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Asbestos, once known
as the miracle rock, is sometimes a case for worry and hasty action
among old house owners. Asbestos has been in use for over 100 years,
and rehabilitation work often means removing - or at least exposing
- building products that may contain asbestos. It's true that awareness
of the health risks associated with asbestos prompted the EPA in
1978 to ban its use in at least one application. Yet not every asbestos-bearing
material is a health concern, and not everything that looks like
asbestos is asbestos. Before you can decide what to do about asbestos
in old houses, you have to confirm it's there. This article will
tell you what to expect.
Asbestos is a general
term for a group of six fibrous minerals that occur naturally in
rocks and soil. The group is divided into two major types - serpentine
and amphibole - each of which is further divided into subtypes found
throughout the world. For example, amosite, a type of amphibole
asbestos, comes from South Africa. By far the most common variety
of asbestos used in the United States is Chrysotile, mined predominantly
in Canada. Chrysotile asbestos is off-white in color and does not
dye well.
All types of asbestos are noncombustible, high in tensile strength,
and good insulators - an uncommon mix of characteristics that makes
them ideal additives to many materials. Asbestos-containing materials
- called ACMs for short - are also classed as either friable or
nonfriable. In nonfriable form, the asbestos fibers are integrally
bound in another hard material. Products that contain asbestos in
friable form, however, can be easily broken, crushed, or ground
so the asbestos fibers are released into the air. Since asbestos
has been demonstrated to cause illness when inhaled, the fibers
hold the most potential for harm if they become airborne.
The first known users of asbestos were the ancient Greeks, who wove
the fibers into lamp wicks. In the United States of the 1890's,
where steam had become the primary source of heat and power, asbestos
was introduced as a component of boiler insulation. Since then it
has been added to over 3,000 building materials to increase their
strength and make them fire retardant. The popularity of asbestos
grew throughout this century, reaching its peak production in 1974.
In that year alone 817,100 tons of asbestos were incorporated into
hundreds of products.
Any likely building product that has a gray or white fibrous layer
might contain asbestos. Some products, such as cement or floor mastic,
have asbestos mixed into them. In these cases, the color or texture
of asbestos may not be noticeable.
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If you are planning any
kind of remodeling activity or simply seeking peace of mind, you
may want to have an EPA-certified asbestos inspector examine your
house. You can locate such firms in the phone book or by contacting
your state or local health department. The inspector will make a
visual examination and carefully collect small samples for analysis.
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Asbestos in the Old House
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materials installed before 1980, asbestos may be present. Here are
some of the most common products where it is likely to occur:
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Exterior Surfaces
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Cement Roof Shingles
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Roof Tar
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Cement Siding Tiles |
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Window Putty
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Deck Undersheeting
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Caulk |
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Roofing
Felt |
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Insulation
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Particularly
Between 1930 and 1950 |
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Loose
Blown-In Fill |
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Rolled
Batts |
Floor Coverings
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Vinyl
Sheet Flooring |
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Undersheeting
(the Backing on Flooring) |
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Mastic Adhesives
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Vinyl
Floor Tiles |
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Boilers, Heaters, and Piping
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Boiler/Heater
Insulation |
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Pipe Lagging
(Insulating Covers) |
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Duct Insulation
(A Lining) |
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Boiler Wall
Gaskets and Lining |
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Duct Tape
(Over Joints) |
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Water Heaters
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Boiler Door
and Cover Gaskets |
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Cookstove
Ovens and Hoods |
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Gas Fireplace
Logs, Embers, and Artificial Ashes |
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Interior Surfaces
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Acoustical
Ceiling Plaster |
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Heat
Reflectors (For Wood Stoves) |
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Wall
Plaster (Usually the Brown Coat) |
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Ceiling
Tiles |
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Textured
Paint |
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Drywall
Joint Compound |
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Gas
Fireplace Logs, Embers, and Artificial Ashes |
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Heat
Shields (For Recessed Light Fixtures) |
Electrical Equipment
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Heat
Shields In Lamp Sockets |
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Outlet/Switchbox/Wire Insulation
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Appliance
Insulation (Toasters to Freezers) |
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Main
Service Panels/Fuse Boxes |
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