How to repair a crack or hole in plaster

How to repair a crack in plaster:

1. If the crack is large, the first thing you want to do is make it bigger. What? Isn’t that more work? No, trust me. You want to extend your work area to make the repair last. If you just fill in the crack, it will come right back Make the crack larger with a utility knife.

2. Then clean the area around the crack. Scrape off any loose plaster or wall texture around the crack. Apply a thin coat of joint com pound in the crack, letting it feather out over the crack.

3. Take fibreglass tape and cover the entire crack. This tape allows for mobility so that future cracks can be avoided.

4. Apply a thin coat of joint compound with a wide dry wall knife, much like you would frost a cake, until the tape is completely covered and smooth.

5. Allow a couple of hours to dry.

6. Take fine sandpaper and smooth out the compound when completely dry.

7. Apply as many coats as necessary to assure that the crack and tape are completely covered and appear to be smooth and flush with the wall. Allow each coat to dry properly.

8. Try to recreate the texture of the wall. Do this by put ting a small amount of joint compound on a wet wash cloth. Dab it onto the wall like you would a sponge, until you have closely matched the surrounding texture, adding or subtracting wherever necessary if you have a smooth wall, just leave it smooth.

9. You are ready to prime. Make sure you use a primer before you paint because the new substance on the wall is much more porous and will absorb paint more quickly, changing the color and texture of the paint slightly.

10. Allow two coats of primer to dry before applying the paint to match the wall.


How to repair a hole in plaster:

1. Smooth out the edges of the hole with a utility knife.

2. Clean all debris from area. Make sure area is dry.

3. Brush concrete bonding agent onto the wood (lath) and old plaster surrounding the hole.

4. Attach wire mesh to the existing wood (lath) with dry wall screws. Why? Because, like the tape when you are fixing cracks, the wire mesh creates a surface that the joint compound can adhere to.

5. Fill in the hole with joint compound and smooth the outermost portion with a wide drywall knife to just below the surface of the surrounding area.

6. Where the compound meets the old edge, apply fiberglass mesh tape. You will basically be making a square box around a round hole.

7, Apply a thin coat of joint compound with a wide dry wall knife, much like you would frost a cake.

8. Allow a couple of hours to dry.

9. Apply as many coats as necessary to assure that the hole and tape are completely covered and appear to be smooth and flush with the wall. Allow each coat to dry properly.

10. Take 100-grit or similar sandpaper and sand over the joint compound until smooth.

11. Try to re-create the texture of the wall. Do this by put ting a small amount of joint compound on a wet wash cloth. Dab it onto the wall like you would a sponge, until you have closely matched the surrounding texture, adding or subtracting wherever necessary.

12. You are ready to prime. Make sure you use a primer before you paint because the new substance on the wall is much more porous and will absorb paint more quickly, changing the color and texture of the paint slightly.

13. Allow two coats of primer to dry before applying the paint to match the wall.

Hole or Crack in Plaster


Problem: A hole or crack in plaster walls or ceiling needs repair.

Background: Two types of patching compounds are available: 1) spackling compound which is convenient for small jobs and can be bought as powder or ready mixed, and 2) patching plaster which can be bought in larger packages and needs to be mixed with water. For repairing holes or cracks in the wallboard.

What to do: Both small cracks and holes can be filled with patching mixture; large holes may need to be filled step-by-step. First remove any loose plaster. Then use a knife to scrape out the plaster from the back of the crack so that the back is wider than the front surface. Thoroughly dampen the surface of the crack with a wet cloth or paint brush, mix up a small amount of patching com pound and fill in the crack with it. Smoothen the surface with a putty knife and sand the patch area after it has dried.
For larger holes or cracks, fill the hole partially and allow it to dry as a base for a final fill. Then add a second batch of compound. Let dry and sand until smooth. For large holes, you may need to fill in the area be hind the crack with wadded news paper. Begin patching by working inward from all sides. Let dry, then apply another layer around the new edge. Repeat until the hole is filled. Allow to dry and sand smooth.

Special advice: If the surface be yond the repair is textured, you can attempt to match the surface of the patch while the plaster is still wet. A sponge, comb, or other device can be used to accomplish the texturing.

Helpful hint: To sand repaired areas, it can be helpful to wrap sandpaper around a small length of wood. This will help keep the surface even. To check for ridges, hold a trouble-light or lamp next to the wall on one side or the other.

Hole in Wallboard

Problem: Damage has resulted in a hole in a wall or ceiling that is made of gypsum board.

Background: Small- to medium- sized holes can be mended with joint compound (either ready-mix or powder which is mixed with water) or with products called patching plaster or spackling compounds. Large holes may require cutting the wallboard back to the studs, and re placing the entire damaged section. For tips on repairing plaster walls or ceilings. For repairing cracks or nail pops in gypsum.

What to do: One way to fix a smaller hole is to use a plug method. With this technique, first mark a neat rectangle around the damaged area and use a utility knife or keyhole saw to cut out the area. Mark the hole’s dimensions on a scrap piece of gyp sum board, which is at least 2 inches larger all the way around. Make an other outline 2 inches around the plug area, then cut through this line completely. Next cut on the border of the plug, without cutting through the bottom paper layer. Peel off the gypsum board material in this 2- inch ring around the plug, leaving the full-sized paper intact around the plug’s perimeter. Spread patching compound around both the opening and the edges of the hole.

Press the plug firmly in place, hold a few minutes until the patch has set, then apply compound over the en tire area.
Another method is to fill smaller holes with crumpled newspaper and patch them with joint compound or patching plaster. A third method is to use a piece of string and a rectangular piece of gypsum board slightly larger than the hole. Put string through the center with the knot in the back and cover the patch’s outside edges with com pound or construction adhesive. Push the patch inside hole, pull on the string to bring the patch against the back of the original wall or ceiling and hold it in place until it sets. Then fill in the area with joint com pound.

Special advice: Another method, similar to the one above, is to insert a section of wallboard longer than the hole, and fasten it in place with sheetrock screws. With all methods, apply patching compound over the entire area, smoothening the material and compound beyond the edges of the damage. Feather the edges so the patch is flush with the wall surface. Remove excess com pound and let the patch dry. Reap- ply more compound if shrinkage occurs, then sand, prime, and paint.

Helpful hint: Patching plaster and spackling compounds are extremely porous and must be primed before painting. In some cases a coat of paint can be used as a primer before a second (final) coat is applied. Check the paint’s label to see if it is recommended as a primer. Allow primers adequate drying time be fore applying final paint.