If there is an old hot mop shower pan it must be removed to the wood framing and subfloor. Also note that the tile hardibacker gets installed after the hot mop.

  • Install a NEW drain. Must be the bolt-together type. (Avoid drains with plastic female threading for the bolts.)

  • Install drain so that the subflange is flush with the surrounding concrete or resting on the wood subfloor.

  • Set water threshold ("dam") to height at least 1" higher than top of finished drain. (usually three stacked 2x4's, or min of 3.5" height).

  • There must be at least 10" of solid blocking around the base of the walls. 2x10’s secured in between the studs flush with the studs is most common.

  • Any benches framed in must be solid on all sides and have at least 4" of backing on the walls around the seat where it meets a wall. Floating style seats must be solid on the underside as well.

  • Shower subfloor must be strong (not bend under weight) and level with no large holes or gaps.


  • The entire shower subfloor must be recessed a minimum of about 3"-4" below the outside subfloor.

  • The subfloor is recessed in order to set the flood level at a height at least 3/4" above the finished drain top. The hot mop will raise the finished drain top about 3/8" when complete.

  • * This 3/4” difference is a minimum technical requirement. Local code may require a larger difference depending on shower size, drain location, and ADA codes. Please consult your city code.

  • The drain subflange must be flush or no more than 1/4" above the surrounding shower subfloor.

  • We HIGHLY recommended using a three piece adjustable top drain for damless showers.

  • When recessing the shower subfloor make sure to keep the recess wall flush with the framing above it. Any jagged edges (due to jack hammer) must be smoothed out.


  • Linear drains must have a bolting-flange (clamping coupling) assembly installed before the hot mop.

  • The subflange of the of drain assembly must be installed with the outer edge flush with slab or resting on top of subfloor.

  • Outer edge of subflange must be at least 1" away from a vertical surface (wall, bench, dam, etc).

  • The linear trough/channel gets inserted after the hot mop.


  • Make sure subfloor is solid (no holes or gaps) and sloped to the drain subflange or gutter.

  • Completely remove any old waterproof membranes and make sure deck is dry and clean.

  • Deck needs to be properly flashed* using at least 4" inch 'L' shaped metal flashing on all walls, steps, and transitions. This flashing needs to go behind wall wall moisture barrier.

* We do not do flashing. You must consult your local code requirements and/or a general contractor to make sure this is done correctly.



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West Coast Hot Mop, Inc. © 2019 CL# 1051155

The sibflange of the drain assembly must be installed with the outer edge flush with slab or resting on top of subfloor.