Building a Master Bath on concrete slab

[Rocky123]

All

Really appreciate this Forum and how everyone is so nice to the DIYs. Thanks in advance for all your help and advice.

We are building an addition to a summer home (retirement home in 5 years) on a concrete slab in Southern Ohio. We are adding a Master Bath that is 10X12 feet. My husband is acting as General Contractor. I plan on buying the materials and I want to ensure the contractors we hire know what they are doing … read too many horror stories on this site (glad I did). The Building Shell and slab (plumbing in slab) is completed … we are on hold for the rest until spring due to weather.

I want to build a door-less & curb-less 5X5 feet shower (Wheelchair accessible). The shower slab has built in ¾ inch slope towards the drain … concrete contractor said that this would be sufficient but based on what I have been reading that slope may not be correct, short 1 ¼ inch? The Shower Drain pipe sticks up 6 inches above the slab. Sorry, but I don’t have any Pics, I will add some later.

I purchased and read the Kerdi Shower Book along with hundreds of other postings. I have a couple of months to select my material and items for my bathroom and make sure we hire legitimate contractors.

1. Based on my research am I correct in thinking the contractor needs to complete the following steps for the shower base?
a. thinset (thinset bonds the mud to the concrete)
b. install drain (Kerdi)
c. Pre-mud base sloping ¼ inch per foot - 5 feet equal 2 inches?
d. Liner (Should it be Kerdi or paint on type?)
e. Final mud base
f. Tile

2. I know a lot of you recommend Kerdi but I don’t think any contractors here are familiar with it … what are the major differences between the paint on vs Kerdi? We are in a small town with limited contractors.

I have many more questions but I don’t want to bombard you with too many.
Thanks!!! Happy New Year!

[jadnashua]

It's much easier to do a barrier free shower if the shower area of the slab is depressed, which yours isn't. You need 1/4" per for, so over 5', that would be 1-1/4". Note, that's from the edge of the shower to the drain, so if the drain is in the middle of the shower area, 3/4" might be enough (that's 3' each way). Unless you can raise the entire floor area of the bathroom, it might be tough to do it now. Anything can be done if you want to spend enough money.

Kerdi is a system, and if you choose that route, go all the way. Unless you want to tear up some concrete, adding any drain now means that low point of the floor being 4-5" higher by the time a shower is build. this is true even with a conventional clamping drain shower.

If you choose Kerdi, the Kerdi membrane is the tiling surface. if you chooose a conventional shower, you'd have a preslope, a liner, then a setting bed, then the tile which would end up being thicker than just the single layer required for Kerdi. While maybe not ideal, if the concrete is a nice, consistent slope to the drain, and you can set the drain at the proper level, you might be able to install the Kerdi directly on it without any added preslope. there's a lot of info in the 'Liberry'...you should start there to understand a conventional shower construction, and then the alternatives, with Kerdi being one of them.