Cement Board
A rigid panel made of Portland cement and reinforcing fiber used as a moisture-resistant substrate for tile installations.
Cement board (brand names include Hardiebacker, Durock, and WonderBoard) is a construction panel composed of Portland cement, aggregate, and glass fiber reinforcement. Unlike drywall, cement board does not deteriorate when exposed to sustained moisture, making it the preferred substrate behind tile in wet areas like showers, tub surrounds, bathroom floors, and kitchen backsplashes.
Installation involves fastening the board to the framing with corrosion-resistant screws, taping seams with alkali-resistant mesh tape and thin-set mortar, and then applying tile directly over the surface. Some installers also add a waterproofing membrane (like Schluter Kerdi or Redgard) over the cement board for additional protection in walk-in showers.
Cement board costs $0.40–$0.80 per square foot for the panel, plus fasteners, tape, and labor. It is heavier and harder to cut than drywall (use a carbide blade or score-and-snap), which adds to labor time. Using standard drywall in shower areas—a common shortcut—is a code violation and will cause mold, tile failure, and structural damage within a few years.
Real-World Example
The tile setter installed 1/2-inch cement board over the shower walls and used Redgard waterproofing before setting the large-format porcelain tiles.