Plaster Home Repair: It’s Easier Than You Think

Of the home repair jobs you'll consider in an older house, few are as contentious as whether to keep or trash the plaster walls. To some, plaster is old, and therefore modern drywall must be superior. To others, plaster is original and should always be preserved.

Both of those statements are true and false, depending on the condition of your plaster. New drywall is better than plaster that's beyond repair. But good plaster is superior to drywall, at least as far as performance goes.

Plaster Home Repair: Anatomy of a Wall

The anatomy of a plaster wall is very different from drywall. Where drywall comes in sheets that are nailed or screwed to the wall studs, plaster is built up in layers. The first layer is horizontal strips of wood, called lath (shown above), that are nailed horizontally across the studs.

A scratch or brown coat of plaster goes over the lath, squeezing through the spaces between the lath. The plaster that squeezes through creates “keys” on the back side of the lath, which once hardened, hold the plaster onto the lath.

Smooth layers of plaster are then skillfully applied over the scratch coat, ending with a finish layer that is so fine it requires little or no sanding. A plaster wall is much thicker than drywall, and it has more fire resistance.

Plaster Home Repair: What's Worth Keeping

Plaster is a valuable material, but not every plaster wall is worth repairing. If your plaster only has a few cracks, chances are it's salvageable. If it's starting to crumble in areas, you have to weigh the amount of effort needed for repair against the benefits of keeping it.

Tap the plaster to determine whether it's still connected to the lath behind it. If you hear a hollow sound, the plaster keys have broken and it has popped loose from the lath. If there's a hard tap sound, then the plaster is still intact. Intact is better, but hollow is usually salvageable.

If some areas are crumbling, examine the rest of the wall. If you can tap loose more crumbles, then the original plaster mix was inferior. The whole wall is at risk of crumbling, and not a good candidate for repair.

Plaster Home Repair: Popped Plaster

Where the plaster is sound but has popped loose (has that telltale hollow noise when tapped), you'll need to glue and fasten it back. You can't reaffix the old keys, so you'll need to attach it through the front side using glue and plaster repair screws, says This Old House. These are special screws with a wide washer.

When driven through the plaster, the washer prevents the screw head from tearing through the plaster as it tightens it back to the lath. You may get some new cracks in the plaster when it secures to the lath, but that's fixable.

Drill small holes through the plaster and into the lath, then spray in some plaster conditioner. Next, squirt in plaster adhesive, and slowly drive in the plaster repair screws until the plaster is snug against the lath again.

Plaster Home Repair: Cracks and Imperfections

If you've ever tried to fix a crack in plaster, you already know that it usually comes back. That's because the house is always settling, and plaster is a very hard material. To overcome this, you'll need a patching material such as drywall mesh tape to help the wall flex instead of crack.

Mesh tape helps cover many types of imperfections, and gives the fresh material something to grab. More important, Tim Carter of Ask the Builder says it helps prevent cracks from coming back. Apply the tape, then spread on plaster patching compound like you would repair drywall. (Read: Peanut Butter and Drywall Mud)

You can also use drywall joint compound, although plaster purists might shake their heads at this idea. It does work. Let each coat dry before applying the next. Once dry, fine tune the surface using a damp sponge to give it that final, smooth finish. If you're not sure about how to use patching compound, watch the videos in our article, “Tape & Mud at Habitat Women Build.” It's essentially the same process.

If you compare a pristine plaster wall with drywall, plaster always wins in performance. It's denser, harder, provides more insulation, more sound buffering, and it just looks more appropriate in an older home. Damaged plaster doesn't mean that it should be replaced unless it's in terrible condition. If you can repair it, it's smart to do so.

Do you live in an older house with plaster walls? What are your feelings about keeping or replacing it? There are definitely two schools of thought on the topic. Some love the unique, hand crafted appearance that only comes with plaster. Others prefer the perfect, flat and smooth look of drywall. Which camp do you fit into?

Careers in Construction

While demand for skilled plaster and cement masonry workers isn't as great as it is for electricians, plumbers or heating and air conditioning (HVAC) contractors, this is a great field for women. It requires attention to detail which women excel at, with opportunities in commercial (roadwork, bridges, dams) and residential construction work. Residential work includes interior and exterior stucco, interior plaster and artisan finishes.