Organic Felt Asphalt Roof Shingle Defect Recognition, Diagnosis, & Repair
InspectAPedia^®  -    

• 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 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 from an asphalt shingle or mineral-covered roll roofing roof 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 embedded in the asphalt used to impregnate and coat the shingle. If there is a lot 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,

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 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 we have 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" condition 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.

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]

The photograph 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.

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

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