Plaster repair for Portland's older homes.

If your home was built before the Second World War, its walls are most likely plaster over lath, not gypsum board. Lath is the strips of wood or metal mesh fastened to the framing. The plaster was troweled on wet, one coat over another, and pushed through the gaps in the lath. When it hardened, it locked onto the back of the lath, and that lock, called the key, is what holds the wall in place. Over the decades the key can loosen, the plaster can crack, and sections can pull away from the lath completely. Repairing plaster is a different job from patching drywall. We re-attach loose plaster to the lath, fill and build it back up with compatible coats, and match a hand-troweled surface that was never perfectly flat in the first place. A plaster repair done that way holds and blends in. Plaster patched the way you would patch drywall usually cracks again within a season.

There are three options, and the condition of the wall decides which one fits: patch the damaged area, skim-coat the whole surface smooth, or replace a section with drywall where the plaster is too damaged to save. We will walk you through the trade-offs for your wall instead of pushing one answer.

Homeowners in old Portland houses ask this all the time, and the answer depends on the wall. Keeping the original plaster keeps the character and the solid, quiet feel of a plaster wall, and it avoids the dust and mess of a tear-out. Replacing a badly damaged section with drywall can last longer and make more sense when the plaster has come loose from the lath across a large area. Cost, mess, and how much original wall is left all matter. When the plaster is mostly sound, with some cracks and a few soft spots, patching and skim-coating is usually the better choice. When a ceiling is sagging or a wall has pulled away from the lath over a wide area, a drywall overlay or replacement is often what we recommend. We do both, so our advice is not tied to which job we would rather sell.

Fine cracks spreading across the plaster of a 1920s Portland home are common, and most are not an emergency. They usually have two causes. The first is the plaster itself. As it ages, the key to the lath weakens, and seasonal changes in humidity make the plaster move, which opens hairline cracks along stress lines. The second is the ground under the house. Soil moisture under the house changes between our wet winters and dry summers, the house settles and shifts, and that movement travels up into the walls.

Most of these cracks are cosmetic and can be repaired. Look more closely at cracks that are wide, growing, or shaped like stair steps, cracks that showed up at the same time doors and windows started to stick, and cracks that keep reopening in the same place after a repair. Those can be signs that the structure is moving. When we see them, we will tell you and suggest a foundation specialist before we skim over anything. We won't cover up a structural problem to book a plaster repair.

When a plaster wall is solid but worn, covered in old cracks, patched unevenly, or textured in a way you no longer want, skim-coating makes it smooth again. We re-attach any loose areas, fill the damage, then spread a thin, even coat of compound across the whole surface and sand it smooth and ready for paint. Skim-coating fixes surface cracks, old patches, and small dips and bumps. It does not fix plaster that has come loose from the lath. That plaster has to be re-attached or replaced first. The finished wall is flat and clean, with the solid plaster still behind it.

The cost of plaster repair depends on how much of the wall is damaged, whether the plaster has pulled away from the lath, whether it is a wall or a ceiling, and how much of the original finish has to be matched. A few cracks and soft spots are a much smaller job than a ceiling that needs re-attaching across the whole room. We don't quote flat rates on plaster, because the condition of the wall varies too much to guess from a distance. Every job gets a free written estimate. Send photos with your ZIP code and you will get a real number back, usually within one business day.