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  1. #1
    Join Date
    Jan 2011
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    Default Does the vapor barrier extend over the shower pan liner?

    There are so many conflicting reports I have heard when building a custom shower pan. I am stuck on where to start. The guy at Lowes told me vapor barrier, cement board, then build the shower pan, mud, liner, mud, etc.

    However, I understood the vapor barrier had to extend past the shower pan liner. In that case, I would have to install the shower pan FIRST, then vapor barrier then cement board on the walls. I am using the standard 6 mil plastic, not kerdi or redguard or any of that.

    Can anyone care to comment?

  2. #2
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    Default Re: Does the vapor barrier extend over the shower pan liner?

    Quote Originally Posted by Ehren View Post
    There are so many conflicting reports I have heard when building a custom shower pan. I am stuck on where to start. The guy at Lowes told me vapor barrier, cement board, then build the shower pan, mud, liner, mud, etc.

    However, I understood the vapor barrier had to extend past the shower pan liner. In that case, I would have to install the shower pan FIRST, then vapor barrier then cement board on the walls. I am using the standard 6 mil plastic, not kerdi or redguard or any of that.

    Can anyone care to comment?
    From what you describe it sounds as though the space is at bare studs.

    The order of -- vapour barrier first , cement board , etc. would be correct.
    The vapour barrier ( the 6 mil ) would run from ceiling to floor. In other words --- the vapour barrier first applied to the walls all the way to the floor would extend it past the pan liner.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Jan 2011
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    93

    Default Re: Does the vapor barrier extend over the shower pan liner?

    You can skip the plastic and use a membrane over the backboard.

    Look into Schlulter or Nobel Company products, or you can use a liquid applied membrane. Either way, much better than plastic behind backerboard and will ensure a waterproof surround if done properly.

    Hands down the best way to go.

  4. #4
    Join Date
    Mar 2008
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    nova scotia, canada
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    Default Re: Does the vapor barrier extend over the shower pan liner?

    vapor barrier goes under the backerboard..to prevent warm moisture laden air from escaping into the exterior wall framing assembly... nothing to do with the membrane
    fire up the saw and make some dust

  5. #5
    Join Date
    Jan 2011
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    32

    Default Re: Does the vapor barrier extend over the shower pan liner?

    Im confused.

    Canuk; if you think about it, if the vapor barrier caught vapor as it condensed, it would run down the sheet, BEHIND the shower pan liner. That is why I am doubting this installation. If you installed the shower pan liner first, any condensing would run down the vapor barrier and drop on the shower side of the pan liner.

    LIHR and jkirk -- I have gone back and forth and have settled on the 6 mil plastic since I did it in the last room. Is one way better than the other? The Schulter Kerdi membrane system looked cool -- and expensive. As I see it, there are two ways to waterproof a shower, from in front of the wall and behind the wall; why does in front of the wall seem like a better option? Can anyone convince me either way?

    Thanks everyone!

    Jkirk - what do you mean by that? I thought a waterproofing membrane replaced a vapor barrier; one goes in front of the wall and the other behind the wall.

  6. #6
    Join Date
    Dec 2010
    Location
    Houston Texas
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    2,919

    Default Re: Does the vapor barrier extend over the shower pan liner?

    There are two ways to build a modern shower; "the traditional method" such as you describe where the studs are covered in 6 mil poly which extends down and overlaps the liner so that any water that makes it to the liner is directed down into the liner. In this style of waterproofing there must be a 'pre-slope' of ceement below the liner. There are a few other important points with this method; benches, niches and curved surfaces need special attention which are challenging unless you opt for the alternative method which is;

    Surface waterproofing such as the membranes listed (noble, schluter's kerdi, hydroban, hydro barrier, aqua defense) In this system, there is no sheet plastic over the studs nor liner on the floor. The backerboards are hung on the studs, a ceement floor is sloped to the drain, and the surface waterproofing is applied to the entire surface including the bench, niche, all the way up tot he shower head at least.

    For very complete information, an extensive library (liberry) and speedy professional answers, head on over to the John Bridge Tile Forum and start a new thread on your project.

  7. #7
    Join Date
    Jan 2011
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    32

    Default Re: Does the vapor barrier extend over the shower pan liner?

    Thanks, so the traditional method; I would build the pan first then the walls so I can run the vapor barrier OVER the liner?

    Is one way better that the other. I know in waterproofing a boat, you would of course waterproof its exterior so you wouldnt have to worry about the interior. The same with a shower? Would you suggest the exterior membrane like LIHR?

  8. #8
    Join Date
    Dec 2010
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    Houston Texas
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    Default Re: Does the vapor barrier extend over the shower pan liner?

    so the traditional method; I would build the pan first then the walls so I can run the vapor barrier OVER the liner?
    YES

    Its been 15 years since we built a 'traditional' shower. Once we found Kerdi, we never went back. Surface waterproofing is a superior method IMHO and much more DIY friendly

  9. #9
    Join Date
    Mar 2008
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    nova scotia, canada
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    Default Re: Does the vapor barrier extend over the shower pan liner?

    water proofing membranes and vapor barrier are two entirely different things.. teh purpose of vapor barrier is to stop warm moisture laden air from escaping the building envelope into the exterior framing where it condenses and can create mold and rot.. this is installed on every exterior wall and the ceiling of the top floor of a house it has to be continous

    kerdi is strictly for showers, it keeps the water inside the shower where it belongs and directs it to the drain. you cannot connect kerdi to a vapor barrier in any way as one is in front of the wallboard hopefully your using denseshield, and the vapor barrier goes dirctly under it.. if this is to be inspected.. the inspector will be looking for vapor barrier before your board even starts to get hung
    fire up the saw and make some dust

  10. #10
    Join Date
    Jan 2012
    Posts
    8

    Default Re: Does the vapor barrier extend over the shower pan liner?

    Ive done it with roofing felt.....first the liner then the felt.......then cement board......remember to lap everything so the water runs in to pan liner......then we pack the shower pan using sand mixed with portland(topping mix)

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