Saving loose plaster
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Reattaching loose plaster
Pull loose plaster tight to the lath with plaster washers. If the screw cracks the plaster as it goes in, predrill through the plaster. Finish by skim coating the washers.
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Applying fiberglass mat
Fiberglass mats can cover cracking in well-adhered plaster walls. In the Nu-Wal system shown in the photo, a base coat is rolled on the wall and then covered by a fiberglass mat.
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Topcoating the fiberglass
Roll a special topcoat over the fiberglass mesh if you use the Nu-Wal product; otherwise skim coat the mesh with two coats of joint compound.
Plaster sags from ceilings or bulges
from walls when the plaster keys
embedded around the wood lath
break loose. To repair it, you've got
two choices. You can break out all
the loose stuff and replaster the
area—not a do-it-yourself project.
Or, you can stabilize the sagging
plaster by using plaster washers to pull it back up
against the lath. Plaster washers
don't always work, but they're
cheap so it's worth a shot.
First, locate the joists or studs
and mark their location in the loose
area. Push up the loose plaster and
place 2-in. screws and the perforated
plaster washers into the joists or studs about every 6 or 8 in. The
convex washer will flatten as the
screw tightens. If the plaster has a
rough surface, you may need to first
scrape the surface to get the washer
to lie flat. Next, secure the loosened
field to the lath between joists with
more washers. Finally, skim-coat
over the washers with drywall joint
compound. It may take several coats
and extra effort to create a smooth
finish or mimic the existing texture.
If you have solidly attached
plaster with cracks spider-webbing
through your walls and ceilings, you
can stabilize and coat the entire surface
with another product—wide sheets
of fiberglass mat. Self-stick mats are available at home centers. Simply stick them to the wall or ceiling and then skim coat with two or three coats of joint compound. Another system,
called Nu-Wal, uses a slightly different method.
First, you roll
on a latex-like base coat. Then embed
the fiberglass mesh, and roll over it
again. This method essentially gives
your plaster walls a new flexible skin so non-structural cracks won't
reappear. Plus, it acts like a vapor
barrier, keeping moisture from
migrating into the wall, and it's
approved for lead paint encapsulation
on interior walls.