Removing mold on sheetrock that has been previously primed or painted is a relatively simple procedure. Before you begin, locate the source of the moisture causing the mold and remove it to prevent future mold growth. To remove the existing mold on sheetrock, you will need to mix a solution of one part chlorine bleach to four parts of water. After donning protective gear as necessary, apply the solution to the sheetrock using a sponge or spray bottle. After the mold has been removed, rinse and dry the surface well and apply a stain blocking primer or sealer before repainting the surface.
Before removing mold on sheetrock, you should inspect the surrounding area to determine the cause of the mold. Any leaks in the roof or plumbing should be repaired to prevent the mold from reoccurring. If the mold is being caused by condensation, you may need to install a dehumidifier in the room. If the sheetrock has been saturated or damaged by water, it will probably need to be replaced. Extremely large areas of mold on sheetrock may need to be disposed of by a professional to prevent the spores from spreading onto carpets, draperies, furniture, or ductwork.
It is important to protect yourself from the disturbed mold spores by wearing a respirator during the mold removal procedure. You will also need to wear latex or vinyl gloves to protect your skin from the chlorine cleaning solution. Proper ventilation is essential during this procedure; open as many doors and windows as possible before beginning the work. If you are working on an overhead area, you will also need protective eye wear. Cover the floor and surrounding areas with plastic sheeting to avoid staining the carpeting, flooring, or furniture.
Next, make a chlorine cleaning solution of one part household bleach to four parts water. You may mix this solution in a plastic bucket or spray bottle. Apply the solution to the sheetrock, wait 15 minutes, and scrub thoroughly with a sponge, soft brush, or cleaning cloth. Repeat this process using a fresh chlorine solution and scrubber until the mold is completely removed. Use as little of the chlorine solution as possible to avoid saturating the sheetrock surface.
After you have successfully removed the mold, rinse the sheetrock surface thoroughly to remove any chlorine residue and use a mild cleanser to prepare the surface for priming and painting. Dry the sheetrock completely using a towel or blow dryer. Dispose of all plastic sheeting, cleaning cloths, brushes, and sponges used during the mold removal procedure to prevent regrowth. If the area is still damp from a previous water leak, it is a good idea to place a dehumidifier in the room for several days prior to painting. Finally, apply a stain-blocking primer or sealer to the sheetrock before repainting it.