Water and drywall do not get along
Drywall is a mineral core faced with paper, and paper holds water. A slow leak behind a bathroom wall, a failed supply line, a roof leak that runs down inside a wall or a flood from a burst pipe all start the same way: the board takes on moisture and softens, stains and, if it stays wet, grows mold. The first decision after any wetting is whether the board can be dried quickly or has to come out.
What EPA says to do
EPA's guide to cleaning up mold in a home is plain about the main steps. Fix the water problem first, because cleanup does not last if the moisture returns. Dry all items completely. Porous materials, which it gives examples of such as ceiling tiles and carpet, may have to be thrown away if they become moldy because the mold is difficult or impossible to remove completely. Hard surfaces can be scrubbed with detergent and water and then dried completely.
The same guide sets a size line. In most cases, the guide says, a homeowner can handle an area of less than about 10 square feet. For larger mold growth or a lot of water damage, it points to separate guidance written for schools and commercial buildings, and says to confirm that a contractor has experience cleaning up mold. Water from sewage or other contaminated sources is a different case, where it says to call a professional with experience in buildings damaged by contaminated water.
Cut out, dry out, replace
- Stop the source. Close a valve, tarp a roof, or repair the line. Nothing else works until this is done.
- Measure the wet area. Soft, stained, bubbled or discolored board is a warning. A moisture meter, which restoration companies carry, shows whether the wall is still damp behind the paint.
- Open the wall. Cutting out the wet section lets the cavity and the framing dry. Insulation that is wet usually comes out too.
- Dry completely. Fans and dehumidifiers speed it. Close up only when the framing and the cavity are dry.
- Replace the board, tape and finish it. The cracks and holes chapter covers patching, and levels of finish covers the finish.
What a good result looks like
The source of the water is fixed, the cavity and framing are dry before the wall is closed, any wet board has been replaced rather than painted over, and the finish matches the room. The wall stays dry and clean from then on.
Choosing the board that goes back
For a bathroom, laundry room or basement, moisture-resistant or mold-resistant board is a sensible choice, but it is a second line of defense and not a cure. Neither type is waterproof. In a shower or tub surround, the standard approach is a tile backer made for wet walls rather than green board. Read drywall basics for the types and ask the contractor to name the exact product.
Texas licensing for mold work
Texas regulates mold assessment and remediation separately from ordinary construction. The Texas Department of Licensing and Regulation's list of regulated industries includes Mold Assessors and Remediators. If a company is hired for a mold job, ask for its license number and check it with the agency before work starts. A general drywall crew replacing a small wet section after a plumbing repair is a different job from remediation of a mold problem, and a good contractor will tell you which one you have.
When to involve your insurer and the city
Insurance rules vary by policy and by cause of loss, so read your policy and call the insurer before throwing away evidence. Photograph the damage and keep samples if the insurer asks. Larger repairs can also need a permit; the City of Austin's express permit page lists drywall repair above 128 square feet. See permits and codes for the details.
Houses built before 1978 add lead-paint rules, and older textured ceilings can contain asbestos, so read older homes before cutting or sanding.
Questions people ask
How big can a moldy area be before I should call a professional?
EPA's home guide says that in most cases you can handle an area of less than about 10 square feet yourself. For larger areas, or after a lot of water damage, it points readers to its guidance for schools and commercial buildings and to contractors with mold experience.
Can wet drywall be saved?
EPA says porous materials such as ceiling tiles and carpet may have to be thrown away if they become moldy, because the mold can be difficult or impossible to remove completely. Drywall paper behaves similarly, and a soaked wall that is not dried promptly is often replaced.
Does Texas license mold professionals?
Yes. The Texas Department of Licensing and Regulation lists Mold Assessors and Remediators among the industries it regulates. Ask for a license number before work and check it with the agency.
What if the water came from a sewer or contaminated source?
EPA says to call a professional with experience cleaning and fixing buildings damaged by contaminated water.
Should I use mold-resistant board when I replace a wet wall?
It is a reasonable choice in rooms that stay damp, but it does not replace fixing the water source. The basics chapter explains the board types.