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At a Glance
Why Choose This Product
WATER-STOP membrane is factory bonded to both board faces
Accepts ceramic, porcelain, and natural stone with compatible thin-set mortar
Easier to carry, position, and handle during installation
Provides a stable substrate for tiled wall assemblies
Cuts with a utility knife for project layouts and fixture openings
Works with wood framing, metal framing, drywall, and existing tile
Creates a uniform tile substrate over properly prepared existing surfaces
Developed to IAPMO PS106 and meets ANSI A118.10 and A118.12
Product Information
GURU® W-S Board is a lightweight, waterproof tile backer board for shower walls, steam showers, tub surrounds, bathrooms, and other wet-area tile installations. Its high-density XPS foam core is factory bonded to WATER-STOP membrane on both faces, combining the backer board and waterproofing layer in one panel.
The high-density XPS foam core provides a sturdy tile substrate in a lightweight panel. W-S Board is easier to carry, position, and cut than traditional cement backer board, reducing handling effort during shower construction and remodeling while maintaining a solid base for the finished tile surface.
The factory-bonded WATER-STOP membrane provides a surface ready for direct tile installation using compatible polymer-modified thin-set mortar. Ceramic, porcelain, and natural stone can be installed without adding another waterproofing membrane across the board faces. W-S Board is developed according to IAPMO PS106 and meets ANSI A118.10 and ANSI A118.12.
W-S Board works with wood framing, metal framing, drywall, existing partitions, and properly prepared ceramic tile surfaces. This versatility makes it a practical waterproof backer board for showers, tub surrounds, wet-area walls, and tile-over-tile renovation projects in residential and commercial spaces.
Product Resources
Common Questions
GURU W-S Board is a waterproof tile backer board for shower walls, steam showers, tub surrounds, bathrooms, and other wet-area wall assemblies. Its lightweight XPS foam core and factory-bonded WATER-STOP membrane create a sturdy, tile-ready substrate for residential, commercial, new construction, and renovation projects.
No additional waterproofing membrane is required across the factory-covered board faces. However, the complete waterproofing system still depends on correctly treating joints, corners, fastener locations, plumbing penetrations, and transitions. Use the required GURU waterproofing products and follow the current installation instructions for the specific wet-area application.
Yes. Ceramic, porcelain, and natural stone tile can be installed directly over the WATER-STOP surface using a compatible polymer-modified thin-set mortar. Select a trowel appropriate for the tile format and follow the mortar and tile manufacturer requirements for coverage, curing, and application conditions.
W-S Board can be used with properly prepared wood framing, metal framing, drywall, existing partitions, and existing ceramic tile surfaces. Fasteners and supporting conditions vary by substrate, so the wall structure must be sound and the board must be attached according to current GURU requirements for that application.
Yes. W-S Board can be installed over properly prepared existing ceramic tile to create a uniform, tile-ready surface for renovation projects. The existing installation must be sound, stable, clean, and suitable to support the new assembly. Follow GURU requirements for bonding, fastening, waterproofing details, and tile installation.
Yes. W-S Board can be used in steam shower assemblies, but the joints and other waterproofing details require the specified banding and sealant treatment. All corners, fasteners, penetrations, and transitions must be completed according to GURU instructions to maintain continuous waterproofing in the high-vapor environment.
W-S Board can be cut with a utility knife to fit wall layouts and create openings for plumbing fixtures. Wood framing requires the specified board screws and washers, while metal framing requires appropriate self-tapping fasteners. Fastener type, penetration depth, and spacing should follow the current GURU installation instructions.
GURU states that W-S Board is developed according to IAPMO PS106 for tileable shower kits and meets ANSI A118.10 waterproofing and ANSI A118.12 crack isolation requirements. These standards support its use as a waterproof tile backer board within properly completed residential and commercial tile assemblies.
