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Plumber452 12-02-2017 02:52 PM

Steam Shower Planning
Hello to all,
I'm new to the forum and look forward to some good discussion and information. I am in the planning stages of a steam/shower install and would like to run my plan by everyone.
1. All new interior stud walls
2. fill walls with unfaced fiberglass insulation
3. Install tar paper on studs extending down into traditional mud/pvc liner.
4. Hang lath
5. install mud. Traditional scratch/brown coat
6. Red Guard walls and ceiling
7. Tile
I'm not thinking of using a vapor barrier because the back side of the shower walls are open to existing walls with the existing back wall being an exterior wall. I plan on using HVAC grilles on the "Dry Side" of the front wall (The wall you enter/exit thru) to allow air circulation around the sides and top of the shower. My thought is should any moisture get thru the Red Guard it would be in the air space between the existing walls and the new shower wall therefore being drawn into the rest of the bathroom by an exhaust fan.

Any thoughts?



Tiger Mountain Tile Inc 12-05-2017 08:58 AM

Hi Everitt it looks like this post has been missed.

For steam showers, my personal preference is for a sheet membrane that goes on the surface. Something like Nobleseal TS that is a vapor retarder and would stop moisture and vapor at the surface as opposed to in the wall cavity. This can be installed right over the mud walls.

But the way that you've outlined is acceptable also.

Are you going to put in the hvac grills rather than an exhaust fan?

Plumber452 12-05-2017 02:53 PM

Thanks for the response!!! My plan with the HVAC grilles would be to allow air circulation "Around" the exterior of the shower as well as behind the walls. I am using the exhaust fan as well to create negative pressure in the rest of the bathroom therefore pulling any moisture, from behind the walls should it occur, to the bathroom and out thru the exhaust fan.

cx 12-05-2017 06:04 PM

Welcome, Everitt. :)

You must have a vapor barrier in any steam shower. These days referred to as vappor retarders, but you still gotta have one. The current tile industry standards call for a barrier with a perm rating of less than 0.5 for a continuous use steam shower. Your RedGard claims to provide that, so you're OK there, but like Jim above I'd prefer to see a sheet membrane. My current choice would be USG's Durock Shower System membrane. Much thinner and easier to work with than the NobleSeal for my money. The roofing felt behind your mud should be sufficiently permeable not to cause you any serious grief.

While your proposed ventilation system might not hurt much, I'd recommend ensuring that you have as much insulation as possible in those shower walls and ceiling to keep the inside/outside temperature differential at a minimum in order to also keep the vapor drive at a minimum.

You're planning also to mud your ceiling? You plan to have the required minimum 2" per foot slope there?

My opinion; worth price charged.

Plumber452 12-06-2017 08:51 AM

Thanks again. Yes I plan on sloping the ceiling although I've read/heard various positions as to the necessity of sloping a residential steam shower ceiling. Also I will use the highest R Value insulation I can in the walls and ceiling. I will defiantly check out the USG membrane you referenced. While I've read very positive things about the liquid waterproofing membranes my "Old" head has a hard time accepting it that while the tile will stay attached to the liquid applied membrane I'm still uneasy about the membrane staying attached to the substrate.

Houston Remodeler 12-06-2017 09:23 AM

Don't feel bad, there are many Pro's who don't trust liquid membranes even though they have been around since the 50's

cx 12-06-2017 10:38 AM

Everitt, the industry standard requirement for the bond of the direct bonded waterproofing membrane, either sheet or liquid-applied, to the appropriate backing material is the same as the bond requirement to the tile bonding mortar and that is only 50psi. The problems you're likely to incur with the liquid-applied is not the bonding, but the proper application of the material in the correct and consistent thickness.

My opinion; worth price charged.

Plumber452 12-06-2017 01:50 PM

I checked out the USG membrane and that looks good. What if I use that along with the backer board instead of the mud walls. I would still use a mud pan

cx 12-06-2017 02:05 PM

That's an acceptable method, too, Everitt, but I'd strongly recommend you use the integrated bonding flange and Durock membrane as your shower receptor in that case.

My opinion; worth price charged.

Plumber452 12-06-2017 02:58 PM

Forgive me but I don't understand what the integrated flange you're referencing is. I didn't see that referenced in the installation instructions. Are you suggesting I use the USG pan assembly in lieu of the mud pan?

cx 12-06-2017 04:32 PM

No, no foam pan recommended. Much prefer mud for that purpose, but you'll need only a single mud bed.

I'm recommending the bonding flange drain that goes with the Durock Shower System membrane so you'll have a steam shower that's completely waterproof and vapor proof immediately behind your tile all the way around.

My opinion; worth price charged.

Plumber452 12-06-2017 08:23 PM

Got it. The membrane replaces the PVC liner that is "Sandwiched" between the mud. Thanks for your advise

Plumber452 12-07-2017 03:15 PM

Hello CX,

After having found this forum and reading several posts I decided to purchase a copy of the TCNA Handbook. It arrived today and I have some thoughts I would like to run by you. In the detail of method SR614-17 I see some things that seem to differ from methods I've seen described on this forum and other websites.
1. They do not show the backer board extending down into the top layer of pan mud. I thought this was required to secure the bottom of the board.
2. Reinforcing is shown in the top layer of pan mud, not the bottom layer.
3. This detail shows utilizing a membrane on the walls but not the pan but it does note that utilizing an integrated drain as you referenced is an option.
4. What does the small round circles at the intersection of the walls/floor/ceiling represent? Backer rod?

After seeing this what are your thoughts to me using the traditional PVC pan liner but doing the following:
1. Install preslope mud
2.Install backer board
3.Install liner
4.Instal Durock membrane on walls
5. Install top pan mud

I see and understand your thought about using the integrated pan drain but I think I would feel better about having an old fashion pan liner under my feet. I realize I may run the risk of some vapor transmission thru the floor but I would think that would be minimal. Perhaps I shouldn't have gotten the hand book. You know what they say about " A little information in the hands of a fool can be dangerous"

jlbos83 12-07-2017 05:49 PM

I would rethink using the traditional liner. Using the membrane on the floor lets you only have one mud pan, no need to notch out studs for the liner, and no water at all out of the "container" you've built. A traditional is a way of trying to control the water that gets out of the container, to my way of thinking (not exactly true, but you make things more complicated). If you use a CBU (not Hardibacker type) you can embed it in the mud. Drywall, too for that matter, but I don't know if that's is ok in the steam shower. CX will know that!

Traditional pan to me means more complicated, more ways to fail.

Plumber452 12-07-2017 07:15 PM

Thanks Jeff,

I guess I" m having a hard time getting my old head around that small area to seal the drain with that small area right around the drain it's self


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