Applying the KERDI membrane over cement backer board is a reliable way to upgrade a shower's waterproofing. While cement board is a common, durable substrate, it lacks the inherent ability to keep water out of the wall cavities. Applying a sheet-applied, bonded waterproofing membrane like KERDI turns that cement board into a fully sealed surface that stops water and vapor from penetrating the wall assembly. For a successful bond, the cement board must be properly fastened according to its manufacturer’s specifications, and all joints must be addressed. Before applying the membrane, ensure the surface is completely free of dust and debris, as any loose material will prevent the thin-set mortar from creating a secure bond. By installing the membrane, you combine the rigidity of the cement board with the waterproofing performance of the Schluter system, resulting in a robust, leak-free shower environment.
Key considerations
- installing KERDI over cement board
- waterproofing cement backer board
- Schluter membrane installation
- Cement Board
- Waterproofing
- Bonding