DIY Repair for Loose Plaster Lath

The technique on this page can be used to reattach loose wood lath on walls and ceilings. To repair broken plaster key use Repairing Broken Plaster Key. Ceilings with extremely loose plaster may be impossible to repair using these methods. In those cases it may be better to cover the ceiling with new drywall. See Drywall Ceiling Installation for help.

Loose plaster can be a problem in walls and ceilings with wood lath. Wood lath plaster will usually be found in houses built before the 1920's, after which time gypsum board was developed for use as plaster lath. Repair wall and ceiling plaster with wood lath using the following technique.

Over many years the nails in wood lath are corroded by the lime in the plaster coat. As a result the lath becomes loose and prone to movement due to vibration from foot traffic, etc. These vibrations cause the scratch coat key to break free from the wood lath. The result is a plaster coat that "floats" over the lath, cracking and crumbling as it moves.

Use Reattaching Broken Plaster Key to repair this type of loose plaster on walls. Ceilings with minor loose plaster can be repaired by reattaching the lath to the framing by pulling the plaster surface back into place. Use the following method to make repairs.

Locate the wood lath and the studs or joists behind the loose plaster. Use a drill and an eighth inch masonry bit to bore hole at one inch intervals along the ceiling or wall until you locate the framing.

Bore a one eighth inch pilot hole thru the lath strips and into the framing. Bore ½in. countersink holes in the plaster coats at each pilot hole. Plaster will dull drill bits in short order so use old bits or masonry bits for countersinking. Use a wood bit to bore pilot holes thru the lath and into the framing. Use 2 to 3 inch drywall or wood screws and ½in. washers to reattach the wood lath to the framing.

Press the plaster back into place before driving the screws. In the case of walls, use a small piece of plywood (about 2ft. by 6ft.) and a 2x4 brace at regular intervals across the wall to press the plaster flat before reattaching the lath. Space the anchor screws at about 8 to 12 inches being sure to hit a lath strip at each point. Repair the holes using the repair methods on the Drywall Repair Nail Pop page.

To reattach ceiling plaster use a tee and a small piece of plywood to distribute the pressure over a large area to avoid breaking the plaster coat. Bore the countersink and pilot holes at 8 to 12 inch intervals along the edge of the support. Move the tee to a little at a time to finish reattaching all the loose lath.