Drywall Stained and Warped by Water

This winter has been brutal on the snowfall front and not only are roofs taking a beating, but interior drywall is as well. Drywall damage and stains are usually the result of a leaky roof or plumbing fixture. Minor damage and stains can be quickly and easily be repaired. Sometimes the damage is not too severe and does not require the replacement of the damaged drywall.

Drywall repair

If you feel comfortable tackling the repair yourself, these are the steps you will need to follow: Before doing anything else, make sure the drywall is still attached to the studs or framing. If you are unsure, look for sagging or broken wallboard, which if found will need to be replaced. What you are looking for is blistered paint or loose layers of drywall mud but the drywall itself is solid and secured to the studs. However if the drywall is sagging only slightly try to snug it up using drywall screws. Begin with the outermost edge of the sag. You want the screws go into the studs and not break through the surface of the wallboard. Working slowly toward the worst part of the sag, slowly use the screws to pull up the board.

Once the drywall is secured scrape off all loose layers of mud and paint. The moisture and resulting stain will have caused the mud and paint to lose its adhesion, making it relatively easy to scrape off. Start in the center and scrape outward until you feel these coatings are no longer soft or easily scraped off. You should use a putty knife with a sharp edge for this job.

If a small amount of mold or mildew is present, you can wipe the surface with alcohol or a solution of chlorine bleach and water to kill the mold. If the mold is prevalent, then you will have to replace the damaged drywall.

Water damage staining is usually the first sign of a problem. The stain will bleed through the finish paint if it is not sealed. There are several paints (primers) that will seal drywall and are labeled appropriately. Paints or primers are available in water, oil and alcohol bases for sealing water stains. Typically the oil and alcohol base sealers work the best. They can be either brushed or rolled on and usually they dry quickly. Most stains will cover with one coat, but you should apply two coats and it is easier to apply the second coat now rather than later in the event the stain has come through a single coat. The seal coat prevents bleed through and provides a clean, dust free surface for any patching materials.

Putty and KnifeTo adequately smooth the surface you will need to use multiple applications of drywall compound (mud), at least three. Drywall compound (mud) can be bought pre-mixed or in a powder (also known as “setting type”) that is mixed with water. The first application should fill the deepest part of the damage and bring up the surface to just about level with the surrounding undamaged board. The second coat completely levels the damage and you should begin to feather out toward the undamaged area. The third coat is used to completely feather out the edges of the repair to hide the transition of the new patch to the surrounding undamaged drywall. When done properly the patch is invisible.

Tips for a successful patch:

  • Work from a drywall mud pan, they are not expensive, but very helpful.
  • Slowly build up the repair with each layer in depth and area, the size of the patch should expand outwardly to blend into the surrounding surface.
  • Sand with a medium to fine grade of sandpaper in between each layer.
  • Brush off or vacuum the surface after sanding to remove the dust.
  • The third coat should be thinner and fill any pinholes, slight imperfections or sanding gouges.
  • Allow the patch to completely dry before doing the final sanding.

Your patch can now be painted using a high quality paint but first use a drywall primer before applying the finish coat. Usually the paint or primer you used to seal the stain can also be used for drywall priming. The primer coat provides a nice transition layer between the drywall mud and the finish coat of paint. By using a primer, you seal the raw materials resulting in the finish paints having a smooth and even appearance.

If all of this sounds overwhelming to you, remember you can always call Andy OnCallĀ® to take care of your drywall repair needs.