Waterproofing Membrane

A waterproofing membrane creates a moisture barrier beneath compatible tile assemblies to help prevent water from reaching moisture-sensitive substrates and surrounding building materials. Waterproofing membranes are commonly used in showers, bathrooms, tub surrounds, floors, walls, and other wet areas where the tile assembly requires moisture protection.

Sheet waterproofing membranes are manufactured materials installed over the substrate with seams and transitions treated according to the system requirements. Liquid membranes are applied directly to compatible surfaces and cure into a continuous layer. Installation thickness, reinforcement, curing, seam treatment, and substrate requirements vary between the two methods.

Waterproofing membranes are commonly used in showers, tub surrounds, bathroom floors, wet-area walls, and other tile installations requiring moisture protection. Some membranes are also approved for additional interior or exterior applications. Always verify the membrane's approved substrates, locations, exposure conditions, and installation requirements before selecting it.

Tile and grout are not normally relied upon as the primary waterproofing layer of a shower assembly. Water can reach areas beneath the finished surface, so the shower requires an appropriate moisture-management system. A compatible waterproofing membrane or other approved shower waterproofing method provides protection behind or beneath the tile.

Many waterproofing membranes are designed to receive tile directly after proper installation and any required curing or drying period. The tile setting material must be compatible with the membrane and finished tile. Follow the membrane manufacturer's requirements for mortar selection, installation timing, surface preparation, and other tile installation procedures.

A shower pan liner forms a waterproof layer within compatible shower floor assemblies and directs water toward the drain system. Pan liners are commonly used with traditional mortar-bed construction. Proper installation must account for the drain connection, floor slope, corners, curb, penetrations, and other transitions within the shower assembly.

Many waterproofing membranes can be installed over compatible cementitious backer boards and other approved tile substrates. Compatibility and preparation requirements vary by membrane and board system. The substrate must be properly installed and prepared before the membrane is applied, and seams, penetrations, corners, and transitions require the specified treatment.

Consider the installation area, substrate, moisture exposure, construction method, drain configuration, and finished tile assembly. Determine whether a sheet membrane, liquid waterproofing membrane, or shower pan liner is appropriate, then verify compatible accessories, setting materials, seam treatment, curing requirements, and other manufacturer specifications for the complete system.