# Shower wall moisture barrier?



## RemodelGA (Nov 3, 2010)

Of the two options I would go with felt paper. Roof tar would work to seal it although it is nasty stuff. Talk to a local tile supplier and ask what products they have to seal it.

We always use hardie backer for the tile underlayment and then tape and seal all of our seams. The backer will go over the lip on the edges of the tub but don't set it directly on the tub - keep it up 1/4" or so to create an air gap to prevent water wicking up the backer. If there's not that tall of a lip then you may have to set the backer directly on the tub.


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## ccarlisle (Jul 2, 2008)

Where are you located? 

You ask about a "moisture barrier"; what exactly are you referring to? are you talking about a "vapour barrier" to prevent air movement behind the tiles towards the colder air i/e do you live in a region that needs a vb?

OR

are you talking about waterproofing the walls to prevent shower water from going through the walls?


Two different issues, then answers to which depend...


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## QuickbeamX (Nov 5, 2010)

I suppose I mean waterproofing.


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## ccarlisle (Jul 2, 2008)

Well, I can tell you from first-hand experience that there a whole industry centered on waterproofing a shower - and we're part of it. And you're wise to ask about it because it affects the lifetime of your shower.

Most showers (and most are built _without_ regard to waterproofing the walls) will last about 5 years before mould sets in behind the tiles or the wall itself. On the other hand, showers built with waterproofing concepts accounted for, last 40-50 years...the difference in "costs" is about $1000. Our average bathroom renovation and we go right back to the studs is about $10000, so it works out to about 10% more....

So it's an economic decision - but most homeowners when given that viewpoint usually go with the "waterproofing"...as it adds to the ressale value of the house (in fact, an advertizing feature)! 

Waterproofing a shower means using some form of membrane to prevent water from penetrating beyond the grout lines...OK, accompanied by construction details that are out there for the asking - but that's the gist of it. There are a number of good suppliers of products meant for waterproofing showers and Schluter comes immediately to mind. Noble is another...

But these companies put out products that prevent water from getting into the walls. Nothing to do with vapour barriers which are membranes that control the circulation of warm moist air through your walls to the exterior wall of your home. That's another issue that depends on where exactly you live. 

If you're back to the studs already, you may or may not need a vapour barrier but you should use a waterproofing system once that has been solved...unless you want to do this all over again in about 5 years from now. Your choice.


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## QuickbeamX (Nov 5, 2010)

I would certainly rather do it the right way, with waterproofing.

The impression I get after doing more research is that whether I go with roofing felt or CPE, both should provide a good waterproof seal. The only apparent difference seems to be what kind of adhesive I would use (special tape, or roofing tar) and the ease of installation. Let me know if I am way off here.


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