Cracks in the walls of a home are caused by the stress from a shifting and settling house frame. The use of mesh wire and drywall compound makes it possible to patch these areas and salvage the wall, instead of cutting and replacing the entire piece of cracked drywall. The mesh wire is a superior reinforcement for a crack repair than a mere application of drywall compound.
Undercut the edges of the crack with a knife. Remove loose wall fragments. Brush debris from the area around the crack before continuing.
Moisten the backing and edge of the cracked drywall area to give the drywall compound a better surface to adhere to.
Cut a piece of mesh wire slightly larger than the cracked area with a wire cutter. If the crack is wide rather than hairline, carefully insert the piece of mesh wire into the cracked area by nudging the overlapping edges of the wire mesh into the area between the loosened paper surface of the drywall and the solid drywall material underneath.
For a hairline crack, smooth a thin coat of drywall compound over the crack with a 6-inch spackle knife. Press the piece of mesh wire firmly into the wet plaster.
Apply the compound so it overlaps the edges of the crack by an inch or two, regardless of the crack's size.
Apply a thin coat of drywall compound over the mesh wire. For larger cracks, in which the wire mesh has been embedded within the drywall to cover a gap, use a more generous coat of drywall compound to cover the crack and mesh wire.
Overlap the edges of the crack with your compound coat by an inch or two, regardless of the crack's size.
Allow the first coat to dry. Apply a second coat, extending the edges slightly beyond the edges of the first coat. This tapers the edges of the compound applications to prevent a raised bump of hardened compound from occurring.
Apply a third coat of compound after the second has hardened, extending the edges an inch or two beyond the second dried coat.
Scrape drywall compound ridges and bumps off the repair area between coats using your spackle knife. After the third coat dries, lightly sand the repair area with a fine-grit sandpaper. Reduce any bumps or ridges where the compound was applied for a blended and seamless appearance.
Use quick drying compound to reduce the waiting time between coats. Aiming a hair dryer at wet coats of compound can reduce the time spent waiting to apply the second and third coats.