How to Fix Drywall in a Bathroom With Damage From Moisture

Repair the drywall surface when the wall is dry. Find the studs behind sagging drywall with a stud finder, and push sagging drywall back up against the wall. Drive nails through the sagging drywall and into the studs to return the drywall to its proper position on the wall where possible.

Cut around the area of damaged drywall if the drywall cannot be returned to its proper position or appears too water-damaged. Use a drywall saw to cut into the wall, and cut a rectangular hole around the damaged area to remove all of the damaged drywall.

Put a mesh tape patch over areas of damage that are less than 5 inches square. Apply the patch by removing the adhesive backing, centering the patch over the hole and pressing the edges in place on the sturdy parts of the drywall around the hole.

Cut a new piece of drywall slightly larger than the section where the drywall was removed if the damaged area was more than 5 inches. For damaged areas of drywall larger than 8 inches, Lowe's recommends cutting a piece of backerboard for the hole along with the drywall.

Attach the drywall patch to the studs in the wall when studs are visible. If studs are not visible, work a piece of mesh screen into the hole and attach it to the backside of the drywall with adhesive or, for holes larger than 8 inches, attach the backerboard to the studs. Lowe's recommends tying string to a mesh screen to hold it in place while the adhesive sets up.

Attach drywall to the mesh screen or backerboard with drywall adhesive. Hold the drywall in place for five minutes to make sure the adhesive takes hold, and let the adhesive dry for the recommended time on the packaging.

Spread joint compound over the mesh tape patch or drywall patch with a putty knife as evenly as possible. Let the compound dry for two to three hours and apply a second and then a third coat. Once the third coat dries, sand the compound until the patch feels mostly even with the rest of the drywall.

Prime the patched area of drywall with primer, and apply paint in the same color as that used on the surrounding drywall. Apply at least two coats of paint to the patched area.