 As
a house settles, cracks often form at the corners of windows
and door frames and on walls and ceilings. As temperatures
and humidity vary, the materials in your house expand
and contract. Each section tends to move at an independent
rate, which can crack your ceilings and walls.
Fix simple cracks and holes using drywall joint compound
and fiberglass joint tape. This involves chipping away
at plaster, which can irritate your skin and get in
your eyes and lungs. To protect yourself, wear safety
goggles, a particle mask, work gloves, a long-sleeved
shirt and long pants.
Small cracks are easy to fix. Although some people
think hairline cracks add character to their homes,
when the cracks reach the thickness of a spaghetti noodle,
they should be repaired to protect the wall. Use a utility
knife to widen the crack so the inside crevice is slightly
wider than the outer edge. Then vacuum out the dust
and chips. Fill the crack with drywall joint compound,
using a 3-inch-wide putty knife. Flush it out so the
finish is level with the rest of the wall or ceiling.
Then let it dry overnight.
The next day, apply fiberglass joint tape over the
sealed crack, pressing down to hold it in place. Follow
with one or two coats of compound, feathering out the
edges with an 8-inch-wide drywall-taping knife or a
trowel to even out the finish.
Fixing small holes—those no larger than 8 inches
wide—requires a few more supplies. You’ll
need plaster of Paris, some wire mesh designed for plaster,
and plaster bonding agent. As with cracks, undercut
the edges of the hole, leaving a beveled edge that flares
into the wall, rather than out. Then brush bonding agent
on the lath or existing mesh, as well as along the edges
of the hole.
Until recently, most plasterboard was formed by applying
several coats of plaster to a backing made of strips
of wood, called laths. For wood lath walls, insert a
small piece of wire mesh into the hole. This creates
additional crevices for the plaster to adhere to. Fasten
it to the wall with drywall screws instead of nails.
Cover the hole with plaster of Paris. Smooth the mixture
with a trowel, then cut off pieces of the flexible tape
and seal the edges of the hole to form a frame. Finally,
apply two or three thin layers of joint compound, using
a trowel. Then blend the compound to match the existing
finish.
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