Then flare the edges with a 5-in-1 tool to increase the bonding surface area. Because this process takes a toll on cutting tools, keep a small sharpening stone at hand to restore their edges.
To repair a crack in solid plaster, first mist it with water to prevent the patching compound from drying out too quickly.
Then fill it with a setting-type joint compound. Cover the filled crack with fiberglass tape and skim it with another layer of compound, then wipe it clean with a drywall knife. Use ready-mix compound for finish coats.
I countersink the plaster washers (slightly) to avoid having to feather the joint compound to create a flush appearance.
I predrill using a 1 1/ 4-inch carbide hole saw, which can be adjusted so the pilot doesn't bore into the wood.
Fastening with 2 1/2-inch screws into the studs clamps the plaster under the washers. If the spaces between washers are still spongy, attach the washers to the lath with 1 1/4-inch drywall screws.
When used with drywall screws, these thin, perforated discs (Charles Street Supply Co., 800/382-4360, charlesstreetsupply.com) flatten under pressure, which draws the plaster tight to the substrate without causing new cracks.
Start by drilling a series of 1/4-inch holes every few inches, being careful to drill through the plaster without penetrating the lath. After vacuuming out the dust, squirt a little water into each of the holes, then inject the adhesive until it oozes out around the edges of the tip.
When plaster washers don’t provide enough clamping pressure, fasten plastic-covered 3/4-inch plywood over the glued area until the adhesive has cured.
To repair a small, severely damaged area, use a flat bar to pry off the loose, crumbling plaster, leaving the lath in place. Square off the edges with a knife and a straightedge, mark the stud locations, and fasten a drywall patch using 2-inch drywall screws. Where edges are fastened to lath alone, use construction adhesive and 1 1/4-inch drywall screws.
For most ceilings, drywall can be applied directly over the plaster. On this job, the furring created a space to run conduit for overhead lighting. When covering plaster walls (photos below), use 1/4-inch drywall to minimize the effect on trim profiles. To ensure a permanent bond, use both constructive adhesive and screws to fasten the thinner material.
To ensure a permanent bond, use both constructive adhesive and screws to fasten the thinner material.
The author used the Nu-Wal Plaster Restoration System to quickly stabilize cracked plaster in a closet without increasing the wall thickness.