Asbestos siding was used on hundreds of thousands of homes throughout the United States before asbestos building products were banned in the late 1970s. According to the Environmental Protection Agency and other experts, asbestos siding only becomes hazardous when it deteriorates or breaks and releases tiny asbestos fibers into the air. Because of that, special precautions must be taken when making repairs or renovations that may disturb or remove asbestos siding.
Function
Asbestos siding is made of asbestos cement, a mixture of Portland cement and asbestos fibers. It was used to cover the exterior of buildings to prevent rot, mildew and pest infestation. In addition, asbestos siding resists fire, which made buildings covered with asbestos shingles or asbestos siding sheets safer in the event of a fire.
Features
The addition of asbestos to the cement created a building that was lightweight, water-resistant, fire-resistant, termite-resistant, easy to clean and resistant to rot. Because the color was typically mixed into the asbestos cement when it was made, it never needed repainting, and because it was non-porous, it was very resistant to dirt. Asbestos siding tiles were manufactured with pre-drilled nail holes at the bottom so that the shingles could be easily nailed to the exterior of the house starting at the bottom and working up. This made it much easier to apply the siding to buildings. The ease of use made it very popular with the construction industry because it reduced the amount of time and labor it took to build a house.
History
Asbestos cement had been in use in the United States for some time before Ludwid Hatschek invented a machine that shaped the cement into sheets and pipes. The new process made it easy for manufacturers to create corrugated sheets of asbestos cement which were further refined into shingles. By the 1920s, the National Board of Fire Underwriters recommended that homeowners use asbestos siding and roofing instead of more flammable wood materials. The recommendation from a nationally known insurance board boosted sales and by the 1940s, there were hundreds of thousands of homes throughout the country that used asbestos siding.
In the late 1960s and early 1970s, the hazards of asbestos began to be reported upon in the public press. By 1979, the U.S. government had outlawed the use of asbestos in many building products, including asbestos cement siding shingles.
Significance
Asbestos dust has been identified as the only known cause of mesothelioma, a deadly cancer with no known cure. Asbestos siding in good repair does not present a health hazard to the residents of a building or the community. When a building is destroyed, however, or when it undergoes major renovations, asbestos siding can be damaged and release asbestos fibers into the air. To prevent this from happening, most city and state governments have strict regulations about demolition and repair of buildings that have asbestos siding and other asbestos products. If those regulations are not followed, the owner of the home can be fined. More importantly, if the proper procedures aren't followed when removing or repairing asbestos siding, the entire community may be at risk of asbestos exposure.
Identification
Asbestos siding was manufactured in a wide range of colors and patterns, but it does have some characteristics that will help you identify it. Asbestos siding shingles are usually 12 by 24 inches. They may have grooves or a wood grain pattern pressed into the cement, or they may be smooth. Each tile usually had two or three nail holes at the bottom of each shingle.
The other main type of asbestos siding came in 27 1/2-inch corrugated sheets of various lengths. These sheets were used the same way that corrugated metal sheeting was used. It can be recognized by the corrugation, but these sheets were seldom used in home construction.
Warning
Asbestos siding is not a health hazard unless it is deteriorating, or unless it is damaged in some way that creates dust laced with asbestos. When asbestos fibers are released into the air and breathed in, they can lodge in the lung linings and eventually may cause mesothelioma or other asbestos-related diseases.
Prevention/Solution
The best way to deal with asbestos siding on your home is with a combination of inspection and general maintenance. These are steps recommended by the Environmental Protection Agency and the National Park Service's Technical Preservation division.
Inspect the asbestos siding regularly to watch for damage.
Protect the asbestos cement tiles from damage with shrubs or bumpers.
Replace missing or damaged tiles with non-asbestos containing tiles.
Patch or repair slightly damaged tiles with epoxy or Portland cement.
Clean soiled tiles with mild detergent or with a diluted mixture of sodium citrate or oxalic acid and glycerin.
If asbestos siding must be removed, or if the building is to be demolished, it should be done by a professional following any local or state ordinances for handling and disposing of asbestos.