how to repair plaster and lath walls

^{How to Repair Lath and Plaster in 6 Steps}

1. Fix the Lath. Replace any missing lengths of lath, and refasten all loose pieces. Use drywall screws, and always drill pilot holes to avoid splitting the wood.
2. Stabilize the Wall’s Edge. Using a 3/16-inch masonry bit, drill holes every 3 inches around the damaged area, about 1 inch from the edge.
3. Wet the Substrate. Dry lath and the exposed plaster edge will suck water out of wet plaster before it has a chance to harden.
4. Apply the Scratch Coat. In a clean bucket with cool tap water, mix Plaster Magic patching plaster to the consistency of natural peanut butter.
Trowel on the Second Coat. Wait until the scratch coat is firm to the touch—about an hour—then mix up a new batch of plaster to a slightly thinner consistency—closer ...
Smooth the Top Coat. Using a 6-inch taping knife, scrape the patch area smooth, and cover the patch with a thin layer of ready-mix joint compound.

Can lath and plaster walls be repaired?

Here are two ways approach your lath and plaster repair whether you have a damaged wall or if you need to patch a hole. If you’re dealing with damaged lath and plaster walls—for example gaping holes in the wall because of electrical work—here are techniques you can use to repair them.

How do you stabilize a lath and plaster wall?

Stabilize the Wall’s Edge Using a 3/16-inch masonry bit, drill holes every 3 inches around the damaged area, about 1 inch from the edge. Drill until the bit hits the lath. If it misses, pencil a mark by that hole.

How do you fix a hole in a plaster wall?

In this video, This Old House host Kevin O’Conner shows you how to patch holes in plaster walls. Force base coat 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 work the material into the spaces between the lath.

What is lath and plaster?

Lath and plaster was a method of finishing off walls and ceilings used from early in the 18th century right up until the mid-20th century — when modern methods for plastering walls began to be used and sheet plasterboard became more commonplace.

Can you patch repair lath and plaster?

Traditional Lath and Plaster Repair Some people do choose to carry out repairs on a DIY basis. In this case, you will need to replace any missing sections of lath, and refasten all loose pieces. You can then re-plaster the walls using a suitable plaster mix. This is a job which often looks and sounds easier than it is.

How do you repair water damaged lath and plaster?

Make the repair Use joint compound and apply in several thin coats. Spread the compound like butter on toast, skimming off any excess as you go. When dry, sand to a level and even surface. Continue this process as many times as necessary to make a long-lasting and invisible repair.

Can I use drywall mud to repair plaster walls?

Drywall mud will adhere to plaster walls, making it simple to patch plaster with a standard joint compound. By taping joints and applying multiple coats of joint compound, you'll quickly fill holes and patch larger areas.

How do you repair badly damaged plaster walls?

How to Repair Holes in PlasterStep 1: Remove Damaged Plaster. Remove the damaged plaster by using a cold chisel and a ball peen hammer to chip the damaged plaster off the wall. ... Step 2: Apply Latex Bonding Agent. ... Step 3: Apply and Cross-Scratch Plaster. ... Step 4: Apply Second Layer. ... Step 5: Apply layer of Joint Compound.

Does water damaged plaster need replacing?

Generally yes, the board should be removed and replaced with an equivalent Gyproc product to maintain the original performance criteria.

Can water damaged plaster be repaired?

Plaster that has gotten wet is best repaired using setting-type joint compound, also called mud. Ready-mixed compound will not be hard enough and is vulnerable to any residual moisture in the wall material.

What is the difference between plaster and drywall mud?

USG and other companies offer corner bead and trim that make the job easier, but mistakes are difficult to fix. That's because plaster, unlike conventional drywall mud, hardens by a chemical reaction and is more difficult to sand. Besides installing lath, you have to apply at least three coats of plaster.

Can I skim coat joint compound over plaster?

0:3212:17Bonding Quickset Drywall Mud to Old Plaster! - YouTubeYouTubeStart of suggested clipEnd of suggested clipI'm gonna just mix it around with this brush. So that it gets a little bit pinned down but not tooMoreI'm gonna just mix it around with this brush. So that it gets a little bit pinned down but not too much. Okay that's looking better. So now I'm just gonna take this stuff and I'm gonna start spreading

Is joint compound the same as patching plaster?

To make a gypsum plaster, manufacturers add cross-linking chemicals to bind the mixture. Without these hardening chemicals, the gypsum paste is called drywall joint compound, or mud -- with them added, the mixture variously becomes patching compound, plaster of Paris or hot mud.

What's the best wall filler?

Gyproc light is probably the best all-round filler on the market. You can do deep holes with it without any issues and there is never any flashing. It's hard to ignore Toupret fillers though.

What are old plaster walls made of?

Historical Background. Plasterers in North America have relied on two materials to create their handiwork–lime and gypsum. Until the end of the 19th century, plasterers used lime plaster. Lime plaster was made from four ingredients: lime, aggregate, fiber, and water.

How do you cover crumbling plaster walls?

4:185:21Repairing a crumbling plaster wall - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd then against molding so the next step is just to do your normal drywall mudding and tape. AndMoreAnd then against molding so the next step is just to do your normal drywall mudding and tape. And then after that I'm going to take the painters caulk and run along the baseboards.

What does water damaged plaster look like?

Paint and water are insoluble and an easy way to identify if plaster is water damaged is looking for flaking paint or air bubbles that burst and flake. Unlike flaking plaster, paint will flake with minimal exposure to water, while plaster often needs to get wet and re-dry before flaking occurs.

What happens when plaster walls get wet?

Saturation. While water can cause damage by softening the plaster itself, the problem may be even worse inside the walls. If the wall is saturated with water, the wooden lath behind the plaster will absorb water and begin to expand. As it expands, it pushes outward and can cause the wall to crack and weaken.

How do you repair a hole in a lath and plaster ceiling?

3:287:58How to Patch a Plaster and Lath Ceiling | Ask This Old HouseYouTubeStart of suggested clipEnd of suggested clipAnd cut the patch to fit the hole. And the patch is made of 3 8 drywall the thickness of the plasterMoreAnd cut the patch to fit the hole. And the patch is made of 3 8 drywall the thickness of the plaster on the ceiling. Perfect i'll attach it with some inches 5 8 drywall screws.

What are plaster washers used for?

Plaster washers are about the size of a quarter and cost pennies. A drywall screw goes through the washer and is driven into the wood lath behind the plaster. The unique design of the plaster washers anchors the plaster firmly against the lath, stopping cracks and sagging.

How to fix a crack in plaster?

Using a 3/16-inch masonry bit, drill a hole in the plaster about 2 inches from the crack. When you hit lath, stop—the bit won't go through wood—pull out the bit, and drill another hole about 3 inches from the first and about 2 inches from the crack. Try to hit a strip of lath with every hole you drill. If you miss, the bit will sink in right to the chuck.

What is plaster used for?

You just gotta love plaster. That rock-hard substance, which was applied to the walls and ceilings of nearly every house in this country until the 1950s, gives us surfaces that are seamless, mold resistant, fire resistant, and noise deadening. But what to do when plaster cracks, buckles, and pops loose? It's a perplexing question for many of our readers, including Tim Thorp, whose house in Providence, Rhode Island, is filled with badly blemished plaster.

How to fill cracks in a joint?

Mix up a small batch of setting-type joint compound and use it to fill the crack and all the holes . Smooth the wet compound with a trowel; then, as it begins to harden, wet it and smooth it again.

How to repair plaster that is more than 1/8 inch?

If the plaster gives more than 1/8 of an inch when gently pressed, plan on repairing with an adhesive kit. You can use a two-part adhesive system which requires you to drill holes every 3 inches into the damaged area of plaster, but not through the lath. A masonry drill bit will go through the plaster not through the wood.

What is plaster wall made of?

Unlike drywall which attaches directly to wall studs, plaster walls consist of two sections. First, lath attached to the wall studs. While lath can be made of metal and stone, you will most likely encounter wood lath. Wood lath consists of a series of horizontal wood strips, approximately 2 inches wide, with a small gap between each slat.

How wide is wood lath?

Wood lath consists of a series of horizontal wood strips, approximately 2 inches wide, with a small gap between each slat. When the scratch coat, or first coat of plaster, is applied, the contractor forces the mixture through the gaps to form tabs known as keys that hold the plaster to the lath.

Can you use joint compound to repair drywall?

Working with plaster is tricky: the surface must be wet before you can apply it. If you prefer, you can use joint compound, commonly used to finish drywall. Whichever you choose, be prepared to apply at least two coats, as both have a tendency to shrink while drying.

Can you replace plaster with drywall?

Despite what you may have been told, you do not have to rip out the old plaster and replace it with drywall. That said, if drywall cracking or surface distortion is severe or there are other indications of significant settling or potential structural ...

Can you use joint compound on plaster?

Working with plaster is tricky: the surface must be wet before you can apply it. If you prefer, you can use joint compound, commonly used to finish drywall. Whichever you choose, be prepared to apply at least two coats, as both have a tendency to shrink while drying. Thomas Ferraioli began writing in 1993.

Can a drill bit be used to drill through plaster?

A masonry drill bit will go through the plaster not through the wood. A conditioner is sprayed into each hole, followed by an injection of adhesive. Finally, a plaster ring is drilled into the lath which pulls the wall tight to the wood. Once the adhesive has set, usually overnight, the plaster rings can be removed.

What is Lath and Plaster?

Lath and plaster can be identified by the presence of laths, thin strips of timber measuring around 25mm x 6mm, behind the plaster. These would be nailed to vertical timber joists or posts to form a framework for the wall. Each lath was spaced with gap of around 6mm to take the plaster which would be applied next.

What Type of Plaster Was Used For Lath and Plaster?

The first two layers of plaster that were applied to the lath were usually made up of lime putty and sharp sand in a 1:3 ratio — often with animal hair added in to help bind them.

How do you Repair Lath and Plaster Walls?

If you live in a house with lath and plaster walls (likely if your house was built before 1940) then you might be wondering how to repair damaged lath and plaster.

Modern Repairs to Lath and Plaster

The two most commonly used modern methods mean cutting back the laths and plaster to the nearest studs either side of the damage. You can then cover the hole in one of two ways.

Traditional Lath and Plaster Repair

There are companies who specialise in lath and plaster repair and if you want to remain true to the original construction of your home it is well worth considering this route.

What Is a Lath and Plaster Wall?

Lath and plaster refer to an interior wall construction technique that typically predates the 1940s. Four-foot-long strips of wood lath, typically 1-inch wide, are nailed directly to the open wall studs. The lath is then embedded with three layers of wet plaster. The plaster dries to form a hard, smooth surface suitable for finishing, first with primer, then with interior paint or wallpaper. Plaster and lath wall systems are rarely used now, except to repair existing walls or to refurbish historic buildings.

How long does it take to build a lath wall?

How Lath and Plaster Walls Are Built. Building lath and plaster walls requires several days due to the length of time it takes for thick plaster to cure. Though lath-building can nominally be thought of as carpentry, most plasterers are adept at nailing up lath. So only one team of workers is needed for the project.

What is a plaster key?

Plaster keys are simply the plaster that has oozed through the lath in irregular shapes. They help to hold the plaster in place on the lath, as well as act as sound-absorbing elements in the wall.

What is the difference between drywall and plaster?

Essentially, drywall acts the same way as lath and plaster walls: a mineral-based substance that creates privacy, deadens sound, and insulates. The chief difference is that the plasterwork, or the wet work, has already been done in a factory, not on site. Thus, the term dry wall.

How thick is fire rated drywall?

Fire-rated, or Type-X, drywall is 5/8-inch thick. Plaster is often thicker than this. When lath is figured into the thickness, then lath and plaster walls are considered to be thicker than drywall.

What is the key in plaster?

Globs of plaster called keys are pushed out of the backside of the lath. These wet portions dry and form myriad secure grips for the rest of the plaster. The keys make demolition of plaster down the road much harder because they grip to the lath.

Which is better, drywall or lath?

Lath and plaster walls provide a room with better soundproofing, as opposed to dry wall walls of an ordinary thickness (1/2-inch). Soundproof drywall, though, rivals lath and plaster walls in terms of soundproofing. Lath and plaster walls have a slightly better insulating R-value than do drywall wall systems.