Flexible patches are best for fixing wall cracks


September 18, 1993|By Gene Austin | Gene Austin,Knight-Ridder News Service

Q: A long crack has reopened in our living room wall, which is covered with gypsum wallboard. I fixed the crack several years ago and thought I wouldn't have to do it again. Are there any "new and improved" crack patchers on the market that might make a permanent repair?

A: Some wall and ceiling cracks are difficult to repair permanently because slight shifting of the house can cause them to reopen. Patches that are flexible enough to move with the house have the best chance of not cracking.

Several crack-patching materials promise lasting repairs. In general, these consist of special tapes and patching compounds that are sold in kits at home centers.

I've tried several special crack patchers with varying results, but I've found that good repairs can also be obtained using conventional materials. Repairs from the conventional approach will hold up well and survive minor shifting of the house.

Start by cleaning the crack of any old patches and loose material. Apply a strip of self-adhesive, fiberglass drywall tape, designed for sealing joints between drywall panels, over the crack. This tape is also available at many home centers and building-supply outlets.

Fiberglass drywall tape is usually sold in 2-inch widths, but wider tape is available. Cut the tape, if necessary, to follow the lines of the crack without making wrinkles, and extend it several inches beyond each end of the crack.

Press and smooth the tape over the crack with a joint-taping knife. A 6-inch-wide knife works well.

Cover the tape and its edges with a thin coat of wallboard joint compound. Be sure to read the directions on the tape to see if a special type of compound is needed; fiberglass tape generally requires joint compound rated as "fast setting."

Smooth the compound carefully with the joint knife and let it dry, then sand the compound and feather the edges. Apply a second coat of compound, extending the edges a bit farther, let dry and sand smooth. A third coat, extended still farther at the edges, is sometimes needed to get an invisible repair.

When the patch is smooth and completely dry, it can be primed and finished with paint or wallpapered over.

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