Gypsum or rock lath is a pre-manufactured plaster board, generally 16
inches by 48 inches in size,
and 3/8 inch thick. Rock lath became popular in the 1930s as a less expensive
alternative to wood lath. It is nailed directly
to the wall studs and receives two coats of plaster over it. The rock lath
is called the first coat and replaces the wood lath and the brown coat of
the previous wet plaster system. The second coat is a cement plaster about
1/4 inch to 3/8 inch thick. The finish coat is then applied, which is
comprised of hard
finish plaster, and is approximately 1/8 inch thick.
Rock laths can be identified by a crack
pattern that may be visible in ceilings and walls or may be visible on the backside of walls in areas such as the attic.
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Interior Main Page Ceiling and Wall Main Page
Drywall
Plaster Wood Lath
Wire (Metal) Lath
Other
Finish Material Other
Ceiling Types Interior Trim
