by Linda Mason Hunter

If you live in a house that was built or remodeled between 1900 and the early 1970s, it's highly probable you're living with asbestos, a carcinogenic building material. Here's where you're likely to find it:

Hot Water and Steam Pipes

In some older houses, hot water and steam pipes may be covered with an asbestos-containing material to reduce heat loss. Manufactured from 1920 to 1972, this insulation was usually preformed in half-rounds, then wet-gauzed in place. Pipes were also wrapped in asbestos-paper tape. Look for this whitish material on pipes in the basement.

Ducts and Furnaces

During the 1940s and 1950s, these were frequently insulated with asbestos-impregnated papers. This chalk-colored insulation was applied as flat sheets as thin as 1/16 inch or as corrugated versions. As this ages, asbestos fibers may be released into the ventilation system. Asbestos cement was the material of choice for heating ducts built into concrete slab floors in houses constructed between 1950s and the late 1970s.

Asbestos Boiler Wraps

Typically made of chalky blocks about two inches thick, asbestos wraps were fastened to boilers by wires or metal lath and then coated with plaster-saturated canvas. They tend to disintegrate rapidly in humid environments or when soaked with water.

Vinyl Flooring

Vinyl floor tiles and sheet flooring manufactured prior to 1979 often contain asbestos to strengthen the flooring and help it resist wear. While asbestos fibers normally can't escape from the surface, tearing, cutting, or sanding can release asbestos content.

Decorative Coating Walls and ceilings may have fluffy asbestos coating that was sprayed or troweled on. This was especially popular during the late 1960s and early 1970s and is found most often in hallways and entries.

Insulation Wall, ceiling, and attic insulation in houses constructed between 1930 and 1950 may contain insulation made with asbestos. This is often found inside the structure sandwiched between plaster walls and the framing.

Roofing and Siding

Asbestos cement used to be a popular material for roofing shingles (1940s through 1960s) and siding (1930s through 1970s). Asbestos-containing roof shingles are usually gray and often bear brownish white streaks along areas where water drains more slowly.

Joint Compound and Textured Paint

Joint compound made before 1977, used to tape joints on wallboard and fill holes in plaster, contains as much as 15% asbestos. Textured paints made before 1978 may also contain asbestos.

Fireproof Board

When wood-burning stoves and oil, coal, or wood furnaces were installed in the past, asbestos-containing cement sheets and millboard were frequently used as a fireproofing material to protect the floor and walls around them. You can recognize it by its gray color and size of the sheets, usually 1/4 to 3/4 inch thick, resembling plasterboard. Avoid scraping, sanding, drilling, or sawing these materials.

Acoustic Ceiling Tiles

Asbestos is found in acoustic tile, the kind you often see in basement recreation rooms. Asbestos in this product is usually a brownish material.

Door Gaskets

Some door gaskets in furnaces, ovens, and wood and coal stoves may contain asbestos. Handle this material as little as possible.

Dealing With Asbestos Always be cautious around materials that you suspect may contain asbestos. Look for areas where asbestos has become damaged by water, dented, corroded, blistered, or changed in any way that might allow the release of fibers into the air. If you find damaged asbestos, don't disturb it. First, determine if it is asbestos.

Encapsulating Asbestos Involves containing the asbestos behind a barrier so the fibers cannot escape. If you have asbestos wrapping around your heating ducts, for example, you can encapsulate it with three layers of duct tape. Be careful, though. You'll want to take the necessary precautions. Contact your local EPA office to learn about those precautions.

An experienced remodeling contractor can pinpoint any materials in your home that contain asbestos. You may want to have the material analyzed by a laboratory if you are preparing a major renovation that will expose materials contained behind a wall or other barrier. A state health agency or your local Environmental Protection Agency (EPA) office should be able to take a sample you and have it analyzed.

© 2007 Green Home, Inc.