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Zero entry shower in a hydronic slab as finished floor, membrane & shower floor material?

Kevn Member Posts: 1
I am solo building an ICF house in Oregon with a hydronic slab over 2 inches of foam (R-10) over 2-4 feet of compacted crushed concrete fill. The only wood in the structure is roof framing which is a minimum of 10' above the shower floors. The hydronic concrete floors will be 5" thick with a cream hardener finish. Floors are supposed to pour in one week, only 6 weeks after originally scheduled. Finished slabs are one of the two trades/skillsets I do not do myself and the other one is not relevant to this project.

There will be two zero entry showers with linear drains installed along the back wall.

This project is being built in a small jurisdiction with only a couple inspectors, one old and coasting to retirement without the benefit of new knowledge and one young and new and unsure about anything that is not conventional wood framed residential construction over a crawlspace.

My concrete guy wants to do a mono-pour and simply slope the shower floor back to the linear drain which he has done in the past in other jurisdictions. This was also my design strategy.

Two code problems/challenges that I just became aware of during the under slab inspections:

1. The older inspector does not think that a concrete slab is legal as shower floor and that I must tile the shower floor.

2. Both think that I must install a shower pan liner which then divides the 4 inch thick slab (remember we lose one inch to the slope) into two thin slabs which will not be thick enough to be stable and will crack per the the concrete slab contractor.

I have spent some hours trying to find relevant codes for this application without success.
Any help appreciated.


  • hot_rod
    hot_rod Member Posts: 20,720
    The main issue would be how to make the wall to floor connection water proof?  Shower pans typically wrap up the wall as high as the curb. On my in-laws we pounded the slab tapered to the center drain which was a clamping ring type. Put a PVC  membrane down, then a mud base. It added an inch and a marble tapered curb finished the opening. the pan wrapped up the three walls of the neo angle shaped shower. It was still wheelchair friendly.

    Its the only way my tile guy would do a roll in shower

    sometimes you are the windshield, sometimes the bug, with AHJs and inspectors.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jon_blaney
    Jon_blaney Member Posts: 313
    Polished concrete sounds like a slip and fall problem. That may be the the reason they want the tile. When I built my zero entry shower, the floor was framed with a depression to accept the added materials necessary to build up a waterproof shower pan with a tile floor. You need to do the same.
  • PC7060
    PC7060 Member Posts: 1,096
    edited April 2022
    Recommend you post your question at tbe John Bridge tile website. This questions comes up all the time. 

    As mentioned above, typical solution is to recess the floor 2” in tbe shower area and use a mud bed to the drain.  Water proofing could be done with a clamping drain with PVC membrane as @hot_rod mentioned or a surface applied water proofing fabric such Schluter Kerdi or Aqua Defense used to water proof the mud bed and tie the floor into the wall water proofing. 

    Usually when the concrete poured bed topic comes up it’s a Florida address where anything seems to go.