Asbestos siding was used in homes mainly between the 1920s and 1970s at which time the use of asbestos was mostly discontinued because of health issues. In those years, asbestos provided a popular alternative to wood or masonry as it provided sound- and fire-proofing and was less expensive than other traditional products. Asbestos siding was often used in locations where natural materials wouldn't last; for example, asbestos was considered a good alternative to wood siding in wet coastal environments. Cement siding - which looks the same - has completely replaced asbestos siding in new construction and can be used to replace asbestos siding planks as needed.
How Asbestos Siding was Produced
Asbestos was used as a composite material in siding usually along with fiber cement. Asbestos - a long, thin fibrous mineral - was mixed in with Portland cement. Interlaced layers of the composite material were obtained by feeding the slurry through a laminating machine. While still malleable, the sheets were either corrugated or left flat.
Later, a dry method was invented in which the asbestos and cement mixture was spread on a conveyor belt. An embossed cylinder applied pressure on the still malleable material and left a textured surface. The composite product was left to cure for 24 hours and was then cut and steam cured.
Types of Asbestos Siding
Shake asbestos siding tiles - either rectangular or hexagonal - were the most popular because they were easily handled and cut to fit. Typical dimensions of shingles were 12 x 24 inches, but a 9.5 x 24 inch size was also available. In the 1930s, clapboard measuring 8 feet long with an exposure of 9.5 inches was manufactured by Johns Manville. A brick-type siding was also offered in the 1930s by Ruberoid. Most siding planks, tiles, and shakes featured a wood grain texture and came in a variety of colors including green, gray, white, and brown.
Warranties on Asbestos Siding
Since asbestos siding has not been used in construction in most states since the 1970s, no warranties would still be in effect. Homeowners requiring repairs or removal of existing asbestos siding should contract with a professional to ensure safe working conditions.
Common Problems with Asbestos Siding
Asbestos siding doesn't release dangerous fibers into the air until disturbed and so is safe to leave it in place. The US Environment Protection Agency (EPA) states: "These products are not likely to release asbestos fibers unless sawed, drilled or cut."
The most important issue with any asbestos building product, including siding, insulation, and popcorn ceilings, is the carcinogenic effects of fibers on the lungs. That is why many states require special permits, training and discarding techniques in case asbestos is released into the air during the removal and disposal processes.
Any repairs including sanding, drilling, scraping, or sawing of asbestos siding should be done by a professional trained in taking the appropriate precautions to avoid releasing asbestos fibers into the air.
- Bird Weather-Tex
- Eternit by Ruberoid
- Johns Manville
- Keasbey & Mattison
- Mineral Fiber