Joint compound alone is not enough to fill anything larger than a quarter. You've got to put something into the hole or onto it and then use compound to make it smooth and invisible.
Holes that are too large to fill with compound, but are no more than 4 or 5 inches across, can be patched with a precut stick-on patch and some joint compound. Use a peel-and-stick patch. Made of stiff metal mesh, these patches can be placed over the hole and covered with two or three coats (or more) of compound. Here's how:
- Cover the hole with the stick-on patch.
- Smear compound over the entire area, feathering the edges. Here, less is more.
A thin layer of compound at a time is the big secret. A thick layer is difficult to sand and shows up on the wall as a bump. Let the compound dry completely.
- Sand lightly.
- Smooth more compound over the patch.
Let the compound dry completely. A third and fourth coat can be applied by repeating this step.
- Sand, prime, and paint.
Holes that are too big for a metal patch require a little different technique. A patch must be made with drywall. The easiest and most effective way to make such a repair is to use drywall clips. These little metal wonders straddle the edge of the hole and create a "shelf" along the back edge of the wallboard, giving you something into which you can screw a cut-to-fit patch. Here's how it's done:
- Cut a square or rectangular patch from a piece of scrap drywall. Make sure it will completely cover the hole.
- Hold the patch over the hole and trace its outline with a pencil.
- Use a utility knife or drywall saw to cut away everything inside the outline.
Watch out for wires and pipes.
- Install drywall clips on all sides of the hole (no more than 12 inches apart) and secure them using the screws provided with the clips.
- Insert the patch into the hole and drive screws through the patch into the clips.
- Snap off the temporary tabs of the clips (the ones that extend from the edge of the hole onto the face of the wall).
To complete a large patch, simply follow the finishing process for a smaller patch in the preceding section. With larger patches the only difference is that the joint tape must be applied to all four joints of the patch (top, bottom, and sides).
When we started in the business, we thought that the only way to fix really big holes was to cut away the damaged area to reveal the studs on either side, then install a new, cut-to-fit piece of drywall. Although almost nothing's changed, we have learned that there is another way to fix cantaloupe-sized cavities or water-damaged areas without cutting back to the studs. The steps are the same-patch, compound, sand, compound, sand, texture, prime, paint.
Instead of cutting back to the studs, we simply cut away the damage and install wood backing. You use the same principal as the clip method. A narrow strip of plywood is attached to the back of the wallboard at each side of the opening. Screws are driven through the drywall and into the wood strip. Half the plywood is held behind the drywall while the other half is exposed, acting as backing for our patch.