Membrane under bath?

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Old 03-14-20, 06:08 PM
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Membrane under bath?

Is it necessary to put membrane under a bath?
 
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Old 03-14-20, 06:15 PM
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A bath TUB? No. Membranes go under tile showers where the drain is in the subfloor. The drain in a tub is in the tub itself.
 
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Old 03-14-20, 06:48 PM
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What about if you have a tiled side of the bath? Membrane under that tile? Might get a bit wet but not much
Also, if it's a shower bath then you membrane the walls?
 
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Old 03-14-20, 07:16 PM
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There are various schools of thought and different products you can use. Our resident pro, Czizzi hasn't been around much to take these kinds of questions. YouTube can be a good source of info.

Old school way from the 60s, 70s, 80s was poly on the walls and over the tub edge then water resistant drywall... which was never very good since rubs hardly have any flange. That didnt last and encouraged mold.

Others swear by no poly and cement board so that the back of the cement board can dry out

Then others apply Redgard or other waterproofing over the cement board. Other waterproofing can include Ditra... or Kerdiboard is used instead of cement board.

With so many options, it's hard to answer your question. Personally I would not use a membrane behind wall tile, I prefer Redgard on the cement board. Go to youtube and type in redguard bath walls.
 
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Old 03-15-20, 07:00 AM
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Used to be that green board was used in tub area, that is pretty much dismissed today, lots of options but IMO, your there, it can get wet, cost to do it right is minimal, do something to the walls!

Let the old out of date tile be the future reason why the bathroom needs to be redone, not because there is water damage!
 
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Old 03-15-20, 08:26 AM
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I agree there are lots of options, but my two preferences for the tub surround are:

1) Cement board with a Kerdi membrane (roll) on top as waterproofing. Then tile on top of that.
2) Kerdi Board. This is a foam board that's easy to work with and acts as both the backing and waterproofing membrane. It's more expensive, but a nice easy system to use.

I'm not really sure which I like better yet. They both have pros and cons during install, but both provide a really great base for tile.

I've used RedGuard, but found it to be messy. I'm sure it's a good solution as well, but isn't a favorite.
 
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Old 03-15-20, 09:01 AM
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My bathroom done 19 years ago only has a membrane in the floor of the shower and 6" up the side walls. The remainder of the shower walls have tile on cement backer board where the joints and screws were sealed with thinset. The rest of my bathroom the floor tiles are set on Hardie Backer while the wall tiles are on plain, gray sheetrock. If I had it to do over I would do things differently but the old school method in my bathroom now has held up very well.
 
 

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