Matching Drywall To Plaster for a Smooth Transition

With most homes prior to the 1950’s mostly made with walls of lath and plaster, the inevitability of wall repair is pretty much unavoidable, from just repairing cracks to outĀ  & out removal of large areas of plaster & lath.

Without going the purest route of repair with actual plaster, which involves multiple coats and drying time, we can use drywall to fill any holes or even large areas without removing more plaster than is necessary, as long as the remaining plaster is still stable and secure.

If you have removed all the plaster from a wall, corner to corner, top to bottom, and want to hang drywall, which may be the best option, then you need not read any further, just clean the studs and hang the drywall, but if your are matching portions of walls, then proceed.

The key to matching drywall to plaster is understanding a few simple dimensions of thickness, 3/8 inch lath, (the wood strips), and about a 1/2 inch of plaster, which totals about 7/8 of an inch on the studs, this is the average thickness that I have found to match up pretty close to the existing plaster finish. These are the critical dimensions of thickness that we want to match so we obtain a ‘flush’ finish.

If you have this total too thin, you will be doing a lot of filling with mud, if you get the patch too thick the opposite happens and you end up trying to hide a hump, with more mud.

There may be various thicknessesĀ  in plaster finishes so each situation needs to be measured to get good flush results, but the most common sum comes to about 7/8 inch. Sometimes plaster at the bottom of the wall is thicker than at the top, but with a little drywall and ‘mud magic’ you can recreate the look of the original wall.

The main part is using the right thickness of shim material, (I love Shims) I use 3/8 thick plywood or even some of the old lath strips, if they are in good condition, along with 1/2 inch drywall for the proper build out. The strips will go on the studs, (firring out) and not back horizontally as they originally were.

Here are the steps I do in placing drywall in a plaster wall:[nggallery id=2]