How can I tell if there is asbestos in a house?
Saturday, October 13, 2018
When Fred Astaire sang the line “heaven rest us, I’m not asbestos” in the 1935 hit song I Won’t Dance, asbestos was a well-known wonder material on the rise in American industry. The fibrous mineral is heat and fire resistant, unaffected by most chemicals, electrically nonconductive, relatively inexpensive, and has good tensile strength. Although its properties have been known since ancient times, asbestos first began to be widely used in construction and manufacturing in the 1880s. More and more applications for its unique properties were found over the years, with usage peaking in the 1960s.
The six types of asbestos minerals are chrysotile, crocidolite, amosite, anthophyllite, tremolite, and actinolite. An example of chrysotile is shown below.
Unfortunately, the material also has a sinister side: it causes several types of debilitating/fatal illnesses and cancers when airborne asbestos particles are repeatedly inhaled or ingested. Even worse, symptoms do not appear until 20 to 40 years after exposure. As scientific evidence mounted proving the relationship between asbestos and multiple lung diseases, production and use of asbestos-containing products was severely restricted by government regulation. It has been banned from use in residential building materials since the mid-1980s, and OSHA enforces strict safety regulations for construction and manufacturing workers that have any level of asbestos exposure during their job.
But homes built before asbestos was banned, and especially ones from the 1920s through the mid-1970s, may still have asbestos-containing materials in place. Because asbestos is inert, moisture does not decompose it over time like organic materials, and 60-year-old asbestos-cement siding—as shown in the photo at the top of the page—is often still in excellent condition. Asbestos was also used in roofing, insulation, coatings, flooring and ceiling tiles.
The good news is that asbestos is only dangerous when the tiny fibers are “friable,” which means loose and able to float in the air. The general recommendation of the U.S. Environmental Protection Agency (EPA) is to leave asbestos-containing building materials alone unless the they are damaged, frayed, or otherwise deteriorating. Don’t disturb them. Sawing, drilling, sanding, or removal will release the dangerous friable particles into the air.
There are no standard visual clues that a product contains asbestos. It can only be positively identified in a lab, using a polarized-light microscope—unless you get lucky and find an asbestos label or imprint on the material. But there are a number of mid-20th century and earlier building products that are known to contain asbestos and fairly easy to recognize. Here are five of the most common:
1) Asbestos-cement siding - The most popular style has a wavy bottom edge and striated surface. We still see it often in the older sections of town, since the stuff is nearly indestructible. See our blog post The house has asbestos siding. What should I do? for more information on this product.
2) Asbestos in floor tile - If you are a baby-boomer, you will recognize the streaked or multi-color spotted tiles from the floor of your elementary school classroom. Mid-century sheet vinyl flooring also contained asbestos. Asbestos was added to vinyl, rubber, linoleum and asphalt floor tile compositions. Beware: you might find older tile with asbestos content under a layer of newer tile during remodeling work. See our blog post Are old vinyl tile floors dangerous? to learn more.
3) Asbestos-cement and asbestos-asphalt roofing - There was an asbestos cement corrugated roof panel used primarily for industrial buildings and rarely encountered anymore, but we still occasionally see asbestos-asphalt and asbestos-cement shingles that are 60+ years old still in place. It is usually a thick shingle and often in a scalloped pattern. Most homeowner’s insurance companies will not insure a roof that old and removal is hazardous, requires a professional abatement contractor, and is expensive. See our blog post What is the life expectancy of an asbestos cement shingle roof? to learn more.
4) Pipe insulation - Asbestos was used for pipe insulation as a wrap of woven cloth, a batt-like blanket, and as part of an applied coating. We recently came across some asbestos insulation in the crawl space of a 1920s house as a wrap for long-abandoned boiler piping. It was a fabric wrap similar to the close-up photo of the material at right, and much of it had been pulled down onto the ground by animals looking for nesting material. An arrow points to the pipe and insulation.
Rock wool insulation is often confused for asbestos, but it is a completely different rock composition and not carcinogenic. To learn more, see our blog post There's old insulation in the attic labeled "rock wool." Is it really dangerous asbestos?
5) Acoustic ceiling tiles and vermiculite attic insulation - Both of these may contain some asbestos, particularly acoustic tiles that predate suspended ceilings and were stapled into place. Read our blog post Why is vermiculite attic insulation a problem for both buyers and sellers of a home? for more.
Determining whether an older home has asbestos-containing materials is beyond the scope of a home inspection and most home inspectors, including us, disclaim responsibility for identifying it. The most obvious examples, like the ones noted above, may be called out for further evaluation when observed.
But there are specialized asbestos inspectors who have the knowledge and experience to recognize an array of materials that are likely to contain asbestos and will also provide lab testing on samples taken. Sampling itself can release asbestos fibers into the air and the pros use a safety protocol that includes wetting the material to be sampled before removal.
The EPA recommends the following guidelines for home asbestos safety:
Asbestos Do's and Don'ts for the Homeowner
- Do leave undamaged asbestos-containing materials alone.
- Do keep activities to a minimum in any areas having damaged material that may contain asbestos, including limiting children's access to any materials that may contain asbestos.
- Do take every precaution to avoid damaging asbestos-containing material.
- Do have removal and major repair done by people trained and qualified in handling asbestos. It is highly recommended that sampling and minor repair also be done by a trained and accredited asbestos professional.
- Don't dust, sweep, or vacuum debris that may contain asbestos.
- Don't saw, sand, scrape, or drill holes in asbestos-containing materials.
- Don't use abrasive pads or brushes on power strippers to strip wax from asbestos flooring. Never use a power stripper on flooring that may contain asbestos.
- Don't sand or try to level asbestos flooring or its backing. When asbestos flooring needs replacing install new floor covering over it, if possible.
- Don't track material that could contain asbestos through the house. If you cannot avoid walking through the area, have it cleaned with a wet mop. If the material is from a damaged area or if a large area must be cleaned, call an asbestos professional.
• • • • • • • • • • • • • • • • • • • • • • • • • •
Here’s links to a collection of our blog posts about MOLD, LEAD AND OTHER CONTAMINANTS:
How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
for Links to Collections
of Blog Posts