How To Repair A Hole In Plaster

If you're dealing with damaged lath and plaster walls—for instance gaping holes in the wall because of electrical work—here are techniques you can utilise to repair them. Start, you'll repair the lath and then patch the hole.

How Do Y'all Repair a Hole in Lath and Plaster Walls?

For lath and plaster repair, it's important to use adept techniques and the right materials. It's better to use a softer, slower-setting lime-based plaster, like the one adult for Big Wally's line of plaster-repair products, takes most an hr to set, isn't decumbent to slap-up or delaminating, and needs no sanding, which keeps dust to a minimum. Don't employ and then-called patching plaster sold at habitation centers, it'due south much harder than the wall's original plaster, and it sets in the glimmer of an eye.

If the board is in good condition and you need to repair holes, patching is a matter of troweling on layers of mud. Into the 20^th century, plaster was practical over wood lath spaced half an inch or then autonomously over the studs or ceiling joists. Several coats were applied, the first keying into the spaces between the lath to make a stable base. Finish coats came after the base had dried. It's a common practice to replace missing plaster with a piece of blue board (a wall board fabricated to exist coated with plaster), but troweling on base coat is faster.

How to Repair Lath and Plaster in 6 Steps

1. Fix the Board

Photo by Ben Stechschulte

Replace any missing lengths of lath, and refasten all loose pieces. Utilise drywall screws, and always drill pilot holes to avert splitting the wood. If there'southward no stud to anchor a lath end, sideslip a piece of lath into the cavity and screw it to the dorsum of the existing ones, parallel with the studs. And so you can screw new or loose lath to it, as if information technology were a stud.

2. Stabilize the Wall's Edge

Photo by Ben Stechschulte

Using a 3/xvi-inch masonry flake, drill holes every three inches effectually the damaged expanse, well-nigh i inch from the edge. Drill until the bit hits the lath. If information technology misses, pencil a mark by that pigsty. Vacuum the holes and spray them with plaster conditioner. Wait 15 minutes, then fill up all unmarked holes with a squirt of plaster adhesive. Wipe off the excess with a clammy rag.

3. Wet the Substrate

Photo by Ben Stechschulte

Dry lath and the exposed plaster edge will suck water out of wet plaster earlier it has a chance to harden. To prevent this, saturate those surfaces with conditioner. Wipe upwardly whatsoever drips or overspray with a clammy rag. Wait until the conditioner dries—about 20 minutes—earlier going to Step 4.

four. Apply the Scratch Glaze

Photograph past Ben Stechschulte

In a clean bucket with cool tap water, mix Plaster Magic patching plaster to the consistency of natural peanut butter. Using a margin trowel, smear the mix against the former plaster edge, as shown, and over the board. Keep this layer recessed by half the thickness of the original plaster. Rough up the patch by scratching it with a scarifier, and so scrape whatsoever blobs off the wall.

5. Trowel on the Second Coat

Photo by Ben Stechschulte

Wait until the scratch coat is firm to the affect—almost an hour—and then mix upwards a new batch of plaster to a slightly thinner consistency—closer to that of buttercream frosting. Utilize a plastering trowel to smooth the mix flush with the wall surface; scrape any excess off the wall. Wait another hour for that glaze to gear up.

6. Shine the Summit Coat

Photo past Ben Stechschulte

Using a 6-inch taping pocketknife, scrape the patch area smooth, and cover the patch with a thin layer of ready-mix joint chemical compound. Let dry overnight. Gently scrape information technology smoothen and use a second coat. On the third day, spread another coat, and after it dries, smooth it gently with a damp sponge. The patch is now fix to prime number and paint.

How to Patch Plaster Walls if the Lath is Expert Condition

If the board behind the quondam plaster is sound, patching is a affair of troweling on layers of mud. In this video, This Old House host Kevin O'Conner shows you lot how to patch holes in plaster walls.

Patch Holes in Plaster in seven Steps

1. Force base coat into the lath. With all the loose one-time plaster removed, use a flat trowel to coat the exposed lath with plaster base of operations coat, being certain to work the material into the spaces between the lath. The plaster that goes betwixt the lath is chosen "keys", and information technology locks the fabric in identify. Use a strong mix and so that it won't sag before information technology sets. Nylon fibers added in while mixing the base of operations coat add together force.
2. Fill the area then it's flush. Once the base coat keyed to the lath, utilise the flat trowel to make full the expanse with more base coat. Once the base coat is flush with the surface of the remaining old plaster, polish it well with the trowel to minimize the need for sanding.
3. Paint on a bonding agent. When the base of operations glaze is dry, brush a plaster bonding agent over it and the surrounding one-time plaster. Essentially a water-based glue, the bonding agent ensures good adhesion between the old work and the new.
4. Tape the joints. Go over the joint between the new base glaze and the old plaster with nylon mesh tape. This step volition reduce the chances of whatsoever corking that happens in the base layers from telegraphing through to the finished surface.
5. Coat the record. Using a setting-type veneer plaster, use a taping knife to trowel a sparse layer over the mesh tape and surrounding wall. Setting plaster hardens quickly, allowing for the next steps to happen in short society.
6. Finish with joint compound. After the veneer plaster sets, knock down any high spots with sandpaper, being conscientious not to sand through to the mesh. Finish the patch with 2 coats of joint compound, allowing the first to dry before smoothing on the second. The thought is to build up a large plenty area to allow information technology to exist blended to the existing wall without creating a noticeable loftier spot.
7. Sand shine. After the second coat of joint chemical compound has dried, blend to the old plaster using 220 dust sandpaper. Focus on blending the edges to the existing wall outset, so polish out the centre of the patch.

Every bit you could run into, patching missing plaster follows a similar path equally the original installation. A base coat is followed by several terminate coats and a quick sanding to brand one-time walls look new.

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Source: https://www.thisoldhouse.com/walls/21015878/how-to-patch-plaster-walls

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