz #2 114 Answer Key for Quiz #3 115 Answer Key for Quiz #4 115 Answer Key for Quiz #5 116 Answer Key for Quiz #6 117 Answer Key for Quiz #7 117 Answer Key for Quiz #8 118
Roof Inspection Safety 5 Roof Inspection Safety
Safety, Standards, and Walking the Roof
An inspection of the roof system is one of the most crucial areas of home inspection and one of the biggest concerns on the prospective home buyer’s mind. Spending a large portion of the inspection dealing with the roof and following some basic rules will pay dividends to the inspector, both in terms of customer satisfaction and in reduced liability.
Before approaching a roof inspection, it’s important to keep safety at the forefront. Too many home inspectors and other tradesmen have been seriously injured by being lax with ladder and roof safety.
Standards of Practice
According to the Standards of Practice, the inspector will inspect from ground level or the eaves: the roof-covering materials; the gutters and downspouts; the vents, !ashing, skylights, chimney, and other roof penetrations; and the general structure of the roof from the readily accessible panels, doors or stairs.
The inspector shall describe the type of roof-covering materials. The inspector shall report as in need of correction observed indications of active roof leaks.
The inspector is not required to: walk on any roof surface; predict the service life expectancy; inspect underground downspout diverter drainage pipes; remove snow, ice, debris or other conditions that prohibit the observation of the roof surfaces; move insulation; inspect antennae, satellite dishes, lightning arresters, de-icing equipment, or similar attachments; walk on any roof areas that appear, in the opinion of the inspector, to be unsafe; walk on any roof areas if it might, in the opinion of
the inspector, cause damage; perform a water test; warrant or certify the roof; or con#rm proper fastening or installation of any roof-covering material.
Some Roofs Should Not Be Walked On
One of the #rst safety issues to consider is that some roof systems simply should not be walked on. In particular, most types of solid tile roofs and all wooden shingle and shake roofs can be accidentally damaged by the inspector. In addition, no type of roof should not be walked on if conditions are wet or icy, or if the roof is mossy (covered in algae), or just too steep.
Even when considering walking a dry roof or a roof of low pitch that’s just one !oor up, it’s important to keep safety in mind. When all other conditions appear favorable and safe, it’s still possible to put your foot right through the asphalt shingle roof covering of a house due to rotten roof sheathing.
Remember that most of the time, a roof covering can be inspected from a ladder at the eaves,
from the ground with binoculars, or from overlooking windows. Many inspectors now employ camera-mounted unmanned aerial vehicles (UAV) or drones for roof inspections, as well as camera-
How to Perform Roof Inspections 6
mounted telescoping poles.
When planning to walk the roof covering, remember to wear soft-soled sneakers or similar footwear, as they oer a far superior grip compared to work boots, unless those boots are specially designed for walking roofs.
Types of Ladders and Safety Guidelines
This section may seem very basic, but some inspectors may be confused as to terminology and what a particular ladder is in its technical aspects, as de#ned by OSHA.
A ladder is an appliance designed for climbing, consisting of two side rails joined at uniform intervals by cross-pieces, called rungs or steps, on which a person may step to ascend and descend.
Common Types of Household Ladders
- A step ladder is a self-supporting portable ladder, non-adjustable in length, having !at steps and a hinged back.
- A single ladder is a non-self-supporting portable ladder, non-adjustable in length, consisting of just one section; its size is determined by the overall length of the side rails.
- An extension ladder is a non-self-supporting portable ladder, which is adjustable in length. Ladders Defined According to the American Ladder Institute, there are ocially nine dierent types of ladders. Not all of them are used by inspectors, however. The following ladders are commonly used by inspectors:
- step ladder. The step ladder is a self-supporting ladder that is not adjustable in length, with a hinged design for ease of storage;
- single ladder. The single ladder is a non-self-supporting ladder that is not adjustable in length, consisting of one section. This type of ladder is rarely used anymore because extension ladders are used instead;
- extension ladder. The extension ladder is a non-self-supporting ladder that is adjustable in length. It consists of two or more sections that travel in guides or brackets arranged so as to permit length adjustment;
- articulated ladder. An articulated ladder has one or more pairs of locking articulated joints, which allow the ladder to be set up in several dierent con#gurations. It may be used as a step ladder or a single ladder; and
- telescoping ladder. This ladder uses a pin system to “telescope” into variable lengths. As it
is more portable than the extension ladder, it is often preferred over that design for indoor applications. Inspectors should be aware that accidents have happened due to failure of the pins, which can be dicult to detect in advance. For this reason, some inspectors refuse to use telescoping ladders.
Types of Ladders and Safety Guidelines 7 Here are some basic rules regarding ladder placement:
- Make sure the ladder is dry before using it.
- Place the ladder on level ground and open it completely, making sure all locks are engaged.
- Remember to use the 4-to-1 Rule for extension ladders. That is, for each 4 feet of distance between the ground and the upper point of contact (such as the wall or roof), move the base of the ladder out 1 foot.
- Always wear slip-resistant shoes, such as those with rubber soles.
- Face the ladder while you are climbing up and down, and keep your body centered. You can gauge your position by your belt buckle, if you wear one. If your buckle passes beyond either ladder rail, you are over-reaching and at risk for falling.
- Stand at or below the highest safe rung. For a step ladder, the safest rung to stand on is the second from the top. For an extension ladder, it’s the fourth rung from the top. Guidelines for Safe Ladder Set-Up and Use Whenever possible, it’s best to use two people to carry and set up a ladder. Since many inspectors are one-person operations, this may not be practical. Then it becomes especially important to ensure that the ladder chosen for use is not too heavy or dicult to move, that it’s properly rated, in good condition, and is easy to set up. Also:
- Keep all types of ladders (and tools) at least 10 feet away from live power lines, connections, cables and equipment.
- Set the ladder on #rm, level ground. Use ladder levelers on uneven ground.
- When setting it up, be sure to secure the ladder by tying it down, using slip-resistant feet, and/ or by having someone hold it in place for you.
- Keep the area around the top and bottom of the ladder clear. In passageways, doorways, and where there is trac or other activity, try to secure the ladder, or limit access to the immediate area while you’re working.
- Do not set the ladder on a scaold, box, or any other object.
- When using a step ladder, remember that all four of its legs must be on solid, level ground. The spreaders must be fully open and locked. Step ladders should not be climbed when closed and leaning against a wall.
- When using an extension ladder, always remember that the ladder base should be 1 foot
from the building (or top support, such as an eave) for every 4 feet of ladder length up to the resting position. Counting rungs will give you a good estimate of the ladder’s length; rungs are approximately 1 foot apart.
- Some ladders used by inspectors are a hybrid of step and extension ladders. Whatever mode the ladder is in, the proper setup and safety guidelines should be followed.
- When using an extension ladder, be sure to lock the top section in place. Extension ladder sections must actually overlap by approximately 3 feet for ladders up to 32 feet long.
- Both rails should rest evenly where set, on both the top and bottom.
- When a ladder is used to get on and o a roof, be sure to secure the ladder by tying it o. The
How to Perform Roof Inspections 8 side rails should extend at least 3 feet above the roof to be safe.
If you have to step around a ladder because of rungs, there should be a grab rail attached to the building to help you. (OSHA requires both a grab rail and a tie-o if the ladder doesn’t extend at least 3 feet above the roof.)
When working on !at roofs, if there is a high parapet wall, use a stairway or some other way to gain safe ladder and roof access and egress.
While on the ladder, always:
- face the ladder;
- consider anchoring the top of the ladder with a bungee cord. Perhaps the most feared move an inspector must make is stepping back onto the ladder from the roof. He must step around the section of the ladder that extends above the roo!ine, placing lateral pressure on the rung as he makes contact with the ladder. A bungee cord is a convenient tool that can be used to reduce any movement that could otherwise result in a serious accident. Also, a bungee cord may prevent the ladder from being blown over in the wind while the inspector is on the roof;
- be conscious of the ladder’s location, especially while walking on the roof. In an emergency, the inspector may need to leave the roof quickly. A ladder becomes much more dangerous when an inspector gets covered in a swarm of stinging bees and must get down in a hurry, for instance;
- keep your body centered between the rails at all times. Do not lean too far to the side while working; and
- utilize three points of control because this minimizes the chances of slipping and falling. At all times during ascent and descent, the climber must face the ladder and have two hands and one foot, or two feet and one hand, in contact with the ladder. In this way, the climber is unlikely
to become unstable if one limb slips during the climb. It is important to note that the climber must not carry any objects in either hand that can interfere with his #rm grip on the ladder. Three-Point Control for Climbing Ladders When it comes to ladder safety, there’s a dierence between three-point control and the traditional three-point contact rule. Three-point control is a climbing method that involves always using three or four limbs distributed over three or four locations for reliable support. Three-point contact involves simply coming into contact with the ladder at three points without necessarily requiring a reliable hand grip for support. Three-point contact is sometimes referred to as the three-point stance, an American football term used to describe the stance of a lineman with two feet planted in and one hand in contact with the ground. Critical to three-point control is grasping the ladder so that one hand can bear the full weight of the body, if needed, and distributing the climber’s weight among three or four rungs. The three-point control method distributes the climber’s weight among three or four rungs, which is safest. If one foot slips during a foot transition, two hands should be grasping the ladder rungs to support the body weight. If either foot slips during a hand transition, the climber’s weight can be supported with a hand and a foot. If both feet slip during a hand transition, the climber’s weight is transferred to one or both hands.
Types of Ladders and Safety Guidelines 9
The images to follow show the safe climbing method: grasping the rungs, rather than the side rails; having only one limb on one rung at a time; and moving only one limb at a time. The image at the left shows the climber using both hands to grasp, with both feet in contact with the ladder rungs. The image in the center shows him using both hands to grasp and one foot to transition. The image on the right shows him making contact with one hand to transition while both feet are in contact with the ladder rungs.
Whenever there’s a risk of a serious fall, three-point control should be used because it helps decrease the likelihood that a person will lose control when an unexpected slip or loss of balance occurs.
The traditional method of climbing a ladder consists of:
• keeping one’s navel or belt buckle between the two side rails; • two hands holding a ladder rung or side rail; and
• one foot on a ladder rung.
The main problem with the traditional method for climbing a ladder is that the hand grip strength is inadequate to hold onto a side rail to support the entire body weight in order to prevent a fall (Young, Wooley, Armstrong, et al., 2009). It is safer for an inspector to grab a horizontal rung rather than a vertical side rail.
Horizontal Power Grip
Holding a ladder rung or horizontal bar is referred to as a horizontal power grip (Barnett & Poczynok, 2000). To help prevent an uncontrolled fall, one hand must grasp a horizontal support using a horizontal power grip at all times. Grip control in contrast with contact is critical. Side rails or vertical holds provide a contact hand grip based mostly on friction. The horizontal power grip has a 75% to 94% larger breakaway force than when gripping a vertical rail (Young, Wooley, Ashton- Miller, et al., 2012).
Vertical Side Rail
Based on a recent study at the University of Michigan, funded by the Center for Construction Research and Training/NIOSH, neither men nor women can support their full body weight through the use of only one hand gripping a vertical side rail (Young, Wooley, Ashton-Miller, et al., 2012).
How to Perform Roof Inspections 10
The hand that is gripping the ladder side rail will, in a fall, slide down and hit the next ladder rung 12 inches below in a quarter of a second. It takes about a third of a second for a human hand to respond and fully grasp an object. Therefore, the climber’s hand will hit and pass the ladder rung before the climber has the muscle response to fully grasp and attempt to stop the fall (Robinovitch, Normandin, Stotz, et al., 2005; Thelen, Schultz, Ashton-Miller, et al., 1996).
Three-point control is not three-point contact. Ladder users may increase their personal safety by using the three-point control method in addition to following the other accepted ladders safety standards.
Consider the following when climbing a ladder:
• Properly stage the ladder according to standards.
• Grasp the horizontal ladder rungs and not the vertical rails. • Use the horizontal power hand grip.
• Grasp, rather than simply make contact.
• Distribute your weight among three or four locations.
From a Ladder 11
From a Ladder
When using a ladder to inspect a roof, keep the following in mind:
- Purchase ladders that are rated for your weight.
- Prior to climbing, ensure that the ladder is properly leveled on solid ground.
- Make sure that the ladder is at the correct angle to the wall.
- Pay attention to what the ladder is leaning against, as it is easy to mark siding or damage guttering if you’re not careful.
- Consider buying electricians’ ladders and steps, as these are made of non-conductive #berglass and will protect you from shocks, should you hit any uninsulated electrical components, such as service conductors. Think safety; clients are not too impressed with inspectors landing in the shrubbery, writhing in agony! Ladder Set-Up Tips To determine whether your ladder is placed safely and properly, follow these tips, courtesy of InterNACHI® member David Lane of Texas:
- Lean the ladder against the building.
- Look at the ladder’s feet and draw an imaginary line between them. Put your toes up to that line.
- Stand up straight and hold your arms straight out in front of you.
- The ladder rung should be just beyond your reach.
- If you can touch the rung, the ladder is too steep. Move it back and repeat these steps.
- If the rung is several inches beyond your #ngertips, the ladder pitch is too shallow. This is also hazardous because the feet can slip backwards when you are on it, causing you to fall. Move the ladder closer and repeat the procedure.
This is a simple process that takes #ve seconds and ensures that you are about to climb a ladder that is properly pitched.
How to Perform Roof Inspections 12 Overview & Requirements
Here are the goals when inspecting the roo#ng system:
- to report on the type of roof covering material;
- to report on the visible condition of the roof covering;
- to inspect and report on the visible !ashings;
- to evaluate the roof drainage and gutter system;
- to report any overhanging tree branches that may have an adverse eect on the roof covering;
- to report on the chimney system;
- to identify any obvious de#ciencies of roof penetrations and through-the-roof components and their !ashings;
- to report on any visible de#ciencies in the underlying structure (for example, swayback ridge beams);
- to report the methods used to inspect the roof (for example, from the eaves with a ladder, or from the ground with binoculars);
- to inspect and report on roo#ng trim, such as rake boards, sots and fascia boards; and
- to report on any visible roo#ng problems that can be inspected from accessible areas of the attic, such as signs of sheathing problems, evidence of moisture intrusion, or damaged structural components, such as split rafters and damaged trusses. It is also important to understand what you are NOT required to do, such as: • walk on every roof surface;
• report on the future life expectancy of roof coverings and systems;
• warranty the roof;
• inspect most connected components, such as antennae, solar panels, etc.; • report on underground gutter terminations; or
• inspect the roof framing system, if not readily accessible. International Standards of Practice Be sure to refer to InterNACHI’s Standards of Practice for Performing a General Home Inspection to read the requirements and exclusions for conducting the roof portion of a residential property inspection.
The Basics 13
According to the InterNACHI® Home Inspection Standards of Practice (www.nachi.org/sop), the
inspector shall inspect the roof-covering materials from the ground level or eaves.
Home inspectors should report on the “roof-covering” or the “roof-covering materials” that they observed during the home inspection.
They should NOT report on the “roof system,” “roo#ng,” or “roof assembly,” the components of which are not readily observable. Components of a roof system or roof assembly are not readily visible during a visual-only inspection. The components of a roof system or assembly may include the roof deck, load-bearing components, trusses, underlayment, substrate, fasteners, thermal barrier, vapor retarder, insulation, ventilation, and the roof covering. Can home inspectors see underlayment? No. Fasteners? No. Decking? No.
“Roof covering” is a term speci#cally used and de#ned in the International Residential Code (IRC) and building standards. Roof covering is the covering applied to the roof deck for weather resistance, #re classi#cation, and/or appearance. And since the covering is layered, not all of the covering material is visible during a home inspection. The other terms refer to a combination of components used together to form a complete assembly. Roof covering and roof-covering materials are typically visible during a visual-only home inspection. A system is made up of its parts. An assembly is made up of smaller components. And most of the smaller parts and components are not readily visible. They are beyond the scope of a home inspection.
The focus for the home inspector should be on roof coverings. A variety of roof-covering materials may be installed on a house or building to be inspected, such as asphalt shingles, clay and concrete tile, metal roof shingles, wood shingles and shakes and metal roof panels. For example, built-up roof covering is de#ned in the IRC as a common roof covering for houses and buildings with relatively !at roofs, and made up of two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating, or similar surfacing material.
Remember that just about everything (every component and system) is limited and restricted in some way for the inspector during a visual-only home inspection.
Roof Slope and Pitch
Both pitch and slope indicate the incline of a roof, expressed as a proportion of the vertical to the horizontal. This section describes both roof slope and roof pitch, and the dierences between them, as they are not the same. Slope aects how roof systems are installed, including dictating which type of roof-covering material can be applied.
Please note that, according to the InterNACHI® Standards of Practice for Performing a General Home Inspection, the inspector is not required to measure the slope of the roof.
How to Perform Roof Inspections 14
The illustration at left shows a simple gable roof and the general relationship between rise, run and span. Roof framing is a practical application of geometry, and roof slope is based largely on the properties of a right triangle.
In roof framing, the base of the right triangle is called the run. The run is the distance from the outside of the wall’s top plate to a point directly below the center of the ridge. The vertical leg of the triangle is called the rise, which is the distance the roof rafter board extends upward above wall’s top plate.
Slope is the incline of the roof expressed as a ratio of the vertical rise to the horizontal run, where the run is some portion of the span. This ratio is always expressed as inches per foot.
A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a “4 in 12” slope. If the rise is 6 inches for every 12 inches of run, then the roof slope is “6 in 12.”
The slope can be expressed numerically as a ratio. The slope ratio represents a certain amount of vertical rise for every 12 inches of horizontal run. For example, a “4 in 12” slope can be expressed as the ratio of 4:12. A “6 in 12” slope is expressed as 6:12.
The triangular symbol above the roof line in this architectural plan provides information on the roof’s slope.
Slope is expressed:
• as a ratio; and
• in inches per foot.
Pitch is the incline of the roof expressed as a fraction derived by dividing the rise by the span, where the roof span is the distance between the outside of one wall’s top plate to another.
Historically, the word “pitch” meant a ratio between the ridge height to the entire span/width of the building, or the ratio between the rafter length to the building width. The ridge was typically in the middle of the span. This is no longer the case in modern building practices. The ridge can be placed
Roof Slope and Pitch 15 anywhere in the span, from directly in the middle to either span endpoint.
A roof that rises 8 feet over a 24-foot span was said to have a “1 to 3” pitch. If the rise is 4 feet over a 24-foot span, then the roof pitch was said to be “1 to 6.”
The pitch can be expressed numerically as a fraction. The pitch fraction dierent from slope, represents a certain amount of vertical rise over the entire span. For example, given a roof with a rise of 4 feet and a span of 24 feet, the pitch is “1 to 6,” which can be expressed as the fraction of 1/6. A “12 to 24” pitch is expressed as 1/2.
The term “pitch” and “slope” are often used interchangeably, which is incorrect. They do not mean the same thing. And slope provides more valuable information than pitch, as de#ned here.
Using the illustration above and information we just learned about slope and pitch, we can see that a 2:12 slope can be expressed as 1/12 pitch, assuming the span is twice the length of the run. If the slope is 4:12, the pitch for the 24-foot span is 1/6. If the pitch is 1/3, the slope is 8:12. Remember that slope is expressed as a ratio and in inches per foot. And pitch is a fraction derived by dividing the rise by the entire span.
The slope of a roof aects the surface drainage of water and can determine the type of roof-covering materials that should be installed. Asphalt shingles should be used only on roof slopes 2:12 or greater. Asphalt-shingle roofs are designed to shed water, and not meant to serve as a waterproof barrier. The slope of a roof aects its ability to shed water and determines the limits for using asphalt shingles.
Most asphalt shingles may be used on roof slopes from 4:12 to 21:12, using standard application methods. Asphalt shingles may be used on slopes from 2:12 to 3.9:12, if special low-slope application procedures are followed. An inspector will usually #nd roll roo#ng materials installed on slopes of less than 4:12.
How to Perform Roof Inspections 16
The following illustration shows common terminology and general roof slopes, including !at, low and conventional terms.
Pitch and slope do not mean the same thing. Slope is the ratio measured in inches per foot. The pitch fraction represents a certain amount of vertical rise over the entire span.
Roof Styles and Features 17 Roof Styles and Features
There are two types of hip roofs, and both have four slopes. The basic hip roof has a level ridge, but the ridge doesn’t extend all the way to the exterior walls. Instead, hip rafters slope diagonally down to each corner.
The illustration at right shows a full hip roof. Full hip roofs have no real ridge. The hip rafters all meet to form a point at the peak of the roof.
Gable roofs are one of the most common styles. They’re easily identi#ed. They have two slopes, and the ridge extends the length of the house. The lower, level edges of the roof are called the eaves, and the sloped edges are called the gables or rakes. (We use both terms.)
Mansard roofs were invented by the French when owners were taxed by the height of
the building as measured to the roof eave. They’re short, steep roofs installed around the perimeter of what’s usually (but not always) a !at-roofed building.
Some of these roofs are nearly vertical, and this can cause installation problems, which can vary with the dierent types of roof- covering materials.
How to Perform Roof Inspections 18
Flat roofs have very little slope. A typical slope would be 1:12.
Flat roofs may drain over the roof edges or through scuppers installed in a parapet wall built around the perimeter.
Flat roofs are low-slope roofs. Low-slope and steep-slope roofs have dierent requirements.
Shed roofs have one slope. Because shed roofs are often used for additions, one potential problem area is along the upper edge of the shed roof where it ties into the wall of the original home.
Gambrel roofs are usually associated with barns but are not uncommon on homes. They have two slopes, each of which changes pitch in a convex manner. The point at which the roof changes pitch should have metal !ashing.
This is a style seen less often. When you inspect a home with a butter!y roof, look closely at the ceiling and !oor beneath the low point.
The house in this photo had recently sold and the sellers had hired a contractor
Bonnet roofs have a change of pitch but are concave — the opposite of a gambrel.
to install a new roof. The buyers moved in. When it rained, the roof leaked. The buyers had to hire both a (dierent) roo#ng contractor and a !ooring contractor.
The roof wasn’t likely to leak due to the design alone, so this well-known architect designed not one, but two penetrations into the low point. The only things lacking are an anchor and a bilge pump!
These photos show roofs with clerestory windows. Although the term “clerestory” refers to the position of the windows, it also generally describes their position as incorporated into
a shed roof. In other words, “clerestory” is commonly used to refer to the combination of roof and windows.
Roof Styles and Features 19
Clerestory windows should have adequate clearance between the sills and the roof below in homes located in regions with heavy snowfall. The home pictured at right doesn’t and is more likely to leak. They should also have proper sidewall !ashing.
Cupolas are small structures built into the peak of a roof, often to provide light to the area below. The inspection concern is the roof framing supporting the cupola. Although the framing is typically hidden behind interior wall-covering materials, look for signs of movement, such as cracking. Other vulnerable areas are at headwall and sidewall
How to Perform Roof Inspections 20 Conical Roofs
Conical roofs are often used to cover towers, and are often steep. The photo at left shows a conical roof that is actually a series of tapered !at roofs, creating a series of hips.
Installing roo#ng round conical roofs requires special roo#ng techniques to get the shingles to lie !at, especially near the peak.
In this photo, you can see that four tiny dormers have been installed near the peak.
Inspecting these steep roofs closely is dicult (or impossible) without special equipment, so you should get as close as you can using binoculars or a camera-mounted
drone to look for signs of leakage beneath these roofs.
Inspection concerns include !ashing at the round sidewalls, and areas where conical roofs intersect with roofs of other shapes. Specially-shaped crickets or !ashing may be needed to provide long-term protection against leakage.
These areas of intersection (which are dicult to see because they’re on the backside of the roof) often collect debris, such as leaves and sediment. This debris holds moisture against the roof and !ashing, which often corrodes more quickly than on the rest of the roof. So, the areas of intersection are dicult to see, and they’re weak point.
If you can’t con#rm the condition of the roo#ng on the backside of a conical roof, you need to disclaim it and recommend inspection by a quali#ed roo#ng contractor. A contractor may need to hook a ladder over the ridge in order to get high enough on the roof to see the backside of the conical roof clearly. This is especially true when the roof is covered with fragile materials, such as slate or tile.
Dormers are projections built into the slope of a roof. At right are dormers with gable, hip and shed roofs. Inspection concerns are valleys, and headwall and sidewall !ashing.
Roof Styles and Features 21 Other Roof Combinations and Styles
You’ll often see several roof styles combined on one home.
Sometimes, you’ll see roof styles for which there really is no name.
In the photo at right, the structure above is a dormer because it’s a projection built into the slope of a roof. The structure below is a second story, since the exterior wall is continuous from foundation to roof.
The only limitations to the number of styles possible are the human imagination, the laws of physics, and the depth of the homeowner’s pockets.
Each dierent style of roof and roof feature has its weak points. Once you learn what these are, you’ll know where to expect problems.
With all roofs, the typical weak points are:
• places where roof-covering materials change;
• places where the roof changes direction;
• places where materials are used that have a relatively short lifespan; • roof penetrations; and
• portions of the roof that lie in the drainage path.
How to Perform Roof Inspections 22
There are many factors that can in!uence the life expectancy of the roof sheathing and covering. You may be interested in InterNACHI’s Standard Estimated Life Expectancy Chart for Homes.
The life of a roof depends on local weather conditions, building and design, material quality, and adequate maintenance. Hot climates drastically reduce asphalt shingle life. Roofs in areas that experience severe weather, such as hail, tornadoes and/or hurricanes, may also experience a shorter- than-normal lifespan overall, or may incur isolated damage that requires repair in order to ensure the service life of the surrounding roo#ng materials.
|Roofing||Life Expectancy in Years|
|Asphalt Shingles (3-tab)||20|
|BUR (built-up roofing)||30|
|Coal and Tar||30|
|EPDM (ethylene propylene diene monomer) Rubber||15-25|
All roof coverings, regardless of materials, are susceptible to additional variables, such as:
• impact damage;
• environmental conditions; • orientation;
Life Expectancy 23
• structural issues; and • installation defects.
We have all seen pictures on the news of homes with their roofs blown o in “Tornado Alley” — the geographic region that lies between the Rocky Mountains and the Appalachian Mountains. But it
is not unusual to see weather damage in all areas of the United States, as well as in various regions around the world. Severe weather damage can leave behind ripped shingles and dislodged tiles aecting just one or two areas of a home’s roof. But, occasionally, there can be more widespread damage that is easier to spot.
This is very common and most often caused by overhanging tree branches. It can also be in!icted by falling masonry, and cracked tiles and shingles from people being on the roof.
This category of rapid deterioration of the roof covering can be attributed to airborne pollutants that are prevalent in industrial areas, as well as from the acidity of pine needles breaking down on the roof’s surface.
The direction that the roof faces can have a signi#cant in!uence on its long-term condition. For example, south-facing roof planes tend to show signs of overheating, particularly those with asphalt shingles. North-facing roofs and those in the shade tend to have more algae- and moss-induced problems, both of which will shorten the life of the roof covering.
Poorly vented roofs, especially those over cathedral ceilings (which are hard to ventilate), will show signs of overheating, and may also show signs of moisture damage.
Inadequately insulated attics will also promote rapid failure of the roof covering due to issues such as ice damming in colder climates.
How to Perform Roof Inspections 24
Both the roof sheathing and framing can sometimes indicate structural issues, as revealed on the roof’s surface. Such problems may be as apparent as cracked shingles or tiles above a structural defect. More commonly, there will be a wavy look to the roof caused by thin roof sheathing that is over-spanned.
All roo#ng systems are only as good as the installer, and it is not uncommon to see all types failing due to poor fastenings or other installation problems.
1. A roo#ng square covers an area of ______ square feet.
∏ 144 ∏ 100 ∏10
2. In most jurisdictions, a maximum of _____ layers of roo#ng is allowed.
∏two ∏ three ∏five
3. Roof slope = _______
∏ rise / run ∏ run / slope ∏ run / rise
4. A roof with a pitch or slope of 3/12 is considered a _______ roof.
∏ low-slope ∏flat
5. T/F: InterNACHI’s Standards of Practice require that all roofs be walked. ∏ True
6. An inspector is not required to report on the ____________.
∏ guttering system
∏ roof covering
∏ TV antennae
∏ condition of covering
7. T/F: The inspector is not required to report on tree limbs overhanging the roof surface, since they are not part of the structure.
∏ True ∏ False
How to Perform Roof Inspections 26 8. A !at roof is one with a pitch or slope of less than _______.
∏ 1/12 ∏ 2/12 ∏ 12/12
9. A standard gable roof has _____ plane(s).
∏ one ∏two ∏ four
10. A roof with four planes meeting at the ridge is termed a _______ roof.
∏ Dutch ∏ mansard
11. Standard 3-tab asphalt shingles generally last _______ years.
∏20 ∏40 ∏ 50+
12. T/F: Slate roofs can last forever. ∏ True
Answer Key is on page 114.
Gutters and Drainage 27
Gutters and Drainage Roof Drainage
Unless the roof is sloped to drain over the roof’s edge, there should be drainage installed for the roof system. Roof drains could be installed at the low points of the roof. Roofs should have some type of controlled method for disposing of water that collects so it discharges to the ground surface at least 5 feet away from the foundation walls, or into a drainage system. Gutters are sometimes not installed in areas that don’t get heavy snow or much rain.
While roof overhangs and porch roofs protect building walls from impinging rain, gutters serve
to protect building walls and the foundation from roof water runo. Roof gutters, downspouts, and leaders or diverters form the initial components of a drainage system for the building and site. A proper design of gutters and downspouts for water-shedding sloped roof systems should be assessed during a roof inspection.
Common problems with guttering are associated with installation and maintenance. Home inspectors can check if properly sized materials are being used, if guttering is appropriately sloped toward adequately sized downspouts, and if discharge is directed away from the building’s foundation and perimeter. Discharging water at the building’s inside corners should be avoided. Some local stormwater codes may require special #ltration treatments of roof water runo.
Effective Roof Drainage
Eective roof drainage is a must for two reasons. First, the roo#ng system needs to drain quickly so that large volumes of water are not trapped on the surface. Second, water runo from the roof needs to be managed so that it is not being directed toward the foundation.
Guttering systems, like everything else, have evolved greatly over the last couple of hundred years, starting out as crude wooden troughs and ending up with the vinyl and metal systems that we
use today. It is fair to say that most guttering systems are high-maintenance. Homeowners with conventional uncovered gutters are required to regularly clean out vegetation and debris that get blown into them. Gutters often need to be re-#tted when severe weather detaches them from the fascia.
Roo#ng gutters should slope down toward the downspout at the rate of 1/16-inch per foot, or 1/4-inch per 5 to 10 feet. An angle less than this won’t allow water to move eectively, and much more of an angle will cause the water to move at too great a speed, potentially resulting in over!ow over end caps and corners.
In terms of standards, home inspectors are not required to measure the amount of gutter slope. To do it accurately would be time-consuming, would require a transit or water level, and would exceed InterNACHI’s Standards of Practice.
A more practical approach is to make sure that all gutters slope toward the downspout. In judging adequate slope, look for signs of standing water in portions of the gutter away from the downspout, and eyeball the margin against the fascia. It is not uncommon to see gutters installed too low on the fascia, or to see roof coverings projecting too far over the gutter. In both cases, this may lead to the water over-shooting the gutters completely.
Typical gutter systems hold up better when the brackets are spiked or screwed through the fascia and into the ends of the rafters, and not just into the 3/4-inch fascia board.
Cornice or Gully Guttering
How to Perform Roof Inspections 28
In this section, we will look at the various types of gutters and their common weaknesses, as well as their materials, installation and maintenance. It bears mentioning that it is dicult to evaluate the guttering systems without also looking at the site drainage immediately surrounding the house, and this topic is covered in other InterNACHI® books and online courses dealing with a home’s exterior.
Let’s look at the various types of gutters and their common weaknesses, as well as their materials, installation and maintenance.
Guttering Types and Materials No Gutters
Not all homes were designed to have gutters. In some areas of the United States, they are deemed unnecessary due to very low rainfall. Even in areas with higher rainfall, some homes were designed with a long eave overhang (as much as 4 or 5 feet) to direct water away from the foundation. However, it does not always have the desired eect.
These are little more than diverters directing water away from speci#c areas of the structure, particularly over doorways and entrances. They are also sometimes installed to protect other areas, such as the eaves. Yankee guttering was the earliest form of water management. On some very old homes, there are still planks held in place by wooden blocks. Normally, they were lined with tar to both protect the gutter and to seal it to the roof. The modern version of Yankee guttering is a metal type that is still seen on new construction directly over entryways.
Wooden guttering is still fairly common. It was still being installed as recently as the 1930s. It originally consisted of little more than wooden troughs, but these were later milled out of close- grain timber and are very similar in pro#le to modern metal and vinyl systems. In many cases, they were lined either with tar or metal, such as lead, copper or aluminum.
Generally speaking, most older systems still in operation have not been well-maintained. When they start to rot, any moisture is transferred straight into the fascia, sot and rafter tails.
Cornice or gully guttering is an integral part of the roof system. Typically, the guttering was laid down with the roof framing and sheathing, and then covered with metal or roll roo#ng running up under the roof covering. The downspouts are often hidden inside posts and pillars to mask their presence. When these fail or when the downspouts become blocked, they can wreak havoc on the roof structure. Most of these systems have now been built over, and normal fascia-applied guttering has been installed.
Gutters and Drainage 29
Metal and Vinyl Guttering
The two biggest problems with steel guttering are rust (if they’re not properly maintained), and the potential for leaks in joints and downspout connections. Steel guttering comes in shorter lengths, so there tend to be many joints in the system — not just at the corners.
Aluminum guttering is quite often formed on- site from a roll of sheet aluminum. This leads to fewer joints, but those at corners and downspout connections should still be fully evaluated.
The most common method of connecting the components is using aluminum pop-rivets. These very frequently fail, either from impact damage or building movement.
Copper guttering was becoming a lost art until recently, but it is reappearing on both high-end new construction and on quality restorations of older properties. What makes copper systems desirable is that all of the joints are soldered, including those of the downspouts. This tends to make for a system with a long service life.
Vinyl guttering is not only very common on new construction, but is also the do-it-yourselfer’s material of choice, as it is available o the shelf at most home improvement stores. Prefabricated angles, corners and connections are readily available, and installation requires no special tools, or even much technical aptitude.
Common Gutter Inspection Issues
Regardless of material or style, all gutters tend to exhibit common problems and should be inspected primarily the same way. Here is the “what-to-look-for” list when evaluating guttering:
- Does the gutter slope downward at a minimum of 1/16-inch per foot?
- Are there downspouts present?
- Is there an adequate number of downspouts?
- Is the guttering securely fastened to the building?
- Are any brackets missing?
- Are any gutter spikes backing out?
- Can you see signs of leaking from the joints?
- Are the gutters blocked by debris, or even rooted vegetation? Take a good look in the bottom of the gutters. The contents will typically point to problems with the roof covering. For example, if there is a large amount of asphalt shingle aggregate in the gutter, that could be a sign that the roof covering is likely nearing the end of its service life. But be careful, as a brand new installation can also result in some aggregate in the gutter.
How to Perform Roof Inspections 30 Downspouts and Terminations
Every square inch of downspout is capable of discharging drainage for 100 square feet of roof surface. Therefore, a 2×3-inch downspout can handle 600 square feet of roof, and a 3×4-inch downspout can manage 1,200 square feet.
Most downspouts are made of the same material as the gutter system, so they tend to suer from similar problems, but with a few twists — especially in the area of mechanical damage from proximity to high-trac areas.
Inspect the downspouts for:
- the connection between the downspout and the gutter;
- proper attachment of the downspout to the structure;
- leakage in joints (because they sometimes will have been installed upside-down);
- impact damage from car doors, etc.;
- downspouts that terminate onto another roof surface, as this will quickly erode the covering at the termination; and
- whether the termination is directing water away from the foundation. The last item in this checklist is very important, as it is pointless to have a gutter system that is directing roof water runo straight down into the foundation. Unless the grade slopes steeply away from the foundation, if the downspout empties too near the foundation, recommend that downspout diverter extensions be installed. In some areas of the U.S., local conditions dictate that the termination of the downspout system be a minimum of 5 feet away from the foundation due to soil conditions. Internal Drainage Many !at roofs have internal drainage systems. Although they are not common in modern residential construction, they will be found on older homes and many commercial roofs. The drainage system relies on the roof having one or more low points to which runo water is directed, where it will then run down internal piping connected to the drainage system. The common problems with this system include: • inadequate slope on the roof (which should be a minimum of 1/4-inch per foot); • poor !ashing between the roof covering and the drain;
• drain blockage due to leaves and other debris;
• failure of the internal pipe system due to pipe corrosion; and • failure of the building’s main foundation drainage system. Signi#cant structural problems can be caused both by water getting under the roof covering and from systems that have not been draining properly. Snow can also overload the roof structure
Downspouts and Terminations 31 and contribute to such problems. These systems should have leaf guards installed at the drains to
prevent blockage, and they should always be monitored.
While the inspector cannot be expected to evaluate underground systems, it is worthwhile to have some basic knowledge of the systems and to understand their potential problems.
Underground terminations usually connect to one of three system types.
- On-site drainage: The gutters connect to subterranean piping that simply takes the runo to a low area on the property and discharges it to the ground, well away from the foundation.
- Connection to foundation drains: The downspouts in these systems are connected via vertical drains to the home’s foundation or drain tile system. This may ultimately be connected to the municipal storm drain system.
- French drains and drywells: A pit or channel is dug and lined with a membrane, and normally #lled with crushed stone. This leaves a lot of airspace in the drywell. When heavy rain is directed into the drainage system, it is able to hold a large volume of water until it is able to percolate into the surrounding soil. These systems are most common as a retro#t to alleviate known rainwater problems, and can be very eective. All underground drain piping can suer from failures, and while the inspector should disclaim these in his report, it is good to understand the potential problems. The most common issues are: • piping silting up due to poor separation from soils;
• blockages from leaves and other debris getting into the system;
• root systems from trees and shrubs in#ltrating and choking o the pipes; and • pipes collapsed from vehicles driving over the ground above them.
How to Perform Roof Inspections 32
1. The proper slope for guttering is ____ per foot.
∏ 1/16-inch ∏ 1/4-inch ∏ 1/2-inch
2. Gutters should be installed by screwing or spiking them _______________.
∏ into the soffit
∏ into the fascia
∏ through the fascia and into the rafter tails
3. T/F: All homes are required to have gutters installed. ∏ True
4. T/F: Rusting steel gutters are a cosmetic issue and need not be reported.
∏ True ∏ False
5. Which of the following guttering issues needs to be reported?
∏ the presence of leaf guards
∏ gutters that slope up from the downspouts ∏ missing downspouts
6. Which of the following is not a guttering material?
7. T/F: The inspector should report on any debris buildup in the gutters. ∏ True
8. T/F: The inspector should inspect all visible downspout terminations.
∏ True ∏ False
Answer Key is on page 114.
Roof Framing from the Exterior 33 Roof Framing from the Exterior
Many roof problems are caused by issues with the framing and sheathing. In this section, we will focus on the defects that may be viewed from the exterior of the property. This is one of those cases where standing back and taking a good, hard look is better than getting “up close and personal” with the roof. Remember that according to the Standards of Practice, a home inspector is not required to walk on any roof surface.
One of the more common things to see, especially on older homes, is what is generally called “saddle” or “swayback.” This happens when the ridge beam has settled down toward the center of the
There are several potential causes for this, including:
• a rotten or broken ridge beam;
• an overloaded roof surface;
• undersized framing members; and/or • a lack of collar ties.
A noticeable step in the ridge can also indicate more serious problems aecting the whole home structure, such as a footing or foundation problem.
Similar to ridge sag, rafters may also be pushed down in the center. Wherever possible, try to get a view along the plane of the roof. There can be many reasons for the rafters bowing. Here is a list of possibilities:
• undersized rafters;
• roof loads too high;
• a lack of purlins or knee walls;
• poorly modi#ed ceiling joists; and/or • improperly modi#ed roof trusses.
Originally, roof sheathing was
made from 3/4-inch to 1-inch planking, but in the 1950s and ’60s, it became common to use plywood or particle board in 8×4-foot sheets laid perpendicular to the roof rafters. It is not uncommon for the roof to have a wavy appearance.
How to Perform Roof Inspections 34
This is most often caused by:
• rafters or trusses set too far apart;
• roof sheathing that’s too thin;
• moisture-damaged sheathing;
• sheathing that’s #tted too closely together; and/or • sheathing that’s missing H-clips.
General Structural Inspection
When inspecting the roof structure from the exterior, the inspector should also pay close attention to the wall structures. If the roof system shows signs of any of the problems listed above, then you may also possibly observe signs of the walls bowing out, or the sots pulling away from the tops of the walls. This is a condition called rafter spread, where the weight of the roof has pushed the roof rafters outward, resulting in a separation of the roof structure from the walls, and pushing the top of the walls outward.
Conventional Roof Framing 35 Conventional Roof Framing
A home inspector should have an understanding of the two main, basic roof structure systems: conventional roof framing and roof trusses.
You’ll be evaluating the roof framing from inside the attic space, but we have an advantage in technology. Let’s strip away the roof and wall coverings of a home and identify some of the more common roof framing members. We’ll start with a conventionally framed roof in which individual roof-framing members are cut and assembled on-site.
Rafters that rest on the outside walls at the bottom and connect to the ridge at the top are called common rafters.
Rafters on opposite sides of the ridge should be installed directly opposite each other in pairs — although, if you see a few that don’t align, it’s really
not a defect. Rafters sometimes have
to be moved a little to accommodate components of other home systems. The illustration at left shows a rafter moved to accommodate a combustion vent.
If you see many rafters that don’t align, you may comment on this, but in existing homes, refrain from calling it a defect unless you see
failure. In newer homes, many rafters that don’t oppose usually indicate poor-quality framing. It’s an indication that you should look carefully for other problems in the roof framing.
How to Perform Roof Inspections 36
Rafters are typically installed on 24-inch centers. If you see rafters installed on centers greater than 24 inches, look for signs of failure, such as sagging of the rafters. If you see sagging rafters, recommend stabilization by a quali#ed contractor. Stabilization typically involves installation of a purlin system.
Hip roofs have hip rafters, which are oriented diagonally to the ridge and outside walls. Hip rafters are simply called hips. Hips rest on an outside corner at the bottom and connect to the ridge at the peak.
Rafters that rest on the exterior walls at the bottom and connect to a hip at the top are called hip jacks.
Where ridges change direction, an inside corner is created, which is spanned by a valley rafter, or simply valley. Valleys are also oriented diagonally to the ridge and exterior walls. Valleys rest on top of the walls at the inside corner at the bottom, and connect to the ridge at the top.
Rafters that connect to the valley at their bottoms and connect to the ridge at the top are called valley jacks.
In homes with conventional ridges, the rafters support the weight of the roof and transmit the roof load down through the walls to the foundation and, #nally, to the soil. The route taken by the weight of the roof through the framing members to the soil is called the load path.
The purpose of the ridge is to provide
an easy method for connecting rafters at the peak of the roof, and to provide better nailing at the peak.
Conventional Roof Framing 37 Older homes may have no ridge at all. That was a common building practice at one point in various
parts of North America, and it’s not a defect as long as the rafters oppose each other.
Engineered lumber used for roof framing has very speci#c requirements for connections. The manufacturers of metal connectors for engineered lumber publish connection speci#cations in their catalogues and on their websites.
In homes with !at ceilings and an attic space, the bottoms of opposing rafters should be fastened together with ceiling joists, which form rafter ties. When rafters have been installed perpendicular to the ceiling joists, rafter ties typically rest on top of the ceiling joists.
Rafter ties prevent the weight of the roof from spreading the tops of the walls and causing the ridge to sag.
How to Perform Roof Inspections 38
Collar ties connect the upper ends of opposing rafters. They should be installed on every other rafter in the upper third of the roof. Their purpose is to prevent uplift. Whether or not they should be installed is an engineering call. They aren’t always required, so the lack of them is not a defect, but when you see them, they should be installed correctly.
Here, you can see collar ties installed in the upper third of the roof, and rafter ties installed down low and spliced over
a wall. You can also see the purlin system.
Purlin systems are designed to reduce the distance that rafters have to span. They consist of strongbacks nailed to the undersides of the rafters and supported by diagonal braces.
The bottoms of purlin braces should rest on top of a bearing wall. Braces that rest on ceiling joists or that somehow pass the roof load to the ceiling below are defective installations. If you see braces that rest on ceiling joists, look for a sag in the ceiling.
Braces are typically installed every other rafter and should be at an angle no steeper than 45 degrees.
Homes with vaulted ceilings usually don’t have rafter ties to keep the walls from spreading and the ridge from sagging, so they use a structural ridge. In a home with a structural ridge, the ridge consists of a beam strong enough to support the roof load without sagging.
Conventional Roof Framing 39
Here’s a purlin system installed in the garage of an older home. With no central wall to carry the braces, it bears on a strongback that rests on the ceiling joists. There is no sagging, so there was no comment in the inspection report.
Purlin systems have been built in many ways — some better than others. Modern building codes call for strongbacks to be of equal or greater dimension than the rafter dimension, but most purlin strongbacks
you’ll see will not meet this requirement. If you know that the home was required to meet this code when it was built, call it a defect; otherwise, limit your inspection to looking for signs of failure, such as sagging, broken rafters, and broken components. Also, look for improper installations, such as braces resting on ceiling joists, braces but no strongback, and too few braces.
In older homes in some areas, it’s common to #nd no strongbacks. It’s a quality issue unless the roof is sagging; then, it’s a structural issue, and you should recommend stabilization by a quali#ed contractor.
The term “purlin” has several dierent meanings, depending on what part of North America you’re in, what part of the roof you’re talking about, and the background of the person you’re discussing it with, so don’t be surprised if someone tries to correct you.
provided. This is especially important if it contains plumbing or electrical components.
When you’re inside an attic, you may see the ridge and a few jack rafters from one roof section framed on top of an existing roof.
This is called an overframe, and it’s quite common in certain areas. Built correctly, it’s structurally sound.
You’ll often see a section of roof sheathing removed to provide a passageway between attic spaces. If you can’t enter a portion of the attic, recommend that it be inspected by a quali#ed inspector after access is
How to Perform Roof Inspections 40
Trusses Roof Trusses
Roof trusses are engineered roof framing systems whose main components — roof trusses — are designed by structural engineers, then assembled in a manufacturing facility before being delivered to the job site by truck.
Let’s take a look at how trusses are built.
Trusses are manufactured in a wide variety of con#gurations and have been around since the early 1950s. Trusses have to be engineered correctly, so if you see trusses fastened together with plywood gussets instead of rings or gangnails…
… you’re looking at a non- professional design, and you should recommend evaluation by a structural engineer.
In this photo of the same home, you can see that roof leakage has caused wood decay of the plywood gusset. By the time decay becomes visible, the wood may have lost up to 50% of its strength, so decay is one more reason to recommend evaluation by a structural engineer.
Most roof trusses are designed to bear on the exterior walls only. Trusses touching interior walls can transfer roof loads to walls not designed to carry a structural load.
Trusses touching interior walls can also
create point loads on trusses at points not
designed to support point loads. In rare cases, this has resulted in exploding trusses.
How to Perform Roof Inspections 42
As you can see in the image on the previous page, the bottom chords of trusses should be fastened to the tops of interior non-bearing walls with slotted clips, which allow for some vertical movement of the trusses. Movement is usually related to changes in the moisture content of the wood trusses. This can be a response to changes in relative humidity or other conditions that cause moisture level !uctuations in attic spaces.
Truss movement can also result when roof loads exceed the structural design loads of the trusses, as might happen with the accumulation of heavy wet snow in an area that seldom gets snow.
Trusses are usually braced with a system of 2x4s and 1x6s at the time of installation. The locations of bracing can be dierent for dierent truss designs, and you’ll have no way of knowing what the requirements are. Trusses are often installed with blocks at the roof peak and above the outside walls, but these are not always required. So, in your report, don’t call missing blocks or bracing a defective condition. Look for signs of failure.
Trusses out of plumb are poor-quality construction, but may still be stable. If they’re badly out of plumb, mention that in your inspection report. Look for broken or damaged truss components, and comment on them in your report.
Trusses should never, ever be structurally altered in any way without approval from a structural engineer. If you see trusses that have been cut or reinforced, recommend evaluation by a structural engineer.
Trusses sometimes rest in hangers instead of bearing on a wall. If you observe this, check the fasteners carefully. The hangers pictured at left were fastened with roo#ng nails, and that’s a defective installation.
Here’s the garage of the house. The neighbor told the inspector that the roof of the garage next door had collapsed during a big snowstorm the previous year.
It’s easy to see that the trusses have been altered. Plywood gussets were added at a connection that would typically have had metal gangnails installed.
In the rare instances when alterations involving plywood gussets have been approved by a structural engineer, the gussets usually have backing for perimeter nailing installed, are glued with a special construction adhesive (such as
Loctite® PL Premium®), and are heavily nailed, with nails every 2 or 3 inches. You should see lots of nails and glue squeezing out of joints. As you can see in the photo, that wasn’t the case here.
Looking over to the wall, notice that the hangers seem to be small for the load they’re carrying.
The hangers turned out to be sized for a 2×4, which is far too small for the roof load they’re carrying. They were fastened with a total of four gold deck screws each! The deck screws are a serious defect, rated far below acceptable hanger nail strength.
In addition to that, they were installed through drywall, which does not support the shaft of a fastener the way wood does.
This roof is structurally inadequate and dangerous. It needs to have corrections designed by a structural engineer, and bids from quali#ed contractors for making the corrections. Corrections need to be completed as soon as possible.
How to Perform Roof Inspections 44 Roof Panel Sheathing
This section goes over some tips and details for home inspectors to keep in mind when inspecting the lumber roof sheathing and the general structure of the roof. Be sure to check with your local building code requirements and manufacturer recommendations related to roof sheathing.
Lumber roof sheathing and lumber roof panels are terms used in the International Residential Code that refer to panels manufactured with fully waterproof adhesive. These include plywood, oriented stand board (OSB), and composite panels made up of a combination of wood veneers and reconstructed wood layers. Plywood panels are manufactured by gluing together three or more cross-laminated wood layers. OSB panels are made from multiple layers of wood !akes oriented 90 degrees to each other. Sheathing provides the base for attaching the roof covering and adds strength to the framed structure.
The minimum thickness of lumber roof sheathing should conform to the measurements in Table 1 below.
Minimum Lumber Roof Sheathing Thickness
|Minimum Net Thickness||Rafter or Beam Spacing|
|1-1/2-inch tongue-and-groove||48 inches|
You may be able to measure the thickness of the roof decking material with a simple ruler.
Roof Panel Sheathing 45 Allowable Spans for Wood Structural Panels for Roof Sheathing
The maximum span for roof sheathing is limited by the stresses and de!ections caused by the design loads. The inspection agencies include a span rating label on the panels, which indicates the maximum spans for that panel.
The labels above are common APA rating labels for roof sheathing.
The rating will appear as two numbers. The #rst number is the maximum span for roof sheathing, assuming that the panels are installed with the long dimension across three or more supports and the edges are supported. The second number is the maximum span when the panel is used for !oor sheathing. The label on the far left is a common rating label for sheathing installed on roof trusses spaced 24 inches on center, which is widely recognized as an economical construction method for residential roofs.
Rafters should be straight and in alignment during the installation of sheathing. This will help keep everything square and aligned while the sheathing panels are laid down and fastened. It is common for framing supports, such as roof trusses, to be spaced 24 inches on center.
Blocking can help correct areas with twisted framing and provide surface for the panels.
Plywood panels should be laid with the face grain perpendicular to the rafter boards. The panels should be installed over two or more spans, with the long dimension or strength axis oriented across the rafter boards or truss cords.
During installation of OSB, the rough surface side should be facing up. This rough side is a screened or skid-resistant coated side.
The panels should be spaced 1/8-inch apart at the ends and edges.
The panel ends must be joined over a support. The panel joints should rest along the centerline of the support framing with at least 1/2-inch of bearing. Tongue-and-groove edges or solid blocking may provide support at the edges. Panel edge clips may be installed to provide additional support along the edges. Clips may be required. One clip is usually installed in each span. Blocking, tongue- and-groove edges, and/or panel clips may provide adequate support for unsupported edges.
How to Perform Roof Inspections 46
Wood structural panels should be attached to the framing in accordance with the following table.
|Fastening Wood Structural Panels to Framing|
|Panel Thickness||Fastener Type||Fastener Spacing on Edges||Fastener Spacing at Intermediate Supports|
|3/8-inch to 1/2-inch||8 d common nail (2-1/2 inch)||6 inches apart||12 inches apart|
|19/32-inch to 1 inch||8 d common nail (2-1/2 inch)||6 inches apart||12 inches apart|
For common installations, the panels are fastened with 8 d common or deformed shank nails. Fastening schedules have certain requirements for high wind zone locations and when the roof is specially engineered.
For common installations, fasteners are spaced on the edges 6 inches apart, and 12 inches apart along the supports. There should be at least 3/8-inch of space between the fastener and the panel edge.
In areas where the wind speed is greater than 130 mph, nails for attaching the roof sheathing to intermediate supports should be spaced 6 inches on center for at least the #rst 48 inches from the ridges, eaves, and gable end walls. The fasteners should be spaced only 4 inches apart on the panel edge at the gable end wall framing.
Fasteners should be driven !ush with the panel surface.
Any wooden trim associated with the roof system is susceptible to rot and, in some cases, insect damage. It is an area that should be fully inspected either from the ground or from a ladder, if possible.
Remember that ladder safety is a priority. Be careful when inspecting roo#ng trim. Also, be careful if you are allergic to insect bites or stings. Sots, gables and fascia boards can literally be a “hive of activity.”
The horizontal board enclosing the ends of the rafter projections (or tails) is normally referred to as the fascia board, and if gutters are attached, they are #tted here. Because the fasciae are at the lowest point of the roof plane, they often act as sponges for any misdirected moisture. Rotting fasciae can also be masking rot in the rafter tails, which can be very expensive to replace.
Rake or Barge Boards
These are the boards that cover the ends of the roof structure from the fascia to the ridge. Like the fascia boards themselves, they are known to rot, especially at the lower ends.
The sot is the area underneath the eaves or rafter tails that is normally enclosed at the front by the fascia boards. There are three main types of sot:
• open sots, with no bottom enclosure;
• closed sots, where the sot board is fastened directly to the underside of the rafter tails; and • box sots, where the sot board extends at a right angle from the wall to the end of the rafter tail.
As with the fascia boards, the sot, placed at the low point of the roof structure, is a typical area for rot. Common causes include water penetrating the roof covering and migrating down the sheathing, ventilation problems, and ice damming. Carefully inspect for these conditions, and report any damp or rotten-looking areas.
Many of the problems with wooden roo#ng trim systems can be avoided when a proper drip edge is #tted between the roof decking and the roof covering. This edge protects both the sheathing and the trim by directing water either into the guttering (if #tted), or at least far enough away from the trim that it cannot wick into the wood.
How to Perform Roof Inspections 48 Drip edge !ashing should be installed over the underlayment (roo#ng paper or felt) at the rake, but
under it along the eave.
The image above is a drip edge !ashing properly installed onto the roof deck (at the eave or gutter edge) before the underlayment is installed on top of it.
The image above is of drip edge !ashing installed at the rake board area. And it is installed on top of the underlayment (roof felt material) at the rake board area.
The image above shows the drip edge !ashing installed at the rake. And it is installed on top of the underlayment (roof felt material).
Other Trim Areas and Issues
Any additional decorative trim installed either onto the fascia or at the sot wall interface is normally referred to as a cornice. These can be as simple as a 1/4-inch round molding, or a larger pro#le, sometimes including dentil molding. All such trims should be thoroughly inspected for rot and insect damage.
Sot with carpenter bee damage
All other wooden trim adjacent to the roof surface should have at least an inch of clearance from the roof covering (and more in snowfall areas). This is particularly important with areas such as the sides of dormers, where water running down the roof can damage the trim and siding.
How to Perform Roof Inspections 50 Structural Issues Disguised as Cosmetic Ones
Although diagnosing the causes behind structural and cosmetic defects lies beyond the scope
of a home inspector’s duties, according to the InterNACHI® Residential Standards of Practice, understanding some of those causes can help inspectors recognize certain defects more quickly so that they can report them and make appropriate recommendations to their clients.
One of those defects related to roofs is rafter sag or a bowed interior ceiling that is mistakenly attributed to a lack of collar ties.
Collar ties are designed to resist uplift from high-wind events. However, they do not prevent
rafters from sagging or bowing downward in the middle. Rafter sag is caused by over-spanned or undersized rafters. A bowed interior ceiling is due to the roof load being transferred to ceiling joists, usually as a result of eorts to brace sagging rafters.
Such a condition is also sometimes caused by excessive roof load, such as too many layers of shingles or other roo#ng-covering material, or a change-out from composition shingles to tile, where the weight is greater than 6 pounds per square foot.
(It is possible that when the slope of the roof descends to a lower slope/pitch, the load on the rafters’ span shifts somewhat from the seat cut toward the middle of the rafter.)
In the case of rafter sagging, the collar ties themselves become bowed or bent inward, since they are not designed to resist a compressive load. Collar ties resist the outward or expansive motion of the rafters, known as tensile forces, but not compression.
It is the framing members that are designed to withstand both compressive and expansive loads. A lack of collar ties (typically 1x wood) would cause the ridge — not the rafters — to sag, as well
as cause the walls to spread. They react by simply bowing as they resist the force of expansive or outward movement.
One of the most common mistakes that homeowners and contractors make during remodeling is that they remove the ceiling plaster and joists (to raise the ceiling and gain room volume, etc.), and thereby also remove the ceiling diaphragm, which is a supportive element and can be an integral seismic element of a building. This not only aects the roof framing and wall spread, but it removes a seismic resistive plane of the structure (the ceiling), regardless that lath and plaster or drywall doesn’t have much shear value.
What generally happens is that, after removing the ceiling, homeowners and contractors sometimes fail to do one of two things:
1. install the appropriate number and size of collar ties that are typically no more than one-third up toward the ridge plate from the wall plates, so as to prevent ridge sag and wall spread; or
2. remove the ridge plate and install a ridge beam in its place, with the load eectively transferred to the foundation. A ridge plate allows rafters to rest against it but does not carry a vertical load. The triangle formed by the rafters and ceiling transfers the load to the walls
of the house. (Contrariwise, the ridge beam transfers the vertical load of the rafters and roof system directly to the foundation, where it is concentrated. An additional footing is sometimes required under that portion of the foundation to support the additional load presented.)
Another issue is that a homeowner or contractor may add drywall to the underside of the rafters, thereby increasing the load on them and causing ventilation problems, which can, in turn, cause
Structural Issues Disguised as Cosmetic Ones 51 condensation and moisture problems, resulting in mold growth, rafter rot, etc.
An inspector who observes a sagging rafter in an un#nished attic, a sagging or bowed ceiling, or, through infrared imaging, detects heat signatures that may indicate moisture in ceiling materials, should note such details in his report and recommend further investigation by a quali#ed professional who can make any necessary repairs and/or structural corrections.
How to Perform Roof Inspections 52 Collar Ties vs. Rafter Ties
Collar ties and rafter ties are both horizontal roof-framing members, each with dierent purposes and requirements. Home inspectors should be familiar with these structural members and the dierences between them, as they are not the same.
Please note that, according to InterNACHI’s Standards of Practice for Performing a General Home Inspection, the inspector is required to inspect the visible and accessible structural components and the general structure of the roof system.
In physics, tension is the pulling force exerted by a solid object on another object. Tension members are solid objects (or structural members) that are subjected to axial tensile forces, or tension. Collar ties and rafter ties are examples of tension members.
A tension tie is a structural member that is subject to net tension.
“Collar tie” is a colloquial phrase that is used among contractors, builders and inspectors, but not usually used in construction or engineering documentation. The correct phrase is actually “collar beam.” For our purposes, we use “collar tie.”
A collar tie is a tension tie in the upper third part of opposing gable rafters that is intended to resist separation of the rafter from the ridge beam during periods of unbalanced loads, such as those caused by wind uplift, or unbalanced roof loads from snow. The 2015 International Residential Code does not require collar ties (or collar beams). However, in those situations when they are speci#ed,
Collar Ties vs. Rafter Ties 53 collar ties or ridge straps are usually installed in the upper third part of the roof between opposing
rafters. In high-wind areas, uplift can tear a roof o of a house if it’s not properly attached. Collar ties must be at least 1×4 inches (nominal) spaced not more than 4 feet on center. Other facts about collar ties:
- They may or may not be required, depending on the jurisdiction. InterNACHI® inspectors should not call out a lack of collar ties as a defect unless they know that collar ties were required at the time the home was built in the jurisdiction where the home is located.
- Collar ties are probably not needed if approved metal connectors were used to fasten the rafters to the ridge.
- Where they are required, they should be installed on every other rafter where rafters are on 24- inch centers.
- Contrary to popular belief, collar ties do not prevent walls from spreading. Rafter Ties A rafter tie is a tension tie in the lower third part of opposing gable rafters that is intended to resist the outward thrust of the rafter under a load. In many situations, you’ll #nd that ceiling joists installed parallel to the rafters are intended to function as rafter ties. The roof framing mock-up below shows a standard rafter tie. Rafter ties are installed between opposing rafters, and they should be installed as close as possible to the top plate. Rafter ties resist the outward thrust that rafters exert on the exterior walls. They help keep walls from spreading due to the weight of the roof. When the walls spread, the ridge board might sag. A sagging ridge is one indication that the roof structure may lack adequate rafter ties. A rafter tie forms the bottom chord of a simple triangular roof truss. When ceiling joists run perpendicular to
the rafters, the inspector may #nd rafter
ties installed above ceiling joists as framing
members every 4 feet running above the ceiling joists connecting opposing rafters. Rafter ties should be at least 2×4 inches (nominal). Other facts about rafter ties:
- Rafter ties are always required unless the roof has a structural (self-supporting) ridge, or is built using engineered trusses. A lack of rafter ties is a serious structural issue in a conventionally framed roof.
- In most homes, the ceiling joists also serve as the rafter ties.
- Where rafters are oriented perpendicular to the ceiling joists, rafter ties should be installed just above the ceiling joists. The ties usually rest on the joists.
- When rafters are installed on 24-inch centers, rafter ties are typically installed at every other
How to Perform Roof Inspections 54
• It’s not unusual to see rafter ties of either 2×4 inches or 2×6 inches.
Rafter and collar ties are subject to enormous tension forces. These forces make securing the ties to the rafter boards a critical issue. The force in each tie increases with the inverse of the slope. So, the greater the roof slope, the weaker the outward thrust.
The load on a structure can be calculated from combining the dead load or weight of the structure itself, the live load that varies for dierent structures, the snow load, and the wind load.
Where ceiling joists are not connected to the rafters at the top wall plate, joists connected higher
in the attic shall be installed as rafter ties, or a continuous tie should be provided. Where ceiling joists are not parallel to rafters, rafter ties shall be installed. Where ceiling joists or rafter ties are not provided, the ridge formed by these rafters must be supported by a wall or girder.
The ends of ceiling joists should be lapped a minimum of 3 inches, or butted over bearing partitions
In a simple gable roof, the rafter boards carry the live and dead loads that push both downward and outward against the top of the load- bearing walls. This horizontal outward thrust can be considerable. To resist this horizontal outward thrust, the IRC calls for each pair of rafters to be securely connected to each other by a continuous ceiling joist, and for a structural ridge beam to be installed for roofs with a slope of less than 3:12 (see illustration at left).
Collar Ties vs. Rafter Ties 55
or beams and toenailed to the bearing member. Where ceiling joists are used to provide resistance to rafter thrust, lapped joists shall be nailed together in accordance with Table R802.5.1(9) in the IRC. For example, if a house has a 4:12 slope, the rafters are on 16-inch centers, the snow load is 30 psf, and the roof span is 28 feet, you need eight 16d common nails (or 40d box nails) at each rafter- heel joint connection. That’s a lot of nails a home inspector can look for.
Cathedral ceilings are popular in many homes, but they have special issues with the downward load on the rafters that push outward on the exterior walls. Open collar ties and ridge beams address many of these issues. The higher the tie is located, the less leverage is available to counteract the outward thrust forces. Many cathedral ceilings often display indications of movement, such as cracked drywall. The most eective way to reduce outward thrust is to use a structural ridge beam.
Bottom Chord of a Truss
In a conventional roof truss, the bottom chord acts as a tension tie between the exterior walls. Alterations to installed trusses are not permitted. Cutting any truss, particularly at the bottom chord,
destroys the structural integrity of the truss. If the inspector #nds that the chord of a truss has been cut, they should recommend that a structural engineer be consulted.
The bottom chord of a truss should not be attached to an interior wall partition. Attaching the bottom chord of a truss to an inside wall can cause the web members designed for tension to become compression members. When the bottom chord is nailed to a top plate of an interior wall, the home inspector might observe cracking at the interior #nishes at the corner of the #nished wall and ceiling.
Older building codes permitted rafter ties to be installed very high above the top wall plate, even as much as two-thirds the distance between the top plate and the ridge. The 2012 IRC now limits this to one-third the distance between the plate and the ridge. For example, if an un#nished garage has a roof with a 4:12 slope and the roof span is 24 feet, the rafter ties should be located no more than 16 inches up from the plate, according to modern building standards.
The roof framing mock-up below shows a standard collar tie. As the load is applied downward, tension in the collar tie is increased.
How to Perform Roof Inspections 56
The illustration to the left shows a king post truss on posts. As the load is applied downward, compression is increased at the posts. Rafter boards and the ridge board are normally under compression while holding up or resisting a load. The exterior load-bearing walls are holding up a load and are therefore under compression.
Collar ties and rafter ties perform dierent functions, but both are essential roof-framing members, and it’s useful for inspectors to be aware of their dierences in order to properly report defects.
A bending moment occurs when a force changes from a straight form into a curved or angular one. The illustration at left shows a collar tie with rafters on top of conventionally framed walls. As the load
is applied downward, the rafters go into a bending moment below the collar tie. This bending moment exerts outward thrust on the walls, forcing them out of plumb.
1. Which of the following would cause the tops of walls to spread?
∏ lack of collar ties
∏ over-spanned rafters
∏ adequate knee walls
∏ too many layers of roof coverings
2. De!ection of the ridge beam is called ______________.
∏ rafter spread
∏ bowing or sagging
∏ saddleback or swayback
3. A gap between the wall and sot may indicate __________.
∏ moisture in the soffit ∏ rafter sag or spread ∏ blocked gutters
4. A sot that is attached directly to the underside of the rafter tails is called a(n) _______.
∏ enclosed gutter ∏ open gutter
5. The clips that are required between many sheathing panels are called ___-clips.
∏T ∏H ∏L
6. Roof ridges and rafters are normally under _________.
∏ deflection ∏ tension
How to Perform Roof Inspections 58 7. Roof sheathing should be installed ___________ to the rafters.
∏ perpendicular ∏ vertical
8. The horizontal board enclosing the ends of the rafter projections (or tails) is referred to as the _________ board.
∏ cornice ∏ fascia ∏ soffit
9. A decorative molding applied to the fascia is called a _________.
∏ barge board ∏ dentil molding
10. The distance that should separate the siding from the roof’s surface is __________.
∏ 2 to 4 inches ∏ less than 1 inch ∏ 1 to 2 inches
11. Drip edge !ashing should be installed ____________.
∏ over the roofing paper/felt along the eave edge ∏ over the roofing paper/felt along the rake edge ∏ under the roofing paper/felt along the rake edge
Answer Key is on page 115.
Introduction to Roof Coverings 59 Introduction to Roof Coverings
One of the big problems with inspecting roofs is that there are so many dierent roo#ng systems out there, and the inspector is required to know a lot about all of them. While they may appear to have little in common with each other, the basic rules for the inspector remain the same:
• Identify the roof covering material.
• Report on any visible de#ciencies.
• Recommend repairs and/or maintenance as needed.
• Don’t report on the future life expectancy of the covering.
The dierent types of roof covering materials reviewed in this section include:
• asphalt shingle;
• tile roo#ng, including:
° slate roofs;
° clay tile roofs;
° concrete tile roofs; and ° asbestos cement tile.
• wooden shingle and shake (and their dierences); • roll roo#ng;
• built-up roo#ng;
• membrane roo#ng; and
• metal roo#ng systems, including:
° standing seam systems; and
° metal oddities (shingle, sheet, corrugated).
Roof surfaces are measured in squares. A square of roof-covering is equal to 100 square feet (10×10 feet) of the roof’s !at surface.
For example, to determine the number of squares on a gable roof, a contractor would divide the total square footage of the roof covering by 100. If the total is 24,000 square feet, then dividing it by 100 would equal 240 squares (24,000 ÷ 100 = 240). This means the contractor would need 240 squares of shingles to cover the roof.
The most common type of shingle is called a laminated strip shingle and it’s generally packaged in three bundles per square.
How to Perform Roof Inspections 60 Asphalt Shingles, Part I
Asphalt Shingle Inspection
Asphalt shingles are the most common roof covering that the inspector will see, as they are relatively inexpensive, easy to install, and last between 15 to 40 years, depending on type.
Despite the fact that there are many dierent styles of asphalt shingles, they are all manufactured and installed in the same way, so they tend to exhibit similar problems over their service life.
Asphalt Shingle Components
The terms “asphalt” shingle and “composition” shingle are general terms for the same thing. The term “composition” is used because these shingles are a composite product made from either a #berglass or a cellulose mat, and asphalt and minerals, as opposed to a single material, such as wood shingles or a clay tiles.
All modern shingles manufactured in North America have mats made of interwoven #berglass strands, so you may also hear them called #berglass shingles. In the past, shingles were also manufactured using mats made of cellulose-based materials, and these are called organic shingles.
In the past, shingles were also manufactured using mats made of cellulose-based materials, and these are called organic shingles.
The mat provides the reinforcement that gives shingles the strength to help resist splitting, tearing, and pulling over the heads of fasteners. Although the mat is less than 2% of the shingle’s weight, a small dierence in mat thickness can make a big dierence in the shingle’s tear strength.
More Resistant to Heat and Humidity
Fiberglass shingles are more resistant than organic shingles to heat and humidity. Warm air can hold more moisture than cold air. Because they absorb less moisture, #berglass shingles deform less as they age, making them more stable in warm or damp climates.
Also, because the #berglass mat does not absorb moisture, as #berglass shingles age and lose volatiles, they deform less than cellulose shingles. Volatiles are compounds in asphalt that help keep shingles waterproof, !exible and durable, but which dissipate over time. Most volatile dissipation is due to evaporation from overheating.
Variations in Performance
The downside of #berglass shingles is that there are wide variations in performance between similar shingles made by dierent manufacturers.
Introduction to Roof Coverings 61
TYPES OF ASPHALT SHINGLES
During inspections of roofs with asphalt shingles, you may see one of four basic types: three-tab; laminated; interlocking; or single-piece shingles. There are variations of these basic types that aect their appearance, weight, performance and durability.
A three-tab (or 3-tab) shingle is a type of strip shingle. Its main identifying feature is two notches, called cutouts, which separate the shingle into three tabs. A three-tab shingle is a single layer thick, usually 12 inches wide, and 36 inches long. Metric shingles are a little larger, but less common in the U.S. Three-tab shingles typically have warranties in the 20- to 30-year range, weigh 200 to 250 pounds per square, and are designed to survive winds of up to 60 miles per hour.
Laminated or Architectural/Dimensional Shingles
Both laminated and three-tab shingles are considered to be strip shingles. Laminated shingles consist of two or more shingle layers bonded together. The uppermost layers are smaller and cut into shapes. This gives the shingles a more three-dimensional appearance and makes them more interesting to look at. They’re sometimes designed to mimic wood shakes. Laminated shingles typically come in metric sizes measuring about 39×13 inches. Laminated shingles with 30- to 50- year warranties typically weigh 250 to 300 pounds per square, and are designed with a maximum wind resistance of 70 to 110 miles per hour. High-quality laminated shingles are more expensive. They may have up to #ve layers and weigh close to 500 pounds per square. These shingles may be designed to withstand winds of up to 130 miles per hour.
Asphalt Shingle Installation
The underlayment for asphalt shingles is usually roo#ng felt with a course of ice and water shield covering the lowest 3 feet. This prevents moisture from backing up under the shingle over the eaves.
The application starts at the bottom of the roof with a single starter course (often, a shingle with the tabs cut o ) #xed so that the #rst proper course is glued at the lowest edge.
This is followed by the regular courses applied so that the joints or gaps between the tabs do not line up with each other, and over three courses to stop water from penetrating the covering. Each shingle has a tar line above the exposed surface, which glues the upper shingle to the previous course.
Ridges are capped with either a special tile manufactured for the purpose (as in the case of architectural styles) or, more commonly, trimmed-
down shingles prepared on-site by the installer from standard 3-tab shingles.
Asphalt shingles are designed to be installed on roofs with a slope equal to or greater than 4:12, but some shingles can be installed on roofs as low as 2:12 when proper precautions, such as double underlayment, have been installed, and the shingles themselves have been additionally glued down in accordance with the manufacturer’s instructions.
How to Perform Roof Inspections 62
Most asphalt shingles may be used on roof slopes from 4:12 to 21:12 using standard application methods. Asphalt shingles may be used on slopes from 2:12 to 3.9:12, if special low-slope application procedures are followed. An inspector will usually #nd roll roo#ng materials installed on slopes of less than 4:12.
Asphalt Shingle Designs
There are many designs and colors of asphalt shingles available. The basic designs are:
• 3-tab shingles; and
• architectural shingles that have added layers of material to give a dimensional appearance.
Asphalt Shingle Problems
All asphalt shingle roofs, regardless of design, will fail due to the following reasons:
• weather issues;
• impact damage;
• debris on the roof;
• poor installation techniques; • material failures; and/or
• ventilation problems.
Asphalt Shingles, Part II Weather Issues
- Sunlight is a big enemy of asphalt roofs. When subjected to the sun’s heat, the shingles will dry out due to o-gassing of hydrocarbons in the asphalt, since asphalt is a petrochemical product. This will promote the loss of granules and make the shingle more brittle. As the shingle dries out, it will also shrink, opening up the areas between shingles or between tabs. This may also cause cupping, bowing, and/or small surface fractures or #ssures in the shingle.
- Rainfall will wash away the granules over time, causing the tile to degrade. Traces of aggregate in the gutter signify potential problems.
- Wind can get under the exposed tabs on the shingle and cause them to be ripped from the roof.
- Hailstones can easily damage the roof covering, causing small depressions in the shingles, and potentially breaking o weak shingles. Impact Damage
- Trees cause the most impact damage by their branches being too close to the roof covering and tree limbs falling onto the roof structure.
- Walking on the roof can, in some cases, cause damage to the covering, especially if it is already in brittle condition.
- Masonry falling on the roof will often damage tiles. It is not uncommon to see damaged
Introduction to Roof Coverings 63 shingles directly below the chimney.
- Moss is a big problem on badly drained and shady roofs because it retains moisture and its root system will get under the roof shingles. It’s fair to say that you will not generally see moss on a good roof, as the roots need to be constantly moist.
- Leaves and pine needles on the roof will also promote fast decay of the covering because they retain moisture on the roof. Also, many species produce acids during the decay process, and these can eat into the asphalt.
- Airborne pollutants are often found in industrial areas. Acid rain will quickly erode a roof covering. Poor Shingle Installation Here are some of the issues that often occur due to poor installation:
- repairs that were improperly carried out;
- shingles on a low-slope roof where the use of shingles was not intended;
- joints that were not overlapped, allowing water to drain right onto the sheathing; and
- improper nailing that was not done to the manufacturer’s speci#cations, where either the nails are too short, causing nail pops, or not enough nails were used. Every 3-tab shingle should have four fasteners (or six in high-wind areas). Material Failures Inspectors will occasionally see failure due to manufacturing defects, such as blistering from within the shingle, or premature cracking of the shingles, particularly with #berglass-based shingles. One particular brand of shingle was the subject of a class-action lawsuit against Bird Fiberglass Shingles of New Hampshire, which was settled in 2001. Ventilation Problems Many problems with asphalt shingle roofs are caused by poor ventilation of the roof space, which leads to overheating of the roof coverings. This is more apparent when the roof has multiple coverings which can trap additional heat. It is very common to see shingles that are less than 10 years old but are in very bad shape due to overheating caused by poor ventilation, or overheating caused by the presence of too many layers of shingles. Reporting Requirements The inspector must report on the following when inspecting asphalt shingle roof coverings: • shingle type;
• missing shingles;
• damaged shingles;
• number of layers of covering;
• signs of previous repairs;
• shingles that are cupping or buckling;
• moss or vegetation growth on the shingles; • granular erosion;
How to Perform Roof Inspections 64
• shrinkage of shingles;
• lack of a drip edge;
• nail pops; and
• shingles that have been incorrectly installed.
Asphalt Shingles, Part III
Generally speaking, people from three dierent industries are likely to be inspecting asphalt shingles: insurance claims adjusters; roo#ng contractors; and home inspectors.
Home inspectors are supposed to be neutral third parties who have no #nancial interest in the conditions they #nd on the roof. Insurance companies and roo#ng contractors can both be aected #nancially by the results of the inspection, and they may have con!icting motivations.
Because of the many factors that can aect the condition of asphalt shingles, it’s not always clear whether a defective condition or functional damage exists. Conditions are not always obvious or either right or wrong.
Let’s de#ne the conditions that indicate functional damage or defective installation in asphalt shingles, as well as the criteria used during an inspection to determine whether functional damage exists.
Learning to diagnose roof conditions correctly will help those inspecting shingles to identify the source of the damage. It will also make it easier for inspectors from dierent industries to come to the same conclusion when they’re each looking at the same condition.
DEFINITION OF DAMAGE
Because inspections are so often connected with insurance claims, much of the criteria de#ned here is based on the standards of the insurance industry. Even if an inspection is for a sales transaction, if damage is found and the roof is under warranty, the transaction may be aected by an insurance claim.
For insurance purposes, “damage” is divided into two categories: functional damage; and cosmetic damage.
Functional damage is damage that insurance companies will pay for. It’s also called covered damage or payable damage.
Functional damage is that which either diminishes the ability of the roof to shed water, or shortens its long-term service life. This is called “premature failure.”
Cosmetic issues are visual issues, such as discoloration, problems with color blending, or damage that doesn’t meet the de#nition of functional damage. Some examples of cosmetic damage are general, uniform granule loss, or marring of the shingle surface.
With asphalt shingle roofs, insurance companies typically don’t pay for cosmetic damage.
Introduction to Roof Coverings 65
Slate Tile Roofing
The dierent varieties of solid tile roofs are basically all inspected in the same way and tend to exhibit similar problems that the inspector needs to report.
In this section, we will look at most of the solid tile types: slate, clay, concrete, and asbestos- cement. We will also look at their installation, common problems, and reportable issues.
Remember: Solid tile roofs
should NOT be walked on.
They should be inspected from
the eaves using a ladder, from the ground using binoculars, or with a camera-mounted drone or telescoping pole.
Slate is a sedimentary rock (which means that it has settled into layers) that is easy to split into tiles. Most slate tiles used in residential construction are 3/16-inch to 1/2-inch thick, but some older tiles are much thicker.
Slate roofs are roughly #ve times the weight of standard shingle roofs; therefore, the roof framing has to be designed to carry a much greater load than normal. Roofs that have been retro#tted with slate should have been re-engineered to carry this additional load.
Slate has been around as a roof covering in Europe for more than a thousand years. Many churches, castles and manor houses were originally built with this type of roof covering. In many cases, the same tiles are still in situ (in their original position), although they have probably been re#tted many times over the centuries due to leaks or failure of their connectors.
American slate diers in quality, depending on where it was mined. For example:
- Pennsylvania slate is somewhat soft and lasts less than 100 years.
- Vermont slate is denser and lasts well over 100 years.
- Virginia slate is very hard and can last more than 200 years. The poorest-quality slate can be recognized by ribboning in the color, where a band of a lighter stone can be seen running through the slate. These slates
How to Perform Roof Inspections 66 tend to break along this band due to dierential weaknesses. Where such slate has been used, the
ribboning should not be visible on the exposed face of the tile. Other rules-of-thumb for slate roof installation:
• Slate roofs should not be installed where the roof pitch is less than a 4/12. • Slate can be applied over battens, plank or sheet sheathing.
• Slate tiles are generally fastened with two copper nails each.
• Joints between tiles should be staggered by 3 inches per course or row.
In every second row, the joints can line up vertically. There should be a minimum of 2 inches of headlap clearance. That is the point where there are three layers of tile, and there can be as much as
4 inches, depending on the pitch of the roof.
|Slate Shingle Headlap|
|Roof Slope (Pitch)||Minimum Headlap|
|between 4:12 and 8:12||4 inches|
|between 8:12 and 20:12||3 inches|
|over 20:12||2 inches|
The most common problem with slate roofs occurs with the fasteners, rather than with the tiles themselves. Slate nails should be of copper, rather than ferrous metal (iron), as copper will not rust over time and cause the tiles to start slipping.
When inspecting a slate roof, inspectors should report on the following:
• missing tiles;
• broken tiles (though some corner chipping is expected and acceptable); • tiles that are slipping out of place; and
• signs of previous repairs.
Clay and Concrete Tiles
Concrete and clay tile roofs are very similar from an inspection perspective, as they are all installed in the same way and tend to exhibit the same problems in service.
Introduction to Roof Coverings 67
They are both made in similar sizes and shapes, such as !at, curved or corrugated, and may or may not be of an interlocking design. In most cases, tile designs are produced to be installed as ridge caps and used in other specialized locations.
Both clay and concrete tiles have a long lifespan. Problems other than those from mechanical damage tend to be from failure of the underlayment or !ashings, rather than failure of the tiles themselves. In many cases, when the roof needs repair, the original tiles are taken up and stored while the substrate is replaced. The tiles are then re-installed, with the addition of new tiles to replace the damaged ones.
Remember that tiles can be up to #ve times heavier than asphalt shingles; therefore, the roof system needs to be much heavier to support the additional load.
Regardless of style dierences, all clay tiles are made from terracotta, the same material that common houseplant pots are made of, and they are damaged just as easily.
How to Perform Roof Inspections 68
Terracotta tiles are produced in molds or extruded from clay with a high silicon content, which, when #red, changes composition and becomes impervious to water. Clay tiles may also be glazed to add color or a high-gloss #nish.
When discussing clay tiles, we tend to think of the Spanish or barrel style of tile, but there are many variations in style, from the corrugated look, to !at and fully interlocking designs.
Concrete tiles are also available in a wide range of designs and #nishes. Many of them are designed to look like other materials, such as slate, clay, and even cedar shakes and shingles.
The process of manufacturing concrete tiles is similar to that of manufacturing clay tiles, except concrete tiles don’t need to be #red in a kiln. A chemical process converts the concrete from a liquid slurry into a rigid tile.
Some concrete roo#ng tiles must be painted in order to extend their lifespan. This maintenance is required roughly every #ve years, depending on the local climate.
Both clay and concrete roof tiles are installed in the same manner. They are installed over traditional planking, sheathing, or on some older installations.
Most concrete and clay tile systems rely on their underlayment for complete weather protection, and the lower the pitch of the roof, the more robust that underlayment needs to be. As a general rule:
• a roof pitch lower than 4:12 should have a double underlayment or the tiles applied over a built- up roo#ng system; and
• a roof pitch lower than 2:12 should not have tile installed at all.
Some fully interlocking designs of tiles do not require an underlayment, as they are considered to be totally impervious when installed and !ashed correctly.
Many designs of both concrete and clay tile roofs require the installation of blocks to correctly position the individual tiles. In the case of traditional Spanish or barrel tiles, these are installed vertically up the roof surface. In other cases, they are required to run horizontally across the roof plane.
All tile roofs should be installed with a minimum of one corrosion-resistant fastener per tile, if the tile weighs less than 9 pounds per square foot. Heavier tiles and those installed in snow-load areas require a minimum of two fasteners.
All open ends of shaped tiles at both the eaves and at any valleys should be sealed to prevent birds and other wildlife from entering the area between the tiles and the underlayment.
Introduction to Roof Coverings 69
As previously noted, tile roofs should not be walked on, as they can be very easily damaged by foot trac. From a ladder at the eaves or from the ground, the inspector should pay particular attention to the following potential issues:
• broken or missing tiles;
• tiles that have moved out of position;
• signs of previous repairs;
• signs of moisture evacuating the roof from under the tiles; • missing, damaged or rusting !ashings; and
• missing or de#cient bird and pest barriers.
The inspector should always report on the following:
• the method used to inspect the roof;
• the material and style of the roof covering;
• missing, damaged or slipped tiles;
• missing or damaged !ashings or bird stops;
• any signs of moisture penetrating the roof covering; and • any required re-painting, where applicable.
Asbestos Cement Tiles
Asbestos-#ber cement tiles were a very common roof covering from the 1930s up to the early 1960s. In fact, many homes of that period had both asbestos cement roofs and wall coverings.
The main problem with asbestos tiles is that they are relatively thin and become very brittle over time. This makes them susceptible to mechanical damage, such as tree limbs falling onto the roof and fracturing or breaking the tiles.
These roofs can be particularly costly to repair, since it is extremely dicult to #nd replacement tiles. If the roof covering needs to be removed and replaced, the debris has to be disposed of under U.S. EPA guidelines.
Again, the inspector should never attempt to walk on an asbestos cement tile roof. He should evaluate the roof system just like any other roof covering material, paying particular attention to:
• missing or broken tiles;
• tiles that have been moved out of position; • signs of previous repairs; and
• missing or damaged !ashings.
The inspector should always report on the following:
• the method used to inspect the roof;
• the material and style of the roof covering; • missing, damaged and slipped tiles;
How to Perform Roof Inspections 70 • signs of previous repairs (tiles siliconed back in place is common); and
• missing and damaged !ashings.
Wood Shingles and Shakes, Part I
Wood shingles and shakes are a popular choice for roof and wall coverings in many parts of the U.S. because of their rustic appeal. However, these aesthetic considerations come at a price, as shake and shingle roofs are far from being maintenance-free or long-lasting.
Generally, wooden shake or shingle roofs should not be walked on. They are easily damaged and can be very slippery when wet or covered with moss.
There are dierent wood species, grain patterns, and lengths of wood shingles and shakes, and such details can be extensive. We’ll cover the fundamental points that the inspector must know in order to be able to evaluate most wooden roof coverings.
- A shingle is machine-cut on both faces and on all sides.
- A shake is hand- or machine-split and, therefore, has a less #nished look and is less uniform.
- Both shakes and shingles are usually made from cedar, as its natural oils are both a preservative and an insect repellent. Inspectors may also #nd shingles made of redwood and some types of pine.
- The steeper the roof’s pitch, the longer-lasting the roof covering.
- Shingles and shakes are graded with numbers, with lower numbers (1) being of far higher quality and longevity than higher numbers (4).
- The tighter the grain is, the longer it will last, with slow-growth trees providing the best-quality shingles, since the wood is denser.
- When inspecting at the bottom edge of the shake, look carefully at the grain. The direction of the grain through the shingle factors into its ability to resist cupping, bowing and splitting. Also:
° Vertical-end grain is the best quality and is known as edge grain.
° Angled-end grain is of lesser quality and is known as sash grain.
° Horizontal-end grain, known as !at grain, is of poor quality and will generally fail quickly. Wood Shingles As explained, a wood shingle is a machine-sawn wooden tile. Its installation requirements are dierent from those of a shake. These include the following::
• Shingles are a 3-ply roo#ng material, meaning that, at any point on the roof’s surface, there
Introduction to Roof Coverings 71 should be three overlapping shingles.
- A gap of 1/8-inch to 3/8-inch is required between shingles to allow for swelling when they’re damp.
- Shingles should be applied over planks or skip sheathing in humid climates, as they need adequate ventilation to prolong their life. They can also be installed over sheet decking in more arid climates, or when installed with a nylon mesh underlayment to promote ventilation.
- Tar paper, or a similar non-permeable grade exposure membrane, should extend up from the eaves a minimum of 3 feet.
- Wood shingles should be installed over tar paper or a similar underlayment, although this is not always required if installed over skip sheathing.
- Joints between shingles should be oset over three courses, with a minimum overlap of 1-1/2 from one course to the next.
- They should have only two corrosion-resistant fasteners per shingle, not less than 3/4-inch from the edge, and not more than 1 inch above the edge of the next course.
|Wood Shingle Weather Exposure and Roof Slope|
|Roofing Material||Shingle Length (in inches)||Grade||Exposure (in inches)|
|3:12 up to 4:12 pitch||above 4:12 pitch|
|shingles of naturally durable wood||16||#1||3&||5|
How to Perform Roof Inspections 72
Shakes are the more rustic-looking wood roof covering and are generally split, not sawn. Their installation is somewhat dierent from wood shingles.
- Shakes are generally a 2-ply covering, so, at any point on the surface, there are only two layers overlapping.
- Shake roofs rely on an underlayment for weather protection. The shake covering itself is not designed to be impervious.
- Every course requires an interlayment
of roo#ng felt above its exposed area and under the next course.
- They require a gap between shingles of 3/8-inch to 5/8-inch to allow for expansion when damp.
- Wood shakes should be applied over planks or skip sheathing in humid climates, as they need adequate ventilation to prolong their life. They can also be installed over sheet decking in more arid climates.
- Joints between shakes should be oset over three courses, with a minimum overlap of 1-1/2 from one course to the next.
- They should have two corrosion-resistant fasteners per shake, not less than 3/4-inch in from the edge, and not more than 1 inch above the edge of the next course.
- Shakes should not be installed on a roof that has a pitch of less than 4:12.
|Wood Shake Weather Exposure and Roof Slope|
|Wood Material||Shake Length (in inches)||Grade (per Wood Shingle Council)||Exposure (in inches)|
|Minimum 4:12 Pitch|
|shakes of naturally durable wood||18||#1||7|
|preservative-treated taper shakes of southern yellow pine||24||#1||10|
Introduction to Roof Coverings 73
|Wood Shake Weather Exposure and Roof Slope|
|taper-sawn shakes of naturally durable wood||18||#1||7|
Wood Shingles and Shakes, Part II Inspecting Wood Roofs
Although wooden shake and shingle roofs look similar, they have dierent installation requirements. Still, inspecting both types is basically the same. It’s worth repeating that neither shake nor shingle roofs should be walked on.
Inspecting wooden roofs can be problematic, especially since they should not be walked. As with all other roo#ng systems, shake and shingle roofs fail for similar reasons, such as:
• weathering issues;
• ventilation and rot problems;
• mechanical damage;
• poor installation;
• lack of maintenance; and
• wood-destroying insects and other organisms.
Weathering and orientation are the biggest factors aecting the longevity of any wooden roof covering. A badly weathered roof will have a bleached-out appearance, show splitting of the shingles, and cupping, bowing and erosion of the softer parts of the grain on the exposed areas of the shingle.
- Rainwater and melting snow will erode the roof covering at a rate of a minimum 1/64-inch per year.
- Ultraviolet radiation via sunlight breaks down the cell structure of the timber. It also
dries out the oils and resins in the wood. This, coupled with the expansion and contraction of the shingles through heating and cooling, shortens the life expectancy of this type of roof covering.
- Orientation is also a factor. South-facing roof planes typically weather more quickly than north-facing ones.
- Wind will also damage shake and shingle roofs, especially if the shingles are already somewhat
How to Perform Roof Inspections 74
dried out and brittle.
Many wooden roof systems fail prematurely due to inadequate ventilation, forcing them to store moisture, which promotes rot. The inspector should always check for dark-looking patches on the roof surface that may indicate permanently damp areas of the roof covering. If possible, the inspector should probe these areas to check whether the roof covering is soft.
Like all other roof systems, shakes and shingles are easily damaged by:
• overhanging branches; • hailstorms;
• foot trac; and
• attacks by golf balls.
Poor Installation and Repairs
Installation problems are common and include:
• under- or over-driven nails;
• nails too close to the edges;
• buckling of shingles due to being nailed too closely to each other; • too much shingle exposure (and not enough overlap);
• gaps between subsequent courses lining up;
• lack of proper underlayment or interlayment; and
• improper or missing !ashings.
More than any other roof type, wooden roofs require regular maintenance, as wood itself is an organic material. Any defects can lead to rapid deterioration of the roof structure. Inspectors should be particularly aware of any vegetation that is trapping moisture on the roof. The inspector may also ask the homeowner/seller how old the roof covering is, and also whether it has received any treatments to seal the surface or repel moss and mildew.
Wood-Destroying Insects and Other Organisms
Like any other wooden component used in construction, shingles and shakes are susceptible to both wood-boring insects and wood rot. This can be very dicult to spot from a ladder, so it’s important to inspect as much of the roof as possible.
Pay particular attention to any roofs that are covered in moss or mildew, as this is a sure sign of dampness in the covering, which will lead to rot very quickly. Chemical treatments are available that will kill moss and mildew.
Introduction to Roof Coverings 75
The MUST-report list includes:
• the type of covering;
• the method used to inspect the covering;
• the location and number of missing or damaged shingles or shakes; • signs of previous repairs;
• evidence of mechanical damage;
• buckling or cupping of shingles or shakes;
• any signs of damp or moisture on the roof;
• moss or mildew buildup;
• any rotten shingles that can be viewed or probed; and
• rotten or missing !ashings.
Again, the inspector should never comment on the future lifespan of a wood roof. There are just
too many variables that need to be taken into account, so it is impossible to be accurate, and this is outside the scope of a home roof inspection. Remember that a roof that appears to be in good shape because the current owners maintain it can very quickly deteriorate if the next owner fails to follow the same kind of maintenance schedule.
How to Perform Roof Inspections 76
1. Asphalt shingles use either ________or _________ as a base.
∏ #berglass….carbon #ber
∏ cellulose….polyvinyl chloride
2. Asphalt shingles that are made up of several layers are called _________.
∏ engineered ∏ architectural
3. T/F: An underlayment is required under all asphalt shingles. ∏ True
4. When installed according to the manufacturer’s instructions, asphalt shingles can be installed on
a roof that has a pitch as low as _______.
∏ 2:12 ∏ 3:12 ∏ 4:12
5. T/F: Tree branches overhanging the structure should be noted because of their potential for damage to the roof covering.
∏ True ∏ False
6. Small dimples or circular depressions on asphalt shingles are often caused by _________.
∏ nail pops
∏ under-driven nails
7. T/F: It is not necessary to note previous shingle repair if the repair was performed by a professional.
∏ True ∏ False
8. Most jurisdictions allow no more than _____ layers of asphalt shingles.
∏two ∏ three ∏ four
9. T/F: Slate tile roofs should never be walked on. ∏ True
10. The lowest quality of slate tile has ____________.
∏ ribboning in it ∏ feathered edges ∏ a dark grey color
11. T/F: Clay tiles are easily distinguishable from concrete tiles. ∏ True
12. T/F: Most concrete and clay tiles are installed the same way.
∏ True ∏ False
13. T/F: InterNACHI’s Standards of Practice require that all clay and concrete tile roofs be walked on. ∏ True
14. Concrete and clay tile roofs with a pitch of less than 4:12 require ______ layers of underlayment.
∏two ∏ three ∏ four
15. T/F: Solid tile roofs should not be installed over solid sheathing.
∏ True ∏ False
How to Perform Roof Inspections 78 16. Fasteners made of ___________ are recommended for tile roofs.
∏ stainless steel or iron ∏ copper or stainless steel ∏ galvanized steel or iron
17. The enclosure at the eaves’ edge of a traditional barrel-style roof is called a _________.
∏ sot vent ∏ bird stop ∏ drip edge
18. Asbestos cement roof shingles were commonly installed between the _________.
∏ 1930s and 1960s ∏ 1860s and 1930s ∏ 1960s and 1990s
19. When reporting on an asbestos cement tile roof, the inspector should ____________.
∏ recommend immediate replacement ∏ note the roof material
∏ walk the roof looking for broken tiles
20. A wood shingle is _________-cut, whereas a shake is split by ________.
∏ machine…. hand ∏ hand…. machine ∏ machine…. saw
Answer Key is on page 115.
Flat Roofs: Roll Roofing 79 Flat Roofs: Roll Roofing
Roll roo#ng is common on low-pitch residential roofs, particularly those on shed roof additions to existing structures. In many cases, these have been installed by the homeowner with insucient regard for the manufacturer’s installation guidelines.
The general rule of thumb with these roofs is that the more plys they have, the longer they are going to last, but none of them has a very long lifespan.
All roll roo#ng is 36 inches wide and is manufactured similarly to asphalt shingles. The base material is felt-impregnated with asphalt or bitumen, making it impervious to moisture. The areas designed for full exposure also feature a granular mineral topcoat, which is provided to protect the roo#ng from the eects of ultraviolet radiation. In some areas, the topcoat has a re!ective surface to prevent the roof’s surface from overheating, which can break down the asphalt or bitumen. There are two methods of attachment to the roof surface: nailed down with all nail heads covered, or
“torched down,” where the sheet is heated with a propane torch to melt the asphalt down onto the roof surface.
Many roll roofs have insucient pitch to properly shed water, and these tend to exhibit signs of ponding on the surface. In dry weather, it is often possible to observe a ring of dirt on the roof’s surface where the pond was until the water evaporated.
Single-Ply Roll Roofing
As the name suggests, this type of roof has only one layer of covering except where the sheets overlap. They typically have a 3-inch lap that has no mineral granules, so the rows or courses on the roof will appear to be 30 to 33 inches apart.
This covering should be installed by working up from the roof’s eaves. The top edge should be nailed every 3 to 4 inches, in accordance with the manufacturer’s instructions. The next roll should be adhered over the lap with roo#ng cement so that no nail heads are visible. Any exposed nail heads should be sealed with roo#ng tar.
These coverings typically last for only #ve to 10 years. They tend to last better if they are fully adhered to the roof sheathing, rather than just at the laps.
How to Perform Roof Inspections 80
Double-Ply Roll Roofing
This covering has two layers at any point on the roof. This can be achieved by a double application of a single-ply material (as discussed above), with the joints between rows oset by half of the roll’s width. Wide selvage roo#ng is a type of roll roo#ng whose bottom half has mineral granules on the surface, so each row has a full 50% lap over the lower courses. Therefore, each course on the roof would appear to be 18 inches wide. Again, this will tend to last better if the whole roll is fully adhered to the roof decking.
Despite the double covering, and even when fully adhered to the roof decking, these roofs still have a lifespan of only 10 to 15 years.
Inspecting Ply Roofs
The inspector should pay particular attention to the following:
• any tears or rips of the covering; • any signs of the lap edges lifting; • exposed nail heads;
• blisters under the roof covering; • loss of the granular covering; and • signs of ponding on the roof.
Issues with roll roo#ng include:
• the type of roo#ng material;
• the number of plys, if it can be determined; • the method of inspection;
• any rips or tears in the material;
• lifted edges;
• exposed nail heads;
• loss of granules;
• blistering; and
• signs of ponding.
Flat Roofs: Built-Up Roofing
Traditional built-up roo#ng is abbreviated BUR and is also sometimes called tar-and-gravel roo#ng. This is the logical extension of roll roo#ng concepts. While no longer used in new residential construction, most inspectors will run into it at some point on older, !at roof systems or, more commonly, on apartment and commercial buildings.
As with roll roo#ng, the more plys or overlapping layers there are, the longer the roof will tend to last. Built-up roo#ng is also not maintenance-free. It needs a periodic application of an additional topcoat of tar or bitumen, or a supplementation of the ballast or granules.
Built-up or tar-and-gravel roofs should not be installed on a roof with a slope of more than 3:12, as the asphalt and ballast will migrate down the roof, especially in warmer climates. However, it’s rare
Flat Roofs: Roll Roofing 81 to see BUR on anything other than a !at roof.
Similar to roll roo#ng, layers or plys of asphalt or tar-impregnated roo#ng felt are applied to the roof decking or sheathing. A built-up roof may have as few as two plys, but four or #ve are more common.
Each layer is hot-mopped down. The heated asphalt or modi#ed bitumen is applied not only to the roof decking, but also between each ply or layer of the covering, and as a continuous top or !ood coat over the entire roof surface.
The #nal #nish may be plain asphalt, mineral granule-impregnated roll roo#ng (again, hot-mopped in place), or separately applied mineral granules or crushed stone or slag, known as ballast.
These roof systems also typically feature parapet designs, with the BUR extending up the sides of these small surrounding walls or other interfaces between planes on the roof’s surface.
Internal drains are common on these roofs and, if installed, the parapet walls should also feature scuppers, which are auxiliary or over!ow drains that allow excess water to !ow o the roof in case of a blockage in the normal drain system.
If the roof has been installed with a stone-ballast covering, you will not be able to see the roof surface and should report that the covering is not visible.
These are the main areas of concern when inspecting built-up roofs:
• Alligatoring is the term for small cracks or #ssures that appear in the surface over time. As
the asphalt dries out, it loses its !exibility and cracks due to thermal expansion and contraction. This can allow moisture to saturate the felt layers and, over time, causes the roof to leak.
• Blistering, as the name suggests, refers to large blisters that form on the roof surface,
How to Perform Roof Inspections 82
indicating trapped moisture between the plys. These will cause the roof to delaminate, reducing its life expectancy. Some roofers will cut the blister o and dry the roof out before repairing the area, but that’s the roofer’s call, not yours. It is beyond the inspector’s job to comment on whether the system is repairable or not.
- Mineral loss occurs on roofs that have a granular #nish, or where ballast has been applied. The #nish should be uniform. Any areas that have worn away by either mechanical damage or erosion will fail quicker than areas where the surface #nish is intact.
- Even in dry weather, it is possible to see evidence of ponding or standing water that has subsequently evaporated. Many roofs have simply settled over the years and no longer slope properly toward the drains or gutters. Sometimes, this sinkage has been caused by too
many layers of roof covering, where the old surface should have been removed prior to a new application. This can be quite expensive to correct because either the roof sheathing has to be rebuilt, or additional drains need to be tied in to the water runo system. Roof drains and scuppers should also be examined, and any blockages noted.
- Cracking at roof-wall interfaces or other !ashed areas, where dierential movement between the roof covering and a wall system has actually caused a full separation of the BUR, is another defect. In these cases, inspectors may see signi#cant water damage on the interior of the building. However, BUR systems are known for not leaking directly under visible damage. Since the roof is a ply system, water often migrates horizontally under the plys before #nding another weak area and migrating downward. The inspector should report any of the following: • type of material, and whether it is ballasted or not; • how it was inspected;
• cracks or alligatoring;
• mineral loss (if applicable); • evidence of ponding; and
• blocked drains or scuppers.
Flat Roofs: Roll Roofing 83
Flat Roofs: Membrane
As roo#ng manufacturers have worked to develop more durable roo#ng materials, they have looked to various plastics and synthetic rubber. Membrane roo#ng systems use rubber and plastic-based, single-ply roo#ng materials. Most home inspectors will not see these types, except, perhaps, on trailers. They are typically used on apartment buildings, condos, and in commercial applications.
The term “membrane roof” applies to many dierent material types and installation methods.
Some systems come in sheet form, with sheets glued or chemically bonded together. Others are sprayed on as a self-setting polymer or as an expanding foam.
The earliest of these systems used PVC sheets (polyvinyl chloride) that were glued or taped together. These had a reputation for failing rapidly from ultraviolet radiation, and also from shrinkage that pulled the roof covering away from the outer edges of the roof. Inspectors may also see problems where joints or tapes have separated, along with problems with wrinkles in the covering. In some cases, it is possible to see ruptures in the roof covering where the forces exerted by the covering itself have torn the membrane.
When evaluating a building that has a membrane roof, the inspector should defer any report on the roof’s condition to a licensed commercial roo#ng contractor.
Mobile Homes and Membrane Roofs
It is quite likely that inspectors looking at mobile or manufactured homes will come across rubber membrane roofs. Inspectors are advised against attempting to walk on these surfaces, as old rubber membranes tend to get very brittle and are easily damaged. Any prior failures of the roof covering will have turned the sheathing into something with the tensile strength of wet cardboard.
From a ladder, or using a camera-mounted drone or telescoping pole, inspect for:
• tears or cracking in the surface;
• de#cient !ashings around the vents;
• signs of ponding;
• ripples in the roof covering; and
• signs of the covering shrinking and pulling away from the sides of the roof.
Flat Roofs: EPDM
EPDM (ethylene propylene diene monomer) is a synthetic rubber membrane with elastic properties commonly used to cover low-slope roofs on both homes and commercial structures.
Its manufacturing includes the use of cross-linked polymers to improve elasticity, strength, and durability. Polymers are custom-designed molecules. Cross-linked molecules are those that bond at the atomic level, which greatly increases their strength and durability.
EPDM is produced by a number of dierent manufacturers. It’s commonly available in thicknesses from 45 mils to 60 mils, and may or may not be reinforced. The standard width is typically 10
feet. The seams are potential leakage points. Other potential leakage points are penetrations, roof edges, and junctions, such as headwalls and sidewalls. For mechanically attached systems, fastener penetrations are also potential leakage points.
How to Perform Roof Inspections 84
EPDM typically has a perm rating of 1 or less, making it a moisture barrier instead of a moisture retarder. EPDM is known as a single-ply roo#ng system because it is a single membrane, as opposed to a built-up membrane consisting of multiple layers bonded together.
Some of the main advantages of EPDM are its outstanding resistance to deterioration from heat, ozone, and weather. Compared to other systems used for similar purposes, EPDM performs especially well in cold weather.
EPDM may be installed in one of three ways:
1. Fully adhered, in which the membrane is fastened down with contact cement. This is the preferred method of installing the membrane. Fully adhered membranes do not allow billowing. Billowing is the stretching and detachment from the substrate, usually due to uplift or in!ation from the wind.
2. Mechanically attached, in which fasteners similar to plastic caps are used to fasten the edge of each course before that edge is overlapped and sealed by the next course. Mechanical fastening allows some billowing of the membrane. The amount of billowing will depend on the spacing of the fasteners and the pressure dierential between the interior of the building and the exterior surface of the roof.
3. Ballasted, in which an aggregate such as gravel, generally called ballast, is installed on top of the membrane. Aggregate is typically &-inch to 1 inches in diameter (#3 or #4 stone). The EPDM membrane is held in place by the weight of the ballast. The advantage of ballast is that it allows expansion and contraction of the membrane.
Ballast systems also typically use larger sheets with factory-made seams which are superior to #eld
seams. The disadvantage of ballast is that such systems are heavy — 10 to 12 pounds per square foot — and have limited wind resistance.
The illustration below is an illustration of the layers of an EPDM commercial installation.
Flat Roofs: Roll Roofing 85
INSPECTING EPDM Seams
Seams have been weak points in EPDM installations for many years. Field experience has shown that seams that are watertight when the roof is installed often develop defects within the #rst three years after installation. They may fail due to application errors or adhesive failure.
Cleaning, priming, and adhesive application must be done correctly, and failure to perform any one of the three steps may result in the failure of a seam.
The thickness of the adhesive layer is more important than surface cleanliness in developing a lasting bond. However, both are important.
For some new, critical-occupancy requirements, all #eld seams (seams created on-site) are double- sealed by adding an additional strip of the membrane over the sealed lap. Double-sealed membranes may carry an extended warranty.
Because seam adhesives are adversely aected by moisture, EPDM should not be installed over materials with high moisture content. Ripples and buckling are sometimes forced into the seam during installation. While these seams may be watertight soon after installation, they are more likely to fail than seams installed correctly. Methods exist to refurbish existing seams that are failing.
At roof-wall junctions, the EPDM should be extended up the wall behind the exterior wall-covering material. At changes of roof slope, the EPDM should extend up onto the steeper slope or plane.
Older installations may have wall !ashing consisting of uncured neoprene, instead of cured (vulcanized) EPDM. It was once thought that the uncured neoprene would conform better to shapes
How to Perform Roof Inspections 86 and would vulcanize with exposure to heat and sunlight. Instead, it tends to craze-crack, which
appears as random cracking.
Membrane shrinkage is a common problem even with recent installations. This can result in tenting at terminations and wrinkling at penetrations. It may pull !ashing loose or cause craze- cracking. Shrinkage can also stress the seams.
The correction is to cut the membrane, let it adjust, and then patch it with a strip of EPDM. This is not something that can be done by a homeowner.
Fasteners Backing Out
Fasteners may back out due to over-tightening during original installation, or they may be pulled loose by repeated billowing of the membrane under a wind load. Repair involves slitting the membrane, replacing the fastener, and then patching the membrane.
EPDM can be damaged by exposure to grease, animal fats, oils, and petroleum solvents. Examples of locations where these problems might appear are at an exhaust vent from a kitchen, and leakage or spillage related to roof-mounted air-conditioning equipment.
If there are areas on the roof where any of these conditions is a continuing problem, have another material installed in place of the EPDM.
To reduce the cooling season heat load, EPDM, which is black, is frequently covered with an energy- re!ective white coating. If the coat is !aking o, it needs to be removed, although removal can be dicult and may be expensive. If !aking is evident during an inspection, the condition should be evaluated by a specialist. Evaluation should include contacting the coating manufacturer to con#rm that the coating was designed for long-term compatibility with the membrane.
Ballast may be displaced by wind scour or by billowing. It typically appears as a heart-shaped section near the roof’s corners, where velocities tend to be highest. As a correction, pavers can be installed, but they require a pad to prevent abrasion. A better solution is often larger aggregate applied at 20 to 25 pounds per square foot for 10 to 15 feet in from the roof edge.
On low-slope roofs, water may sometimes collect in low spots. This is called ponding. Seams that get soaked by ponding may fail. Even when the roof is dry, you can usually spot the areas that have ponding problems by the sediment that collects in them, or the dried rings that the evaporated moisture leaves behind.
Damage from Foot Traffic
Areas of heavy travel are especially subject to damage from abrasion and cuts to the membrane.
Flat Roofs: Roll Roofing 87 This can damage the underlying substrate. These areas should have an extra layer of the sacri#cial
membrane for protection.
It is dicult to start a tear in both reinforced and unreinforced EPDM, but once a tear starts,
it propagates relatively easily in unreinforced EPDM. Since tearing is more common with mechanically fastened systems, if you see a mechanically fastened roof with extensive tearing, it may not be reinforced EPDM.
EPDM is made by a number of dierent manufacturers and will vary slightly in chemical composition and properties but, in general, it fails in the ways described above.
Metal Roofs: Sheet and Tiles
Until fairly recently, it appeared that metal roofs had gone out of style. In the U.S., they have been associated with run-down rural properties.
Contrary to their aesthetic reputation, metal roofs are sturdy and long-lasting, when properly maintained, and modern paints and powder coatings make them nearly maintenance-free. In the Northeast, metal roofs are making a comeback because of their superior ability to shed snow loads quickly. They are also free
of the ice-damming problems associated with shingles and tiles.
Metal roof components are manufactured from steel, galvanized steel (zinc-coated steel), copper, lead, aluminum, and terne (a tin-lead alloy-coated steel). Tin-plated stainless steel is available for locations where regular steel would not last too well, such as salt-air coastal regions.
Steel, either galvanized, painted, or both, has been used in sheet form with standing seams, corrugated, or in tile form.
Tin is now used primarily as a coating on steel or in an alloy. At one time, pure tin was common both as tiles and as sheet material.
Copper has long been the choice for high-end metal roofs because of its long lifespan. Normally, it is used as standing-seam roo#ng, but it can also be soldered together (as was the case in the past).
Aluminum is not very common as a residential roo#ng material, although some shingles of this material are designed to look like wood shakes. It is used extensively in commercial applications where its low weight is a design advantage on wide-span roofs. Aluminum sheet roo#ng is easy to spot, since it comes in small lengths and has to be installed using rubber gasketed screws through the surface and into the roof decking.
How to Perform Roof Inspections 88 Terne is the same as steel or galvanized steel, and is sometimes used to manufacture both sheet and
tile roof coverings.
Lead is not commonly used in North America as anything other than a !ashing material. In Europe, however, it was used extensively in sheet form on smaller !at roofs, particularly those with parapet walls and internal drainpipes because the material is malleable and easy to solder together.
Styles and Installation
Tiles are coming back into fashion. They were common from the early 1900s and still in use until the 1930s. Manufacturers produced unusual designs, aping slate and terracotta. Some used very ornate features, and designs with scalloped edges and diamond shapes were not unusual. All metal tiles have a pressed or embossed design which not only increases their rigidity, but also adds texture to the tile. They sometimes have a granular coating, but most are just painted.
Metal tile roofs were originally installed over plank sheathing and a layer of tar paper, and then #xed to the roof with regular roo#ng nails. Some designs were also fully interlocking to prevent moisture intrusion.
Modern metal tile roofs can be installed over regular sheet ply or OSB sheathing, with an underlayment of roo#ng felt. Today’s tiles are fully interlocking to provide better weather protection and resistance to being torn up by high winds.
Standing seam is the product that #rst comes to mind when discussing metal roofs. Its distinctive ridges serve two purposes: the seams connect one section to the next, and they also hide the bracket that connects the lengths of steel roo#ng to the decking. Flat-seam roofs generally follow the same pattern but are less pronounced.
Most modern systems are
manufactured on site from rolls of coated steel or copper. The rolls are 20 to 24 inches wide and typically come in 50-foot lengths. The
metal is cut to length and then fed through a forming machine that folds up the two outside edges to form a pan about 1 inches high, with the other edge 1 inches high when the edges are butted together. The extra 1/4-inch is folded over the adjacent !ange, and then both are folded over again, with the clip holding the material to the decking sandwiched in the middle.
Some older copper roofs have over-locking standing or !at seams and were also soldered together where the plane of the roof was too long to be spanned by a single sheet.
Older sheet-metal systems came in only 8-foot lengths, so inspectors will sometimes see an over- locked or !at seam joint part of the way down the roof plane.
All metal roofs can be installed over plank or sheet roof sheathing, but they should all be installed with a tar paper or roo#ng felt underlayment. Also, since metal systems do not breathe well, the roof ventilation needs to be sound in order to cope with moisture issues. This tends to be less of a problem on older homes, but modern homes with metal roofs need to have properly designed ventilation.
Flat Roofs: Roll Roofing 89
Many older homes were #tted with corrugated sheet-metal roo#ng, usually made of steel, galvanized or terne. Although some people #nd it aesthetically lacking, it is used all over the United States, which speaks volumes for its longevity. It was normally installed over plank sheathing with a layer of tar paper underneath, with the sheets overlapping by one corrugation, and with sheets above overlapping those below.
In most cases, the installation and !ashing of metal roof systems is just like clay or concrete tiles.
Inspecting Metal Roofs
The major issues to check for when inspecting a metal roof are:
- mechanical damage from branches or other impact;
- rust, in the case of steel or coated roofs;
- signs of repairs;
- splitting along seams;
- galvanic reaction between dissimilar metals (for example, aluminum vents are a bad match for steel roofs);
- paint peeling from the surface; and
- damaged, rotten or missing !ashings. What to report for metal roo#ng: • the material and style of the roo#ng; • how it was inspected;
• missing and damaged components; • splitting seams; • loose tiles;
• signs of rusting;
• painted #nishes in poor condition; • signs of previous repairs; and
• !ashing issues.
How to Perform Roof Inspections 90
Although this section is intended as light relief, some of these systems are more common than inspectors may realize.
Plastic Corrugated Roofing
Nearly everyone has seen this material installed over a carport or homeowner-built lean-to. Obviously, any attempt to walk this type of roof is extremely unsafe.
Many modern properties have big areas of the roof that are fully glazed, usually as a feature of an architect’s dream home. However, common problems include leaks and diculty keeping them clean enough to allow adequate light to pass through.
Plastic Tile Roofs
These are rare. One style has a fully interlocking design over sheet sheathing. It is a very tight system, so ridge and sot vents should be installed to provide adequate ventilation.
Even in wet climates, and especially in
Great Britain and other areas of Northern
Europe, thatched roofs have been used for
centuries. A popular misconception is that they are made from grasses, when, in fact, river reeds are the most common material used because they are more rot-resistant.
Grass Roof Coverings
There is a strong movement toward green building, and live turf coverings are believed to be both sustainable and energy-ecient.
It goes without saying that the roof needs a very good membrane under the covering, as well as a skilled landscaper.
1. Standard roll roo#ng is ___ inches wide.
∏ 24 ∏ 36 ∏ 48
2. The layers that make up a built-up roof are called ________.
∏ layers ∏ overlaps
3. Two-ply roll roo#ng is also called ________ roo#ng.
∏ wide-selvage ∏ built-up
4. The following should be reported when inspecting ply roo#ng:
∏ exposed nails ∏ blisters
∏ all of these
5. Built-up roo#ng is also known as ________ roo#ng.
∏ asphalt-and-stone ∏ tar-and-gravel
6. Blisters in built-up roo#ng are caused by ____________.
∏ water or air expanding below the covering ∏ movement of the building
∏ inadequate nailing
7. T/F: Alligatoring of a roof covering is only a cosmetic issue.
∏ True ∏ False
How to Perform Roof Inspections 92 8. Water stains on a !at roof are signs of previous ________.
∏ pooling ∏ repairs ∏ ponding
9. A metal roof covering with ribs down it is called ________.
∏ standing seam ∏ edge-lip roofing ∏ terne roofing
10. T/F: Metal tile roofs should have exposed nails. ∏ True
11. Sheet copper roofs are jointed with __________.
∏ solder or roofing adhesive ∏ standing seams or solder ∏ standing seams or flashings
12. A steel roof and an aluminum vent are a bad match because of __________.
∏ the wrong fasteners ∏ acids in the air
∏ galvanic reaction
13. T/F: Metal tile roofs require no underlayment. ∏ True
14. Metal roof tiles are typically made of __________.
∏ aluminum ∏ copper
15. Crushed stone or gravel ballast on a built-up roof __________.
∏ never needs replacing
∏ protects the roof from sunlight ∏ keeps the roof weighted down
Answer Key is on page 116.
Roof Flashing 93
Edge and Ridge Flashings
Roof !ashing is at least as important as the roof covering itself. A covering can be brand new, but unless the !ashing is in a similar condition and properly installed, the roof is going to leak.
Basically, any interface between a roof plane and any other component, including another roof plane with a similar covering, needs a !ashing. If it is missing or incorrectly installed, or has already failed, there will likely be problems with the whole roof system. Complicating matters is the fact that it’s impossible to see most !ashings.
The only thing better than one !ashing is two !ashings doing the same job, which is where counter- !ashings come into the picture.
Flashing should be made from corrosion-resistant metal, the most common metals for this use being galvanized steel, copper, aluminum, lead and stainless steel. Aluminum should not be used in coastal areas, as the salt air rapidly corrodes any !ashings made from this material.
The main types of !ashing include:
• edge !ashing;
• ridge and hip caps;
• valley !ashing;
• roof-wall !ashing;
• roof-roof !ashing;
• chimney and vent !ashing; and • skylights.
According to the 2018 International Residential Code (IRC), Section R905.2.8.5, all eaves and rake edges need a !ashing. These prevent rainwater from wicking into the roof sheathing or decking as it leaves the roof covering. The pro#le of this !ashing ensures that any drips from the edge fall away from the roof sheathing. It is for this reason that edge !ashing is also commonly referred to as drip edges or drip !ashing.
Ridge and Hip Flashing
How to Perform Roof Inspections 94
A drip edge !ashing should be installed at the eaves and rake edges of shingle roofs (eaves: along the gutter; rake: along the gable edge). Adjacent segments should overlap. The drip edge !ashing should extend at least 1/4-inch below the roof sheathing and extend backward up onto the roof deck at least 2 inches. The drip edge !ashing should be fastened to the roof deck at every 12 inches, maximum.
Eaves and Underlayment Cover Flashing
The underlayment should be installed over the drip edge along the eaves, meaning that the metal drip edge !ashing is covered by the underlayment. Another way of saying it is that at the eaves, the underlayment should overlap or cover the metal drip edge !ashing.
Rake and Flashing Cover Underlayment
Along the rake edges of the sloped roof, it’s the opposite installation. The underlayment at the rake edge should be installed under the metal drip edge. Another way of saying it is that at the rake, the metal drip edge !ashing should overlap or cover the underlayment.
Again, along the rake edges, the drip edge !ashing should be installed over the underlayment, covering the underlayment. At the rake, the metal !ashing covers the underlayment primarily to
prevent wind-driven rain from getting under the underlayment at an exposed edge.
The image above is a drip edge !ashing installed on the roof deck at the eaves (at the gutter location). At the eaves, the underlayment will cover the metal drip edge !ashing.
The inspection image to the right is underlayment installed
on top of the drip edge !ashing along the eaves (at the gutter location). The underlayment is covering the metal !ashing. The underlayment in the picture is actually waterproof underlayment material in this area. Sometimes referred to a “peel-and-stick” or
“ice and water shield.” It’s a polymer-modi#ed bitumen that self- adheres to the roof deck surface.
The image to the left is the metal drip edge !ashing installed on top of the underlayment along the rake board (covering the underlayment). At the rake, along the sloped edge of the sloped roof, the metal drip edge !ashing covers the underlayment.
Many asphalt shingle roofs have a second drip edge installed with a second roof covering, making it hard to see how many layers of shingles there are. It is worth getting up on a ladder at the eaves to look carefully for a second !ashing under the top one.
In most cases, the ridge or hip !ashing is made of the same material as the rest of the roof covering and is often referred to as ridge or hip caps.
On asphalt shingle roofs, ridge !ashings are made by cutting down standard 3-tab shingles, or they
Roof Flashing 95
can be bought as a special shingle. In the case of architectural styles, the special shingles #t better and are more eective. Architectural shingles are often cut down and installed over ridge vent systems that not only look unattractive, but have cracks at the peak due to being bent over the ridge.
Asphalt shingle caps should extend 4 inches down from the roof peak on both sides.
Ridge caps on slate tile are normally made from a terra cotta material, which is glazed to match the slate color, and then mortared into place. Some of these also feature very ornate designs. Several slate roofs use metal ridge !ashing of either copper or lead.
Asbestos cement roofs universally use specially molded roof cap tiles that are #tted right over the peak, and are overlaid in the same manner as asphalt tile to hide the nail heads.
Clay and concrete tiles usually feature specially manufactured ridge caps and ends that are either nailed or mortared into place. It is common to see damaged tiles and cracked mortar with these systems.
There are three types of ridge caps for wood shake and shingle roofs. The #rst type is a special ridge cap produced by manufacturers that are actually two thick shingles connected together. The second type is a ridge cap, which is formed on-site by trimming down standard shingles and shakes, and side- jointing them at the peak with alternating side-lap joints. The third method is to butt together two cedar planks (generally, 1×6 timber).
In all cases, there should be a metal or heavy roo#ng felt under the cap extending below the uppermost course of shingles or shakes.
The two dierent metal roof styles generally have dierent ridge caps or !ashings. Sheet metal roofs tend to be installed with ridge caps of the same material and color. Metal tile roofs generally have a ridge system that mirrors the style of the roof itself. All must be installed in line with the manufacturer’s instructions.
Valley Flashing Materials
Valley !ashing can be made of dierent materials and designs, depending on the type of roof covering. The common materials include:
• roo#ng felt or tar paper;
• roll roo#ng;
• membrane material (ice and water shield); and
• metal !ashing, generally galvanized or coated steel, or stainless steel, lead or copper.
Asphalt Shingle Valleys
Open valleys are a rare sight on asphalt shingle roofs and should be formed with:
• roll roo!ng in two layers. The #rst layer should be 18 inches wide laid face down in the valley, and the second layer should be 36 inches wide laid face up. Both plys should be cemented down, and the shingles cut back to 3 inches from the centerline; and
• metal “ashing a minimum of 24 inches wide, with a center rib at least 1 inch high, nailed at 18 inches on center, and not more than 1 inch from the outer edges. Ideally, this would also have a layer of ice and water shield installed under the !ashing, extending the !ashing protection to 18 inches on either side of the valley.
How to Perform Roof Inspections 96 In both cases, it is good practice to also cut an angle on the top of the shingle to help stop water
from migrating across the top of the shingle.
Closed and closed-cut valleys are more common with asphalt shingle roofs.
• A fully closed valley is formed when the shingles from both planes are interwoven across the valley and extend a minimum of 12 inches onto the adjacent plane.
• A closed-cut valley is formed when the shingles from one roof plane cross over to the next, but the covering overlaid from the other plane is cut back 2 inches from the centerline of the valley.
In both cases, the valleys should still have additional protection, with one of the following applied, in addition to the normal felt or tar paper underlayment:
• one layer of 36-inch roo#ng felt or tar paper; • one layer of 36-inch roll roo#ng; or
• one layer of 36-inch ice and water shield.
The shingles should not be nailed within 6 inches of the valley centerline, and the un-nailed areas should be cemented down.
One area of the roof often overlooked is the junction where two roofs of dierent slope meet each other. Like any other interface, this requires !ashing.
It is common to see changes in roof slope, especially where the house has an addition and the roof plane transitions from a conventional slope to a lower slope. In many cases, two roof planes are covered with dierent styles of roof covering. For example, regular shingles on a steep slope will transition to roll roo#ng on a !at roof.
In most cases, the material of the lower- slope roof should be extended at least
12 inches up under the covering of the conventional-slope roof. In some areas, particularly those with high snow loads, it
is better if the lower-slope covering is extended as much as 3 feet up the conventional plane.
Even in cases where the same roo#ng material is continued down both planes, there should be additional protection underneath the roof covering at the junction. At a minimum, the inspector should see an extra layer of roo#ng felt or an impermeable membrane.
The design of these !ashings is dependent on whether the roof surface is horizontal or inclined down the wall. It also varies based on the type of roof covering and the material that the wall structure is covered with.
Roof Flashing 97
All roof-wall interfaces should be protected with two !ashings:
• base “ashing, to prevent moisture from entering the roof-wall structure at the interface of the two; and
• counter-“ashing, to prevent water that’s running down the wall from getting behind the base !ashing.
In some cases, the base !ashing
can be an integral part of the roof covering. This is common with roll and membrane roo#ng products where the covering can be extended up the wall surface.
In some instances, the siding, in eect, becomes the counter-!ashing, such as vinyl siding covering the step !ashing on a traditional shingle roof. When this is the case, the siding should be installed with 1 to 2 inches of clearance to prevent water from wicking into it.
Obviously, metals are the main choice, with galvanized steel, aluminum, copper and lead all used extensively. Lead is still the most common choice for !ashing against masonry, as it is very malleable and retains its shape over rough surfaces. Base !ashing must be made of either corrosion- resistant metal or a mineral-surfaced roll roo#ng. Cap !ashing must be made of corrosion-resistant metal.
Base !ashing installed against a vertical wall can be continuous or step !ashing. It should be at least 4 inches in height and 4 inches in width. It must direct water away from the wall onto the roof or into a gutter.
If siding is installed on the vertical wall, the vertical part of the base !ashing should be continuous under the siding.
How to Perform Roof Inspections 98
The illustration above shows the position of the bent pieces of step !ashing installed at a sidewall on an asphalt shingle roof.
Many roof tiles do not lend themselves to interwoven base !ashing due to their complex shapes. In this instance, a pan !ashing is installed before the roof tiles are laid down. This is especially common with Spanish style roofs. This !ashing is commonly made from galvanized steel, but could made of any metal. One of the major problems with tile roofs is that the tiles themselves will often outlast the !ashing.
Roof Flashing 99
Continuous Roof-to-Wall Flashing
Obviously, a continuous roof surface, such as roll roo#ng, BUR or membrane, needs no step !ashing, as such. Very often, the covering is its own base !ashing. In this type of installation, one would expect to #nd a cant strip that transitions the roof covering to the wall.
In any location where a roof-wall !ashing exists and the roof terminates on the wall, a kickout !ashing should be installed.
This !ashing is designed to prevent water from running down the !ashing and entering the wall system by diverting the !ow away from the bottom of the roof-wall interface and to the side outside of the siding material.
How to Perform Roof Inspections 100
At the chimney, there are essentially #ve types of !ashing to inspect. They include:
• step !ashing;
• counter !ashing;
• apron !ashing;
• cricket !ashing; and • backer !ashing.
Step !ashing is installed where the roof intersects a vertical sidewall. The step !ashings are the small individual pieces of metal installed with each shingle course. They “step” with each course.
Counter-!ashing is !ashing material that covers and protects the top edges of all the other types of !ashing to prevent water intrusion.
Apron !ashing is installed where a roof intersects a headwall. Common locations for an apron !ashing are at the front side (or downslope side) of a dormer, at a chimney, and anywhere there’s a transition between a horizontal and a vertical surface.
Cricket !ashing is installed where the roof intersects a chimney or a curbed roof penetration. The cricket diverts water around, while the backer !ashing provides a weatherproo#ng transition material right where the backside of some type of penetration intersects the roof. A recommended best practice is to install a cricket if a chimneystack is more than 30 inches wide (the NRCA recommends 24 inches wide).
Roof Flashing 101
Backer !ashing is installed when a chimney that is not very wide (only 20 inches) intersects a roof, and there’s no requirement for a cricket. A backer !ashing would be installed on the upslope backside of that stack.
The best practice is to install
the top edge of the counter- !ashing at a masonry chimney by inserting at least 1 inch of
the !ashing materials into the masonry. For a brick chimney stack, this insertion would be at the mortar joint. Some installers will cut a groove in the masonry for the !ashing insertion.
Vents and Other Penetrations
On any roo#ng system, the most common failures are those associated with any component that projects through the roof covering. In many cases where a roof has been re-covered, the original !ashing has either been damaged or re-installed incorrectly, leading to leaks into the interior.
Depending on location, there are primarily two dierent types of plumbing vent !ashing. The most common in northern climates is the neoprene or metal boot. In Florida and in many other southern states, a lead !ashing, which also protects the plastic vent pipe from ultraviolet damage, is more common.
The stack vent is provided for the waste stack. The stack vent is the extension of a soil or waste stack above the highest horizontal drain that is connected to the stack. This is the main commonly observed pipe that is observed penetrating the sloped roof surface, and it may also be visible in the un#nished attic space.
Most skylights show signs of moisture penetration. This is especially a problem when the roof has been re-covered and the original !ashing was damaged while being removed and re-installed.
How to Perform Roof Inspections 102
1. Which of the following materials is not normally used for !ashings?
∏ aluminum ∏ steel
2. The !ashing that goes between the roof covering and the sheathing around the roof’s perimeter is called _______ !ashing.
∏ drip edge ∏ rake edge ∏ counter-
3. A !ashing along the peak of the roof is called the ________ !ashing.
∏ valley ∏ gable ∏ ridge ∏ soffit
4. A closed valley means that the valley !ashing __________.
∏ is visible
∏ cannot be seen
∏ can be seen from only one side
5. Metal valley !ashing should be a minimum of _____ inches wide.
∏18 ∏24 ∏30
6. Traditional step !ashing should overlap ___ inches in every direction.
∏2 ∏3 ∏6
7. For most tile roofs, a standard step !ashing cannot be used against a wall, so a _______ !ashing must be installed.
∏ pan ∏ bucket ∏ drip
8. The bottom of a roof should have a ________ !ashing where it meets a wall.
∏ kickout ∏ step
9. A secondary !ashing that prevents water from entering a base !ashing is called a ________ !ashing.
∏ counter- ∏ drip edge
10. The lowest face of a chimney should have a(n) _________ !ashing.
∏ 3-tab ∏ apron ∏ cricket
11. The !ashing around a plumbing vent pipe is called a ________.
∏ shroud ∏ boot ∏ sock
Answer Key is on page 117.
How to Perform Roof Inspections 104
Roof Ventilation Basic Ventilation
Poor ventilation causes many problems, not the least of which is substantial reduction in the lifespan of asphalt-based roof coverings.
General Venting Requirements
Roofs with unconditioned attic spaces require some type of ventilation.
All attic spaces require ventilation at a minimum of 1 square foot of venting per 150 square feet of attic area. This may be reduced to 1 square foot of ventilation per 300 square feet of attic space where most of the vents are high on the roof and air !ow is induced from a lower point, as is the case with ridge and sot vents.
The “1-in-300 Rule” may also apply where a vapor barrier is installed on the warm side of the ceiling.
These basic rules apply both to traditional attic spaces and to enclosed areas where the ceiling material is applied directly to the underside of the roof rafters, as one would #nd with a cathedral ceiling.
The primary reason for these requirements is to allow moisture-laden air to be evacuated from the attic space, and also to attempt to balance the temperature of the roof coverings and sheathing with that of the outside air.
There are many methods employed to achieve adequate venting, among them:
• gable vents, which are screened openings in the gable ends, allowing cross-ventilation;
• turbine vents, which are wind-powered vents that promote air !ow out of the roof area;
• passive vents, which are used to provide some air !ow between the sheathing and ceiling areas on !at or low-slope roofs;
• sot and ridge vents, which are installed so cooler air can be drawn in from the sot and exhausted through the ridge vents. This style is the most common in new construction and is generally considered to be the most ecient;
• powered vents, which use a thermostat or a switch in the attic space to energize the fan when the attic air reaches a pre-set temperature; and
• combination venting, which refers to employing two or more of these methods, and, in some areas, using through-the-roof vents installed a few feet below the ridgeline.
As with any other system, roof venting may have been installed incorrectly, may not have enough area, may have been rendered inoperable by changes to the home, or may have been badly modi#ed by the homeowner in an attempt to save energy. Such problems include:
• a lack of vents. It is not uncommon to see a complete lack of ventilation. In these cases, the
Roof Ventilation 105
high temperatures within the roof covering will induce a rapid breakdown of the materials. This not only aects asphalt shingle roofs, but also !at and tile roofs that use roll roo#ng as the primary water barrier. It is also common to #nd high levels of moisture in these attics, which promotes moisture-related issues, such as rotting sheathing and mold growth.
• inadequate venting. Poorly vented roofs will show some of the same issues as roof systems having no venting, but to a lesser extent. Particularly in northern climates, there will be evidence of ice damming and moisture on the roof sheathing. In some cases, inadequate venting will eventually manifest as rusting shingle nails, and even frost on the underside of the roof sheathing in cold weather.
• too much ventilation. In some cases, this can be a problem, particularly with large but poorly screened vents that allow rainwater to enter the attic space. The key with ventilation is to strike the correct balance between insulation, moisture barriers and ventilation. A bad installation is, in many respects, worse than none.
• blocked vents. Very often, inspectors will see instances of poorly installed insulation blocking the sot and other vents. This should be reported as in need of repair.
• false vents. It is all too common to see what appear to be vents installed that are, in fact, not connected through the structure. Inspectors will sometimes see instances of ridge vents apparently installed, but the roofers did not trim back the roof sheathing along the roof’s peak to allow the vents to actually work.
• damaged vents. It is recommended that all vents be visually inspected for proper operation wherever possible. Be sure to check to ensure that the !ashing system is in good shape and is not leaking. Inspectors will often see vents that have been mechanically damaged, or galvanized vents that are rusting away. These de#ciencies should always be reported as in need of repair or replacement.
• ice damming. This is typical of poorly insulated vented roofs in colder climates and is caused by snow melting on the roof above the home’s heated envelope, and then running down
the roof and being trapped by frozen snow and ice above the eaves. The ice will act as a dam and force water to back up under the roof covering, rotting out the sheathing or migrating through into the interior of the structure. The cure for this is an adequate design incorporating proper insulation, ventilation, and an ice and water shield installed under the roof covering in potentially aected areas.
Unvented Roof Systems/Attic Assemblies
Spray foam (open- and closed-cell) and #berglass insulation can perform successfully at unvented roof systems (or unvented attic assemblies) when airtightness is provided and humidity is controlled.
There are many other important factors involved when inspecting unvented roof systems, including: the climate zone; roo#ng solar and exposure properties; air vapor barriers; and interior humidity levels.
Wood-framed pitched-roof systems are traditionally constructed with #brous insulation materials installed on the ceiling plane (attic !oor), or along the sloped underside of the roof deck. Proper ventilation is critical for these types of systems.
For vented wood-framed pitched-roof systems, the primary concern is the potential for moisture to build up at the sloped underside of the roof deck during cold weather. The underside of the roof deck is the condensing plane.
How to Perform Roof Inspections 106
For unvented roof systems, the condensing plane is the underside of the air-impermeable foam. When this insulation is properly installed, condensation should not exist because the temperature of the interior face of the foam should be about the same as the interior air temperature.
To control airtightness, an air-barrier system must be installed in the roof’s insulation assembly.
An air-impermeable layer may be installed on the inside of air-permeable insulation (such as #berglass or cellulose) to control both air and moisture movement. For roofs sealed with spray-foam insulation, air leakage is eectively stopped. Failure will be likely via accidental or unintended air !ows at unvented wood-framed pitched-roof systems, such as around roof penetrations, including plumbing vents.
Unvented attic assemblies should meet the following conditions:
- The unvented attic space must be completely contained within the building’s thermal envelope.
- Interior vapor retarders must not be installed on the ceiling (attic !oor) of the unvented attic assembly.
- At wood shingle/shake roofs, a vented air space of -inch should separate the shingles/shakes from the roo#ng underlayment above the roof deck.
- Air-impermeable insulation can be applied in direct contact with the underside of the roof deck. For Climate Zones 5, 6, 7 and 8, air-impermeable insulation must have a vapor retarder in direct contact with the underside of the insulation. As long as airtightness is provided and wintertime humidity is controlled, unvented roof systems can perform successfully.
1. An attic with an area of 600 square feet with ridge and sot vents should have a total vent area of __ square feet.
∏2 ∏4 ∏6
2. For most roofs, the most eective venting system is _________.
∏ powered fans
∏ ridge and soffit vents ∏ gable vents
3. An attic space with only gable vents should have a vent area of 1 square foot per ____ square feet of !oor area.
∏150 ∏ 250 ∏ 650
4. T/F: Roof vents are required for roofs with unconditioned attic spaces. ∏ True
5. Flat roofs normally have _________ venting systems.
∏ ridge and soffit ∏ gable
6. T/F: Ice damming is caused by both poor venting and poor insulation. ∏ True
Answer Key is on page 117.
How to Perform Roof Inspections 108 Inspecting Chimneys
A visual inspection of the outer chimney structure should be performed along with inspection of the roof covering.
On most homes, the chimney will usually be the largest projection through the roof, or the component with the longest !ashed area abutting the roof. Proper !ashings, therefore, are of the utmost importance. Also, the structure should be inspected for signs of moisture intrusion and failure.
General Chimney Requirements
All chimneys are required to meet a minimum standard for height above the roof coverings. The basic rule for this is:
• a minimum of 3 feet high,
• as well as 2 feet higher than any roof • within 10 feet horizontally.
Most chimneys are manufactured with brick, stone or concrete blocks, some of which may be part of a manufactured chimney system. All chimney systems should be visually inspected for signs of deterioration, which can lead to moisture intrusion of the chimney system.
Masonry systems are not maintenance-free and will fail over time. The most common failures are those related to weathering of either the masonry itself or the mortar that holds it together. Deterioration of the masonry or the mortar will allow moisture into the chimney structure, accelerating other problems. It’s common, particularly in the northern United States, to see brickwork that is missing its face. This is caused by moisture saturating the brick and then freezing, pushing o the front face. Once this has happened, the brick will erode very quickly because the inside of the brick is relatively soft.
Inspectors will also see signs of the mortar failing in the joints between the bricks. This happens as the mortar breaks down and becomes powdery. The cure for this is to
Inspecting Chimneys 109 have a mason scrape out the aected mortar and replace it with fresh mortar. This process is called
re-pointing. Erosion of the brick and mortar is called spalling.
Chimney Crown Failures
All chimney systems should have crowns installed. They serve two purposes. First, they seal the area between the chimney !ue and the masonry structure, preventing rainwater from running down the outside of the !ue within the chimney. Second, the crown generally extends beyond the masonry structure so that the water drips o the edge, rather than wicking into the brick or blockwork. The chimney crown, which is usually made of poured concrete, should be pitched downward, away from the chimney !ue.
A rain cap should not be confused with a chimney cap. A rain cap is installed to protect the inside of the chimney !ue from both weather and wildlife intrusion. In some cases, a rain cap can also be helpful in preventing downdrafts into the !ue. It is also not uncommon to see a rain cap acting as a damper for a traditional #replace.
Rain caps are always manufactured out of metal. The highest-quality ones are made from stainless steel or copper. Many are manufactured from galvanized steel, and these tend not to last as long and will frequently rust out.
Some jurisdictions also require rain caps that incorporate spark arresters, especially in arid regions where wild#res are relatively common occurrences.
While the inspection of chimney !ues is a highly specialized procedure, any obvious de#ciencies in the !ue should be noted. In particular, pay attention to !ues that are damaged, collapsed, or show signs of previous chimney #res. Extra care must be taken when inspecting chimney systems that are being used to vent fossil-fuel appliances, such as boilers, furnaces, water heaters and manufactured #replaces, as any de#ciency in either the liner or the chimney structure could be a potential #re starter, or could allow carbon monoxide into the habitable space within the home. It is now required that any traditional !ues being used as vents for these appliances be #tted with continuous metal !ue liners to ensure that no noxious gases can #nd their way into the home.
The home inspector should evaluate and report on the following:
• the material that the chimney is made of; • the condition of the chimney stack;
• the visible condition of the !ashings;
• the condition of the chimney cap;
• the condition of the rain cap (if installed); and
• that the chimney meets minimum height and safety requirements.
How to Perform Roof Inspections 110 Manufactured Chimneys
The term “manufactured chimney” generally relates to prefabricated chimney components, as opposed to a traditional chimney that would normally be manufactured from masonry products.
In most new housing, a manufactured chimney typically consists of a steel vent
or !ue built inside an arti#cial chimney stack. For the most part, the clearance requirements are the same as for any other chimney system; however, special attention must be paid to the proper clearance of combustibles where the chimney or vent passes through the roof covering.
In most cases, a manufactured chimney !ue is covered over with a timber frame structure, and #nished in a siding material to match the rest of the property, or a stucco, traditional brick, or masonry veneer covering the structure.
Any failure of the system will allow considerable moisture to enter the general framing of the structure, so it is vital to pay particular attention to any and all !ashing systems related to the chimney. In many cases, especially those chimneys that are sided with traditional timber siding, the inspector must ensure that there is at least a 1- to 2-inch clearance between any wooden components and the roof covering.
Carefully inspect the areas of the chimney that abut the roof covering, as there will often be considerable signs of dampness.
Rain or Termination Caps
Inspecting Chimneys 111
Most manufactured chimneys are supplied with rain caps or de!ectors built to the manufacturer’s speci#cations. In many areas, these caps or de!ectors are required to be installed with spark arresters to prevent sparks from leaving the !ue. These are usually manufactured from either aluminum or galvanized steel, and are susceptible to mechanical damage, rusting, and galvanic reaction between dissimilar metals.
Because all manufactured chimneys have metal !ues that conduct heat very eciently, it is important that proper separation is maintained where the !ue passes through any ceiling-!oor structures, as well as through the roof sheathing. The minimum acceptable clearance is 2 inches. It is required that an approved thimble is used where the vent goes through the roof sheathing and covering in order to maintain the 2 inches of separation and prevent moisture entry at this point.
When inspecting manufactured chimney systems, the inspector should pay particular attention to:
• the material that the structure is built from;
• the type of covering;
• any signs of moisture entering the covering or structure; • the condition of the !ashings;
• the condition of the chimney cap;
• the condition of the rain cap or de!ector;
• the clearance from combustibles (where visible); and
• the height clearances to adjacent structures.
Normally, a manufactured chimney has a metal chimney cap to prevent water from entering the structure between the !ue and the framing. Inspectors will often #nd that this !ashing has failed due to moisture ponding on the cap, resulting in rust through this !ashing. The rain cap should incorporate a drip edge similar to what one would expect to #nd under any roof covering. This is required to de!ect water away from the vertical sides of the chimney.
How to Perform Roof Inspections 112
1. The minimum height for a traditional chimney is ___ feet.
∏2 ∏3 ∏4
2. If a roof ridge is closer than 10 feet to a chimney, the stack should be ____ feet higher.
∏2 ∏3 ∏10
3. Flaking or powdering of masonry or mortar is called ________.
4. The process of repairing missing mortar between brick joints is called _________.
∏ mudding ∏ grouting ∏ re-pointing
5. The dierence between a chimney cap and a rain cap is __________________.
∏ a rain cap protects the structure, and a chimney cap protects the inside of the flue
∏ a chimney cap protects the structure, and a rain cap protects the inside of the flue 6. T/F: All chimneys should have a spark arrestor #tted.
∏ True ∏ False
7. A clearance gap of ___ inches is required between a manufactured chimney and combustibles.
∏2 ∏3 ∏6
8. T/F: A rain cap or de!ector is required on all manufactured chimneys.
∏ True ∏ False
9. The proper name for the connection between a manufactured chimney !ue and the roof is called a _______.
∏ bucket ∏ thimble
10. T/F: Manufactured chimney systems are not required to maintain the same separation from adjoining structures as traditional chimneys.
∏ True ∏ False
Answer Key is on page 118.
How to Perform Roof Inspections 114 Appendix I: Answer Keys
Answer Key for Quiz #1
1. A roo#ng square covers an area of 100 square feet.
2. In most jurisdictions, a maximum of two layers of roo#ng is allowed. 3. Roof slope = rise / run
4. A roof with a pitch or slope of 3/12 is termed a low-slope roof.
5. T/F: InterNACHI’s Standards of Practice require that all roofs be walked.
6. T/F: An inspector is not required to report on the TV antennae.
7. T/F: The inspector is not required to report on tree limbs overhanging the roof surface, since they are not part of the structure.
8. A !at roof is one with a pitch or slope of less than 2/12.
9. A standard gable roof has two plane(s).
10. A roof with four planes meeting at the ridge is termed a hip roof.
11. Standard 3-tab asphalt shingles generally last 20 years.
12. T/F: Slate roofs can last forever. Answer: False
Answer Key for Quiz #2
1. The proper slope for guttering is 1/16-inch per foot.
2. Gutters should be installed by screwing or spiking them through the fascia and into the
3. T/F: All homes are required to have gutters installed.
4. T/F: Rusting steel gutters are a cosmetic issue and need not be reported.
5. Which of the following guttering issues needs to be reported?
Answer: missing downspouts
6. Which of the following is not a guttering material?
7. T/F: The inspector should report on any debris buildup in the gutters. Answer: True
Appendix I: Answer Keys 115 8. T/F: The inspector should inspect all visible downspout terminations.
Answer Key for Quiz #3
1. Which of the following would cause the tops of walls to spread? Answer: over-spanned rafter ties
2. De!ection of the ridge beam is called bowing or sagging.
3. A gap between the wall and the sot may indicate rafter sag or spread.
4. A sot that is attached directly to the underside of the rafter tails is called a(n) enclosed sot. 5. The clips that are required between many sheathing panels are called H-clips.
6. Roof ridges and rafters are normally under compression.
7. Roof sheathing should be installed perpendicular to the rafters.
8. The horizontal board enclosing the ends of the rafter projections (or tails) is referred to as the fascia board.
9. A decorative molding applied to the fascia is called a cornice.
10. The distance that should separate the siding from the roof’s surface is 1 to 2 inches. 11. Drip edge !ashing should be installed over the roo!ng paper/felt along the rake edge.
Answer Key for Quiz #4
1. Asphalt shingles use either cellulose or !berglass as a base.
2. Asphalt shingles that are made up of several layers are called architectural.
3. T/F: An underlayment is required under all asphalt shingles. Answer: True
4. When installed according to the manufacturer’s instructions, asphalt shingles can be installed on a roof with a pitch as low as 2:12.
5. T/F: Tree branches overhanging the structure should be noted because of their potential for damage to the roof covering.
6. Small dimples or circular depressions on asphalt shingles are often caused by hailstones.
7. T/F: It is not necessary to note previous shingle repair if the repair was performed by a professional.
8. Most jurisdictions allow no more than two layers of asphalt shingles.
How to Perform Roof Inspections 116 9. T/F: Slate tile roofs should never be walked on.
10. The lowest quality of slate tile has ribboning in it.
11. T/F: Clay tiles are easily distinguishable from concrete tiles. Answer: False
12. T/F: Most concrete and clay tiles are installed the same way. Answer: True
13. T/F: InterNACHI’s Standards of Practice require that all clay and concrete tile roofs be walked on. Answer: False
14. Concrete and clay tile roofs with a pitch of less than 4:12 require two layers of underlayment. 15. T/F: Solid tile roofs should not be installed over solid sheathing.
16. Fasteners made of copper or stainless steel are recommended for tile roofs.
17. The enclosure at the eaves’ edge of a traditional barrel-style roof is called a bird stop.
18. Asbestos cement roof shingles were commonly installed between the 1930s and 1960s.
19. When reporting on an asbestos cement tile roof, the inspector should note the roof material. 20. A wood shingle is machine-cut, whereas a shake is split by hand.
Answer Key for Quiz #5
1. Standard roll roo#ng is 36 inches wide.
2. The layers that make up a built-up roof are called plys. 3. Two-ply roll roo#ng is also called wide-selvage roo#ng.
4. The following should be reported when inspecting ply roo#ng: Answer: all of these
5. Built-up roo#ng is also known as tar-and-gravel roo#ng.
6. Blisters in built-up roo#ng are caused by water or air expanding below the covering.
7. T/F: Alligatoring of a roof covering is only a cosmetic issue. Answer: False
8. Water stains on a !at roof are signs of previous ponding.
9. A metal roof covering with ribs down it is called standing seam.
10. T/F: Metal tile roofs should have exposed nails. Answer: False
11. Sheet copper roofs are jointed with standing seams or solder.
12. A steel roof and an aluminum vent are a bad match because of galvanic reaction.
Appendix I: Answer Keys 117 13. T/F: Metal tile roofs require no underlayment.
14. Metal roof tiles are typically made of steel.
15. Crushed stone or gravel ballast on a built-up roof protects the roof from sunlight.
Answer Key for Quiz #6
1. Which of the following materials is not normally used for !ashings? Answer: timber
2. The !ashing that goes between the roof covering and the sheathing around the roof’s perimeter is called drip edge !ashing.
3. A !ashing along the peak of the roof is called the ridge !ashing. 4. A closed valley means that the valley !ashing cannot be seen.
5. Metal valley !ashing should be a minimum of 24 inches wide.
6. Traditional step !ashing should overlap 3 inches in every direction.
7. For most tile roofs, a standard step !ashing cannot be used against a wall, so a pan !ashing must be installed.
8. The bottom of a roof should have a kickout !ashing where it meets a wall.
9. A secondary !ashing that prevents water from entering a base !ashing is called a counter–
10. The lowest face of a chimney should have a(n) apron !ashing. 11. The !ashing around a plumbing vent pipe is called a boot.
Answer Key for Quiz #7
1. An attic with an area of 600 square feet with ridge and sot vents should have a total vent area of 2 square feet.
2. For most roofs, the most eective venting system is ridge and sot vents.
3. An attic space with only gable vents should have a vent area of 1 square foot per 150 square feet
of !oor area.
4. T/F: Roof vents are required for roofs with unconditioned attic spaces.
5. Flat roofs normally have passive venting systems.
6. T/F: Ice damming is caused by both poor venting and poor insulation. Answer: True
How to Perform Roof Inspections 118 Answer Key for Quiz #8
1. The minimum height for a traditional chimney is 3 feet.
2. If a roof ridge is closer than 10 feet to a chimney, the stack should be 2 feet higher. 3. Flaking or powdering of masonry or mortar is called spalling.
4. The process of repairing missing mortar between brick joints is called re-pointing.
5. The dierence between a chimney cap and a rain cap is a chimney cap protects the structure,
and a rain cap protects the inside of the “ue.
6. T/F: All chimneys should have a spark arrestor #tted.
7. A clearance gap of 2 inches is required between a manufactured chimney and combustibles.
8. T/F: A rain cap or de!ector is required on all manufactured chimneys. Answer: True
9. The proper name for the connection between a manufactured chimney !ue and the roof is called a thimble.
10. T/F: Manufactured chimney systems are not required to maintain the same separation from adjoining structures as traditional chimneys.