Plaster repair: what to know

What the job involves, what changes the price, and what to ask a pro.

What plaster repair is

Plaster repair fixes cracks, holes and crumbling areas in plaster walls and ceilings by securing loose sections, applying patching layers and blending the texture. People need it in older homes where the plaster has cracked, bulged or lost its key to the lath, and they want the repair to disappear under paint.

Signs you need it

  • Cracks run across the wall or ceiling and open up when the house moves or the seasons change
  • A section of plaster sounds hollow when tapped, or bulges away from the wall or lath
  • Chunks of plaster are falling off, leaving holes that expose the lath or the wall behind
  • Water has stained the plaster, and the surface is soft or crumbling near the stain
  • The texture or the color has been damaged, and the repair has to match the old finish

What the pro does

  • Tap the plaster to find hollow or loose areas, then mark the boundaries of the damage with a pencil
  • Secure loose plaster by injecting a bonding adhesive behind it and screwing a plaster washer to the lath or the framing
  • Cut back the damaged plaster to firm edges and clean out the dust and loose material
  • Apply a bonding coat, then build the patch in thin layers, letting each one set before the next
  • Match the texture to the surrounding wall with a float or a sponge, then sand and feather the edges
  • Prime and paint the repaired area, then check it in raking light to find any flaws to fill

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • The total area of cracked, hollow or missing plaster that needs repair
  • Whether the plaster is loose and must be secured with adhesive and washers, which takes more time
  • The depth of the holes and how many layers of patching the repair needs
  • The texture of the existing wall or ceiling, and how hard it is to match
  • Lath condition, such as broken or missing lath that needs new support
  • Access to ceilings and high walls, and whether scaffold or a lift is needed

What a written quote should spell out

  • Each area of repair listed by location, with the size and the method named
  • Adhesive and washer method for loose plaster, and the lath repair if needed
  • Patch materials named, such as the bonding coat, the base coat and the finish coat
  • Texture match method and the finish type on the surface
  • Priming and paint steps, with the paint type and sheen listed

Questions to ask before you hire

  • Can the loose plaster be secured, or does it need to come off entirely?
  • What do you use for the bonding coat and the patch layers?
  • How do you match the texture, especially if the wall has a special finish?
  • Will the repair show through the paint, and how do you check for that?
  • What causes the cracks, and will they come back after the repair?
  • Can you show me a plaster repair you did in a home of similar age?

Red flags

  • The pro fills large cracks with a single thin coat of filler and calls it done
  • The pro does not check the lath or the framing behind a bulging section
  • The pro says every crack is cosmetic without checking whether the wall moves
  • The pro wants to replace whole walls without explaining why the repairs will not work

What you can do yourself

Filling small hairline cracks and nail holes with a lightweight filler and painting over them are reasonable homeowner tasks. Securing bulging plaster, repairing large holes, and any crack that is wide, moves or appears with a structural change should be checked by a plaster specialist, because loose plaster can fall and cause injury.

Licenses and permits

Plaster repair commonly does not need a license, but structural or lath repair may require a permit or qualified contracting. Check with your state or local licensing agency and your local building department about the rules for work that involves the wall structure.

Plaster repair questions

Why does plaster crack?

Common causes include house movement, settling, water, and a repair made without a proper bond or without the right base. Ask the pro to look for the cause before repairing, since a crack that returns usually has a cause that was not fixed.

Can plaster be patched with drywall compound?

Drywall compound can work for small patches on drywall, but on plaster it often does not bond well. Ask the pro to use the right bonding coat and patch materials for plaster.

Should old plaster be replaced with drywall?

Not always. Plaster can be repaired and looks different from drywall. Replacing a wall is a bigger job with its own disruption and finish work, so ask the pro to show the repair option first.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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