Shower Waterproofing

I am constructing a large combination walk-in shower and toilet room. The shower area will be sloped ¼”per foot to a Kerdi line drain, the toilet area will be flat and the area in between will be sloped 1/8” per foot towards the shower area, all using deck mud. The walls will be tile over Densshield

My initial plan was to hang the Densshield down to the (concrete slab) substrate, tile the walls (leaving out the bottom course), and then float the floor over the concrete, and waterproof that with Kerdi Membrane wrapping it up the Densshield wall, subsequently installing the tile bottom tile course. This will mean that the bottom of the Densshield will rest on the concrete slab and be buried in the deck mud.

After studying GP’s methods calling for a 1/8 inch caulked gap at the bottom, and reading other’s concerns about the Densshield “wicking moisture", I am seeking an alternate method.

Since the sloped areas will have varied slopes. It would be challenging to try to trim the bottom of the Densshield prior to floating the deck mud.

After some thought, I came up with the idea of substituting Kerdiboard for the lower 12’ or so.which can be buried in the deck mud in lieu of Densshield. Of course I would caulk the joint between the Densshield and the Kerdiboard with silicone and cover with Kerdiband.

Does anyone see any problems with this plan?