DIY Repairing Loose Lath Plaster

plaster lath diagram

Loose plaster is often a problem in walls, and especially ceilings with wood lath. This type of plaster will usually be found in houses built before the 1920's. After that time gypsum board was developed for use as lathing material which greatly improved on plaster durability.

This older type of plaster can become loose over many years, as the nails in the wood are corroded by the lime in the scratch coat. The result is loose lath strips that move and vibrate due to normal foot traffic, etc. These vibrations cause the plaster key to break free from the wood and the surface of the plaster to crack or crumble as it moves.

To stabilize the plaster and prevent further cracking, the techniques on this page can be used to reattach the wood lath and the plaster coats to the framing. This will work nicely in cases where the key is still generally intact, but extremely loose ceilings may be impossible to repair using this method. In those cases it is advisable to cover the ceiling with new drywall instead.

reattaching plaster lath with washers and screws

Reattaching the Wood Lath



driving screws to pull lath and plaster back in place


marking a wall for plaster key repair

Reattaching the Plaster Coats



boring holes to repair broken plaster key
