DIY Repair Broken Plaster Key
Also see:Reattach loose wall plaster where the key has broken using setting-type joint compound. In this process new wall compound is "injected" at 8 to 12 inch intervals across the wall. Start by marking the wall at the ceiling and along corners.
Use a chalked string to snap a line between corresponding marks forming a grid on the wall.
Use a masonry drill bit to bore ¾ inch holes in the plaster at each point on the grid. Check to be sure that the lath is exposed in the holes. Be careful not to damage the plaster more in this process.
Alternately the point of a screwdriver may be used to make an opening in the plaster putty and brown coats. This is usually possible with very loose plaster.
Mix setting-type joint compound following the directions on the Skim Coating Techniques page. Press the mud into each hole using a drywall joint knife. Fill the holes until mud over flows. Scrape off the excess with an upward stroke of the knife blade before moving to the next hole. Let the mud set for about an hour or until the wall feels solid when pressing against it. Use the joint knife to scrape any excess mud off the wall and sand to smooth. Mix and apply a skim coat of mud over each patch. Repair cracks in the plaster following the instructions on the Repair Wall Cracks page.
