# Forgot Vapor barrier



## ISUzj (Oct 27, 2010)

So, I feel like a bonehead, threw all of the cement board up in the bathroom last night, but forgot to put a vapor barrier behind it.

Does Redgaurdwork as a good moisture barrier, or do I ahve to go through and tear it all out and put it all back in?

I feel pretty dumb


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## inspectorD (Oct 27, 2010)

This is where it gets a little tricky, red guard works as a good "moisture barrier" for any water that gets behind the tile. But it also works as a "vapor barrier" since it does not let water vapor through. 
However, any larger breaks in the barrier are where you can end up with issues, and only you know what the bathroom walls look like inside.

Bottom line,and to really keep it simple, you should be ok with the redguard, as long as you can imagine where the entire barrier is, and do your best to get it to be continuous....and never double it up.

Hope this helps.


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## DrHicks (Oct 27, 2010)

^ What he said.

I'm not a professional, but if it was me I'd leave it.  Yes, it's possible you'll have problems.  But if you do, and it's 10 years down the road, you may be ready for a change anyway. 

Just a thought...


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## Jaz (Oct 28, 2010)

It's actually a good thing that you're a bone.......ah ah, I mean you forgot. (hehehe)  A surface membrane, whether liquid or sheet is better than the moisture barrier on the studs.   You're using a thin set mortar adhesive that comes in a bag right?

Jaz


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## ISUzj (Oct 29, 2010)

Jaz said:


> It's actually a good thing that you're a bone.......ah ah, I mean you forgot. (hehehe)  A surface membrane, whether liquid or sheet is better than the moisture barrier on the studs.   You're using a thin set mortar adhesive that comes in a bag right?
> 
> Jaz



yeah thats what I plan on, unless there is a better method out there... 

maybe JB weld or two sided duct tape... he he he:banana:


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## Miero (Nov 6, 2010)

I also think you should just leave it as it is and find the right solution for the given situation.


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## Perry525 (Nov 14, 2010)

If there is one room in a home that needs a vapor barrier it is the bathroom.
And this means covering the walls and ceiling.
Here you have the principal generator of water vapor, that will find its way into your walls, cause damp and mold.
A bathroom must always be sealed off from the rest of the home, unless you use it with the window open, or a powerful extractor fan.
Water vapor always makes for the nearest cold surface, if the window is open then out it will go. The outside is nearly always colder and drier than the inside of a home. The times when it is not are during the summer and then it does not matter.


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## gmicken (Nov 14, 2010)

As a Contractor, I find a large number rotten studs and plywood when someone uses a plastic barrier. The hot outside and the a/c inside causes condensation and then the insulation gets wet and has no "R" value. The mold and bugs are next. I am working on a project this week with the same problem. If you can seal the concrete backer, between the tile and backer, you will be okay.  Good Luck.


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## budro (Nov 15, 2010)

you are ok. vapor barriers are a double edge sword. lots and lots of debate. i've seen the good and the bad. i would probably caulk the joints before before putting the redguard on but then again, i'm a plumber who moonlights laying ceramic tile. done it both ways, never had a call back on either. thanks, budro


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## Perry525 (Nov 15, 2010)

Des Moines has three warm months and nine coldish months.
Some people think of it as humid some of the time?

You are correct in that where people have their air conditioning set very cold during the summer, water vapor from outside can and does settle inside the walls, with the potential for wood rot and mold.

It is also true that during the colder months the opposite is the  case and high humidity in the bathroom moves into the walls condensing on the framing and again causing wood rot and mold.

The question are. Is it better to have three months of possible condensation inside the walls during the heat of summer.........if the residents have a truly cold bathroom? (Unlikely?)

Or to have condensation inside the walls for nine months............where the resident like to have a warm bathroom? (More likely?)

Surely it is best to avoid both possibilities by using tightly packed sheets of polystyrene or polyurethane foam sealed inside the walls and ceiling to avoid condensation and mold in the first place?


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## gmicken (Nov 15, 2010)

Perry525, good call, The last three bathroom remodels I did, I had the walls spryed with foam. At $1.55 per sq ft,its well worth the cost. I get all of the walls in the bathroom done, and it cuts down on the noise also. G


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