Substrate Preparation
Cement board, backer board, subfloor requirements, deflection standards, flatness tolerances, and self-leveling compounds.
- Install cement board correctly including fastener spacing and joint treatment
- Evaluate subfloor requirements and deflection standards for tile
- Measure and correct surface flatness to meet tile installation tolerances
Lección 1
Cement Board Installation
Why Cement Board Matters
Cement board (also called backer board) provides a stable, moisture-resistant substrate for tile. Unlike drywall, cement board does not deteriorate when exposed to moisture, making it essential for wet areas like showers, tub surrounds, and countertops.
Approved Substrates
Cement board - HardieBacker, Durock
Fiber cement board - moisture resistant
Foam board - Kerdi-Board, GoBoard
Mortar bed - traditional mud method
NOT Approved for Wet Areas
Regular drywall - deteriorates with moisture
Green board - NOT waterproof, only moisture resistant
Plywood alone - swells and delaminates
Installation Procedure
- Cut to fit - score and snap or use a carbide-tipped saw
- Apply thinset to the subfloor before setting cement board (creates a bond layer)
- Fasten with screws at 200 mm (8") intervals in the field and 150 mm (6") on edges
- Stagger joints - offset from subfloor joints and drywall joints
- Tape joints with alkali-resistant mesh tape embedded in thinset
Common Mistake
Green board (moisture-resistant drywall) is NOT a substitute for cement board in wet areas. Green board softens and fails when saturated. Use cement board or an approved waterproof substrate in all shower and tub areas.
Cement board is required in wet areas - green board is not waterproof and will fail. Install over a thinset bond layer, fasten at 200 mm intervals, stagger joints, and tape with alkali-resistant mesh tape embedded in thinset.