InspectAPedia ^TM

Causes of Wear or Leaks in Asphalt Roofs
RoofAPedia ^©

	Enter your search terms Submit search form
	Search This Website - InspectAPedia.com

• Causes of roof shingle wear and failure

SHINGLE LIFE / WEAR FACTORS for Asphalt Shingle Roofing Products

• Asphalt Shingle Quality: type, quality, thickness, shingle design (cutout 3-tab versus laminated) and rated or design-life of roofing material selected
• Asphalt Shingle Color: in hot sunny climates lighter colors tend to resist sunlight damage and last longer.
• Roof Shingle Age: the shingles in the photo at the top of this page are organic based asphalt (asphalt-impregnated paper coated with mineral granules) at or near the end of their life. Typical life expectancy for roofing products can vary widely as a function of the material composition, type, installation details, and other factors discussed in depth at this website. Typical shingle life expectancies range from about 15 years to 40 years.
• Roofing material storage conditions before & during installation
• Sunlight and Heat Effects on Asphalt Shingles: Storing shingles in hot sun makes them stick together, making damage likely as they are pulled out of their bundle.
• Cold and Freezing Effects on Asphalt Shingles: Storing shingles in freezing conditions increases the chances that a shingle will crack when being used if applied in cold weather, especially ridge cap shingles which break when bent. We used to cut those and then leave them inside on a radiator until needed.
• Rain Effects on Asphalt Shingles: believe it or not, shingles are not quite waterproof and depend on roof slope to shed water effectively. Shingles that are left exposed to rain and then installed may violate the manufacturer's warranty and may fail early, possibly due to the effects of temporarily trapped moisture at the time of application. I've found sections of asphalt shingle roofs all showing early wear traceable to a specific bundles of asphalt shingles that were at the top of the stack and exposed to the weather. This photo shows the effects of rain on shingles when the bundles were left outside for some time before use.
• Stacking Shingles in Storage: shingles should not be stored at the supplier nor at the job site stacked higher than two pallets. If shingles need to be stacked higher, separator boards or plywood are needed under each pallet to protect the shingles below from damage by the weight and edges of the pallet and shingles stacked above. We've seen shingle pallets eight-high with no inter-pallet protection at HG Page Lumber in Poughkeepsie and at an occasional Home Depot. But don't try giving the supplier your personal advice about how to stack their product, you'll just annoy them. Inspect and reject visibly damaged shingle bundles and hope that there are not more subtle damage effects not visible at first sight.
• Bending Asphalt Shingle Bundles: roofers like the shingle bundles to get up on the roof by magic - by a special loader or carried up by an assistant. A smart assistant spreads the bundles out over the roof to avoid too much weight in one place (point-load structural failures). But especially on a steep pitch roof, some "experts" put all of the bundles of shingles across the ridge. Bending shingles over the ridge, especially in cold weather, may violate the manufacturer's warranty and may damage the shingles, including subtle damage that appears after installation as early cracks, tears, or failures. Reference: http://www.owenscorning.com/around/roofing/specs/Classic-C.pdf from Ownens Corning cites their requirements for handling and storing shingles.
• Asphalt shingles should be stored: flat, in un-opened bundles with labels intact and legible, in cool, not freezing and not hot temperatures (under 110 degF.), under cover, protected from the weather, protected from damage by stacking more than two pallets high, and kept that way until they are ready for use.
• Asphalt roof shingles should be delivered: in flat, un-damaged, un-opened bundles, protected at the job-site (as described above), and when moved to the rooftop, shingle bundles should be laid flat, not over the ridge, and should not be placed with too much weight in locations that may damage the building structure.

• Building factors: roof slope, problem areas in roof shape & design, orientation towards sunlight
• Roof Ventilation: attic or under-roof ventilation. Un-vented roofs, especially in sunny hot climates, stay at a higher surface temperature and can be expected to have a shorter life.
• Technical material composition and asphalt shingle design details (roofing material components, manufacturing process, wind-uplift prevention)
• Marketing and economic considerations (aggressive sale of new roofing material by some contractors, reluctance to or economic reasonableness of patching damaged areas on older roofs)
• Manufacturing Defects and Asphalt Shingles: even the best manufacturers are at risk of episodes of producing a defective product. The asphalt shingle manufacturing line is a challenging environment where variations in control of the process can produce a defective product with a reduced life. The thermal splitting failure discussed at this website is an example of a widespread fabrication defect that affected many asphalt shingle manufacturers.
• Weather and Weather Exposure: variations in climate and other local weather conditions affect roof shingle life
• Wind Effects on Roofing: exposure to damage (wind, tree limbs, hail, snow, ice, foot traffic). Key in wind blow-off of asphalt shingles is whether or not the shingles were properly installed, especially properly nailed according to the manufacturer's recommendations. Also on occasion a brand new roof that has not had a chance for its self-sealing adhesive to work may blow off in windy conditions even if it was nailed properly. Review the workmanship defects below as a number of them constitute improper nailing and can cause a wind failure of roofing that may otherwise may be mis-diagnosed.
• Roof Installation Workmanship: installation/workmanship details such as the following:
• • Nailing of Asphalt Shingles: asphalt shingle roof nailing errors: improper nailing pattern, omitted nails, too many nails, nails not properly placed in the shingle, and lazy use of the roofing nailing gun: nailing without moving on the roof, leaning out too far, making nails enter the shingle on an angle so that the nail head cuts the shingle; failure to set nails properly (too deep - cuts shingle, too shallow, cuts shingle above). The older roof nailing guns that used staples required even more careful use of that tool. If the roof shingle staple was driven too deeply it cut the shingle and it would blow off of the roof. If the shingle was left too high or canted (lazy-leaning out too far again) the protruding staple cut the overlapping shingle above.
  • Underlayment Effects on Shingle Life: omitting the underlayment, installing underlayment or shingles over a wet, icy, or snow-covered roof deck
  • Roof Flashing Errors: there are too many of these to list on this asphalt shingle page. Water runs down hill. Flashing installers sometimes forget that, misplacing flashing, omitting flashing, using continuous rather than step flashing at roof-wall abutments and at chimneys, improper valley flashing, nails through flashing, relying on roof cement rather than flashing, and misplacement of drip edge with its vertical section behind rather than over gutters. OPINION: some roofers opine that underlayment is completely unnecessary. I go with the manufacturer's recommendations. They have a high interest in the successful application of their product.

• Effects of Climate On Asphalt Shingles:Carl Cash asserts that the mean durability of "20-year" shingles is less than 20 years everywhere in the U.S. except Alaska. Variations in climate permit calculation of a wear-acceleration factor for various cities. Higher thermal load (hotter climates) means shorter life. Yuma, AZ mean durability was calculated at 12.6 years, for example, and Ft. Meyer FL 14.1 years while Chicago at 19.7 years and Erie, PA at 20.7 years showed longer life in cooler climates.

Cost Effectiveness of Asphalt Shingles:

Other roofing materials also are affected by thermal loading. Cash calculates that the life cycle cost of steep-slope roofing shows that asphalt shingles still provide the most economical performance for the home owner! ("Asphalt Shingle Performance," Carl Cash, P.E., Construction Business and Technology Conference, Providence Rhode Island, 2/28/97.)

Given these variables, it is not likely that a "20-year" shingle will expire exactly twenty years after it is installed. When a roof lasts longer than its promised life no one complains. If a roof needs replacement substantially sooner than its anticipated life, consumers are understandably concerned.

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

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website. If you just "scroll down" you'll miss some important articles. See links at page left.

More Information on Building Diagnostic Inspections and Repairs

...

InspectAPedia ^TM Home & Site Map - Building Inspection, Diagnosis, & Repair, Environmental Inspection & Testing - Research Website

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Home Inspection Construction Consulting Services & advice for home buyers

Contact Daniel Friedman for website content suggestions or for fee-paid consulting

	Enter your search termsSubmit search form
	Search This Website - InspectAPedia.com