Replacing a garden tub with a Sterling 72120100 4′ shower. Have an existing water heater closet with outside access on one end, the other is an outside wall. Plan to demo both walls on the heater closet, and replace them with new walls that fit the shower enclosure, and will give access to the shower controls from the closet from inside the bath. Green board on all these walls, but I’m wondering if foil backed 3 1/2″ rigid foam will give as good a barrier as the batts. I’l seal around the controls with spray foam. This is Texas, so heat is a bigger problem than cold.
Thanks
Off yer azz and on yer feet,
Outta th’ shade and into the heat.
Replies
Around a shower you mainly want to avoid trapping moisture where it shouldn't be. What you don't want to do is to hold moisture against the framing. You need to evaluate the potential for leaks, splashing, condensation, etc to estimate whether significant moisture might be trapped in a specific area. Where moisture might accumulate you're better off with "leaky" insulation like fiberglass (so the moisture can escape), but foam is generally superior elsewhere.
happy?
I've put 3-1/2" (3"+1/2") XPS in stud bays around my tub surround. I'm going to put 3/4" XPS over the studs (thermal breaks), then 1x3 vertical furring strips, CBU, Schluter Kerdi, porcelain tile. There is an access panel behind the tub, I'll put a louvered opening in the panel door, this and the furring strips should provide air passages to ventilate the space between the tub surround wall and the insulation.
I'm relying on the Kerdi to be my moisture barrier, my principal concern is that the space between the tiles and the insulation not become a mold factory (Kerdi is not a VB but porcelain tiles are moisture impermeable).
Bringing the blocking out while still allowing air passages will be a royal PITA.
Every where I have ever lived, the shower has been the coldest part of the house. Not this time.
Tom,
There is a foam board available probabl;y from tile suppliers which might be just the thing for you. I think it is XPS coated both sides with mesh and mortar. Comes in different thicknesses from about 3/4" up to around 2 1/2". Cut it with a hand saw you don't like very much. Tile it on both sides and it is as rigid as a wall. Corners add rigidity and are easy to make. Just tape the two sides together with mesh and mortar.
I have never used it myself, but I can't see a problem with it as long as you know how to install Kerdi fabric.
Ron
If that is Wedi board, it's pretty expensive, and you normally wouldn't use it with Kerdi, it is supposed to be its own VB (so you have to caulk the nail holes). They're two competing systems.
Taylor,
That's what it is - Wedi board. As I said, I have never used it. Not suitable for this application? I had the impression it was most suitable for a freestanding wall as long as you tiled both sides.
It wouldn't be that hard to make up a substitute for it would it? EPS, stucco mesh, thinset.
Ron
I recently used redgard for our shower for the VB. It went on really nicely. You just paint it on before tiling and you have a nice VB on the 'wet side' of the wall.
I talked to someone at Wedi about using it with Kerdi. He seemed to think I was from Mars.I think it only comes in 1/4" and 1/2", same as CBU. It's XPS with 1/16" of cement either side. Once tiles are on, it's apparently quite sturdy. You must use their nails, caulk the nail holes. I heard something like $20/board from the nearest supplier (only one for entire NYC area). I'd use it if I were tiling a basement or slab floor, for the thermal break.I wouldn't try to make up one of these things myself. Custom has done it with their Easyboard, EPS instead of XPS, I have the impression it is not as sturdy.
Taylor,
I have seen 1" and I think the supplier who showed it to me said he could get 2" and 2 1/2" . He has gone out of business since then.
He told me the main use of it in Germany was for freestanding walls - no framing.
Ron