Hi everyone. After our toilet decided to ruin our floor, we are now remodelling our bathroom earlier than expected. We’re going to tile the bathroom shower. I’m confused about whether or not to add felt paper behind the backerboard. Some of the contractors in Seattle don’t add it and state they have had no problems. I have read that it is a good idea to install felt. Is it just preference, or is there a true right or wrong way to do this? Would it depend on the type of shower or geographical location?
Thanks,
Ryan
Replies
Definitely add felt or plastic behind the backerboard in the shower.
ditto.
Jeff Buck Construction
Artistry in Carpentry
Pgh, PA
Could be too that they're using Denshield tile backer, which doesnt need addl. waterproofing behind it (or so they claim).
It needs it...In fact, I wouldn't even use Denshield in a shower...
ALL
I'll just go ahead and piss off everyone.
Denshield installed carefully and correctly will probably go 20 years. i have no doubt.
I don't use it near the water table if I can help it. CBU there, but DS on up.
While me thinks the vapor barrier is a good IDEA.........
I'd rather be PL'ing the cbu to the studs.
I've taken apart 1 or 2 ;) old mud jobs and have yet to find any serious penetration of moist vapor in the wall cavities. I've found plenty of dry crisp old newspapers from the 40's and 50's but never a whole lot of moisture.
That's gotta tell ya something. And I'm in the NE.
Eric
If ur gonna shoot, just make sure ya hit the target!
I Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
[email protected]
Edited 4/4/2005 6:35 pm ET by Eric Paulson
No argument here. I do it too. Just trying to get into the heads of the tile guys the poster was talking to.
It's so cheap it's a no-brainer.
It is necessary, too. Grout is not waterproof, in fact, it wicks moisture like a sponge. That will transfer water to the cementitious board. If you live alone and have a well ventilated shower then perhaps it will dry enough each day and never soak all the way through to the wood. But, if the shower is wet for a while each day, it could soak through, and in some installations it does.
I would always use it in my work.
Just do it. After someone charge you 20.00 sf to install the tile, your worried about 5.oo worth of vapor barrier, for the whole bathroom.
We don't do the vapor barrier unless it is an exterior wall with insulation. Maybe it's wrong but I don't see what good it would do. As an above poster said, grout is somewhat porous but as another mentioned, I've never seen water get behind tile that wasn't failing, and lets say that some water got behind there; would you rather have it enter a wall cavity that had a possibility of drying out or just sliding down between the barrier and the cbu?
When I install the cement board, I put on fiberglass tape and mud it in with thinset. I always recommend grout be sealed anyway.
...would you rather have it enter a wall cavity that had a possibility of drying out or just sliding down between the barrier and the cbu?
Um....barrier and cbu.
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I always use felt paper, like the other guys said, how much money are we talking about here.
I consider it the membrane of last resort and it should overlap your showerpan lip or the membrane if it's a custom pan. It is worth remembering that morter beds are not waterproof nor is wonderboard another common tile substrate they are water resistant. Hardibacker is waterproof, which I use, and like the other gentleman I scrim all the joints with mesh tape and thinset before tiling as well.
Water in the walls is never a good idea.
"Water in the walls is never a good idea."Agreed. But how much water do you expect to get through properly installed tile and cement board? I can't see more than a drop.
I allways use a felt behind the backerboard and have it drape over the lip of the tub or pan. But I`ve allways thought - where does the water go? The gap between the tub and tile is caulked with silicone. So I try and prevent water from entering through openings and I seal real well.
I went to a seminar that Micheal Byrne ( he has written many articles and books for FH) and he was recommending this product called Red Guard that he said would work well as a waterproofer. I remember him as putting it on the floor however and not the walls. Does anybody have any experience with this product?
I have seen something similar to red guard at my tile supplier. They sell itr as a combinitaion crack control membrane and waterproofer, primarilty for the floor.
Denshield is just high dollar sheetrock. Somebody said they use it in the shower, but not below the water table. Well, if it's not good enough below the water table, why use it in a wet area?
I'm sorry, I thought you wanted it done the right way.
When I demo'd my bathroom, the bottom plate and several studs had to be completely replaced because of extensive water damage. No VB.
I tear out these kind of problems every other week or so. It is tile failure, or grout, or caulk, or plumbing, etc. What would a vapor barrier have done to save this?
Has anybody done this approach.
First start with hardi-board which is taped and sealed with mortar at the seams then a liquid waterproofing agent (which also serves as an isolation membrane) then the thin set and the tile?
We used this method when we tiled our exterior wood stairs and I check underneath them a couple of times every rainy season and have seen no evidence of leaks.
I like the idea of stopping the water before it hits the CBU.
I have included a before and two after shoots. SWMBO did the flame mosiac herself...she really likes fire.
Daniel Neuman
Oakland CA
Crazy Home Owner
I have done something similar to this, we used blueboard as the base, then an epoxy based paint on membrane which we coated the entire bathroom with (we were paranoid and on the 24th floor of a very expensive hotel/condominium, not the place for leaks). We then put mortar beds over this and tiled.With regard to the question how much water can get through, you'd be surprised. I've seem the damage done from badly installed showers, and ain't pretty. It seems to take a remarkably small crack in the grout or split in the silicon to let enough water through to do damage. Thinset, grout and mortar are not waterproof, and you do not want water getting to the studs - they rot.One word of warning, out here in San Francisco, they are very particular about the code requirements for shower pan membranes. If it doesn't have a UPC stamp on it will not pass. Other jurisdictions may be less picky. That is for the membrane however and they care nothing about what happens 3" above the curb!
Standard operating procedure required by law here. I'm sorry but in general America is way behind the eight ball as far as waterproofing issues go. Here is a shot of a bathroom I just waterproofed last week.
Sorry for the size ( new camera )http://www.quittintime.com
Now THAT looks interesting.
Do tell us more please!
EricI Love A Hand That Meets My Own,
With A Hold That Causes Some Sensation.
[email protected]
http://www.quittintime.com has an article on waterproofing in its "How To" section.
regards
Markhttp://www.quittintime.com
This shouldn't be an issue or discussion on this. The TCA requires this installation, and any installation that does not have a membrane behind the CBU is faulty. Period.I would take the installation another step--why not waterproof the CBU with a trowel on waterproofing, like Laticrete 9235? Totally and completely waterproof.Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Here's my view and approach:
I assume no LIQUID water will get through the grout and tile. If it does, I have bigger problems. I don't like the idea of moisture getting trapped between the tile and the back of the backer board. I would prefer that moisture be free to evaporate into an interior wall cavity. I would use a vapor barrier on an exterior wall (cold climates) to prevent condensation in the cold wall cavity. I do use a spline of folded ice and water barrier in the corners. I figure the corner is most likely to crack from movement of the frame. (Not in MY showers!)
All these strongly held opinions sound to me like conjecture. Until confronted with evidence to the contrary, I will think any water damage behind a cement backer board and tile shower wall was caused by leaks of liquid water through cracks or plumbing penetrations.
I have an easily-opened access door to the plumbing for my tub/shower that is used at least twice a day. I have never seen any sign of water of any kind coming through the backer board.
Al Mollitor, Sharon MA
Go here....http://www.johnbridge.com/vbulletin/index.phpThey do tile everyday and are at the top of their fields. They will ALL agree with the felt/plastic issue held here in CONJECTURE. They'll even give you real world examples with alot of experience to back it.Ask the question there...I dare ya.
You DARE me? What is this? Grade school playground?
Thanks for the link. It looks like a great resource. There's a lot of stuff there. Can you direct me to a specific thread?
Al
Thanks everyone for such a great discussion! I appreciate everyone's input. Someone talked about Redguard. I found out it's a sealer painted on the backerboard to create a barrier. One of the companies I called uses it, but they do not use a barrier behind the backerboard.
The money for the vapor barrier is not the issue as some have mentioned. But it's whether or not it is a good idea.
There certainly are two very dedicated groups here. I won't say either is write or wrong. Especially since I'm not an expert. But it seems to me that in most cases no vapor barrier behind the backerboard (as opposed to the Redguard, or the like, as a vapor barrier) would be a better choice. I'm sure nobody will be shy about telling me if I'm completely wrong. :) But thinking about it, water vapor is what gets behind the the tiles and into the walls. Water as a liquid does not because the surface tension is too strong for it to go into the walls unless it sits long enough for it to soak in. I guess you could argue that the soap would reduce the surface tension, but that is another discussion. With gravity and proper bathroom ventilation I can't imagine enough water would sit long enough on the shower walls to do much harm. Once vapor has penetrated the wall I would think that the vapor barrier may promote condensation due to it likely being cooler than the vaper (which is 100 degrees C), the vapor has no place else to go except back into the higher pressure shower space (which is unlikely until the area cools), and the barrier provides a physical object for vapor to condensate on. I would prefer the vapor have adequate air space to move into and out of the wall and wall cavity, and this breathability would keep water from condensing and then staying within the wall itself. If a barrier did cause condensation then the water droplets could only migrate down the wall to the bottom of the wall and cause rot, or soak into the backerboard and cause cracking.
Now I can see that it would be more complex when one of the shower walls is adjacent to an exterior wall. It may be a wise idea to have a barrier here as Mad Dog mentioned. But that is beyond my knowledge. I can certainly see the reasoning for having a barrier all around, but I'm not convinced yet. Major damage is probably caused by a leak somewhere and not whether or not there was a barrier. Also, if you think about it, the vapor barrier does not prevent moisture (steam or water) from entering the backerboard, but from entering the wall cavity. The backer board is in front of that type of barrier. So are we not worried about the backerboard at all? The studs and other framing structures probably do see increased moisture levels than the other areas of the house, but by how much, and does it actually cause a problem? Does anyone know of a study or of someone looking at the increase in moisture within a wall from a shower? Maybe that would help settle this debate.
I did look on the website MojoMan mentioned. They advised someone installing a steam shower to not use a vapor barrier. At the websit see the "Professionals' Hangout" and then find "Waterproofing a steam shower". The post is by MHI.
Again, thanks for everyone's input. Please tell me if I'm completely wrong.
Ryan
mmmm,
I think you might be misreading the general concensus. I think most of the posts are saying, and I absolutely agree, that you do need to use a moisture barrier.
Either a system with a moisture barrier on the tiling surface like DensShield, but with this product you have to be very carefull that you have sealed all fasteners and joints. Or use Cement Board with a vapour barrier behind it. Again..... the vapour barrier keeps the water out of the wall cavity. If you get water dripping into the wall cavity you will eventually get mold and rotting wood studs. Also remember Cement Board does not support mold growth that's why it's used. You want your shower to dry out into the bathroom.
I'd be interested to hear anything more you learn about tile side moisture barrier systems, if you decide to experiment with that, but you would really be setting yourself up for another renovation to go without anykind of moisture barrier.
the ontario tile setters have a good discussion forum you might want to check out:
http://www.ontariotile.com
anyway,
good luck with it.
Edited 4/6/2005 1:49 am ET by Bunny
Edited 4/6/2005 1:57 am ET by Bunny
Hi Bunny. Well, the majority on this site do prefer to have the barrier. But all the contractors I've called around my area don't use a barrier, which is why I say that it is split. Also, I'm not convinced I should do something just because someone says that it's cheap to do, so why not do it.
Another question I would have for you, or anyone else, is if it is so important to have the barrier, then why don't you have a barrier above the tile and on the ceiling? Heat and steam rise, and paint is not waterproof. Moisture still gets in the cavities around the tile. The bathroom vent should not be directly above the shower.
I'm still on the fence on this one. I like the debate so far. It's interesting.
Ryan
yes the ceiling, good question. I guess that's because the water, once it has condensed on the ceiling, will start to move down. so you want to control how it moves down and where it ends up, ie. in the bathtub, drain, within the room and not at the bottom of the wall cavity. I'm suprised to hear that the contractors you've talked to say you don't have to use a vapour barrier. are you sure they aren't talking about using some kind of system that has an integrated vapour barrier instead? or do you ask them if they use felt and they say no, but they do use another kind of moisture barrier? let us know all the details of the system they are recommending.
is there some unique situation about your project that you're not letting us in on? is it against an exterior wall for instance?
cheers.
Edited 4/6/2005 4:42 pm ET by Bunny
Edited 4/6/2005 4:47 pm ET by Bunny
Edited 4/6/2005 4:52 pm ET by Bunny
Some contractors don't use anything for a vapor barrier. One I talked to uses Dens-Shield or Redguard, but he said if he was doing his house he would use felt. I'm still getting mixed responses, but on the websites more say to use some method rather than nothing. No special situation in the bathroom. One wall is an exterior wall part of the way. The shower is not on the exterior portion of the wall. I've heard some say that a vapor barrier would only be needed if the wall was an exterior wall since when the vapor meets the colder air it will condense, but otherwise the barrier is not needed.
I'll most likely use some sort of barrier, and likely felt, unless you think poly is better. I can see how it would be very nice to have if there were some cracks that allowed water behind the tile. I'm still undecided how useful it is just for vapor. I just pulled the tile off the wall of the bathroom. There was no vapor barrier behind the greenboard. The only place there was water damage (and there was very little) were places where the tile or grout had cracked. It surprises me how so many people recommend using the barrier and how so many don't acutally use it.
Thanks,
Ryan