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Organic Felt Asphalt Roof Shingle Defect Recognition, Diagnosis, & Repair RoofAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Types & photographs of organic felt asphalt roof shingle defects & failures
• Asphalt roof shingle granule loss, photographs
• Asphalt roof shingle cupping, curling, fishmouthing, photographs
• Asphalt roof shingle blisters and splices, photographs

This website tells readers how to identify & explain the most-common asphalt roof shingle failures and how to obtain asphalt roofing shingle failure claims assistance. These defects occur on organic-mat or fiberglass-mat asphalt roof shingles. Common shingle failure factors include improper storage and handling of the asphalt shingles before installation, improper nailing, improper flashing (which pertains to any roofing material), and defective asphalt shingle product material leading to thermal splitting, cracking, blistering, staining, and in some cases curling or cupping shingles. Storm damage from wind and hail occur and need to be distinguished from defective asphalt shingle product or asphalt shingle installation errors. By listing common causes of asphalt roof shingle failures and how to recognize them, building owners and roofing contractors may also be able to reduce the occurrence of asphalt roof shingle storage, handling, and installation errors that affect roof life. Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

ORGANIC FELT SHINGLE DEFECTS - Organic-mat-based Asphalt Roof Shingle Wear & Failures

Mineral granule loss from asphalt roof shingles

This photograph shows severe loss of mineral granules from an asphalt shingle roof. This roof is way past needing replacement and is almost certainly leaking. Even a roof with less dramatic granule loss is showing signs of wear and reduced future life. Anywhere that a shingle has lost the protection of its mineral granules that shingle has a reduced life expectancy. In all climates the loss of granules means that area of the roof shingle has lost its protection from sunlight. In freezing climates, shingle wear may accelerate in the area of lost granules as the roof ages and is exposed to freeze thaw cycles. Once the shingle substrate is exposed by mineral granule loss, that area of the shingle will absorb more water than its neighbors. While in this photo the roof is "worn out", there are several other conditions that can produce mineral loss on asphalt shingle roofs: Granule loss on a new asphalt roof, loose mineral granules wash down the roof and will appear in gutters and at the ends of downspouts. This is a normal condition unless it continues and begins to show black exposed roof shingle substrate. Granule loss on a roof being walked-on: walking on any asphalt shingle roof loosens some of the mineral granules from their attachment embeddedin the asphalt used to impregnate and coat the shingle. If there is alot of roof traffic, such as when work is being done on a chimney, you may see "bald" areas of shingles with lost granules where people have been walking. This is damage caused by workers and is not a product defect. Granule loss on old asphalt shingle roofs: when an asphalt shingle roof is nearing the end of its life we may see that granules have begun to wash off of the shingles so as to leave large "bald" or nearly bald areas showing black shingle substrate. These shingles have more porosity than those where their mineral granules remain in place and may already be leaking even if leaks are not quite visible in the building interior. Such a roof is ready for replacement. Granule loss on asphalt shingles due to storms: it is possible that severe weather, such as hailstorms, may damage shingles producing pitting and granule loss. Such roofs have a reduced remaining life, depending on the severity of damage. Granule loss due to blistering: blisters or "pimple-like" protrusions from a shingle surface may be a "cosmetic" manufacturing defect (at least in the opinion of the manufacturers). On at least some roofs we find that these blisters ultimately become the first wear points on the shingle when their upper surface wears away (perhaps from foot traffic or weather) exposing small round dots of missing granules on the shingle. We discuss this defect and how to distinguish between defective shingle product and storm damage at ASPHALT SHINGLE BLISTERS,

Cupping Asphalt Shingle Explanation & Photos

Asphalt roof shingles often show cupping (a concave center), curling (raised edges which curl downwards), and fishmouthing (raised edge of a shingle tab at its center with little curling). Each of these is discussed below. Cupping asphalt roof shingles (see photos below), particularly on organic or felt-based asphalt shingles, are a normal wear pattern that shows up with shingle age. This "normal" cupping or curling pattern will display shingles which are concave in their center, with the corners and possibly the three exposed shingle tab edges curled such that the very edge of the shingle curls downwards. Shingles in this condition are fragile and nearing end of life. In this condition, if someone walks on cupped shingles the raised cupped sections will break and can lead to early failure and leaks.

Curling Asphalt Shingle Explanation & Photos

Curling roof shingles (see photos below) will show a curling-under at the edges of the shingle tab, first at the lower edge and sometimes also at the two sides of the shingle tab. In fact I've seen a "failed" roof that was not leaking until the fellow who was asked to inspect it walked across this fragile surface. From a ladder at the roof edge one could clearly see the virtual footprints of broken shingle edges where the "inspector" had walked. It's best to stay off fragile roof surfaces to avoid converting a "near end of life" condtion to a "failed, leaking" condition. Curling and cupping may occur together on the same roof, or shingles may appear to be curled-only (or fishmouth-curled-only as you'll read next). We don't see cupping without some curling.

Fishmouthing Asphalt Shingle Explanation & Photos

You may not realize it but asphalt roof shingles are not quite waterproof and in particular the back side of asphalt shingles is much less water resistant than the upper or exposed side. The exposed side of an asphalt shingle is protected from sun damage by a coating of mineral granules. These shingles rely on the pitch of the roof and mechanical drainage combined with proper placement or pattern of shingling on the roof to avoid leaks. [Photo: Carl Gerosa, New Rochelle, NY.]

Fishmouthed asphalt roof shingles: An example of the less-waterproof back of asphalt roof shingles is seen below in our photo of "fishmouthed" roof shingles. In these cases a specific "curling" pattern of shingles called "fishmouthing" is not simple age and wear. This pattern displays a raised shingle edge (it's not cupped over at the very edge) which, if inspected closely, will typically occur first and worst over the shingle butt joints where shingle sides abut one another.

Fishmouthed cupping of asphalt roof shingles is caused by excessive under-roof moisture such as by a poorly or un-vented attic or roof cavity. Moisture escaping through the roof sheathing and up through the bottom of the shingles contacts the uppermost shingle which spans the butt joint of shingles below, placing more moisture at that point on the shingle tab than elsewhere. This uneven moisture, probably combined with weather exposure, leads to a raised, cupped "fishmouth" look on those shingles.

Laddering and stair-stepping of roof shingles

The first photograph here shows a sloppy "ladder pattern" installation of strip-type asphalt shingles. While opinions (and expertise) vary among roofers, this ladder pattern shingle application may not be as durable a roof installation as one which staggered the shingle offsets more than a single six inches (or in this case only 3") left and right with each shingle course. On other asphalt shingle roofs, particularly older ones, you may notice that the pattern of fishmouth occurrence on an asphalt shingle roof follows a fairly regular or stair-stepped pattern, or it may follow a regular "ladder" like pattern up the roof such as is shown in these photographs. That's because the fishmouthing is occurring at the butt joints of the shingles where more moisture is passing out of the roof structure into the back side of the shingle above each butt joint.

You can thus determine the actual pattern in which the shingles were applied to the roof. "Laddering," while permitted by some manufacturers and standards, is a less workmanlike shingle installation and may result in a localized early wear area on a roof. Ladder-pattern shingle application shows that the roofer liked to work up the roof from one position for as long as possible before moving.

Like cupped and curled asphalt shingles, fishmouthed shingles are also fragile and near end of life and are, as with ordinary cupping, damaged if walked-on.

In some other cases a defective product might cup or curl but I don't have authoritative data on the frequency of that defect. [Photo of fishmmouthed shingles courtesy of Carl Gerosa, New Rochelle, NY.]

Roof shingle fragility and damage risks

I would stay off of cupped-shingle roofs, particularly in cold weather (shingles are more likely to break). If I absolutely have to walk on such a roof, I'd tiptoe carefully, avoiding stepping on the raised or cupped shingle sections, or if doing repairs, I'd prop a ladder up off of the roof surface and work from that scaffold as is sometimes done with slate or other fragile roof surface repairs.

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Head lap coating shingle wear

[Text and photos are under preparation, July 2007]

Blistering on asphalt shingle roofs

See BLISTERS on ASPHALT SHINGLES

Algae, fungus, and bleeding, & staining on asphalt shingle roofs

See STAINS on ROOF SHINGLES

Moss and lichens on asphalt shingle roofs: causes, prevention, photos

[Text and photos are under preparation, July 2007]

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Workmanship and Wind Damage Assessment for Asphalt Shingle Roofs

Wind damage can happen to any asphalt shingle roof in severe weather conditions. However if shingles are not properly nailed, shingles are far more likely to blow off of the roof in even a modest windstorm. Manufacturers are careful to specify where shingle nails should be placed in each shingle and the number of nails required. These specifications may vary by shingle type and building location, with more nails specified for high-wind areas such as asphalt shingle roofs applied in coastal areas. Asphalt shingle wind resistance combines several factors including the effectivness of the glue strips on the shingle backs which adhere the shingle courses against wind-uplift, roof pitch, roof orientation with respect to prevailing winds, and importantly, proper shingle nailing patterns. Not only must nails be properly placed and spaced, improper nailing itself, such as driving a nail through the shingle, leaving a nail sticking up to cut a shingle above, or using a roofing stapler improperly leaving cocked staples or shingle-cutting staples will all encourage shingles to fly away with the wind. The photographs here include examples of improperly or inadequately-nailed shingles which blew off in modest windstorms of far less than hurricane strength. In the first photograph below, our correspondent has laid-out shingles retrieved after the storm, showing the location and pattern of nail holes in each shingle - clear evidence of just how they were nailed. Workmanship: Fasteners/Nailing Problems, Wind Damage appeared to have led wind blow-off of these Atlas shingles, though an investigation of whether or not the shingles had self-sealed was also needed. Workmanship: Fasteners/Nailing Problems lead to holes or wind blow-off Workmanship: Fasteners/Nailing Problems lead to holes or wind blow-off. Notice that not only has one shingle already fallen or been blown off of the roof, but its neighbors are sliding down. Diagnosis from a photograph is questionable but there appears to be a nailing problem here. Workmanship: Installation Pattern Problems:Laddering [Photo: Carl Gerosa, New Rochelle, NY.] Workmanship: Flashing and underlayment problems Workmanship: Improper materials/roof-slope problems Holes and nail-pops in shingle roofs

In discussing wind damage to roofing with your insurance adjuster or roofing contractor, be sure to review the details of original and replacement shingle installation as this can give evidence about the underlying cause of roof failure as well as informing you of how to avoid roof shingle blow-off in the future./P>

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Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com
• Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com
• Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY.
• Daniel Friedman - principal author
• Technical reviewers are invited to comment or ask questions - contact us

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