Moisture-resistant drywall, which has a light-green or blue face paper to distinguish it from other types of drywall (hence the name greenboard or blueboard), is designed to minimize moisture problems. The panels, which are moisture-resistant all the way through, are made to withstand high humidity and low levels of moisture. Moisture-resistant drywall is used mainly in bathrooms, and to cover the bottom 4 ft. of a laundry or utility room or the wall behind a kitchen sink. It is an excellent base for ceramic, plastic or metal tile applied with an adhesive, or for other nonabsorbent finishes such as paint, wallpaper or plastic tub surrounds.

Moisture-resistant drywall should not be used in wet or high-moisture areas, or in areas exposed to constant moisture. If used on the lower portion of a tub wall or on a shower enclosure, it should be covered with a tub surround or tile. In addition, it should not be hung over a plastic vapor barrier or a painted wall: Moisture-resistant drywall should be attached directly to the framing to avoid creating a double vapor barrier, which would eventually deteriorate the drywall if any moisture were to get in. In areas that are not covered with tile or other wall coverings, moisture-resistant drywall can be taped and painted the same as any other type of drywall.

Moisture-resistant drywall, which is available in 1/2-in. regular or 5/8-in. fire resistant, is used mainly as a wall covering over 16-in. o.c. framing. If you plan to install it on a ceiling, use 5/8 in. over 16-in. centers and 1/2 in. over 12-in. (or less) centers. (If the ceiling is insulated, check to make sure that unfaced insulation was used to avoid creating a double vapor barrier.)