How to Fix a Long Crack in Your Wall

Widen the crack. Use the edge of a utility knife or the pointed edge of a can opener to widen the crack to at least one-eighth inch. Widening the crack will increase the surface area and help the joint compound form a tighter bond with the drywall.

Trim any irregularities from the edges of the crack with your utility knife. Scrape out any remaining loose debris out of the crack. Use a vacuum cleaner to then remove any small particles.

Drive some 2-inch nails through the drywall and into the wood behind it. Space the nails so that they are one-fourth inch to one-half inch away from the crack, on both sides. Place a nail every two to three inches along the length of the crack. The nails will anchor the drywall to the wood backing board behind it and will prevent the drywall from shifting and cracking again. Hammer the heads of the nails until they are slightly below the surface of the drywall.

Cover the entire length of the crack with fiber mesh drywall tape. Make sure that the tape also covers the heads of the nails. If the crack forms irregular angles, tear the tape into smaller sections and place it over each straight section of the crack.

Dip the edge of a 4-inch-wide putty knife into a container of drywall joint compound. Spread the joint compound over the surface of the crack. Feather the putty knife over the joint compound until it is spread evenly. Allow the joint compound to dry.

Apply another coat of joint compound over the crack once the first layer is dry. Repeat this one more time for a total of three layers of joint compound. Allow it to dry.

Sand down the dried joint compound so that it is flush with the surface of the all. Wipe the area clean with a rag, and then vacuum any remaining dust. Apply a coat of primer, and allow it to dry. Paint over the primer with the color that matches the rest of the wall.