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I had some water damage at the base of a wall. I ended up tearing out the bottom half of the wall, about 55" high. I now need to close it back up.

The wall that I tore out is about 3/4" thick. It looks like it is 3/8" drywall with a healthy dose of plaster on top. What's the best way to butt another sheet of drywall up to it?

I have never plastered before, so I'd like to avoid that as much as possible. I'm thinking that I can just put some 1/4" shims/plywood on the studs, then screw some 1/2" drywall to it. The only question that leaves open is joining the edge of the drywall to the plaster.

The edge of the plaster that is still in place is not terribly clean. It's ok in some places, and other places it will leave a ~1" gap when I butt the new drywall against it. I'll assume that I'll need to fill in the gaps. Will joint compound suffice here, or should I pick up a small batch of plaster?

(As an aside, I should add that most of this work will be hidden behind cabinets. Only the top few inches of the work will ever be visible.)

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Spend the time to clean the edge of the plaster so it is straight, this will save you time and make those top two inches that will be visible look nice. I personally would use a heaver drywall (5/8) to closer match the original and use thinner shims (they sell a cardboard like shim for drywall). Butt the new drywall up the cleaned up line and make sure to use a drywall tape to interface the old to the new. If you don't, the two will surfaces will form cracks between them.

You say the top two inches are the part that will show, but that will also be the hardest and most critical two inches to get right. Drywall and plaster are two skills where experience makes huge difference in the quality of work. It doesn't hurt to get an estimate from a couple of guys and compare that to the amount of time it will take you (plan on taking three times the amount of time as a pro)

  • Any tips for cleaning up the edge? It's been tough going near the studs where I can run my rasp. I should add that the edge occurs right at the boundary of the old drywall - that edge is clean. It's only the plaster on top that has issues. – dave mankoff Nov 10 '14 at 21:57
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    @davemankoff - I have not worked with plaster, only drywall in my own homes and friends. But if I had to approach this, I would probably hang the drywall first. Patch the plaster with plaster (joint compound is not designed for filling large holes). After the plaster cures, then tape the seam and use joint compound to merge the two together. Proflanz was referring to using a backer board between the two surfaces to help attach them together but if your studs are 16" apart you should be ok without it. Anyone else correct me if I'm wrong about this. – diceless Nov 11 '14 at 15:40
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I have done many patches in both drywall and plaster. As the previous answe r suggested, take the time to clean up the edges of the hole and open it up all the way to the floor if this has not been done. Attach a back up board to the inside of the wall by driving 2 inch long drywall screws through the plaster into the board. This should be about 3 to 4 inches wide and 3 to 4 inches longer than the hole is wide. The backer board should be at least halfway into the hole so that the drywall patch contacts the backer board and the framing lumber at the bottom of the wall.

Using shims as needed, attach drywall to the bottom wall framing member (sole plate) and the backer board. Be sure that the plaster and drywall are flush (the patch should not b

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    I'm a little confused by this: "This should be about 3 to 4 inches wide and 3 to 4 inches longer than the hole is wide.". I removed the whole length of the wall (and part of the joining wall). – dave mankoff Nov 10 '14 at 22:04

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