Cement Board
Affiliate link — we may earn a commissionCement board is a sheet material made from Portland cement and reinforcing fibers (fiberglass or cellulose), sold under brands like Hardie Backer, Durock, and WonderBoard. Standard sizes are 3x5 feet in 1/4-inch and 1/2-inch thicknesses. It's waterproof, won't grow mold, and provides a rigid substrate for tile. You score and snap thin cement board with a carbide scoring tool, or cut it with a circular saw fitted with a diamond or fiber-cement blade. Cutting it with a standard wood blade fills the air with silica dust and destroys the blade in minutes.
Why It Matters
Cement board goes behind tile in showers, tub surrounds, and backsplashes where moisture is constant. Drywall in those spots absorbs water, grows mold, and eventually disintegrates behind the tile. If you're tiling a wet area, cement board is the correct substrate. Wear a respirator when cutting it. The dust contains silica.