For curbless showers in wood framing, what deflection, waterproofing, and splash management prevent failures?
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Make sure your floor joists are stiff; aim for no more than L/360 deflection, especially if you’re putting in large tiles. Slope the shower pan ¼ inch per foot towards the drain, and use a continuous waterproofing system that connects to the drain flange. Extend the waterproofing at least a foot beyond the wet area. For extra protection, consider a linear drain at the entrance or a slight slope break. Size the shower, so water stays inside the glass. This will prevent splashes all over the bathroom floor!
Deflection
-Minimize floor deflection: Ensure the floor joists are adequately sized and spaced to support the weight of the shower, water, and users. Typically, floor joists should not deflect more than L/360 (1/360th of the span length) under live loads.
Waterproofing
-Sealed shower system: Use a sealed shower system, like Schluter Kerdi or Wedi, which includes a waterproof foam shower tray or bonded waterproofing membrane. These systems are designed to prevent water damage and are recommended by the Tile Council of North America (TCNA).
Splash Management
-Proper slope: Ensure the shower floor is sloped towards the drain to prevent water from pooling. A minimum slope of 1/4 inch per foot is recommended.
For curbless showers on wood:
Deflection: Limit subfloor to L/360 under tile.
Waterproofing: Continuous membrane up walls greater than 6 inches, sealed at seams and drains.
Splash: Floor sloped quarter of a inch per foot to drain; prevent water pooling at edges.
Optional: extend waterproofing slightly beyond shower for extra protection.