# Tub Surround...where does the moisture go?



## r4r&r (Feb 22, 2012)

This rings of the futile "pursuit of perfection" to me. 
Trust me when I say I am right there with you guys as I have a full bath reno in the very near future and it has been a long time since I have done a full shower from the ground up, so be expecting many posts from me on the subject. 
As a result I have been reading every shower related post that has popped up and researching my a$$ of and racking my brain on haw to tighten both the shower and the jacuzzi tub against water, because I fully expect to have to redo a lot of structure because of a failed shower. 
As much as playing devil's advocate here I am also of the opinion that sometimes we cause ourselves a lot of problems with our own technology.


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## bluebird5 (Dec 13, 2010)

Inner10 said:


> Jarvis, I did that but again what happens to any moisture that penetrates the tile? Lets say you had a few pinholes in your grout...the water would collect behind the tiles and would drain down to the bead of silicone and rest there.


Inner you are right. I never have though of this. I think you have proven in counter active to waterproof cbu. If any water did happen to penetrate the grout, it would be better for the cbu to absorb it because it would eventually dry out rather than run down the waterproofer and all be trapped at the bottom of the tub


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## jarvis design (May 6, 2008)

Inner10 said:


> Jarvis, I did that but again what happens to any moisture that penetrates the tile? Lets say you had a few pinholes in your grout...the water would collect behind the tiles and would drain down to the bead of silicone and rest there.


You would need a lot more than a few pinholes to allow that much water in to drain down. If you have lots of pin holes in your grout, well, change grouts or figure out why you are getting so many!


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## Inner10 (Mar 12, 2009)

jarvis design said:


> You would need a lot more than a few pinholes to allow that much water in to drain down. If you have lots of pin holes in your grout, well, change grouts or figure out why you are getting so many!


Alright maybe my example was a little far fetched...but my point was making a completely water tight backer, making a water tight tile layer and sealing the bottom seems counter productive...in general sh!t works better when it can breathe. 

I think if I were ever to do another tub-shower before I die I would just skip all the red-guarding I did and use concrete board.


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## angus242 (Oct 20, 2007)

bluebird5 said:


> Inner you are right. I never have though of this. I think you have proven in counter active to waterproof cbu. If any water did happen to penetrate the grout, it would be better for the cbu to absorb it because it would eventually dry out rather than run down the waterproofer and all be trapped at the bottom of the tub


There's a big difference between "water" and "moisture". If you have water behind the tile installation, you have big problems. However, if talking about vapor, that's when materials make all the difference. Both epoxy and urethane grout have the same absorption properties as porcelain tile. How much vapor do you think is getting behind the tile?

Using standard grout (which a majority will), would you rather have moisture penetrating the wall cavity or settling on the tub flange? If it's such a concern, as long as the CBU to tub flange is properly sealed (and the CBU waterproofed) you can leave a few weep holes on the tub to tile gap.


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## bluebird5 (Dec 13, 2010)

Angus do you just waterproof your screw holes or do you do the whole board in a tub shower combo?


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## jarvis design (May 6, 2008)

Inner10 said:


> Alright maybe my example was a little far fetched...but my point was making a completely water tight backer, making a water tight tile layer and sealing the bottom seems counter productive...in general sh!t works better when it can breathe.
> 
> I think if I were ever to do another tub-shower before I die I would just skip all the red-guarding I did and use concrete board.


I think if you use concrete board, set your tile with thinset, and (again!) use epoxy or urethane grout, you still have a solid installation. I waterproof as added insurance and the fact the majority of my jobs include a recessed soap/shampoo niche, which needs waterproofed for sure


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