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ROOFING INSPECTION & REPAIR
AMERICAN CEMWOOD ROOFING
BEST ROOFING PRACTICES
BUILT UP ROOFS
CATHEDRAL CEILING VENTILATION
CERTIFICATIONS for ROOFING CONTRACTORS
CHIMNEY FLASHING Mistakes & Leaks
COLD WEATHER ROOF TROUBLE
DECKS, ROOFTOP CONSTRUCTION
EPDM, RUBBER, PVC ROOFING
EXTRACTIVE BLEEDING on SHINGLES
FIRE RETARDANT PLYWOOD
FLASHING on BUILDINGS
FLAT ROOF MOISTURE & CONDENSATION
Green House or Solarium Roof Leaks
HEAT TAPES & CABLES on Roofs for Ice Dams
ROOF ICE DAM LEAKS
MASONITE WOODRUF FIBERBOARD ROOFING
NOISE CONTROL for ROOFS
PLASTIC ROOFING TYPES
PVC, EPDM, RUBBER ROOFING
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF DORMER TYPES - PHOTO GUIDE
ROOF INSPECTION SAFETY & LIMITS
ROOF JOB PROBLEMS, RESOLVING
ROOF LEAK DIAGNOSIS & REPAIR
ROOF NOISE TRANSMISSION
ROOF REPLACEMENT SNAFUs
ROOFING FELT UNDERLAYMENT REQUIREMENTS
ROOFING MATERIALS, Age, Types
ROOFING TILE SHAPES & PROFILES
ROOFING UNDERLAYMENT BEST PRACTICES
SADDLE CONSTRUCTION at CHIMNEYS
SNOW GUARDS & SNOW BRAKES
STANDARDS for ROOFING
STRESS SKIN INSULATED PANELS
TEST LABS - ROOF SHINGLE
TREES & SHRUBS, TRIM OFF BUILDING
TRUSSES, Floor & Roof
UNDERLAYMENT REQUIREMENTS on ROOFS
VENTILATION in BUILDINGS
WALK-ON ROOF SURFACES
WARRANTIES for ROOF SHINGLES
WORKMANSHIP & ROOF DAMAGE
Guide to asphalt shingle roofing: this article series explains 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.
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"Organic felt" roof shingles refers to using cellulose (paper) as the substrate on which the shingle is constructed. The cardboard or cellulose shingle mat is impregnated with hot asphalt and coated with mineral granules to form a sunlight and weather resistant upper surface.
By contrast, at CRACKS in FIBERGLASS SHINGLES we discuss a previous history of thermal splitting of fiberglass-mat-based asphalt roof shingles.
Also see ASPHALT SHINGLE PROPERTIES and see Choosing an Asphalt Shingle: Organic vs. Fiberglass, Ted Cushman, The Journal of Light Construction, May 1993 for more about the debate around the advantages and disadvantages of organic mat asphalt shingles vs. fiberglass mat-based asphalt roof shingles.
Mineral granule loss from asphalt roof shingles - details are at GRANULE LOSS from 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 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:
We recommend that inspectors stay off of cupped-asphalt shingle roofs, particularly in cold weather (shingles are more likely to break).
If we absolutely have to walk on a cupped shingle roof, we would tiptoe carefully, avoiding stepping on the raised or cupped shingle sections, or if doing repairs, we would 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.
While the requirement for felt underlayment beneath asphalt roof shingles seems to be a topic of almost timeless argument subject to much arm-waving and little reading of manufacturer's instructions and warranties, various sources recommend or require installation of a felt underlayment over the roof deck before asphalt roof shingles are installed.
Booth & Roberts reported at length on the uses of underlayments on asphalt shingle roofs, citing (quoting):
The authors point out that
NRCA, Building Code, & Manufacturers Recommend or Require Felt Underlayments on Shingle Roofs
Booth & Roberts also report that [Reference numbers are to references in the cited document.]
Inadequacy of Roofing Felt as a Vapor Barrier for Asphalt Shingles in Hot Humid Climates?
A Building Sciences Corporation report also elaborates the usefulness of placing a vapor barrier on the roof deck below shingles in hot humid climates. BSC points out that: [some paraphrasing -DF]
[OPINION-DF: from exterior roof inspections at all times of day and seasons, we have not observed this time-related morning roof shingle buckling in the Northeastern U.S. nor in Florida, nor the Southwest, though the authors report the phenomenon. It is possible that the authors are not quite correct that daily buckling and relaxing of roof shingles can be ignored on a vented roof as harmless, since certainly the product is expected to remain flat, and flexing daily might reduce its anticipated wear life.]
[OPINION-DF: we argue at ROOF VENTILATION SPECIFICATIONS that un-vented roofs are not a best building method in any climate.]
[QUESTION-DF: we note that the test chamber constructed by BSC was itself in an enclosed, air-conditioned space, and that the underside of the test chamber roof was at least in part exposed to the air conditioning. It seems possible that the reduced humidity and lower temperatures on the "interior-side" of the test roof may have contributed to moisture behaviors that vary from what occurs in the field. Attics and under-roof spaces such as in an un-vented "hot roof" cathedral ceiling are certainly not exposed to cool dry conditioned air. BSC may have addressed this concern but we did not find it in the referenced article.
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Technical Reviewers & References
Please see CUPPING ASPHALT SHINGLES for the full text of this article.
Please see CURLING ASPHALT SHINGLES for the full text of this article.
Please see the full text of this article at Fishmouthing Asphalt Shingles.
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
Please see LADDERING vs STAIR STEPPING SHINGLES for the full text of this article.
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 we don't have authoritative data on the frequency of that defect. [Photo of fishmouthed shingles courtesy of Carl Gerosa, New Rochelle, NY.]
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.