What Is Cement Board and Where Should It Be Used?

Cement board is built from Portland cement, sand, and glass or polymer fibers, pressed into rigid panels. It resists water damage far better than standard drywall, which can crumble and grow mold when soaked. Because it does not absorb moisture the way gypsum does, it holds up in bathrooms, laundry rooms, and other damp spaces.

The surface is rough and porous, which gives tile mortar something to grip. You can cut it with a utility knife or a carbide-tipped blade, and it is heavy enough that two people often handle large sheets. For most homeowners, the main trade-off is the extra effort to install it compared to drywall.

• Resists rot and swelling from moisture
• Provides a solid base for tile and stone
• Does not feed mold growth like paper-faced drywall
• Works indoors and outdoors
• Requires special cutting tools and fasteners
• Heavier than drywall, so plan for extra help

Drywall is still a fine choice for ceilings, living rooms, and bedrooms where water is unlikely to hit the surface. It is cheaper, lighter, and easier to finish with joint compound and paint. For a quick patch or a room with no moisture, drywall saves time and money.

If you are unsure whether a space needs cement board, think about how often water touches the wall or floor. A half-bath with a sink but no shower may be fine with drywall, especially if you keep it ventilated. A full shower, however, deserves the extra protection of cement board.

Cement board itself rarely rots, but the wood studs behind it can still get wet if water seeps through seams or around fixtures. Check caulk and grout regularly, and fix any cracks right away. If you notice a musty smell or soft spots near the base of a wall, water may be getting behind the surface.

If water has already damaged the area, the pros can inspect the wall structure and remove any wet insulation or rotted wood. They can also dry out the cavity and replace damaged sections of cement board before you re-tile. Acting quickly helps prevent mold and keeps the repair simple.

• Inspect caulk and grout lines every few months
• Look for discoloration or crumbling in the board
• Keep bathroom fans running during and after showers
• Seal around pipes and fixtures with waterproof caulk
• Address leaks in the roof or walls without delay
• Call the pros if you suspect hidden water damage