How to Repair Water Damaged Drywall

Cut out the damaged section, dry the area completely, patch with new drywall, then sand and paint to match the existing wall.

1. Find the Source First. First, locate and fix whatever caused the water damage before touching the drywall. Check for leaks in pipes, roof damage, or other moisture sources. Mark the extent of the damage with a pencil. If the drywall feels soft or spongy, or if you see mold growth, the section needs to be removed completely.
2. Extract All Compromised Material. Use a utility knife to score the drywall in a rectangular shape around the damaged area. Make your cuts at least 2 inches beyond any visible damage. Cut through to the studs behind the wall when possible, as this gives you solid backing for the patch. Remove the damaged section carefully to avoid disturbing surrounding areas.
3. Dry Everything Completely. Allow the wall cavity to dry completely for at least 24-48 hours. Use fans and dehumidifiers to speed the process. Check the insulation behind the wall and replace it if it's wet or moldy. The framing must be completely dry before proceeding, or you'll trap moisture that can cause future problems.
4. Build Solid Support. If your cuts don't align with wall studs, screw 2x4 backing strips behind the drywall opening. Position them so half the strip sits behind the existing drywall and half extends into the opening. This gives you something solid to attach your patch to.
5. Hang the New Patch. Measure the opening and cut a piece of drywall to fit snugly. The patch should be the same thickness as your existing wall. Position the patch and secure it with drywall screws every 6-8 inches around the perimeter. Drive screws slightly below the surface but don't break the paper face.
6. Seal the Seams. Spread a thin layer of joint compound over the seams where the patch meets the existing wall. Press paper tape into the compound, then smooth it with a putty knife to remove air bubbles. Apply another thin coat of compound over the tape, feathering the edges outward about 6 inches from the seam.
7. Build a Seamless Surface. Once the first coat is completely dry, sand it smooth with 120-grit sandpaper. Apply a second coat of compound, spreading it wider than the first. Let it dry, sand again, then apply a final coat if needed. Each coat should extend further from the patch than the previous one, creating a smooth transition.
8. Blend and Conceal. Apply primer to the repaired area once the compound is completely smooth and dust-free. This prevents the compound from showing through the paint and helps the paint adhere properly. Once the primer is dry, paint the area to match the surrounding wall, blending the edges carefully.