Tub Surround Hydrology

punkab

You go to a lot of effort to prevent water from entering the wall cavity. If water gets behind the tile (which I'm presuming will happen, otherwise why worry about it in the first place), where then does it go?

I'm roughing in a window in the wall above the tub in a small bathroom remodel. There's some rot in the wall and it makes me curious about waterproofing a tile tub surround. You put a poly sheet or felt over the studs, then backer board over that membrane, then thinset the tile down, grout and seal, and caulk corners. The two questions that come to my mind are: don't nail/screw penetrations from the backer board ruin the membrane? And shouldn't weep holes be left in the caulk where the tile meets the tub? I know it gets pretty wet down there, so maybe skip the weep holes, but then where will the water that gets behind the tiles go? Won't it just ride up the membrane until it gets to a penetration and leak into the wall if you caulk the bottom edge of the membrane to the tub flange? Or leak behind the membrane into the wall if you don't?

Is this hypothesis correct: some water will get behind the tiles. Sealing up the surround to keep the water within the backer board/tile envelope will only permit so much water to exist there. The moisture will eventually evaporate back out of the tile surface from where it first came. Penetrations in the "waterproof" membrane are negligible paths for the water to escape through. Doesn't make sense to me. Seems like if water gets back there, you'll just have a poochy membrane with pockets of water pooling up at the bottom until it finds a way out, probably at a poorly sealed corner or penetration and into the wall cavity.

PunkAB

MattCoops

You're thinking too much into things.

If you follow recommendations in the TCNA handbook and install your products to manufacturers' specifications you won't have any problems.

Just follow the "rules" and you'll be ok.

__________________
Matt with Cupan Custom Tile & Paint of Lowell, Massachusetts
Design and installation of ceramic tile and natural stone for floor, wall, and countertops
(978) 601-8774 | cupantile@gmail.com | view tile pictures and more

Tileworks

Remember, we have gravity on our side, so water is going to run down. A very small amount of moisture may penetrate the sealer and grout, and get behind the tile. Then there is 1/2" of backerboard to find it's way through only to hit plastic. Granted, there are nails in the backerboard and into the studs, but I doubt moisture will every find it's way there. Your tub surround would have to be submerged by a flash flood.

If all this still keeps you lying awake at night, then forego the plastic on the studs behind the backerboard, and coat the surface of the backerboard with Redgard or similar product instead. This way, the tile is adhered to a waterproof surface... even the nails are protected!

- Bob

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Classic Tileworks
http://www.classictileworks.com
Ohio Tile and Stone Installation Contractor in the Akron area serving Summit, Portage, Medina, Stark, & Cuyahoga counties in Northeast Ohio

kevjob

kerdi

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Kevin
Basement Finishing Highlands Ranch Colorado
Littleton Colorado, Basement Remodeling
Kitchen Remodeling Denver

jarvis design

Concrete board with Kerdi!!

PrecisionFloors

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Precision Flooring
(772) 237-9900
Tile, Hardwood, Laminate, and Resilient
Installation, Sales & Repair - "We do it right the FIRST time"

JazMan

YUP, Kerdi. Only way to make it waterproof for me.

Jaz

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Tile 4 You llc
KERDI Shower
specialist...DITRA Installs...
www.tile4you.com

MattCoops

Anybody ever do a Kerdi shower more than 15 years ago?

I know it was first introduced in about 1987. But I never touched the stuff til about a couple years ago.

Just curious to see how long people been using them for.

__________________
Matt with Cupan Custom Tile & Paint of Lowell, Massachusetts
Design and installation of ceramic tile and natural stone for floor, wall, and countertops
(978) 601-8774 | cupantile@gmail.com | view tile pictures and more

jarvis design

I have been using Kerdi for about 4-5 years - used it the first chance I got when I learned about it!! - Used it ever since