Older buildings were built with a plaster ceilings. There might be times when you’ll need to patch the plaster ceiling, and as with everything, there are right ways and wrong ways to do it. The more you know before you start, the fewer mistakes you’ll make.
1. Not Patching
If you have a small crack in the plaster on your ceiling, you can get away with filling it rather than patching it. However, the crack should be no more than ¼-inch wide and there should be no discoloration on the plaster. If the plaster is discolored, you’ll need to remove an area and patch it properly.
2. Not Finding the Cause
It’s possible that your plaster ceiling is simply old and needs some patching. It is more likely that there’s a reason behind it all. It could be due to dampness or some kind of structural problems. You need to find and fix the root cause before you patch the plaster ceiling, otherwise you’ll have to do it again in a few months.
3. Old Plaster
Don’t just knock out the old plaster randomly. Use a chisel and hammer and cut out an area that’s square or rectangular instead. This way, it will be much easier to cut and fit the patch on your plaster ceiling.
4. Patch Size
When you remove part of the ceiling to prepare it, you need to be sure there’s something to which you can attach the patch. If your plaster ceiling is backed by lath, you’ll have no problem. However, if its backed with the wire mesh that is often used on walls, you’ll need to expose a joist in order to attach the patch successfully. The drywall patch needs to be slightly smaller than the hole in order for it to fit. An exact match is unnecessary.
5. Securing the Patch
Don’t just screw the drywall in at each corner when you’re putting a patch in a plaster ceiling. The screws should be about 5-inches apart to create the best, most secure fit. Remember that it has to be structurally secure to be at it's best.
Don’t believe you can simply put the patch in and then paint it. You need to use drywall tape to cover the gap around the patch. Cover the tape with drywall compound.
Even now, you can’t go straight to painting. You need to make sure the patch is the same height as the plaster ceiling. You can do this with drywall compound by applying it slowly and evening it out with a knife.
7. Textured Ceiling
If your plaster ceiling is textured, you’re going to have to replicate that finish. Don’t just apply drywall compound. Instead, you need to use a dry powder texture paint (depending on your ceiling finish, you can also use a pre-mixed latex texture paint with an appropriate applicator).
Even then, don’t just apply it to the ceiling and hope for the best. Practice on some old drywall or plywood until you’ve mastered the technique. This way, you’ll end up with a seamless patch on your plaster ceiling.
Repairs can be difficult. Patching your plaster ceiling will be easier now that you know to avoid these seven mistakes.