Using Warped Cement Backer Board When Tiling a Floor

We’re putting cement backer board over our subfloor before tiling, but the cement board seems to be warped slightly. Is it still okay to use? -Lynn

Hi Lynn,

Unless the cement backer board is severely warped, it should be fine to use if:

• The subfloor is flat and smooth with no depressions or humps.
• The cement backer board is set in a bed of thinset and attached securely to the subfloor with backer board screws, so that the backer board lies flat against the subfloor. Be sure to screw down the cement backer board at regular intervals, as well as anywhere it warps upward away from the subfloor.

Good luck with your project,

Further Information

• Installing Tile Over a Wood Subfloor (article)
• How to Level a Subfloor (video)
• Tips for Cutting Cement Backer Board (article)
• How to Lay a Tile Floor (article)