When indoor water damage strikes, drywall is often among the most conspicuous casualties. A ruptured pipe inside a wall cavity, a roof leak dripping down through the ceiling during heavy rain, water flooding a room and rising to meet the bottom of the walls—any of these scenarios can affect the highly absorbent combination of gypsum core and thin cardboard backing that composes a sheet of drywall. Is it a lost cause?
Maybe, Maybe Not
If wet drywall loses structural stability and sags or becomes deformed —or crumbles or collapses—it’s not a candidate for anything other than replacement. But what about drywall that remains intact, yet displays the discolored blotch that’s often left behind when wet drywall dries? Can you successfully seal and paint that ugly stain out of your life?
Here are some guidelines for painting stained, water-damaged drywall.
Rule 1: You can’t paint drywall until it’s completely dry. Ideally, this should be verified with the use of a moisture meter to be certain. To adequately dry soaked drywall and prevent mold growth, professional water damage remediation experts utilize equipment such as an industrial dehumidifier running inside the sealed room as well as high-volume fans that continuously move air to accelerate the drying process. Only when the moisture meter reading drops below 1% —usually not before at least three days of intensive drying following the initial contact with water—should painting intact drywall be considered.
Once it is tested and confirmed dry, seal the drywall by painting the affected area with a thin application of an oil-based or alcohol-based primer. Allow the first coat to dry completely, then apply a second coat of primer.
After the primer has fully dried, you can apply the first coat of latex or whatever another type of paint was originally used. It may be difficult to match the existing color when painting only a small stained area affected by water, so you may have to paint the entire wall or ceiling for consistency’s sake. After the first coat dries thoroughly, apply a finish coat.