Asbestos in Building Siding Materials - How to identify asbestos-cement wall siding
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How to recognize asbestos building siding or wall cladding materials: asbestos cement or "cement-asbestos siding"
During what years was asbestos included in building products?
Photo guide to asbestos-containing siding products: Cement Asbestos Siding
Fibrous asbestos cement products [FAC "Fibro or AC sheeting" in Australia]
Non-asbestos replacement cement siding is available, it's sometimes mistaken for asbestos
Questions & answers about asbestos cement siding on buildings

Asbestos-containing building siding identification: this document provides a photo guide and text for the 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.

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Photo Guide to Cement-asbestos Wall Shingles or Siding Products

Also see other cementious siding materials such as JamesHardie HardiPlank Siding (also see Hardie's Fibrolite™ or Fibro where used in Australia) and cementious roofing materials such ASBESTOS CEMENT & FIBER CEMENT ROOFING and Corrugated Cement-Asbestos Roofing. Also see Environmental Issues - Asbestos Roofing/Siding. Readers should also see Siding, Sheathing Identification - Photo Guide.

Is it safe to buy a home with cement asbestos siding? Most cementious building materials are considered to be non-friable, and are probably less hazardous than other friable asbestos products such as asbestos pipe insulation. However removal of asbestos-containing roofing products is regulated as we discuss at ACRM Roofing Disposal Regs.

Asbestos-cement products were developed in an era of ingenuity for creating easy to install and economic building materials. Although asbestos-cement has acquired a poor reputation by association of its title, it has not gained that reputation through a lack of durability or utility. In order to preserve this twentieth-century material, understanding what makes, or does not make, asbestos a hazard is truly important. In this case, no hazard is created when asbestos-cement building materials are sound and left in place, or when treatments incorporate non-abrasive means. - "Keeping a Lid on It...|, Woods, NPS technical brief

Asbestos cement wall shingles were in popular use in the U.S. from the 1920's (est) through the 1960's (est). A mixture of asbestos fibers and portland cement the material was durable and fire resistant.

Siding materials that use fibers and aggregate other than asbestos are properly called "fiber cement" building siding products. Some manufacturers use the term "fiber-reinforced cement" for these products.

All of these products use some sort of fiber along with cement. Before 1978 in the U.S. the common fiber used was asbestos.

In this photo of a house in New York State we can see both original cement-asbestos wall shingles and newer fiber cement replacement wall shingles that do not contain asbestos. But only an expert or a lab can tell the new fiber cement from the old asbestos fiber cement shingles - or you can with help of the inspection and repair tips we provide below.

How can we tell the difference between asbestos-containing shingles and fiber-cement wall shingles?

It's tricky. But here are some ways to distinguish between asbestos containing shingles and non-asbestos fiber-cement shingles:

Age or date of installation: installed before 1978 the shingles probably contain asbestos.

Layers of paint or finish coatings; the original shingles of both asbestos-cement and fiber cement usually come from the factory painted white on one side.

Owners often painted cement asbestos shingle siding to make it look fresh, or if it was weathered and fuzzy, to preserve it. On a building that has has a portion of its original cement asbestos shingles replaced with newer fiber cement shingles, and where some original asbestos cement shingles remain, you'll see a difference in the thickness of layers of paint on the two materials.

The shingle at the right in this photo clearly has fewer paint layers than the one at left. The left shingle is an older asbestos-cement shingle and the right photo is a new fiber cement shingle we installed.

If an asbestos-cement sided home has been re-modeled such as by adding a window or door, it's likely that the old asbestos cement shingles were broken around that new opening during the construction work - expect to see newer fiber cement shingles there.

The back of a new fiber cement wall shingle will probably have a code stamped on it such as we show here.

The presence of old dirty demotion materials may suggest that old asbestos cement shingles have been removed from the home even when new, completely different materials are installed.

We found this cement asbestos siding debris on the ground around a home that boasted new vinyl siding.
The presence of multiple layers of exterior siding can be spotted by noticing that the wall cladding extends out past the original window or door trim. But beware; when we renovated the building shown above we built-out the exterior trim so that it would continue to project beyond new vinyl siding installed on some wall surfaces.
The nails used to secure the shingles probably won't help unless some are obviously different from others; installers use the same galvanized box nails to hang these shingles as they did in 1955.

Planning demolition of cement asbestos siding or shingle siding materials?

The risk of high levels of airborne asbestos from cementious products is probably very low unless the workers are using power equipment like sanders and saws on these substances.

Using cement asbestos roofing products as an example, according to NRCA, the National Roofing Contractors' Association, their studies up to February 1992 had not found a single roofing job at which these limits were exceeded, and NRCA reported that in some cases no fiber release was detected. But it appears that the association may have been referring only to asphalt-based roofing materials, not jobs involving the demolition of other ACRM such as cement-asbestos roof shingles (or "asbestos roof tiles" as some consumers refer to them) which might produce different statistics.

See ASBESTOS MATERIAL REGULATIONS and ASBESTOS REGULATION Update that address the handling of asbestos containing building materials, including ACM (asbestos containing materials), PACM (presumed asbestos containing materials), SACM (suspect asbestos containing materials), and ACRM (asbestos containing roofing materials).

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Questions & answers about asbestos cement siding on buildings.

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ASBESTOS CEMENT & FIBER CEMENT SIDING
  Asbestos vs. fiber-cement
  Re-Sale Issues - Cement Asbestos siding
  Wear signs on cement asbestos walls
  Maintenance & Repair Asbestos Cement Shingles
  Remove & Replace Asbestos Cement Shingles
  Siding over asbestos cement
  Sources of Replacements for Asbestos Cement Shingles
  Tools to Cut Fiber Cement Shingles
  Painting Cement Asbestos Siding
  OSHA Asbestos Roof/Siding Regulations

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
Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your 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
Bullet Tools 920 Pro Magnum Shear I-20 Electricity Free 20 Inch Flooring and Siding Dust Free Cutter -(sold at Amazon and at other tool distributors) this is a great tool, but $900. http://www.bullettools.com/ Bullet Tools Company, 3390 W. Hayden Ave., Hayden ID 83835 - 800-406-8998 or international: 208-772-0175. sales@bullettools.com
"Copy on file as - /exterior/Asbestos_Cement_Shingles_NPS.pdf - Keeping a Lid on it - Asbestos Cement Building Materials - ", Amy Lamb Woods, Technical Preservation Services, National Park Service, 2000. Web search 07/08/2010 original source: http://www.nps.gov/history/hps/tps/recentpast/asbestosarticle.htm
Asbestos-cement products were developed in an era of ingenuity for creating easy to install and economic building materials. Although asbestos-cement has acquired a poor reputation by association of its title, it has not gained that reputation through a lack of durability or utility. In order to preserve this twentieth-century material, understanding what makes, or does not make, asbestos a hazard is truly important. In this case, no hazard is created when asbestos-cement building materials are sound and left in place, or when treatments incorporate non-abrasive means.
- END NOTES to the above article provide excellent historical references for asbestos cement products:
  1D.V. Rosato, Asbestos: Its Industrial Applications (New York: Reinhold Publishing Corp., 1959), 1, 62. This text is an excellent resource for information on the manufacture and production of asbestos products.
  2 L. Michaels and S.S. Chissick, eds., Asbestos, Properties, Applications, and Hazards (New York: Wiley, 1979), 1-2. Resource for various kinds of asbestos, their properties and chemical constituencies.
  3 Arnon Bentur and Sidney Mindess, Fibre Reinforced Cementitious Composites (London: Elsevier Applied Science, 1990), 288-304. This text reviewed long-term performances of asbestos-cement and concluded that “in natural weathering the composite is excellent.” More detailed quantitative material properties are also given in this text.
  4 L. Michaels and S.S. Chissick, eds., 306-312
  5 United States Department of the Interior Bureau of Mines, Materials Survey: Asbestos, (Washington D.C.: US Government Printing Office 1952), I-1 - I-4.
  6 Caleb Hornbostel, Construction Materials: Types, Uses and Applications (New York: John Wiley & Sons, 1978), 82.
  7 H. W. Johns, Patent Trademark Materials: Asbestos (New York: H. W. Johns Manufacturing Co., 1878), 12.
  8Rosato,63.
  9 D.A. St John, A.B. Poole, and I. Sims, Concrete Petrography: A Handbook of Investigative Techniques (London: Arnold Publishers, 1998), 320-322.
  10"Asbestos-Cement Products for War buildings," Asbestos (April 1942), 2-4
  11 Rosato, 75.
  12 The National Board of Fire Underwriters, Dwelling Houses (New York: The National Board of Fire Underwriters, 1920), 36-37.
  13 Ernest G. Blake, Roof Coverings: Their Manufacture and Application (New York: D. Van Nostrand Company, 1925), 144-171. Resource for detailed descriptions of many asbestos-cement roof shingle forms, styles, and hardware.
  14 James McCawley, Asphalt and Asbestos-Cement Shingle Residing (New York: United Roofing ContractorsAssociation, 1940).
  15 E. Lechner, “Recent Innovations in the Manufacture of Asbestos-cement,” Cement and Cement Manufacture, 7:6 (June 1934), 180-181.
  16 R.C. Smith, Materials of Construction, Third Edition (New York: McGraw-Hill Book Company, 1979), 358-359
  17 Asbestos Shingle, Slate and Sheathing Company, Asbestos Corrugated Sheathing (Ambler, Pennsylvania: The Keasbey & Mattison Company, 1913), 1.
  18 “Johns-Manville” product advertisement, Sweet’s Catalogue of Building Construction (F. W. Dodge Corporation, 1906-1961), 8b/4.
  19 Rosato, 63.
  20 National Trust for Historic Preservation, "Coping with Contamination: A Primer for Preservationists," Information Bulletin No. 70 (1993), 12.
  21 Bentur and Mindness, 304.
  22 Guidance given here only makes recommendations based on national agency laws and regulations; all applicable federal, state, and local laws and regulations must be followed for any asbestos-containing material project.
  23 Roger C. Whitman, More First Aid for the Ailing House (New York: McGraw-Hill Book Company, 1977), 282.
  24 Martin E. Weaver, Conserving buildings, Guide to Techniques and Materials (New York: John Wiley & Sons, Inc., 1993), 26.
  25 D.J. Hannant, Fibre Cements and Fibre Concretes (New York: John Wiley & Sons, 1978), 146-155. This reference give quantitative engineering properties for asbestos-cement and other fiber-cements..
  26 "The Industrial Uses of Asbestos," Scientific American (22 April 1876), 258-259.
  27 John E. Wilden, A Guide to the Art of Asbestos Cement (Winchester, England: Taylor & Partners Translations, 1986), 108. This resource is primarily concerned with the experience or art of producing asbestos-cement and reflects the practical side of production.
Malco® TSFC Tubo Shear fiber cement cutting tool (sold at Amazon and at other tool distributors) and also the Malco TSF2A Shear Cutting Tool, a heavy-duty pneumatic shear cutting tool for the same purpose (available at Amazon.com) Malco Products, http://www.malcoproducts.com/ specializes in producing tools for the HVAC trade. Malco Products, Inc. - PO Box 400, 14080 State Highway 55 NW, Annandale, MN 55302-0400 P: 800-328-3530, F: 320-274-2269

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 a lot 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

Please see Remove & Replace Asbestos Cement Shingles for the full article on this topic.

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.

Siding over asbestos cement siding

Please see Siding over asbestos cement for r the full article on this topic.

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.

Sources of Replacements for Asbestos Cement Wall Shingles

Please see Sources of Replacements for Asbestos Cement Shingles for the full article on this topic.

One manufacturer of cement-asbestos shingles was Ruberoid Co., who made 8" x 16" tapered singles with a surface pattern resembling wood and called "Ru-Ber-Oid-Eternit Tapered Timbertex Asbestos-Cement Shingles." 260 singles/525 lbs/square, were available in a wide range of colors.

Contemporary cement asbestos product manufacturers make reinforced fiber-cement wall and roofing shingles and other products which look like, perform similarly to, and need to be installed similarly to the original asbestos-cement shingles - but these new products are free of asbestos. The replacements for asbestos cement wall siding products are reinforced with a variety of fibers including fiberglass. Other replacements for asbestos-cement siding use both different fibers and a different aggregate (perlite) to replace the asbestos. Some of the substitute products have been in use for more than 30 years (2008).

For maintenance or replacement of asbestos-cement wall siding or roof shingles (or wall siding) contact Supradur Manufacturing Corporation, PO Box 908, Rye NY 10580 800-223-1948, or from within New York State, call 914-967-8230. Ask about their Supradur(R) mineral fiber shingles.

For handling and disposal guidance concerning old cement-asbestos wall siding material contact the US EPA, your state Department of Environmental Protection/Conservation, or your local building and health departments.

Painting Cement Asbestos Building Siding

Please see Painting Cement Asbestos Siding for the full article on this topic.

Should I paint my asbestos cement shingles? Do you need to use special paint for cement asbestos siding?

Painting cement asbestos siding or non-asbestos fiber cement siding is mostly a cosmetic decision. We have never seen this material in a worn, friable condition, but should that occur, one might paint the surface also to stop fiber shedding and to preserve the material.

Fiber cement shingles, both new non-asbestos product and the older asbestos-cement product are provided from the manufacturer with a coated surface, usually white. When the asbestos cement siding is soiled or moldy or has an algae coating we prefer to gently clean the surface with a sprayer, perhaps a deck cleaner solution. If you use a power washer be careful to spray "down" (to avoid blowing water into the building walls) and to keep far enough away that you do not damage the siding or "rough it up" which may cause more rapid deterioration or even fiber or asbestos release.

But sometimes the asbestos cement or fiber cement shingles just look soiled and do not clean up enough to satisfy the homeowner. In general, this siding material can be painted using normal house paints. Check with your paint suppliers because some paints may not be recommended for the surface. But once you paint the siding, you've converted a "no maintenance" surface into one that will occasionally need to be re-painted for cosmetic reasons.

OSHA Regulation of roof demolition where asbestos containing roofing materials ACRM are present may also pertain to wall siding demolition

Please see OSHA Asbestos Roof/Siding Regulations for the full article on this topic.

According to NRCA, the National Roofing Contractors' Association, their studies up to February 1992 had not found a single roofing job at which these limits were exceeded, and NRCA reported that in some cases no fiber release was detected.

We note that the NRCA would have been referring only to asphalt-based roofing materials, not jobs involving the demolition of other ACRM such as cement-asbestos roof shingles (or "asbestos roof tiles" as some consumers refer to them) which might produce different statistics.

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

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Asbestos Hazard, Testing, Removal, References & Products

Environmental Health & Investigation Bibliography - our own technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
ASBESTOS IDENTIFICATION IN buildings How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials
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

Asbestos in Good Condition
Asbestos in Good Condition
Asbestos in Your 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
Asbestos HVAC Ducts and Flues field identification photos and guide
Asbestos NESHAP Adequately Wet Guidance, EPA340/1-90-019, December 1990, U.S. ENVIRONMENTAL PROTECTION AGENCY, Office of Air Quality Planning and Standards, Stationary Source Compliance Division, Washington, DC 20460,original web source: http://www.epa.gov/region04/air/asbestos/awet.htm
Asbestos paper duct wrap
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, text and images available at InspectAPedia.com).
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
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.
"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

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Photo Guide to Cement-asbestos Wall Shingles or Siding Products

How can we tell the difference between asbestos-containing shingles and fiber-cement wall shingles?

Planning demolition of cement asbestos siding or shingle siding materials?

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Maintenance & Repair Tips for Asbestos Cement Wall Siding Shingles

How to Remove and Replace Broken Asbestos Cement Wall Shingles

Siding over asbestos cement siding

Sources of Replacements for Asbestos Cement Wall Shingles

Painting Cement Asbestos Building Siding

OSHA Regulation of roof demolition where asbestos containing roofing materials ACRM are present may also pertain to wall siding demolition

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

Asbestos Hazard, Testing, Removal, References & Products