Can Concrete Patch Be Used On Lath For Repairing Plaster Walls

If yous're dealing with damaged lath and plaster walls—for example gaping holes in the wall because of electric work—here are techniques you tin use to repair them. Showtime, y'all'll repair the board then patch the pigsty.

How Do You Repair a Hole in Lath and Plaster Walls?

For board and plaster repair, information technology's important to utilise proficient techniques and the right materials. It'southward better to use a softer, slower-setting lime-based plaster, similar the one developed for Big Wally's line of plaster-repair products, takes about an 60 minutes to fix, isn't prone to great or delaminating, and needs no sanding, which keeps grit to a minimum. Don't use so-called patching plaster sold at home centers, information technology's much harder than the wall's original plaster, and it sets in the blink of an heart.

If the lath is in adept status and you need to repair holes, patching is a matter of troweling on layers of mud. Into the 20^th century, plaster was applied over wood lath spaced half an inch or so apart over the studs or ceiling joists. Several coats were applied, the starting time keying into the spaces betwixt the lath to make a stable base. Finish coats came later on the base had stale. It'due south a mutual practice to replace missing plaster with a slice of blue board (a wall board made to exist coated with plaster), but troweling on base of operations glaze is faster.

How to Repair Board and Plaster in six Steps

1. Set the Lath

Supervene upon whatever missing lengths of lath, and refasten all loose pieces. Use drywall screws, and ever drill airplane pilot holes to avoid splitting the wood. If in that location's no stud to ballast a lath end, slip a piece of lath into the crenel and spiral information technology to the back of the existing ones, parallel with the studs. So you tin can screw new or loose lath to it, as if information technology were a stud.

2. Stabilize the Wall's Edge

Person uses plaster magic on to repair lath and plaster.

Using a 3/sixteen-inch masonry chip, drill holes every three inches around the damaged expanse, virtually 1 inch from the edge. Drill until the bit hits the lath. If it misses, pencil a mark by that hole. Vacuum the holes and spray them with plaster conditioner. Await xv minutes, so fill all unmarked holes with a eject of plaster agglutinative. Wipe off the backlog with a damp rag.

3. Wet the Substrate

Person uses spray to wet plaster before repairing.

Dry lath and the exposed plaster edge volition suck h2o out of moisture plaster earlier it has a chance to harden. To forestall this, saturate those surfaces with conditioner. Wipe upwardly any drips or overspray with a damp rag. Look until the conditioner dries—near 20 minutes—before going to Stride four.

4. Utilise the Scratch Coat

Person applying scratch coat to repair lath and plaster wall.

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 erstwhile 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 information technology with a scarifier, then scrape any blobs off the wall.

5. Trowel on the Second Coat

Wait until the scratch coat is firm to the touch—almost an 60 minutes—and so mix up a new batch of plaster to a slightly thinner consistency—closer to that of buttercream frosting. Employ a plastering trowel to smoothen the mix flush with the wall surface; scrape any excess off the wall. Look another hour for that coat to set.

half-dozen. Smooth the Top Coat

Person using taping knife to smoothen out patch area.

Using a 6-inch taping knife, scrape the patch area smooth, and cover the patch with a thin layer of set-mix joint compound. Let dry overnight. Gently scrape it smoothen and apply a second coat. On the 3rd solar day, spread some other coat, and after it dries, smooth it gently with a clammy sponge. The patch is now set to prime and pigment.

How to Patch Plaster Walls if the Lath is Good Condition

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

Patch Holes in Plaster in seven Steps

Force base coat into the lath. With all the loose one-time plaster removed, apply a flat trowel to coat the exposed lath with plaster base of operations coat, existence sure to work the textile into the spaces between the lath. The plaster that goes between the lath is called "keys", and it locks the fabric in place. Apply a stiff mix then that it won't sag before it sets. Nylon fibers added in while mixing the base coat add strength.
Fill the area so it's affluent. In one case the base coat keyed to the lath, employ the apartment trowel to fill the area with more base coat. Once the base of operations coat is flush with the surface of the remaining old plaster, smooth information technology well with the trowel to minimize the need for sanding.
Paint on a bonding agent. When the base coat is dry, brush a plaster bonding agent over it and the surrounding former plaster. Essentially a water-based mucilage, the bonding agent ensures skilful adhesion between the old work and the new.
Tape the joints. Get over the articulation between the new base coat and the old plaster with nylon mesh record. This step will reduce the chances of any cracking that happens in the base layers from telegraphing through to the finished surface.
Glaze the record. Using a setting-type veneer plaster, use a taping knife to trowel a thin layer over the mesh tape and surrounding wall. Setting plaster hardens quickly, allowing for the next steps to happen in short order.
Finish with joint compound. After the veneer plaster sets, knock down any loftier spots with sandpaper, beingness conscientious not to sand through to the mesh. Stop the patch with two coats of joint compound, allowing the outset to dry earlier smoothing on the second. The thought is to build upwards a large enough area to allow it to exist blended to the existing wall without creating a noticeable high spot.
Sand polish. Afterwards the 2d coat of joint compound has stale, blend to the old plaster using 220 grit sandpaper. Focus on blending the edges to the existing wall first, and so smooth out the center of the patch.

As yous could meet, patching missing plaster follows a similar path as the original installation. A base glaze is followed by several cease coats and a quick sanding to make old walls look new.

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