Kerdi tray for a walk-in shower in basement

[karmapolice]

Hi there,

I'm planning to build a walk-in shower in my basement using the pre sloped kerdi shower tray (32"x60" offset drain). The tray (1 1/2" thick) will sit right on the concrete slab in the corner of the basement and the rest of the bathroom floor will be covered with delta-fl (5/16" thick) and 2 sheets of 5/8" thick plywood to bring the rest of the floor up to the shower tray's height. Do you think this is doable?

(My first idea was to dig in the concrete and embed the tray in the conrete flush with the rest of the floor but this seemed to much work unless someone convinces me otherwise).

I will break the concrete soon to relocate the drain and install a p-trap and am trying to figure out how to best install the kerdi drain while everything is opened up. I'd appreciate any suggestions..

Cheers,
Jay

[bbcamp]

Jay, you need to make sure your floor has a good vapor barrier to protect your plywood and other flooring that you intend to install. As far as the joint between the Kerdi tray and the flooring buildup, I guess that you would have to be triply certain that you've installed enough caulk between the tray and the plywood, and the shower tile and the plywood to keep any water from sneaking past that joint.

Let me suggest you save yourself a bunch of time and money by busting your the concrete and recessing the shower. You can still use the Kerdi drain, but you can return the tray. You will be doing most of that anyway. You'll just have to get past your fear of playing in the mud. Your concrete slab can be tiled, and you won't have to worry as much about vapor barriers, rotted subfloor, etc.

The Kerdi drain was originally designed to be installed where there is access to the underside of the shower. Installing it on grade with a Kerdi tray presents a few problems, most of which is the lack of visibility. You have to cut the drain pipe exactly the right height, then glue it on the pipe. You get one chance. Installing the Kerdi drain where you build your own mud bed allows you to mis-calculate a bit, and still recover. It also allows you to install your drain in the center of the shower, too.

[jadnashua]

You could build up the floor with deckmud, and include the sloped shower pan. Regardless, though, how would you get up the ramp into the room?

You'd be better as Bob said to recess the pan and move the drain to the middle.

[karmapolice]

Thanks guys, I'm seriously looking into the mud bed option now..

BTW, is it just me or the installation order of the Kerdi membrane is a little awkward in their video? I noticed the guy puts in the bottom corners first, then the walls and leaves the floor part to the end. I think the order should be floor first, then the corners (overlapping the floor layer), then the walls (overlapping the wall side of corners)? I mean the corners must overlap the floor to direct water over it, not under eh?

Anyway, how do you guys properly slope a mortar bed again??

[ddmoit]

BTW, is it just me or the installation order of the Kerdi membrane is a little awkward in their video? I noticed the guy puts in the bottom corners first, then the walls and leaves the floor part to the end. I think the order should be floor first, then the corners (overlapping the floor layer), then the walls (overlapping the wall side of corners)? I mean the corners must overlap the floor to direct water over it, not under eh?

Welcome to the forum, Jay.

As it turns out, it truly doesn't matter which way you overlap your Kerdi, so long as the overlap is at least 2 inches. It's just one more beautiful thing about Kerdi.

[Lazarus]

I was impressed with that aspect of Kerdi, as well. You don't need to follow the traditional advice of "Top Overlaps Bottom" like shingles. As long as you have a 2" overlap....that puppy is waterproof!

[Trask]

That ability to run the kerdi in any sequence was initally interesting to me...Now after we've done hundreds of them( and costing profit & loss on each job) it is really "THE" most profitable and compelling reasons for using it.
<The waterproofing is a given.>