Can You Put Sheetrock Over Top Plaster Walls?

Condition of Plaster

• If you're only looking at hairline to moderate cracks, you won't need to do anything to the plaster to prepare it for drywall. However, if there are chunks of plaster missing, you'll need to install a piece of drywall where the plaster is missing to get as even a wall surface as possible. Also, if large areas of plaster are bulging and separated from the wall, cut out those areas of plaster and install a piece of drywall to fill the void.

Baseboard Trim, Window Casings and Electrical Outlets

• One key consideration when deciding to put drywall over plaster is how it will affect the baseboard trim, window casings and electrical outlets. Adding more depth to the wall will now mean the outlets won't be flush with the wall surface and the trim may be recessed into the wall. You will need to have an electrician come in and pull the electrical boxes forward. Also, before installing the drywall you'll have to remove the baseboard trim and then any door or window frames will need to be shimmed out so they are even with the wall before you reinstall the door and window casings.

What Sheetrock to Use

• Sheetrock comes in different thicknesses, ranging from 1/4 inch to 1/2 inch. USG recommends using 1/4-inch or 3/8-inch drywall when applying it on top of another surface layer, such as plaster. While using 1/4-inch drywall is acceptable, the thinner drywall won't do as good a job leveling out high and low spots in the drywall; 3/8-inch drywall is a better option.

Installation

• While 1 5/8-inch drywall screws are standard when installing drywall, when putting it over plaster, use 2-inch screws. The extra screw length will help penetrate through the plaster and lath and provide the necessary grip. Unlike the case with standard drywall installation, in which the screws must be driven into the wall studs, that isn't a concern when putting it over plaster. Driving screws through the plaster and lath every 12 inches will be satisfactory.