Wear Indicators in Asbestos Cement Roofing Materials InspectAPedia® -
Indicators of wear and age of cement asbestos roofing materials: shingles, corrugated, sheets.
How to recognize asbestos materials in building roofing materials, roof shingles, roof tiles
Photo guide to asbestos-containing roofing products, asphalt shingles, cement-asbestos shingles
Photographs of asbestos containing roofing materials (ACRM)
Non-asbestos materials sometimes mistaken for asbestos
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Here is our photo guide and text that can identify the condition of cement asbestos roofing products like asbestos-cement roof shingles. Our page top photo shows a cement-asbestos roof that is worn out and leaky.
Asbestos cement roof shingles were in popular use in the U.S. from the 1920's (est) through the 1960's (est) and were sold in the U.S. into the 1970's and according to some sources even in the 1980's.. The mixture of asbestos fibers and portland cement to form a hard material that was was durable and fire resistant is credited to Ludwig Hatschek who, in 1900, came up with the name Eternit associated with a U.S. producer of these products.
The typical life expectancy of an cement asbestos shingle roof was given as 30 years, But we have seen these roofs that were now 50 years old in good condition. Typical roof wear or failure patterns are either failure of the shingle fasteners or broken and falling shingles.
Some wear signs to watch for on cement asbestos roofs include these
Active roof leaks - showing up in the attic or living area
Broken cement asbestos roofing shingles (at the left of my hand in the photo above), possibly leaving exposed openings or nails - roof leaks (patch with sheet metal if necessary). Do not try walking on an asbestos cement shingle roof - you'll almost certainly break shingles at every step. (Page top photo).
Freeze-thaw damage: some modern reinforced fiber cement roof shingles are not intended for use in freezing climates and may lack resistance to frost damage. (That's why we don't like leaving moss on shingles.) If you are buying replacement fiber-cement shingles to repair an asbestos-shingle roof, check with the manufacturer about the suitability of the product for your location.
Missing roofing shingles, probably leaving exposed roof sheathing and leaks Moss growing on the roof: we don't like seeing heavy moss or lichens or even leaves or pine needles on a building roof because these hold moisture which can speed the wearing out process, especially in freezing climates.
Moss or lichens on a roof, especially the moss (lichens are hard to remove) can be reduced using industrial cleaners (like deck cleaner) if the contractor works carefully, or even by light brushing; usually we leave moss or lichens alone on an older roof as we are afraid of causing more damage than good.
Mold and staining on roofs (mildew does not grow on roofs) is a mostly cosmetic concern that can be addressed by light gentle spray cleaning with a mildewcide or deck cleaner; be careful not to cause roof damage by too-aggressive use of a power washer.
You can gradually kill off and prevent future moss or lichens or mold on most roof surfaces by installing aluminum or copper strips along the width of the roof near the ridge. Metal salts washing down the roof seem to kill off moss and lichens and most molds. You can convince yourself of the efficacy of this trick by simply noticing how often a roof surface is clean of moss and lichens below areas of metal flashing that are washed by rain. See ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES and also ALGAE STAINS ON ASPHALT ROOF SHINGLES for details.
Prior repairs using tar, flashing cement - not a durable remedy, leaks likely
Prior roof leaks showing up in the attic or living area, possibly repaired in a less than durable manner.
Roof-over or re-cover limitations for fiber-cement roofs: NRCA says that some fiber-cement roofing products may not be suitable for a "roof-over" application; some roofing manufacturers permit roof-overs with their shingles, but the placement of any new roofing material on an old surface which is not smooth risks future shingle breakage, damage, and leaks. A "tear off" of the old roof is always a better roofing job (and it about doubles the cost).
Slope limitations: beginning in about 1996 the NRCA recommended a minimum slope of 4 in 12 (33%) for these products; use on a low slope means shorter roof life or leaks.
Underlayment requirements: in snow climates an underlayment is recommended to reduce the chances of ice dam leaks. See ... Prevent Ice Dam Leaks on Buildings
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Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print).
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in Buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
"Asbestos in the Home," U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
NRCA Roofing and Waterproofing Manual, 4th Ed., available from the National Roofing Contractors' Association.
"Tips for working with fiber-cement roofing products", Thomas L. Smith, AIA, RRC, Professional Roofing, September 1996
"About Asbestos Cement Roof Shingles", Ann Johnson, at ehow.com, a nice article about the history of this material - November 2008.
Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
Enviro-Scare: Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues
Dust from the World Trade Center collapse following the 9/11/01 attack: the lower floors of this building contained spray-on fire-proofing asbestos materials.
Asbestos Information Links: Asbestos Detection, Testing, Recognition, Hazards, Field Photos, and Information Sources, including
health-related links such as legal services and information about mesothelioma and other cancers.
Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
For more information about fiberglass as an indoor air quality concern see:
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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
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.