InspectAPedia ^®

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.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. 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.

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

Share this Article      

...

Technical Reviewers & References

Search InspectAPedia

• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
• Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
• Additional technical contributors & reference sources for this article are listed below.

Use links just below or 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.

ASBESTOS IDENTIFICATION IN BUILDINGS
ROOFING INSPECTION & REPAIR
ASBESTOS CEMENT ROOFING
  Asphalt-asbestos Roofing Materials
  Cement-asbestos roof shingles
  Environmental Issues - Asbestos Shingles
  Wear Signs on Cement Asbestos Shingles
  Maintenance Tips for Asbestos Cement Shingles
  Replacements for Asbestos Cement Shingles
  Corrugated Cement-Asbestos Roofing
  Asphalt-asbestos Paints & sealants
  OSHA Regulation Asbestos Roofing
  ASBESTOS REGULATION Update
Asbestos in unusual places
Asbestos-Free Insulation Materials
Insulation Material Identification Guide
  Asbestos-Free Insulation Materials
ASPHALT ROOF SHINGLES
CHIMNEY INSPECTION & REPAIRS
FIRE RETARDANT PLYWOOD
ROOF INSPECTION SAFETY & LIMITS
ROOF VENTILATION SPECIFICATIONS
ROOF VENTING ENERGY SAVING DETAILS
SLATE ROOF INSPECTION & REPAIR
SOD ROOFING
SIDING WOOD
STAIN DIAGNOSIS on Building Exteriors
STAIN DIAGNOSIS on Roofs
STANDARDS for ROOFING
STONE ROOFING
THATCH ROOFING
THERMAL EXPANSION of MATERIALS
THERMAL MASS in BUILDINGS
THERMAL MASS in UPSTAIRS
TILE ROOFING
WARRANTIES for ROOF SHINGLES
WORKMANSHIP & WIND DAMAGE

• 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.

More Information on Building Diagnostic Inspections and Repairs

• Asbestos: How to find and recognize asbestos in Buildings - visual inspection methods, list of common asbestos-containing materials
• Asbestos HVAC Ducts and Flues field identification photos and guide
• 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:

• Fiberglass in Indoor Air, HVAC Ducts, and Building Insulation
• Fiberglass Particle Identification in the Fiberglass Test Laboratory
• Goodman Gray Flex Duct Deterioration and Failures
• Mold in Fiberglass Insulation
• Optimum Indoor Air Filters
• Owens Corning Flex Duct Deterioration and Failures
• World Trade Center Dust Particle Identification

For more information about asbestos as an indoor air quality concern with focus on easy ways to identify asbestos materials in buildings, see:

• Asbestos Identification in Buildings: How to find & identify asbestos-containing materials
• Asbestos in Good Condition
• Asbestos HVAC Ducts - Asbestos Materials On or In Heating and Cooling Duct Work
• Asbestos paper duct wrap
• Asbestos Transite Chimneys, Flues, & Pipes in Buildings
• Asbestos under the microscope
• Asbestos Vibration Dampers & Asbestos in the Air Handler
• Ceiling tiles: How to recognize ceiling tiles that may contain asbestos
• Examples of unusual uses of asbestos in buildings

InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.

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

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

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.

Building Inspection, Problem Diagnosis, Forensic Investigation & Testing, Repair Consulting

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