[jtb587]

So, I am rebuilding a shower because the floor in the old one cracked.

I installed a new acrylic shower pan and am ready to start building the walls. I want to tile the walls and have a few questions.

1. Can I use Kerdi-board for this? I had planned to use cement board but the kerdi board sounds like it is easier to work with. Is there any reason I shouldn't use this?

2. There is a small gap between the outer edge of the pan and the framing, maybe 1/2" at most all around. When I install either kerdi-board or cement board should I fur the studs out so that the panels sit down over the flange or should I attach them directly to the studs so that the panels butt up to the top of the flange? I have seen it done both ways on the internet and it almost seems like builders preference. My concern with furring it out is that there will be a ledge where the existing sheet rock meets the new panels and that will be something I have to deal with.

Thanks for the help.

 

[chandler48]

No matter which you choose, you'll need to add 1/2" to the walls. Durock or Hardie in 1/2" and you're done. With Kerdi, you'll have to install greenboard, so that's another step, or kerdi panels, which are a little expensive.

Bring your greenboard, Kerdi panels, Durock or Hardie down to touch the lip on your pan. Your tile can jump that small gap and it will reduce possible wicking of water upward.

 

[NotYerUncleBob2]

6 mil vapor barrier? That's in Canada, right? I mean, eh?
The standard here is the water proofing membrane applied to the cement board, correct?

 

[jtb587]

Thanks. That is how I hoped I could do it. I can buy the backing material of the right thickness to account for the gap around the shower pan. I was hoping I wouldn't have to make it overlap the flange because that would make things harder.

As for the kerdi-boards vs cement boards, do you have a preference? I haven't priced kerdi-boards yet but they sound like they are easier to work with and don't need the waterproofing membrane either. Any thoughts?

 

[SLSTech]

Kerdi Board is up there in cost but the savings in time does offset the price. The other factors is easier to shape, can be semi-structural, & oh yeah, it's so much lighter. You still need the band for seams, corners, etc...
Plastic - god no, put the vapor barrier (whether Kerdi, RedGuard, etc...) where the water will be especially for cement board that you are screwing to the wall (thus ripping & putting holes in)

 

[flyingron]

My favorite tile substrate is GP's DenShield. Like Kerdi when installed properly it is entirely waterproof (unlike cementboard which must have some water barrier behind or on its face). DenShield is a modified drywall product which is more substantial than Kedi (but half the weight of cement board).

Denshield uses mesh tape and silicone caulk where as kerdi uses their own sealing tape with thin set.

 

[jeffnc]

As for the kerdi-boards vs cement boards, do you have a preference? I haven't priced kerdi-boards yet but they sound like they are easier to work with and don't need the waterproofing membrane either. Any thoughts?

Kerdi Board is WAAAAAAAAY easier than cement board. And drywall. If I never have to deal with cement board again in my life I'd be happy. But Kerdi Board is expensive. If trying to save money, my next option would be Kerdi Membrane installed over drywall. This is a little bit of a hassle messing with the thinset. Moving and cutting drywall is second on my list behind Kerdi Board. Last would be cutting cement board. Since I would always use a Kerdi product one way or another there's never any reason for me to use cement board. I hate carrying and cutting the stuff. If I used it I'd still put Kerdi Membrane over it. I have on some occasions partially repaired an existing shower that was installed with cement board to begin with, and if so I'll use cement board there.

I do this for a living and I have a lot of leftover materials. In my own house I'm rebuilding my shower, and I'll be putting Kerdi Membrane over drywall. That's because I have a lot of Kerdi Membrane left over, and there was already drywall behind the old prebuilt shower stall, so it's basically free for me. When I work for a client, I now normally install Kerdi Board. It's a higher material cost but lower labor cost, so price is a wash for my customers. Also, it allows me to get done with the job a little more quickly.

 

[jeffnc]

Denshield uses mesh tape and silicone caulk where as kerdi uses their own sealing tape with thin set.

I have not used Denshield, but Kerdi also uses their own Kerdi Fix sealant/adhesive. This works well with the "structural" uses of Kerdi Board you mentioned, as well. One problem is Kerdi Fix is very expensive.

https://www.lowes.com/pd/Schluter-Systems-Kerdi-Fix-9-81-fl-oz-White-Sealer-And-Finish-Squeeze-Bottle/1001071888

I get it for less so I still use it. An alternative (at least for sealant purposes, not necessarily structural purposes) is an elastomeric polyurethane sealant. For example I've used this one

https://www.lowes.com/pd/BASF-NP1-10-1-oz-Medium-Bronze-Paintable-Advanced-Sealant-Caulk/50205185