How to Use Plaster Washers to Save Loose Plaster Walls and Ceilings
When old plaster starts sagging or separating from the wood lath behind it, many people think replacement is the only option. But in many cases, plaster washers can bring your walls and ceilings back to life — without the mess and expense of a full tear-out.
At Seamless Walls & Ceilings, we specialize in keeping repairs efficient, durable, and cost-effective. Here’s a step-by-step look at how plaster washers work, along with refinements and upgrades you can use depending on how badly the plaster has separated.
What Are Plaster Washers?
Plaster washers are small, perforated metal discs (about 1¼″ in diameter) that work with standard drywall screws. When driven through the plaster into the lath, they spread the holding power of the screw across a wider surface, pulling loose plaster tight against the lath.
Once the area is stabilized, the washers are buried under a skim coat of plaster or joint compound, leaving the surface ready for paint.
Tools and Materials You’ll Need
- Plaster washers (available online or at specialty hardware stores)
- Drywall screws (1¼″ to 1⅝″, coarse thread)
- Drill/driver
- Setting-type joint compound or patching plaster
- Taping knife and hawk or pan
- Optional: 1¼″ spade bit for countersinking
- Optional: Adhesive in caulk tubes (e.g., Big Wally’s Plaster Magic® Adhesive)
Step-by-Step: Standard Washer Method
1. Identify Loose Plaster
Tap gently with your hand. Hollow or soft areas indicate plaster has separated from the lath.
2. Drill and Screw Washers
Starting at the edge of the loose area, drive a screw through a plaster washer and into the lath. Place washers about every 6–8 inches across the damaged section. Tighten until the plaster is snug, but don’t overtighten — you don’t want to crack it further.
3. Stabilize the Entire Section
Continue adding washers in rows until the whole area is pulled flat and firm against the lath.
4. Cover With Compound
Apply a thin coat of setting compound over the washers. Once dry, feather out a wider coat to blend the repair into the surrounding wall.
5. Sand and Finish
Lightly sand smooth, then prime and paint as usual.
Refinement: The Countersink Method
If you’re not planning to apply a relatively thick skim coat, you may want the washers to sit slightly below the plaster surface:
- Before driving the screw and washer, use a spade bit (about 1¼″) to carefully cut a shallow recess in the plaster.
- Drive the washer into this recess so it sits flush or just below the surface.
- Finish with a skim coat of compound.
Pros: Requires less compound, reduces the chance of a bump showing through. Cons: Adds a step and removes a small amount of plaster.
Upgrade: Adhesive Injection for Severe Separation
When plaster has pulled significantly away from the lath, washers alone may not create a strong, lasting bond. In these cases, adhesive injection adds a second line of defense:
- Drill small holes in the loose area to access the space behind the plaster.
- Inject adhesive (such as Big Wally’s Plaster Magic®) into the cavity.
- Install washers over the area to pull the plaster back to the lath while the adhesive cures.
- Finish as usual with compound or plaster over the washers and filled holes.
The adhesive re-bonds plaster to the lath, while washers keep everything snug until the adhesive sets — ideal for historic plaster where long-term preservation is the goal.
Choosing the Right Method
- Minor Separation → Standard washer method is usually enough.
- Moderate Separation → Add the countersink method for a smoother finish where no full skim is planned.
- Severe Separation → Use adhesive injection plus washers to restore a strong bond to the lath.
Why This Approach Works
- Preserves original plaster in historic and character-rich properties.
- Saves time and money by repairing instead of replacing.
- Customizable based on severity of separation.
At Seamless Walls & Ceilings, we evaluate each plaster repair individually — applying the right mix of stabilization, smoothing, and re-bonding to deliver seamless, lasting results.
Final Tip
If plaster is failing across large areas, it may be time to discuss broader solutions like partial replacement or a full skim coat. But for most repairs, plaster washers — with or without adhesive — remain one of the simplest, most effective tools for keeping walls and ceilings strong.
