Cement asbestos building siding shingles (C) Daniel FriedmanAsbestos in Building Siding Materials
How to identify asbestos-cement wall siding

  • ASBESTOS CEMENT SIDING - home - CONTENTS: Guide to Cement-asbestos Wall Shingles or Siding Products - How to recognize asbestos building siding or wall cladding materials: asbestos cement or "cement-asbestos siding". How can we tell the difference between asbestos-containing shingles and fiber-cement wall shingles? Planning demolition of cement asbestos siding
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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 cement asbestos siding article series 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

Cement asbestos roof shinglesIn 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. This is the "wavy edge" asbestos cement shingle siding product.

But only the installer (me in this case) 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.

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 shingle siding, Hughsonville, NY (C) Daniel FriedmanAsbestos 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.

The building shown at left, located in Hughsonville, NY, using the "thatch edged" shingle siding style is almost certainly sided with asbestos-cement shingles.

From the 1940's to perhaps the early 1970's it was popular to cover peeling wood clapboard buildings with this durable material. We estimate that this building was probably re-sided in the 1960's.

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 reinforcing fiber used was asbestos. Asbestos in granular or powder form may also have been mixed in with cement as a filler when these products were m anufactured.

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. At below left I point to an older asbestos cement siding shingle while to the right of my finger the next shingle is a modern asbestos-free fiber cement siding shingle.

I know the difference because I installed the new material. Otherwise, without close inspection or a lab test it would be difficult to say which was which.

  • Age or date of installation: installed before 1978 the shingles probably contain asbestos.
New and old fiber cement and asbestos cement shingles side by side (C) Daniel Friedman New and old fiber cement and asbestos cement shingles side by side (C) Daniel Friedman
  • 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 the above-left 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.

    At above right we illustrate why additional coats of paint on a fiber cement or asbestos cement siding shingle means future painting maintenance will be required. Proper paint preparation (cleaning) and priming, then painting with paints recommended for use on this material may give better results than we see at above right.

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

  • The back of a new fiber cement wall shingle will probably have a code stamped on it such as we show above.
Demolition debris from asbestos cement shingles (C) Daniel Friedman
  • 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?

Corrugated asbestos cement building siding in New York City (C) Daniel FriedmanThe 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.

Our photograph at left illustrates that corrugated asbestos cement (or on newer buildings corrugated fiber cement) panels are also used as siding, not just as a roofing product.

This building was observed in New York City and based on its age, we suspect that the material shown is asbestos cement corrugated siding, not a newer fiber cement product.

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.


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