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Cutting clean holes in plaster

10:24AM | 05/21/02

Member Since: 05/20/02
2 lifetime posts

Cutting clean holes in plaster

Tags: Painting

A missing flashing on a window in the floor above caused some 80-year-old plaster to sag in our dining room. The leak has stopped, but it did its damage. The wood lath behind the plaster is soft in the center of the area, but of course, I have a huge, jagged section of loose plaster at the perimeter.

I've worked with plaster a little before and not been entirely pleased with the results. This job is very high profile, and I don't want to make our dining room look worse than before. The hardest problem I have always had with plaster repairs is cutting a straight, square hole in it with a keyhole saw. No matter how hard I try, I can't cut a clean hole through the stuff. The wood laths always vibrate with my saw strokes and crack the plaster further out. Not to mention the number of keyhole saws you go through doing that.

I'm considering using a sawzall, but I'm not certain that even that will work. If I saw through all the layers of plaster and the lathing in a square outside the damaged area, would it help to deeply score a line or lay down masking tape, or is there another way to help improve my chances on making a nice, square patch? If it is a good idea, any particular type of blade the best?

Thanks,
Rip

Lawrence

01:43PM | 06/03/02

Member Since: 11/14/00
333 lifetime posts

I don't know what a sawzall is, but you might want to try a spiral saw (like Rotozip or Dremel tool), which essentially is a drill with a bit that cuts sideways. You might want to place a 2x4 along the edge of the cut (on the side you want to preserve) to reduce vibration further as well as guide the cut. A spiral saw does not have up-down cutting action that causes your vibration, but instead a smooth rotating cutting action that tremendous reduces vibration. You can also adjust the depth so as to not cut through the lathes.

A circular saw with a very fine-toothed blade would also have less vibration that a jigsaw or reciprocating saw. You can similarly adjust the depth, as well.

The only other way would be to use a utility knife to cut throught he plaster, then chip the plaster off.

You can also just install a thin layer of drywall on top of the plaster for the entire ceiling and be done with dealing with plaster repair for good.

[This message has been edited by Lawrence (edited June 03, 2002).]