To properly apply a vapor barrier to a steam shower, use the following.

Once you have your PVC pan liner in the shower floor area, drape solid sheeting of plastic across the stud. Do not break the sheet into two or more pieces if possible, but instead, use a solid piece. if you must segment it, use a good tape (duct tape), and seam the segments. Make sure the plastic drape is dropping INSIDE..... INSIDE.. of the shower pan material for the shower floor. Then drape the ceiling studs with additional plastic sheeting, making sure it also falls INSIDE.... the wall drapes. Cut the openings for the pipes/body sprays, etc and close up with silicone caulk or duct tape. Hang your cement board to studs/plastic. Be sure to seam all joints with fiberglass tape and fully modified cement/thinset. You could then apply an additional treatment of RedGuard Waterproofing. I usually apply a two coat process, 1 direction, dry time, then 1 in the other direction. Never use a framed seat in a shower. You should make sure to use, instead, a cinder block seat, built inside the cement board walls, and make sure you drape shower pan material in the wall 2' high to prevent any runoff.

 

To properly apply a vapor barrier to a steam shower, use the following.

Once you have your PVC pan liner in the shower floor area, drape solid sheeting of plastic across the stud. Do not break the sheet into two or more pieces if possible, but instead, use a solid piece. if you must segment it, use a good tape (duct tape), and seam the segments. Make sure the plastic drape is dropping INSIDE..... INSIDE.. of the shower pan material for the shower floor. Then drape the ceiling studs with additional plastic sheeting, making sure it also falls INSIDE.... the wall drapes. Cut the openings for the pipes/body sprays, etc and close up with silicone caulk or duct tape. Hang your cement board to studs/plastic. Be sure to seam all joints with fiberglass tape and fully modified cement/thinset. You could then apply an additional treatment of RedGuard Waterproofing. I usually apply a two coat process, 1 direction, dry time, then 1 in the other direction. Never use a framed seat in a shower. You should make sure to use, instead, a cinder block seat, built inside the cement board walls, and make sure you drape shower pan material in the wall 2' high to prevent any runoff.

Are you specifically considering the plastic behind your tile substrate as a vapor barrior and your red guard in front of your tile substrate as a water proof barrior?

To me the best system is to keep your waterproofing/vapor proofing on top of the tile substrate, keeping the moisture on one side of things.

 

look into the kerdi system.

www.schluter.com

 

I've never used kerdi system, although I've used a lot of schluter products

regardless of which waterproofing you might use topically, you still need a vapor barrier behind all the wall substrates (cement board) that drains inside the shower pan material.

 

No vapor barrier with kerdi, once you usethe kerdi especially in steam rooms you will never look back, they are coming out with kerdi panels like wedi panels even faster as you only need to do the seams and screw heads.

 

That orange kerdi stuff is the way to go. Kerdi panels. INTERESTING. I also think the stryofoam showerpan they make looks interesting. I seen them use that all the time on TV.:clap:

 

my guess is the kerdi system isgoing to be exponentially more expensive than a roll of plastic, tar paper, and/or a gallon of RedGuard. I generally stick with what works. I'll look into kerdi, though...I'd be curious how much it cost and how long it takes to install. I can rough in vapor barrier, walls, seams and a coat of redgaurd in a single day. I dont' know how kerdi could be any more expedient.

Update
Kerdi sheeting looks like it goes over the cement board. it also looks expensive-thus cost prohibitive, considering Noble Seal sheeting works the same at around $3-4SF. I'd definitely use a plastic vapor barrier and RedGuard. I wouldn't trust sticking to a sheeted material, not to mention, its way more work and way more expensive.

 

I'd definitely use a plastic vapor barrier and RedGuard.

I'd be interested in a spec showing your proposed system.

my guess is the kerdi system isgoing to be exponentially more expensive than a roll of plastic, tar paper, and/or a gallon of RedGuard.

...it also looks expensive-thus cost prohibitive...not to mention, its way more work and way more expensive.

From your own signature, "The bitterness of poor quality last far longer than the sweetness of a cheap price". (anonymous)


Continuous (meaning not liquid) SA membranes are far superior to the poly, felt system, especially in a steam room. Even a liquid membrane is better, but subject to getting proper coverage and mil thickness to be effective.

 

There's a great deal of debate in the tile community about the use of vapor barriers with various membranes and substrates--particularly with surface waterproofing liquids. There is a significant risk of a "moisture sandwich" when combining different systems and care should be taken to investigate the specifications of the products you're using.

As Mike said, keep the water and vapor on one side.

I highly recommend you look into the Kerdi system. While it's material cost is higher--it more than makes up for it in labor savings and longevity.

 

I have to repeat the question -

Are you specifically considering the plastic behind your tile substrate as a vapor barrior and your red guard in front of your tile substrate as a water proof barrior?

Let me be more specific - To me the best system is to keep your waterproofing/vapor proofing on top of the tile substrate, keeping the moisture on one side of things. (avoiding sandwiching moisture between the two barriers.)

I know there is felt a distinction between vapor and liquid water, but essentially they are moisture.

The water proof barrier (red guard) would keep sprayed water from penetrating the red guard (water proof barrier), but if red guard isn't a vapor barrier you are allowing the vapor to penetrate it, turn to liquid and be trapped behind it now since it isn't going to go through the vapor barrier and it won't go back through the water proof barrier now, and it certainly all won't drain down and out through the tile membrane.

I would propose considering the issue of clear glass tile installation in a steam shower to illustrate the issue even if it's not the issue of seeing the darkening behind the glass, it does illustrate the moisture issue exists and can only be solved by keeping the moisture/vapor barrier on the wet side of the tile underlayment.

 

Mike, how did that glass steam shower you had to re-build turn out BTW?

 

I think it probably turned out like sh*t or he is living with the original mess, cause once I gave him the numbers I took his visible choking and gagging to mean he was thinking that redoing something installed wrong the first time should be cheaper then what it cost to do it wrong the first time. :no:

 

Paul,

I have the current TCA and and is not spec'd in it. Poly behind the cbu and redguard on the face is a double vapor barrier. Plus, doing both is redundant and can be problematic, especially in a steam shower if penetrations aren't carefully detailed. The vapor, if it gets through the membrane, will saturate the backer, then hit the poly.

Also, a SA membrane is a vapor barrier as well as waterproofing. SA membranes cannot let moisture pass into the stud cavity, therefore it does not contribute to excess moisture in the wall. If you are using plastic film or 15-pound tar paper behind the board to waterproof a tub/shower, do not be surprised if your customers encounter problems with mold, mildew, leaks, etc.

Wicking is also a problem with all mortar bed showers made without surface-applied membrane systems.

If you are using redguard or similar, I would be doing at least 3 coats to ensure complete coverage and proper mil thickness. Even though many claim 2 coats for waterproofing, you will most likely need 3 or 4 for it to be completely effective.


BTW, I get Kerdi for $1.24/SF.

 

=Shawn Prentice;868241]Paul,

I have the current TCA and and is not spec'd in it.

Actually it does specify a layer of waterproofing behind either cement board or cement mortar bed walls. 2003-2004 41st edition, TCA Manual, pg 39 (steam showers- sr613-03)

Poly behind the cbu and redguard on the face is a double vapor barrier.

the poly works as a safe guard. Even with sheet surface membrane, leakage could occur. With either liquid or solid membrane, I'd rather have a safeguard in place (poly) than risk a possible leak. Even with solid membranes, if they're not installed properly, there's nothing to stop water from passing through.

Plus, doing both is redundant and can be problematic, especially in a steam shower if penetrations aren't carefully detailed. The vapor, if it gets through the membrane, will saturate the backer, then hit the poly.

Also, a SA membrane is a vapor barrier as well as waterproofing. SA membranes cannot let moisture pass into the stud cavity, therefore it does not contribute to excess moisture in the wall. If you are using plastic film or 15-pound tar paper behind the board to waterproof a tub/shower, do not be surprised if your customers encounter problems with mold, mildew, leaks, etc.

Prior to the advent of todays technology, steam showers were built with tar paper/poly and mud walls over lathe. The preventive source of protection was the vapor barrier.

The inherent issue with a plastic vapor barrier on the back side of the wall board material is that it is mechanically fastened to the studs.

Tar paper and/or poly sheeting behind lathe/screed mud walls were used 50 yrs ago. I'm unclear how something that worked then is no good now. :blink:

 

Too bad hammerswinger didn't get this kind of response a month and a half ago. :whistling


When it comes to waterproofing in a shower, steam or otherwise, it's a "perm rating" that determines the difference between vapor retarder or barrier. Look at the perm rating of any material you're considering before thinking you are actually waterproofing something. If it's over 1, you're not building your wet location sufficiently. :no:
That goes for ANY sheet membrane or liquid barrier. All are not created equal.

The inherent issue with a plastic vapor barrier on the back side of the wall board material is that it is mechanically fastened to the studs. What do you think that does to it's "barrier" quality? :blink:

Folks can still build showers (of any kind) with CBU and a vapor barrier behind it and pretend they have an actual waterproof shower.

 

The inherent issue with a plastic vapor barrier on the back side of the wall board material is that it is mechanically fastened to the studs. What do you think that does to it's "barrier" quality? :blink:.

Another good point

 

I have this saved in my file on this site
http://www.contractortalk.com/members/stonehorsetile-37461/albums/specs/
Feel free to upload it and adjust magnifier for optimal viewing.

 

I didn't say the illustrations weren't the same, I said you weren't following the spec you posted with your "double" waterproofing method.

I know plenty of old school mud installers that utilize waterproof membranes over their installs because they know it's the better way of doing it.

As far as never having had a problem with your old way installs and no mold or wicking issues, you can't say that definitively. In my experience, the customer never calls back the original installer about the failures.

Keeping the cbu off the pan liner 3/4"? But you still have the saturated, mud bed in contact with the cbu. Do you think it might wick?

Old style mud beds in heavily used showers are nothing more than a thin-bed septic tank.

 

Shawn, out of curiosity, I checked your profile. I see no pictures of any work, no link to any web pages, but there are 224 postings on Contractortalk. And while you seem fairly intuitive at debating issues, I can't help but think it's just an invidious act, at this point.

Per your first concern about double waterproofing, I think I covered this in my most recent post, but I will repeat it here for you; whether I use RedGuard, Noble Seal or some other "surface" waterproofing, there is always a "chance" that somewhere along the way, you've missed a potential leak. Poly sheeting behind whatever substrate is used, draining into the shower pan liner, is "insurance against such chance. And the 1% moisture that might get through either method would be contained with Poly sheeting. I dont' see the argument here. I think there's been much ado about nothing if we're debating trapped moisture; IE, if surface waterproofing is working 100%, the poly sheeting is a non-issue. If it IS leaking, I would think they'd be glad they have the insurance of poly sheeting.

Second, regarding your assertion that I couldn't "definitively" know about such issues, I keep good records, AND I've done followup with clients years later. It's called "reputation". In the case of the steamer I'm referring to, of 20 yrs ago, I have, in fact, repeated with work for that family within the past 2 yrs (yes, 20 yrs later) and I've seen that shower myself. If you would like, I could ask my client to come here and attest to this herself, but I'm hopeful you'll take my word on the subject. Your mileage may vary and your customers may not call you back because.... well, I'm not going to speculate here...but....:laughing: mine do.

And once again, I will stick to my guns on shower floors. Read my lips; pre-pitching pans eliminates buildup of water in a shower pan, something most plumbers don't even do. cbu has to come into contact with a mud bed and so long as it isn't down against the pan liner, it has a chance to dry properly.

BTW, why dont' you provide a suggestion for the shower floor/mud bedding concern, the one you call a septic tank, since you find it such a critical issue.. I'm not hearing your input as much as your criticism. Are you a master tile mechanic with a better plan or a jack-of-all-trades trying to stir the pot? Is there some newfangled solution to shower floor mud?

 

I'm not gonna throw any gas on the fire here or anything. I'm not gonna question anyone's abilities. I'm a simply trying to state why the newer methods have become so important.

Here's another way to look at their differences:

* A complete mud bed installation is designed to allow moisture in THEN deal with it.

* A waterproof membrane system is designed to NEVER allow the moisture in.

Floating walls and the floor is a lost art (at least becoming one). However, even in that situation, there are many benefits to installing a membrane OVER the mud.

 

Angus, I Wasn't suggesting mud walls or floors were waterproof. If I had a call for a mud wall steam shower construction, I'd treat it with waterproofing too. I was just noting the fact that I'm hesitant to jump all over some new product before I've come to know it as being a viable alternative. I appreciate your input, and I can tell you know what you're talking about. I wasn't trying to dispute your knowledge.

 

I didn't feel you were questioning me at all :thumbsup:

When a discussion like this pops up, I feel it's a good way to get others that may be reading this to understand what "waterproof" really means.

I won't say a liquid applied membrane can't work, I just feel it's much more work than a fabric membrane. For instances, to get RedGard to a < 1 perm rating, you need to apply 60-70 mils wet on a wall and 90-93 mils wet on a floor. Especially in a steam shower situation, those are critical specs to follow.

As an installer, not only is quality important to me, but time is too. Once Kerdi-Board is released, I will be able to start from framing and have a shower ready to tile in a few hours. That's a completely waterproofed shower. I can plumb the walls and build niches or benches without much extra time needed.

As an experienced installer yourself, you should keep an open mind when it comes to how waterproofing can benefit your installations....and your bottom line. Upgrades are a good word in our business :shifty:

 

OK guys, let's try to keep it civil. I'm not trying to be a mini-moderator but I feel this thread contains some pretty good info and I'd hate to see it get locked down.

HUGS!!!!

 

Changing technology brings strife and uncertainty.

Ignoring the last 5,000 years of tile tech is foolish. One must learn and respect those lessons.

Clinging to out dated tech out of stubborn fear is limiting and leads to extinction.

Each must choose his own path as he sees best, learning, listening and weighing advice carefully, while assuming that each man, although his path may differ from one's own, has the same goals of quality and honesty in his heart until shown otherwise. There is not, and never has been, one answer.

The difficulty in our trade stems from the wisdom of a certain path being unknown for 20 years. Thus old ways are considered best. What you may see as stubborn resistance to change is the choosing of the sure footing on a muddy slope.

Confucius say.

 

Each must choose his own path as he sees best, learning, listening and weighing advice carefully, while assuming that each man, although his path may differ from one's own, has the same goals of quality and honesty in his heart until shown otherwise. There is not, and never has been, one answer.

Wow. That was good. :notworthy

I was wondering when you were gonna chime in :thumbup:

 

Why would anybody care if you are nailing CBU to curbs, walls, ceilings etc...?

Unless you can build the entire shower underlayment behind the tile and waterproofing out of 1 solid injection molded material, what difference does it make? You've got penetrations all over it, including huge ones at every seam in every corner.

A nail or screw through CBU, or a deck mud built curb are both porus materials until the membrane or water proofing is applied.

 

WHY .....would they care if you nail cbu to curbs? Uhm... becuase THEY LEAK, :thumbsup:?

Curbs are entirely different than walls, and endure sheets of water cascading down the glass door directly over the curb, through the grout, and through the nail holes. The wood beneath absorbs water, swells, and blows out the curb. If you use a quik curb, that won't happen, but there are limitations to using quik-curbs. The best method is to tightly form wire lathe over the rough curb/pan liner, and make 5-6" forms with durock, wood, or sheet rock, and pour a solid curb. Next day you pull away your forms and voila~ you have a solid curb in any configuration needed. Check my website under shower pan repair for a specific example.

Walls are entirely different than curbs. For instance.....you wouldn't put nails in your shower floor pan liner would you? I hope you wouldn't because it's a straight leak. there's no difference in nailing cbu to a curb....I've actually repaired a shower whre some hacks nailed durock to the inside pan liner and didnt' have a clue how to mud a shower floor. LOL>...`

(>>>My first case in point ^^^^)

 

Paul,
You are correct in saying no nails through the liner and I know all agree if the shower is done that way. Mike is talking about surface applied membranes which don't utilize a pan liner, so you can nail/screw the cbu to the curb since the membrane will cover it all.

 

Interesting double speak, considering all the to do about double vapor barriers and trapped moisture.

My understanding was Mike was referring to nailing cbu to a curb with pan liner wrapped over rough frame and under cbu. I dont' recall his stipulating otherwise, and stated that "the same technique applied to curbs as did to walls", which I entirely disagree with.

As far as I am concerned, anyone who has to nail cbu to the top or inside of a curb is begging for failure.; it's a highly inferior method to mudding a curb with mortar, and an indication that the installer doesn't possess the resources or knowledge to create a completely watertight curb without it. IOW's, I wouldn't put all my trust in the liquid membrane as the end-all-be-all to creating a waterproof curb, when it can be done entirely without the use of liquid membrane, nor would I fully trust 100% moisture blocking from any surface preparation in a steam shower.

Furthermore, in the event a radius curb is required, forming with cbu would be a complete nightmare, whereas forming/pouring a solid mortar curb would be little more work than for a straight/grid configuration. The OTHER downside to relying on liquid membranes to waterproof curbs is the mil thickness achieved (earlier discussed) and the multiple layers required to achieve 100% waterproofing (dry time per layer (24 hrs) (73 mil thickness earlier discussed). In effect, it would take 3 days to build and waterproof a curb with liquid membrane (according to manufacturers warranties and applications guidelines) vs 12 hrs wait time for a pour/formed curb configuration.

In most cases, the hacks I've seen who are nailing cbu to a curb aren't even waterproofing over it, they don't seam joints with fiber mesh tape, and tile straight over a nailed piece of durock. Their rational for nailing the inside of the curb is that they only nail at the top. :jester: What can I say.... other than.... it's job security.

 

Paul,

This is the system many of us use, http://www.schluter.com/media/brochures/ShowerHandbook2008.pdf. Hopefully, it explains more clearly what we have been talking about. Out of personal preference, I don't use the preformed pan or curb. I make my own mud bed and mud curb, then wrap it all in kerdi. But, either way is effective. Schluter also says you can use drywall behind their system and many do successfully, but again by personal choice, I always use cbu under the kerdi.

 

Schluter also says you can use drywall behind their system and many do successfully, but again by personal choice, I always use cbu under the kerdi.

Question. And I'm not picking on you, just more of a poll. Why use CBU behind Kerdi? Isn't that, in a way, saying you don't trust the Kerdi?

Again, no offense. Actually aside from myself, there's only 1 other installer on here that doesn't use CBU (that I know of).

Curious....

 

No offense taken and it's a fair question. A couple reasons: 1)The way I see it, kind of like Paul does on the poly behind the cbu with redguard on the front, is that there is a weak link to every installation. I do trust the kerdi to a point, but in the unlikely (but not impossible) event that I had a failure in the kerdi wall, I'd like to think the shower wouldn't be a complete loss as it would with drywall. Although, my thought process doesn't work in the event of a failure in the pan kerdi since I don't back that up with a liner , and 2)out of habit. In any case, I am very careful to follow the installation instructions exactly for the kerdi, as well as, every other product I use. Though, the kerdi instructions do spec cbu, probably for those too stubborn (me) to do it like they recommend with drywall.

So, were you saying that you still use cbu with the kerdi, or you don't?

Add: Even though I know you can lap the seams any which way as long as the proper overlap is maintained, I lap everything away from the water source and shingle style from the pan up the wall. My attempt at even more protection.

 

So, were you saying that you still use cbu with the kerdi, or you don't?

Add: Even though I know you can lap the seams any which way as long as the proper overlap is maintained, I lap everything away from the water source and shingle style from the pan up the wall. My attempt at even more protection.

I use DensArmor, not drywall. While it's not as moisture resistant as CBU, it is a lot more resistant than straight drywall. Another benefit to using DensArmor is I don't have to seam it to regular drywall outside of the wet location. I use it for the entire bathroom.

Funny, you mention the shingle style lapping...I do the same. I know it's not necessary. I guess I do it more out of common sense more than anything else. :thumbsup:

 

Densarmor, now that's a thought. About as much in cost as cbu, but less weight, plus it does have some moisture resistant properties. Funny, I hadn't thought of densarmor under kerdi even though I'm hanging some in a bath remodel I'm doing right now (existing shower stays, so I'm only tiling the floor.) I may just try that on my next one.

When I seam cbu to drywall, I make sure my seam hangs back from the tile edge a few inches, then thinset/mesh tape the seam. I like idea of not dealing with that.

 

SO I'm the only one here who installs poured curbs? (shocking)

SO now I'm curious... what did you do before they invented Kerdi?

Also, let's say you're remodeling a house that's 100 yrs old and the subfloor and curb rough in is severely out of level. How do you compensate with the kerdi system if the curb formation would naturally follow the subfloor level?

 

SO I'm the only one here who installs poured curbs?

I do, I do Seriously, I do all my curbs poured. There is more flexibility, as you noted, than using the preformed. Plus making your own is much cheaper. I think the preformed foam one for kerdi goes for about $40+ for a 4 foot section, around here.

 

So from 3 posts from me you have determined I cant pour mud curbs even thought the thread is about waterproofing?:laughing::no:

no one here is trying to change your mind about anything other than there are more than one ways to skin a cat and just cause you dont use one doesnt mean the rest of us has no idea what they are doing.

 

What I have determined is that you seem bent on flaming my post's. For instance, there could be a reply regarding how to compensate for severely out of level subflooring. And honestly, I don't know what you're capable of, Im going on what you're posting, but if you're using EasyBoard.....

I cant use drywall because i have inspections and they require cbu not drywall, I use easyboard.

.....to build curbs, that speaks volume. :thumbsup: Keep it up- I need more work!:laughing::no: I can push my finger through EasyBoard; it's less resistant than sheetrock. OK, so it's lighterweight-that isn't going to stop it from giving in when enough pressure is being applied to it.

AS far as steamers, I'd reassert that even if someones swearing by Kerdi waterproofing, they're betting the ranch that every single millimeter of surface is covered and protected, and my only comment is that regardless of whatever waterproofing is used, a vapor barrier is added insurance against a leak, vapor lock, notwithstanding.

 

Ok last time, I use easyboard on WALLS, covered with kerdi, which is what my post your quoting is confirming.

curbs are either mud or preformed curbs from schluter.

your assupmtion that kerdi needs a vapor barrier speaks volumes about your experience with kerdi, i have done mud showers and kerdi so I can say which is better for me, you however cannot attest to kerdi so....