For a field fabricated shower stall (no base), what must be installed and connected to the drain?

• A. Shower pan liner
• B. Shower curb
• C. Waterproof membrane
• D. Drain basket

Answer: (A)

In a field-fabricated shower stall, the essential element is the shower pan liner. It provides the primary waterproofing barrier and is connected to the drain so all water is directed into the drain rather than soaking into the subfloor or framing. The liner is laid over the subfloor, rises up the walls to form a curb line, and is cut to fit around the drain, then sealed to the drain assembly with a clamping drain to create a continuous, watertight path for moisture.

The curb is part of the enclosure but it isn’t something that must be connected to the drain for the waterproofing system to work. A waterproof membrane can be used in some installations, but the item that must be installed and integrated with the drain in a field-fabricated shower is the pan liner. A drain basket is a component of the drain itself, not the waterproofing barrier that prevents leaks.