Many older homes have plaster walls. As time goes by, you may see cracks forming in them, especially around doors and windows. Fixing cracked plaster is a simple, inexpensive project you can do on your own in just two to three hours over a span of three days. Here’s what you’ll need to take on this task:
TOOLS & MATERIALS
- Various Joint Knives
- Power Drill
- 1/8” Masonry Bit
- Sanding Block
- Mesh Joint Tape
- All-Purpose Compound
- Plaster Buttons
- 1-¼” Galvanized Screws
- Mud Pan
When taking on this DIY task, be sure to equip yourself with the proper safety gear.
Create keyway. Start by pressing your hand against both sides of the crack. If you can push the plaster in, it’s come loose from the lath underneath it, and you’ll need to reinforce it with plaster buttons as described in Steps 2 and 3 of this project. If there’s no gap in the crack and your plaster is firmly attached to the wall, skip to Step 4. If the crack is deep or wide, undercut both sides of the crack with the corner of a utility knife to form a dovetail-shaped keyway, then clear the dust from the crack with a shop vac.
Predrill for plaster buttons. Plaster buttons, also called plaster washers, are used to pull loose plaster against the lath and are typically installed every three inches along both sides of the crack. Start by predrilling holes roughly one inch from the crack with a one-eighth-inch masonry bit. If the bit goes through the plaster without hitting lath, mark the hole with a pencil to designate that it doesn’t need a button, then drill another hole an inch or so away.
Install buttons. Place a one and one-fourth-inch drywall screw through the buttons and carefully drive it until the screw head is below the surface of the plaster, and the button is concave. Be sure to use galvanized screws, as plaster is corrosive.
Apply fiberglass tape. Use scissors or the edge of your drywall knife to cut a piece of fiberglass mesh joint tape to cover the crack. If the crack is jagged, cut multiple pieces to follow the crack’s path, making sure not to overlap the pieces.
Apply first coat. In order for your repair to look flat, you’ll need to feather it with three successively wider coats of compound. Apply the first coat of compound with your smallest joint knife and a larger taping knife for the second and third coats.
Apply second coat. Allow the first coat of compound to dry overnight. Once fully dry, smooth any ridges in the compound and sand if needed. Your second coat should be about twice as wide as the first. Let it dry overnight as you did with the first coat, sand if needed, and apply your final coat of compound.
Apply skim coat. After your third coat, you’ll add a final skim coat to fill any indentations. To do this, apply the compound, then skim it off by pressing hard with a large drywall knife. This will leave you with a smooth joint with no ridges to sand.
Your plaster repair is complete!