Cement asbestos roof shinglesAsbestos Dust Hazards from Cement Asbestos Roofing or Siding Shingles

  • ASBESTOS ROOFING / SIDING DUST - CONTENTS: Asbestos dust hazards from using tools to saw, cut, or drill cement-asbestos shingles or siding. Difference between asbestos-containing shingles and fiber-cement wall shingles?asbestos. Dust hazards from demolition of asbestos cement siding or shingle materials?
  • POST a QUESTION or READ FAQs about dust hazards from removal or demolition of cement asbestos roofing or siding

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Dust hazards from asbestos cement siding or roofing demolition or removal: this article discusses potential asbestos-dust hazards from power-sawing cement-asbestos siding materials.

This document series 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.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Asbestos Dust Hazards from Cement-asbestos Wall Shingles or Roofing Products

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

Question: I was sawing cement asbestos wall siding - should I be worried?

I was helping an older gentleman fix a screen door that was brushing the siding of the over hang of his house.

I just got a saw and trimmed a quarter inch off of a 4 foot section ....later it came to my mind that it was likely cement asbestos type siding...loks just like the picture you have that is pointing to the siding.

The cutting was overhead and dust and debris was flying. I did not wear a mask ...I didn't realize it was that type siding.

Should I be concerned? Or is it long term exposure that would typically be more of an issue?

I would appreciate any feedback you can give me. - M.S.

Reply: Maybe ..

For an accurate answer to your question of whether or not you exposed yourself (and anyone else nearby) you'd need to:

  1. Confirm that the material you were sawing contained asbestos - though in fact breathing high levels of nearly any construction demolition dust can be a respiratory irritant or worse. 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.
    See ASBESTOS CEMENT SIDING or for a more broad look at identifying asbestos-containing materials

  2. Estimate of the amount of asbestos-containing dust to which you were exposed, its concentration in the air, how long you were breathing it. In our opinion it's not so likely that making a single 4-foot power cut along asbestos-containing material produced a large asbestos contamination issue, but it is more of a concern that using a power saw to cut any asbestos-containing product produces a cloud of fine dust particles that was right in the face of the person operating the equipment.
  3. Consult with a doctor who specializes in environmental medicine.
  4. Clean up asbestos-containing dust and debris from the job. A acceptable approach to cleaning up any asbestos dust mess that you may have left at the jobsite

So really we don't know the answer. Very acute exposure to high levels of asbestos containing dust, such as workers at the world trade center collapse on 9/11/01, indeed has led to health problems for those individuals, as has been much in the news.

A different example of hazardous dust exposure that was serious was that of workers in industry or shipyards who were exposed to high levels of dust (less than the WTC collapse) over long periods of time.

A short exposure to low dust levels may not produce a measurable effect on someone. For example, asbestosis among contractors who installed asbestos-insulated heating piping has not been widely reported, while asbestosis among shipyard workers, workers in brake shoe factories, and emergency workers at the 9/11 site has been a concern.

We can suggest several steps:

  1. Consult with an environmental physician, describe your exposure, and ask what symptoms, complaints, or tests you should watch out for or consider
  2. Watch out: there are many many lawyers, a few doctors, and others who profiteer on environmental-fear and who may be happy to offer you costly services that you don't need - that's why you should start with a professional MD who has experience in this field
  3. DO NOT do that again - it's a bad idea to run power saws, grinders, etc. that make dust out of asbestos containing siding.

Background On Asbestos Dust Hazards

Cement asbestos roof shinglesAs we discuss at ASBESTOS CEMENT SIDING:

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:

New and old fiber cement and asbestos cement shingles side by side (C) Daniel Friedman

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.

Fiber cement siding shingle back side identification stamp (C) Daniel Friedman

Demolition debris from asbestos cement shingles (C) Daniel Friedman

What are the asbestos dust hazards created during demolition or removal 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.


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).

Also see other cementious siding materials such as JAMES HARDIEPLANK® FC SIDING (also see Hardie's Fibrolite™ or Fibro where used in Australia) and cementious roofing materials such

and Corrugated Cement-Asbestos Roofing.

Also see Environmental Issues - Asbestos Roofing/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. Please
see ASBESTOS CEMENT SIDING-OVER for the full article on this topic.

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.

What about replacing the cement asbestos siding or roofing ?  Can you side over the existing asbestos cement siding or roof over cement asbestos roofing or does it need to be removed? It is very difficult to remove individual broken asbestos-cement wall or roof 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.

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


Continue reading at ASBESTOS REMOVAL, WETTING GUIDELINES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




Or see DUST SAMPLING PROCEDURE for a strategy for collecting building dust samples, when, where, how many samples to collect,

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