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Here we discuss the maintenance, repair, or replacement of cement asbestos shingle siding on buildings. This article series includes a photo guide and text that can help in identification of asbestos-containing wall siding products like asphalt shingles & asbestos-cement siding shingles. This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection. In the website sections listed below, we provide photographs and descriptive text of asbestos insulation and other asbestos-containing products to permit identification of definite, probable, or possible asbestos materials in buildings.

While an expert lab test using polarized light microscopy may be needed to identify the specific type of asbestos fiber, or to identify the presence of asbestos in air or dust samples, many asbestos-containing building products not only are obvious and easy to recognize, but since there were not other look-alike products that were not asbestos, a visual identification of this material can be virtually a certainty in many cases.

Maintenance & Repair Tips for Asbestos Cement Wall Siding Shingles

We consider asbestos cement wall shingles a durable and fire-resistant roof and an asset to the building provided that the siding is in good condition. But because the material is easily damaged by a heavy-handed worker unfamiliar with the materials involved, asbestos cement siding has to be repaired and maintained with care.

Replacement cementious wall shingle materials are now available that look almost exactly like the original materials, but that do not contain asbestos. That's the product we have used to repair the building shown in the photographs in this article.

Small temporary wall siding repairs to individual shingles can be made using copper or aluminum flashing material -- it can be painted color that looks alot like the remaining cement asbestos shingles, and this approach minimizes the chances of breaking more shingles during the repair.

How to Remove and Replace Broken Asbestos Cement Wall Shingles

What about replacing the siding?  Can you side over the existing asbestos cement siding or does it need to be removed? First let's discuss replacing individual broken sections of fiber cement siding:

It is very difficult to remove individual broken asbestos-cement wall shingles, but working carefully it can be done.

Work by an inexperienced contractor can ruin a cement asbestos shingle wall siding and lead to complete replacement that could have been avoidable.

• Use vise-grips or a pair of horse-shoe nail clips or similar tool to carefully pull out the nails from the intact, un-damaged cement-asbestos shingles above and around the damaged shingles. Pull nails carefully so as not to break the intact shingles. Do not try to pry up asbestos cement shingles - they are brittle and will break.
• Slide out the damaged asbestos cement wall shingles
• Inspect the wall sheathing for leak or water or insect damage that may need repair
• Install a house-wrap or roofing felt over any exposed wall sheathing, sliding its upper edge under the older materials so that any water that penetrates the wall will be directed out not into the wall cavity.
• Carefully slide the new fiber cement shingles into place. If cement-shingles have to be cut, use the manufacturer's recommended cutting tool, not a power saw that will make a lot of dust.
• Line up the nail holes between the old (upper layer) cement asbestos shingles and the new fiber cement shingles to be secured underneath. They wont' line up, right? OK so use a tiny masonry bit and drill through the existing hole in the old asbestos cement (intact) shingle and through the new fiber cement shingle below.
• Nail the new shingles in place, carefully - don't let your final hammer strokes drive the nail so hard against the fiber cement shingle or asbestos-cement shingle that you break it.

Guide to Siding over asbestos cement siding:

A common remodeling practice is to install new vinyl or aluminum siding over cement asbestos shingle siding as well as over many other older siding materials when the old siding has become damaged, leaky, or cosmetically ugly. A typical procedure is to install furring strips on the existing wall, avoiding breaking the existing siding. The new siding is then secured to the furring strips so that the new wall siding will be smooth and flat.

Additional steps may be needed to build out window and door trim for aesthetic reasons - so that the windows and doors do not appear to "recede" into the walls of the structure.

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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

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
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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

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