Appropriate Backing for Shower

Hey all,

I'm in the middle of total bathroom remodel of a 1917 house in the Cleveland area. I have the bathroom down to the studs and I need to build a shower surround that will be tiled. The back wall of the shower/tub surround is an exterior wall. Here's what I'm thinking...

1. Install 6mm plastic over the studs. I was thinking of 15lb paper, but I've since read that plastic is more appropriate for an exterior wall.
2. Install Durock
3. Roll on waterproof membrane.
4. Tile/Grout

Your thoughts?

Thanks!

You need to insulate the exterior wall. you don't want two layers of vapor barrier. If you are going to use a surface membrane, don't use one behind. If the insulation has a vapor barrier, slash it some to compromise it. I'd forget the cbu entirely and use drywall covered by Kerdi from www.schluter.com myself. The hassle with roll-on or paint on membranes is they only work if you get the proper thickness - people tend to make them too thin. then, it's not hard to have pinhole leaks. Drywall is so much easier to put up (you don't tape and mud the seams - the membrane does that), and with the surface membrane, they'll stay entirely dry. WOrks great. Been there, done that. Check out www.johnbridge.com .

ensure you put your waterproof layer (this is NOT the tile) on the shower pan on a sloped surface. if you use Kerdi, your preslope becomes your setting bed. If you do a conventional shower, you need the preslope, then liner, then setting bed, then the tile. An extra layer, and thickness. The single layer with the Kerdi system is easier. Their drain is more adjustable as well (both up down which is common to all PLUS, some flexibility on horizontal positioning as well, which is not part of a conventional drain).

Thanks Jim.

Just to clarify, this is a tub. I called it a tub/shower, but it's really a standard alcove tub with a shower on the wall. Anyway, if I understand you correctly, you'd suggest:

1. Insulate
2. Regular drywall on the studs surrounding the tub
3. Kerdi

Correct?

I did the same last year during a bathroom remodel. One of the walls was an exterior wall.......I removed the 40 yr old spun wool insulation and used Kraft faced fiberglass, then put up drywall. The Kraft is your vapor barrier (make sure you staple it to the studs)

I actually paid a tile installer to do the tile, Kerdi, etc but he sure ended up liking the Schluter products. Beats the heck out of lugging around and cutting CBU, and it saved both of us time and money (he didnt waste labor installing CBU, and all I had to do was throw up some un-taped drywall)

Im tackling our other bathroom myself in the next few months and I plan on doing the whole thing myself. Kerdi for the walls in the shower/tub and Ditra for the floor

With a tub involved, I might lean towards cbu since the seam at the tub surface is the weak point (not so in a shower only since the membrane goes all the way around the shower and floor). You can still use Kerdi (I did on my tub/shower). If you want to eliminate all caulk in the installation, consider Dilex, also from www.schluter.com. It is an engineered expansion joint that you tile in for the tub/wall and wall/wall joints. If you do choose to use this, you want to ensure your corners are truely square and plumb. The preferred tub installation when using Kerdi is to run it down below the tiling flange, then put a band of it over onto the tiling flange. If you did it that way, you could use the drywall. A more typical retrofit has you install the tub, then bring the wall surface down over the lip. In that case, the bottom of the wall surface is not fully protected, and that's why I chose to use cbu rather than drywall. you don't want drywall edges sitting where it could wick up any moisture. Cbu doesn't care.

You can still use Kerdi on a tub enclosure like that if you want to, their manual outlines how (basically bring the drywall within 1/4" of the tub lip then fill the gap with mortar or caulk before installing the Kerdi).

I was weary of it at first as well, but once the Kerdi was installed you actually couldnt tell where the gap used to be. Schluter also sells an adhesive purposely meant for that gap called Kerdi-Fix.

-Chris

You might consider den sheild it is a non wicking drywall

My suppliers only sell complete kits of the kerdi and wedi products so if the customer is cost conscious I will suggest den shield. It is a dry wall product that is non wicking. It is easy to work with and gives a sound surface to set tile to, it is the same thinkness as drywall if you are trying to match surfaces. The joints do need to be taped and mudded. I have used it for years it is a great alternative to concrete and greenboard...