09/03/2026
Shower waterproofing slope: you sloped the tile to the drain.
Did you slope the waterproofing underneath it?
Water doesn't just sit on top of the tile. Some of it gets below
the surface and reaches the waterproofing layer.
If that layer is flat, that water has no path to the drain. It sits.
Minimum shower pan slope is 1/4" per foot to the drain — TCNA.
And it applies to the waterproofing, not just the tile.
Running a clamping-ring drain and a liner? That pre-slope under
the liner is its own separate step. Running Kerdi or Hydroban?
You slope the bed and the membrane follows it.
It's the detail you never see once the shower's closed up. It's
also already decided whether that water drains or sits.
Comment SLOPE and I'll send you the full breakdown — drop table,
both systems, and the spots that get missed.