Kerdi shower in Basement Clarification

[regulartom]

Hi All,
This is my first post here. Many thanks for the help from previous postings.
I had to tear out my old shower because builder didn't install moisture barrier between tile and the wooden subfloor.
I had to tear out the mudpan, osb subfloor and the hard plastic barrier between the subfloor and the concrete foundation.
I've got a few questions I'm hoping to get reassurance about.
1 - I'm installing the drywall now, but because i read in the kerdi book that i should use bricks instead of wood for the curb I am wondering how can i affix the drywall to it?

2-The subfloor i pulled up looked like an inch thick. Is that thickness the recommended one?

3- there's also a window cutout. the cement block starts at the window and i just shaved the wooden framing so the slope is towards the shower. - how does the drywall affix to the cement block?

4- I've got about two inches of iron pipe above the concrete slab. After plastic then subfloor, I'll only have a little less than an inch of piper remaining. Can I just affix the fernco coupling and then the drain in order to get the required 1.5" space below the drain?

Pardon my wordiness...i'm relatively new to this.

Thanks,
Tom M
Chicago

[bbcamp]

1) You don't need drywall on your brick curb. Just adhere the Kerdi-mat to the bricks with thinset. You might want to skim coat the bricks first so the surface is smooth and straight. Use either brick mortar or thinset.

2) I'm assuming you are referring to the setting bed or the preslope from the original shower. To make it simple, remember that the Kerdi drain needs to be 3/4" to 1" above the slab so you can pack mud under it easily.

3) Normally, you would attach furring strips to the block, then attach the drywall to the furring strips. Around the window opening, you can use construction adhesive to attach the drywall to the block, since you may not have room for wood, and wood isn't such a good idea there, anyway.

4) I'm going to suggest more work for you. I'm assuming you have cast iron drain piping, and further, it is more than 40 years old. Your p-trap has lived a long and happy life, but it's time for it to be retired. Remove the p-trap and install a new one of PVC, using a Fernco coupling down stream of the trap location on the cast iron pipe. Do that, and your Kerdi drain installation will go more smoothly and you can control the height better.

[Houston Remodeler]

2- That's what the white foam blocks are for inside the kerdi drain box. Slide the slit in the foam over the side edge of the flange to get that 3/4" spacing. Pretty cool huh?

[John Bridge]

I have actually set Kerdi-drains right down to within about a quarter-inch of the slab and used thin-set under them instead of deck mud. You can keep the curb low that way.

Welcome aboard, Tom.

P.S. You can apply the Kerdi direct to the cement block with thin-set unless you need the drywall for build-out.

[regulartom]

Thanks so much for th the quick replies. BB - Fortunately/unfortunately the house is only 5 years old, so the cast pipe should be intact. But are you saying it's much easier to get right with the fernco coupling set down in the foundation?
Thanks for the help on the window.

regarding the subfloor, do i not need to put in a wood subfloor over the concrete foundation and vapor barrier? just put over the concrete foundation thinset, then mud, then drain, then kerdi, then thinset, then tile?

Thanks!

[Houston Remodeler]

1- With the kerdi drain flange, its easier to have a riser made from PVC or ABS to get the height of the drain where you want it.

2- No need or desire for sandwiching wood between layers of ceement like that. Yes to plan B

[regulartom]

Thanks guys,
I got down to the hub and put in a new donut and got the pvc riser in there.
I have to finish the drywall and install the curb. I got some concrete bricks from home depot. Should i put the drywall in first and curb up to the wall or the curb first and drywall around the curb?

Gracias!

[regulartom]

now i'm thinking maybe i should put the mortar bed in first. but i wanted to do that last. does it matter?
The picture in the kerdi book looks like the drywall is in first, then the mud pan, then he starts on the curb. hmmm

[bbcamp]

With Kerdi, you can do the walls first, then set your drain, mudbed and curb later.

[regulartom]

Hi,
I installed the kerdi drain yesterday and then moved to make the level outer edges with deck mud. All 4 sides are level and at the right height. My problem is that I got pulled away for a family emergency before I could fill in and screed the area between the wall height and drain height. I'd like to just fill in this open space with new mud. Will it adhere to day old mud?
Thanks,
Tom

[bbcamp]

If you are building on a slab, then yes, you can leave the mud screeds as they are and place your new mud against them. Paint the surfaces of the mud screed and slab where the new mud will go with thinset. Place the new mud over the thinset before it skins over.

If this was over a wood subfloor, then I would suggest tearing out the mud screeds and as much mud as you can from under the Kerdi-drain, then starting over. This avoids cold joints. They are more likely to give you a problem over a wood floor than a concrete slab.

[regulartom]

That's what I was hoping to hear!
Thanks for the help.