How To Repair Lath And Plaster Walls

If you lot're dealing with damaged lath and plaster walls—for instance gaping holes in the wall because of electrical work—here are techniques you tin can use to repair them. First, 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'due south important to use good techniques and the right materials. It'due south meliorate to use a softer, slower-setting lime-based plaster, like the one developed for Big Wally's line of plaster-repair products, takes nigh an hour to set, isn't decumbent to cracking or delaminating, and needs no sanding, which keeps dust to a minimum. Don't use so-called patching plaster sold at dwelling centers, it'due south much harder than the wall's original plaster, and it sets in the blink of an eye.

If the lath is in good condition and y'all demand to repair holes, patching is a matter of troweling on layers of mud. Into the 20^th century, plaster was applied over woods board spaced half an inch or and so apart 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 afterwards the base had stale. It'south a mutual practice to supercede missing plaster with a piece of blue board (a wall lath fabricated to exist coated with plaster), but troweling on base of operations coat is faster.

How to Repair Lath and Plaster in vi Steps

1. Fix the Board

Photograph by Ben Stechschulte

Replace any missing lengths of lath, and refasten all loose pieces. Use drywall screws, and ever drill airplane pilot holes to avoid splitting the forest. If there's no stud to anchor a lath stop, slip a slice of board into the cavity and spiral information technology to the dorsum of the existing ones, parallel with the studs. Then yous tin can screw new or loose board to it, as if it were a stud.

2. Stabilize the Wall'south Border

Photo by Ben Stechschulte

Using a iii/xvi-inch masonry fleck, drill holes every 3 inches around the damaged area, about 1 inch from the edge. Drill until the flake hits the lath. If it misses, pencil a marker by that pigsty. Vacuum the holes and spray them with plaster conditioner. Wait 15 minutes, then fill all unmarked holes with a squirt of plaster adhesive. Wipe off the backlog with a damp rag.

three. Moisture the Substrate

Photo by Ben Stechschulte

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

4. Apply the Scratch Coat

Photo by Ben Stechschulte

In a make 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 old plaster edge, every bit shown, and over the board. Keep this layer recessed by one-half the thickness of the original plaster. Crude upward the patch by scratching information technology with a scarifier, so scrape any blobs off the wall.

v. Trowel on the Second Glaze

Photograph by Ben Stechschulte

Await until the scratch coat is firm to the affect—well-nigh an hour—then mix upwardly a new batch of plaster to a slightly thinner consistency—closer to that of buttercream frosting. Utilise a plastering trowel to smooth the mix affluent with the wall surface; scrape any excess off the wall. Wait another hour for that coat to set.

6. Smooth the Top Coat

Photo past Ben Stechschulte

Using a 6-inch taping knife, scrape the patch area smooth, and cover the patch with a thin layer of set-mix articulation compound. Let dry out overnight. Gently scrape it polish and apply a 2d glaze. On the third day, spread some other coat, and afterward information technology dries, smoothen it gently with a clammy sponge. The patch is now ready to prime and paint.

How to Patch Plaster Walls if the Lath is Skilful Condition

If the lath behind the quondam plaster is audio, patching is a thing of troweling on layers of mud. In this video, This Old Business firm host Kevin O'Conner shows you how to patch holes in plaster walls.

Patch Holes in Plaster in seven Steps

1. Force base glaze into the lath. With all the loose old plaster removed, use a flat trowel to coat the exposed lath with plaster base coat, being sure to piece of work the material into the spaces between the lath. The plaster that goes betwixt the lath is called "keys", and it locks the fabric in identify. Utilize a stiff mix so that it won't sag earlier it sets. Nylon fibers added in while mixing the base coat add force.
2. Make full the area so information technology's flush. Once the base glaze keyed to the lath, use the flat trowel to fill the expanse with more base coat. In one case the base glaze is flush with the surface of the remaining old plaster, smooth it well with the trowel to minimize the need for sanding.
3. Paint on a bonding amanuensis. When the base coat is dry, brush a plaster bonding amanuensis over information technology and the surrounding old plaster. Essentially a h2o-based gum, the bonding agent ensures good adhesion between the onetime work and the new.
4. Tape the joints. Go over the joint between the new base coat and the old plaster with nylon mesh tape. This footstep will reduce the chances of whatever peachy that happens in the base layers from telegraphing through to the finished surface.
5. Coat the tape. Using a setting-type veneer plaster, use a taping pocketknife to trowel a thin layer over the mesh tape and surrounding wall. Setting plaster hardens quickly, allowing for the next steps to happen in brusque order.
6. Finish with joint compound. After the veneer plaster sets, knock downwards any loftier spots with sandpaper, existence careful not to sand through to the mesh. Finish the patch with ii coats of joint compound, assuasive the first to dry out before smoothing on the second. The thought is to build upwardly a large enough surface area to allow it to be blended to the existing wall without creating a noticeable high spot.
7. Sand smoothen. Later on the second coat of joint compound has dried, blend to the old plaster using 220 grit sandpaper. Focus on blending the edges to the existing wall first, and then polish out the center of the patch.

Every bit y'all could see, patching missing plaster follows a similar path every bit the original installation. A base of operations coat is followed by several finish coats and a quick sanding to make onetime walls look new.

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

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