How to repair water damage on walls | Pro Construction Guide

How to repair water damage on walls

repair water damage walls

Remove any insulation behind damaged panels. It can hold water for months, causing odor and mold.

To repair water damage on interior walls, they must dry from the inside out before you start. Even if the surface feels dry, the inside can still be wet.

Problem: There is still noticeable dampness in the room.


To dry the room so you can begin to repair water damage, remove any rugs or carpeting to allow the area to dry more thoroughly. Use air movers and a large capacity dehumidifier. Drying time will vary depending on the amount of dry air you can circulate through the studding and wall.

Cut a few small drain holes in the affected drywall panels 1 to 2 inches above the floor between the studs with hand tools. Never use an electric saw or electric drill for this step.

If water seeps out, cut a larger square hole in the drywall above the original hole to allow access and then sponge dry the inside of the wall. Another option is to cut 10 to 15 inches of drywall along the base where there is water damage.

Problem: You want to reuse some of the drywall as you repair water damage.


As a rule of thumb, you should remove any drywall that displays black mold, bulges or cracks before you begin to repair water damage on walls . Also remove any insulation behind the damaged panels because it can hold water for months, causing odor and mold problems.

When dealing with mold, wear protective goggles and gloves. A respirator is also strongly recommended. If the area that contains mold is greater than 10 square feet, have a mold removal expert handle this step.

Before you decide which drywall you can salvage, remember that additional damage may not be immediately evident. Rusting fasteners or mildew may not appear until the drywall has dried completely.

When you are sure the drywall is completely dry, replace all rusted fasteners and clean any small areas of drywall that shows signs of mold or mildew, using a mildew remover, mildewcide or bleach. Follow manufacturer guidelines for proper use.

If you replace drywall, always use panels with the same rating or better for sound, fire and humidity resistance.

Problem: What is the best way to repair water damage on walls?


When drywall is exposed to water, the joint compound, tape and paint bubble and stains appear, ranging in color from dark yellow to brown. The stains are caused by substances in the drywall that have leached to the surface.

If the surfaces themselves aren’t damaged, you can paint over stains, after applying a sealer to prevent further leaching.

When patching drywall, cut the hole as close to the nearest stud as possible, so you can firmly secure the new clean patch.

Repairing water-damaged walls 2

Replace the tape with fiberglass mesh and apply a thick coat of joint compound, pressing hard to fill the gap and tape fibers.

If the water damaged walls don’t show any other signs of damage, remove the tape and joint compound, lightly sand the surface, clean the dust and apply a primer-sealer. After it dries, replace the tape with fiberglass mesh and apply a thick coat of joint compound, pressing hard to fill the gap and tape fibers.

Skim off the extra compound to leave a thin coat. When it is dry, sand it lightly with medium grit sandpaper.

Repeat this process three or four times, allowing 30 minutes drying time between coats, until the tape is covered completely. Allow it to dry for at least an hour and sand smooth, blending the edges into the surrounding area. Wipe up any dust and prime and paint the surface.

If a section of water damaged walls has only small sections that are damaged, use a saw to cut a square hole around the damaged edge and remove it. Then patch the section as you normally wood and complete the repair.

‒By Gabriel Ascencio

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