vapor barrier behind a shower?

[punkabilly136]

do I need to put up a vapor barrier behind my shower? I plan on gutting it down to the studs and laying cement board then tiling the enclosure. I have heard good and bad about a vapor barrier behind the shower; keeps out moisture and traps the moisture in. So what do I actually need to do?

 

[rickairmedic]

I put in kraft backed insulation ( on the extreior wall ) when we redid our bathroom no plastic vapor barrier. Then cement board then tile.


Rick

 

[nate379]

Just studs behind my showers. They are on inside walls though.

 

[Grumpy365]

Just studs behind my showers. They are on inside walls though.

Mine too.

 

[punkabilly136]

my shower will have one outside wall...there is no vapor barrier on it now but if I'm going to rip it down now would be the time to put one up if need be

 

[larry4406]

Right or wrong, the production home builder I worked for, we had unfaced batts in the shower area at exterior walls.

 

[Stephenw]

I used asphalt roofing cloth. I started at the bottom and stapled it horizontally. I worked up to the ceiling with an overlap at each layer. I then screwed cement board over the roofing cloth. I filled the cement board joints with thinset mortar. Finally I installed the tile.

 

[punkabilly136]

asphalt paper was another thing I was thinking of. I plan on installing a shower niche and was contemplating using that for the niche

 

[idoine in toronto]

You may want to look into the Kerdi shower system. It has many waterproofing components for showers. It will at least give you some ideas.

http://www.schluter.com/5288.aspx

 

[Frank The Plumber]

Kraft face batts, sealed with proper plastic sheet and tuck tape green board and this orange stuff above us here is all the rage. I used cement board and bonding mortar for a long time but now this system is the hot ticket for mould barrier and proper sealing. Recommended for interior and exterior applications.

 

[scotw]

Yes, you need a vapor barrier. Water will get through the grout and slowly rot things. Cement board is not a vapor barrier.

I always start with bare studs, put up a cement board (use the correct screws), and apply a waterproof membrane. My favorite is Kerdi. You put thinset on the cement board and press the kerdi into it with a drywall knife.

The tiles are then thinsetted to the kerdi and then grouted.

What are you doing for the base of the shower?

It is easy to make a shower that works for ten years, much harder to make one that lasts twenty years.

Kerdi link: http://www.schluter.com/8_1_kerdi.aspx

 

[Frank The Plumber]

Use a Keralastic membrane made by Kera bond over a formed base using forming sand, This system is the best system I have seen since the properly done lead pan. A lead pan will last for 80 years if done correctly, the secret to properly doing the pan was in the tile mans secret of using jute wicks to properly evaporate the area between the pan and the forming sand that he poured into it. The lead pan could last longer if we built the structure better, there is a Roman tub that still holds water in Rome, it was constructed for Ceasar.

 

[5lima30]

Is the shower a fiberglass unit or tiled?

 

[ddawg16]

Not trying to hijack the thread....
But I'll be building a shower in a few months.....new construction.....

My intent is to use a pre-made fiberglass showerpan....on the walls I was going to use tar paper.......then hardiboard.....with it overlapping the lip of the shower pan....actually, if I remember correctly, the install instructions said to overlap the tar paper on top of the shower pan lip as well.

I only want to do this once.....

 

[Frank The Plumber]

Tar paper is too flammable for this application. If you are concerned about the walls behind the shower enclosure use kraft backed insulation, vapor barrier and tuck tape, carefully place the unit and rough caulk your seams. Drywall the walls using the new green board replacement product out there, caulk your flashings on the unit and use this drywall replacement product. I know it's pricey but it works well. I also recommend setting the shower base on a masons mortar bed., keeps the floor strong.

 

[punkabilly136]

there is already a porcelain tub in place I am just ripping down the enclosure and putting up tile.

 

[Busted_Knuckles]

Not trying to hijack the thread....
But I'll be building a shower in a few months.....new construction.....

My intent is to use a pre-made fiberglass showerpan....on the walls I was going to use tar paper.......then hardiboard.....with it overlapping the lip of the shower pan....actually, if I remember correctly, the install instructions said to overlap the tar paper on top of the shower pan lip as well.

I only want to do this once.....

Ditto, I picked up a jacuzzi 48"x48"x24" shower pan this morning, saw this thread and subscribed. Im too am going to tile the top, and was wondering what the best way to go about the vapor barrier on this...

 

[Stephenw]

My intent is to use a pre-made fiberglass showerpan....on the walls I was going to use tar paper.......then hardiboard.....with it overlapping the lip of the shower pan....actually, if I remember correctly, the install instructions said to overlap the tar paper on top of the shower pan lip as well.

I only want to do this once.....

I overlapped the pan with both the roofing cloth and the cement board.

I don't get the "tar paper is too flammable" statement someone made???

 

[nate379]

Ok I was talking about fiberglass surround, which is what I have. Tile is a different story.

The tar paper I bought when I did my roof wasn't flammable. The scraps I had went in my burn barrel. When I emptied the burn barrel... many HOT burns later, the scraps were all still there.

 

[Frank The Plumber]

I overlapped the pan with both the roofing cloth and the cement board.

I don't get the "tar paper is too flammable" statement someone made???

Take it out to your fire pit, light a match to it. It goes up very fast, want it in your house? There are better products and systems out there than tar paper. If you had an inspection, tar paper would get bumped on the interior of the home.

 

[Stephenw]

Take it out to your fire pit, light a match to it. It goes up very fast, want it in your house? There are better products and systems out there than tar paper. If you had an inspection, tar paper would get bumped on the interior of the home.

It's commonly used...

http://www.diyadvice.com/diy/tiling/bathroom/shower-tub-enclosure/

 

[nate379]

While I agree there are better things out there for shower than tar paper, I haven't see a kind that was flammable like you are talking about!

Take it out to your fire pit, light a match to it. It goes up very fast, want it in your house? There are better products and systems out there than tar paper. If you had an inspection, tar paper would get bumped on the interior of the home.

 

[Frank The Plumber]

.......by hacks and slobs, that is the rest of the sentence. If it moulds your house it is not a proper product, if a contractor installed it in your home and it moulded you would have a legal basis. It is a product designed for roofing, as a vapor and friction barrier on a roof. There are far superior products available to use for your shower. Just cause some goof posted how great it is on a DIY site does not make it all A OKEY DOKEY. If you want use it hey knock yourself out, that Kerdi system stuff is the new standard and they have anti mould wall board that is great stuff. The EPA is passing air quality laws on homes, in the future they will require spore tests, they are doing it here on all remodel jobs. No pass, no occupancy.

 

[Stephenw]

.......by hacks and slobs, that is the rest of the sentence. If it moulds your house it is not a proper product, if a contractor installed it in your home and it moulded you would have a legal basis. It is a product designed for roofing, as a vapor and friction barrier on a roof. There are far superior products available to use for your shower. Just cause some goof posted how great it is on a DIY site does not make it all A OKEY DOKEY. If you want use it hey knock yourself out, that Kerdi system stuff is the new standard and they have anti mould wall board that is great stuff. The EPA is passing air quality laws on homes, in the future they will require spore tests, they are doing it here on all remodel jobs. No pass, no occupancy.

That DIY site was something I found with a quick Google search. I'm not saying roofing felt is the best product, but I've seen it used on many websites, in how to books, and on TV shows. My brother-in-law is a licensed plumber and helped with my project.

 

[Frank The Plumber]

Watch a few episodes of Holmes on Homes where he tears out the mouldy installations of professional builders and general contractors, let us know what you think. It is extremely difficult to not get mould in a bathroom environment in the first place, now televised shows are detailing how bad it is for your health. The trend is to go after the seller in these situations and get reimbursement for damages. This makes it all that much more critical to use the best possible mould retardant products and methods. See what the attitude is on some of these DIY rescue shows towards roof felt, tar paper,and products and methods that were recently endorsed. If I installed felt or tar paper as a vapor barrier on one of my bath remodel jobs it would be tagged by the inspector for removal. At this point my client base is educated enough that if they saw it being installed they would question it. In your brother in laws defense, plumbers are generally not trained as mould prevention or remediation experts. That training has been generally over looked and not really assigned to a specific contractor or trades group. Trust in the fact that I am trying to help you with a quality installation.

 

[54FordPanel]

Take it out to your fire pit, light a match to it. It goes up very fast, want it in your house? There are better products and systems out there than tar paper. If you had an inspection, tar paper would get bumped on the interior of the home.

The "flammable" argument makes no sense to me. It's stapled to 2x4s, for pete's sake. If the 2x4s behind the tile & the cement board are burning, then I suppose once the house has burned down, I will have to replace the tar paper.
I used tar paper to line my studs under the hardibacker.

However...
I would absolutely agree the Kerdi product is better. I wouldn't discourage anybody from using it. I'm pretty sure there's a steep learning curve to putting it in properly.
But it's way more expensive, and I couldn't even buy it at Home Depot. So I went with tarpaper behind the cement board, and I put down 3 coats of 'Red Guard on top of the cement board.

Trust in the fact that I am trying to help you with a quality installation.

I think you know what your talking about, I just don't buy the flammable stuff.
I agree that shows like Holmes on Homes makes the public think they know what to watch out for.
My nephew does tile work, and he hates the guy. He'll get a customer who starts out by saying "Mike Holmes says..."

Whenever I have found a shower or tub that leaks, (and causes mold) it's obvious why. Crumbly grout and horrible caulking.

 

[Frank The Plumber]

The problem is that the moisture causing the mould is not coming from the tile side of the wall. You can have a wall that is expertly sub based, (drywalled, boarded etc) and expertly tiled as well, that will have mould on the studs within the wall. This moisture is caused by condensation of the vapors that are in the wall and a concentration of these vapors into water. The warmth of the water warming the wall causes a dew point reaction within the wall. Once water is within the wall it pulls moisture from the bathroom towards it, through the grout and products. The only real way to stop the dew point phenomenon is to insulate the wall properly holding heat from the room, seal the insulation in the wall making a physical heat barrier and stopping the moisture draw, and properly grouting and finish caulking the final product. Due to the fact that the structure wood expands and contracts, the house moves and shifts, it cracks any type of grout joint that could ever be used. This liner type system being pliable provides a good mat membrane that will shift with the structure and keep the water from being drawn into the wall through grout cracks. Simple tar paper can not provide this protection. As far as it's flammability, A pine stud flames at a sustained heat of 450 To 475. A sheet of regular non fibre glass impregnated tar paper catches a flame at a 375 prolonged heat source. This can be critical when a sheet is installed in close proximity to an electrical box or possible combustion source. This temperature exposure rating also affects the amount of time you will have to get out of a structure that is on fire, by using products that burn at a lower temperature within the walls the home goes a blaze faster giving you less time to escape from it. For this reason most urban fire codes do not allow base tar paper as a product for within the structure.

 

[54FordPanel]

The problem is that the moisture causing the mould is not coming from the tile side of the wall. You can have a wall that is expertly sub based, (drywalled, boarded etc) and expertly tiled as well, that will have mould on the studs within the wall. This moisture is caused by condensation of the vapors that are in the wall and a concentration of these vapors into water. The warmth of the water warming the wall causes a dew point reaction within the wall. Once water is within the wall it pulls moisture from the bathroom towards it, through the grout and products. The only real way to stop the dew point phenomenon is to insulate the wall properly holding heat from the room, seal the insulation in the wall making a physical heat barrier and stopping the moisture draw, and properly grouting and finish caulking the final product. Due to the fact that the structure wood expands and contracts, the house moves and shifts, it cracks any type of grout joint that could ever be used. This liner type system being pliable provides a good mat membrane that will shift with the structure and keep the water from being drawn into the wall through grout cracks. Simple tar paper can not provide this protection. As far as it's flammability, A pine stud flames at a sustained heat of 450 To 475. A sheet of regular non fibre glass impregnated tar paper catches a flame at a 375 prolonged heat source. This can be critical when a sheet is installed in close proximity to an electrical box or possible combustion source. This temperature exposure rating also affects the amount of time you will have to get out of a structure that is on fire, by using products that burn at a lower temperature within the walls the home goes a blaze faster giving you less time to escape from it. For this reason most urban fire codes do not allow base tar paper as a product for within the structure.

It sounds like you know what you are talking about Frank and you are a professional. I believe you don't cut corners and you do it right. And like I said, I believe the Kerdi system is superior to tar paper.
But...
I've read your explanation 4 times about how the moisture in the wall doesn't come from the tile side of the wall, and but from vapors inside the wall, and once that water is within the walls it pulls moisture from the tile side...you lost me there.
Again, I believe you are right in saying the Kerdi is superior to tar paper. I also think my system will hold up to my use for the next 15-20 years.

 

[Frank The Plumber]

Sorry I lost you, here it is again a bit different. We all know that in the morning on a warm day we can walk outside at the first dawn and everything is wet. That is caused by a phenomenon known as dew point. The ambient air is exposed to a condition that causes it to dump it's moisture. Basically the water is shocked out of the air by a temperature change. This can happen in chimneys, within block walls, in your attic, anywhere that you have air and the possibility of a sudden temperature change. This phenomenon can occur within the walls of your shower due to the sudden application of warm water to the cold surface of the shower wall, the air within the wall is warmed, shocked and dew is formed. Simply, it rains in your wall. In a dark place that has any type of nutrient this becomes an area for mould growth. Over the ages mould was not generally looked at as an evil demon, so we didn't really build to stop it. Most of our tried and true construction methods took no consideration at all over mould prevention or it's total control. We have as of late learned that it can be very bad stuff, so we have to adjust our way of construction to completely eliminate it's environment.
Once a wall has water within it the water draws addition moisture into the wall, there is a name for this but I don't remember it exactly, like how capillary attraction can draw a liquid up a pane of glass, defying gravity. A properly done system should only ever have to be redone because the wife is sick of looking at the tiles, it should hold as log as the structure. You could say, well why didn't my 1935 house have these troubles. Well your 1935 house may have been brick, brick breathes and moisture can escape from the brick just like it came in. Your 35 house had no insulation, the air pocket was large and not trapped so it could not be shocked. Your wall on the 35 house was a concrete mortar subbase tile job, it was 2 inches thick, the house could burn down before the heat would go through a 2 inch concrete wall. Most of the cases where you see a tar paper used in a home of 35 it was used as an insulant against sound, to stop floor squeaks etc. It is designed for a roof to shed water, in a wall on a parallel plane where is it shedding this water to? The floor? Back into the shower pan? It just doesn't fit into the modern mould prevention mentality. It has been exposed as an omen or precursor of bad things to come. I have seen people actually say as I opened a wall "Oh my God!, there is tar paper in there!" trust me I was taken a back by this myself.

 

[bigdav160]

.you lost me there.

Agreed, but I'm near the Gulf coast so building practices are intentionally different.

I've seen tile showers with kraft paper backed fiberglass bats underneath greenboard fall apart in 5 years.

I've seen concrete backboard shower start leaking in 10 years.

The tar paper backed showers tend to last twenty years or more. (the one in our home is 40+)

But I'm a big fan of Kerdi. All the other methods will have perforations from nails or screws. Kerdi doesn't have that problem.

 

[Busted_Knuckles]

Sorry I lost you, here it is again a bit different. We all know that in the morning on a warm day we can walk outside at the first dawn and everything is wet. That is caused by a phenomenon known as dew point. The ambient air is exposed to a condition that causes it to dump it's moisture. Basically the water is shocked out of the air by a temperature change. This can happen in chimneys, within block walls, in your attic, anywhere that you have air and the possibility of a sudden temperature change. This phenomenon can occur within the walls of your shower due to the sudden application of warm water to the cold surface of the shower wall, the air within the wall is warmed, shocked and dew is formed. Simply, it rains in your wall. In a dark place that has any type of nutrient this becomes an area for mould growth. Over the ages mould was not generally looked at as an evil demon, so we didn't really build to stop it. Most of our tried and true construction methods took no consideration at all over mould prevention or it's total control. We have as of late learned that it can be very bad stuff, so we have to adjust our way of construction to completely eliminate it's environment.
Once a wall has water within it the water draws addition moisture into the wall, there is a name for this but I don't remember it exactly, like how capillary attraction can draw a liquid up a pane of glass, defying gravity. A properly done system should only ever have to be redone because the wife is sick of looking at the tiles, it should hold as log as the structure. You could say, well why didn't my 1935 house have these troubles. Well your 1935 house may have been brick, brick breathes and moisture can escape from the brick just like it came in. Your 35 house had no insulation, the air pocket was large and not trapped so it could not be shocked. Your wall on the 35 house was a concrete mortar subbase tile job, it was 2 inches thick, the house could burn down before the heat would go through a 2 inch concrete wall. Most of the cases where you see a tar paper used in a home of 35 it was used as an insulant against sound, to stop floor squeaks etc. It is designed for a roof to shed water, in a wall on a parallel plane where is it shedding this water to? The floor? Back into the shower pan? It just doesn't fit into the modern mould prevention mentality. It has been exposed as an omen or precursor of bad things to come. I have seen people actually say as I opened a wall "Oh my God!, there is tar paper in there!" trust me I was taken a back by this myself.

Hey Frank, nice posts, thanks for your input, Ive tripped over several of your posts, a belated "welcome to the G/J", nice to have you around ! Nice to have new member show up with useable "content" !

 

[Frank The Plumber]

Thanks, notice you are a fellow victim of "Ill and annoyed". I figured I would try to keep some of these DIY guys from poisoning themselves or ending up in court when they go to sell their homes or garages. My mentality is that I would rather spend an extra $20 today and do a proper code legal installation that lasts 50 years than save that $20 and have to redo the whole damn thing in ten years at a cost of $5000. It's a cryin shame that the $20 will be saved and spent on an Egg Mc Fluffin and a coffee and sacrifice the whole job quality. And down right criminal when the guy is charging a person as a contractor and pocketing the $20.

 

[54FordPanel]

Yes, Frank, glad you're here.

Thanks for your experience & input.

 

[ishiboo]

Thanks, notice you are a fellow victim of "Ill and annoyed". I figured I would try to keep some of these DIY guys from poisoning themselves or ending up in court when they go to sell their homes or garages. My mentality is that I would rather spend an extra $20 today and do a proper code legal installation that lasts 50 years than save that $20 and have to redo the whole damn thing in ten years at a cost of $5000. It's a cryin shame that the $20 will be saved and spent on an Egg Mc Fluffin and a coffee and sacrifice the whole job quality. And down right criminal when the guy is charging a person as a contractor and pocketing the $20.

Frank, I respect your opinion but also the fact there are other ways of doing things...

Realize Chicago code/inspections are some of the most **** retentive in the nation, and you can go TOO overboard on a lot of things, waste money and end up in no better a situation even though you have "better" materials. Just because one product is "better" than another, often times in theory, does not make people wrong for using what you find to be an inferior product. Your idea of "proper and code-legal" is a combination of your idea of what's proper, and code in your area.

Roofing felt is NOT a vapor barrier and that is not its purpose in this application, it sheds water as a backup to the other "systems" in place, like the tile job itself. The fact it's flammable is mostly irrelevant in this application. Kraft paper is flammable and is routinely used around electrical boxes. Many closed and open celled foam insulations are as well. It's not going to harbor any more mold than the insulation in the stud cavity is, which also creates a temperature gradient between the back of the shower and the cold air so there should be little cold air on warm surfaces if everything is working correctly.

In terms of expansion/contraction, on a tile job the cement backerboard, tile and grout/thinset/etc are all very similar materials and expand at the same rate. A properly tiled shower should not crack grout joints. In practice, the corners and joints between the walls, walls/ceiling and walls/floor can see some shift based on the home's construction and wood behind it, and these are a good application for a more flexible grout.

In terms of "If you are concerned about the walls behind the shower enclosure use kraft backed insulation, vapor barrier and tuck tape, carefully place the unit and rough caulk your seams.", realize that the kraft papers purpose is that of a vapor barrier, so with this method you'd have two. The plastic barriers are easier to make effective than the plastic, so since you're concerned about fire safety you can simply avoid the kraft-faced and go with an unfaced insulation and plastic (also flammable) barrier alone.

 

[Homoudont]

the best place to post a question about tile, tilesetting, vapor barriers etc is John Bridge forums

The folks over there are about as friendly as you can get and will give you the correct advice.

 

[Busted_Knuckles]

Okay, so what its the "best practice" for building a custom tiled shower, as far as keeping "mold growth" potential on the back side of the wall to a minimum ?

What about using the schlulter membrane on the tile side, and spraying the backside of the durock with closed cell foam, thus providing a vapor barrier and insulation, which kills the whole "dew point" problem ?

 

[Busted_Knuckles]

the best place to post a question about tile, tilesetting, vapor barriers etc is John Bridge forums

The folks over there are about as friendly as you can get and will give you the correct advice.

Thanks for the tip ! Im checking it out as I type...

Edit,... been looking, excellent forum/info place, most excellent !

 

[slip knot]

It's taken me a lot of years to realize that I really need to listen to the professionals. I used to do all my own interior remodels and had varying degrees of success. Over the last few years I've gotten way too busy to do my own work and started contracting some of it out. I argued with them for a while but finnaly realized that they do this every day and they have a reputation to protect. and as Frank stated it aint that much more expensive to do the job right the first time and not have to worry about it later.

As an added benefit my plumber and electrician can tell me they need to correct a problem and I'll tell them to get it done. I can trust them to repair the problem and they can trust that I'll pay them the going rate without squabbling over a few bucks. Life is so much simpler this way.

 

[Homoudont]

Okay, so what its the "best practice" for building a custom tiled shower, as far as keeping "mold growth" potential on the back side of the wall to a minimum ?

What about using the schlulter membrane on the tile side, and spraying the backside of the durock with closed cell foam, thus providing a vapor barrier and insulation, which kills the whole "dew point" problem ?

Just want to let you know that Kerdi or Schulter membrane is EXPENSIVE. And you want to make sure you read read read and follow the directions to a T. You don't want to waste any of it or put it up incorrectly. One of the things I purchased was a low speed drill from Harbor freight to mix the thinset before applying. You don't want any air bubbles in your thinset when your adhering this stuff to sheet rock or durarock.

 

[josall]

+1 Kerdi is your best option.