Shower Waterproofing

There being seemingly endless ways to do a shower pan, I opted for the tried and true (mortar bed, Durock walls coated with Redgard). However I’ve chosen not to bury the cement board in the mortar bed. There is a lot of controversy about embedding the cement board in the mortar due to concerns about water wicking up the cement board, hence my choice.

My plan is to leave just enough room at the bottom of the wall panels to extend the tile beneath. Actually I’m going to lay the floor tile on the mortar bed and then put in the final bottom section of Durock panels such that they are just a bit up off the tile surface.

This of course does leave a small air gap in that corner where one might imagine water could settle. Do folks generally fill this small void with caulk or thinset?

One other concern, though probably minor, is that this approach leaves the bottom few inches of cement board unsupported.