We're currently having our bathroom remodeled and the contractors have put up durock/cement board everywhere they're going to tile. In the shower pan they put a rubber liner and what I'm assuming is concrete on top of that. But everywhere else they just have the cement board, on the shower walls, the floor, around the tub, etc.
I'm a bit worried because everything I've seen or read says that you have to water proof everything somehow, but it doesn't seem as if they are going to (they're about to start tiling). A former contractor friend I talked to yesterday claims he never used to water proof beyond the shower pan basically.
So, will the durock/cement board + thinset and tile on walls and floor be enough? Or should I insist on them doing more to water proof it before tiling?
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The cement board instructions are for a wet area. Since there is no need to waterproof behind a toilet you should not be worrying about this.
I would buy cement board tape and stick it across cover both boards. As you trowel the mortar for your tiles feel free to push as much into the mesh that it can hold. That is your install.
If you try to set your seams first and you let them dry inevitably you will have a ridge. That ridge can cause a lot of depth issues when applying mortar to the wall and tile (backbuttering). I advise not cover your seams in non-wet areas and apply the mortar in one go.
As you might imagine, there are various levels of latex additives and you can control the mixture yourself if you use latex additive instead of water. Most thinsets on the market today are "modified" or "fortified" and these terms are fairly interchangeable; unmodified thinsets are marked as such ("unmodified" means its bonding agent is just portland cement, which does a fine job by itself).
If you look on HD website for that product, it includes a link to the SDS (safety data sheet, listing what concerns there are with chemicals used) that lists "vinyl acetate - ethylene copolymer" as 1-5% of the total mixture.
Practically speaking, thinset is thinset and just about anything will do the job of filling in joints between cement boards. There's a fiber mesh tape to help bridge the gaps. Most professionals mix their own thinset instead of buying the already-sludge stuff, because this gives them the ability to add additives or customize the water ratio a little to achieve the desired consistency, and they'll typically bulk-buy and use the same thinset for multiple jobs, mixing just what they need to exactly how experience tells them works the best.
I'm seeing a ton of waterproofing posts here lately leading people to believe they're going to have to tear out entire bathrooms because redguard wasn't applied. We need to set the record straight here and I'm sure a lot of you aren't going to like it.
Is waterproofing a good idea? YES, ABSOLUTELY. Water damage is a nightmare to deal with and you as the customer are better off having it and you as the contractor are better off talking the customer into upgrading to it if it's not required by code.
Is waterproofing necessary? NO/MAYBE, CHECK YOUR CODE AND MANUFACTURER RECOMMENDATIONS FOR YOUR MATERIALS. A full Durock shower encloser, using proper hardware, tape, joint sealer, a correctly installed pan, modified thinset and ceramic tile will result in a shower that has no moisture issues.
How do I know this? I've helped install these showers for decades in Florida and have never once had an issue (we keep in touch with our clients and have even redone the same bathrooms years later because they wanted upgrades). We have also used Schluter systems and redguard and advocated for that. But if the client doesn't want to spend the money, not using a waterproofing barrier is perfectly acceptable based on code and will not cause any harm. I've torn out showers from the 1980s that had none of the materials we use today and found little to no moisture problems.
So let's cut down on the panic when homeowners post here and try to give them the facts. Otherwise we are leading them to spend way more money than necessary and are creating a nightmare of a client do deal with for good contractors*.
*Most of the stuff posted here is not done by good contractors and waterproofing is the least of your worries.
Edit: I figured I'd get down voted but I'm literally quoting code for my area and manufacturer instructions for the product I mentioned.
I'm not talking about drywall, greenboard, purple board or any other gypsum based product which require a barrier.
Hi everyone,
I am a first time home owner and are remodeling my shower room.
My contractor promised he will use cement board for shower wall waterproofing. Now I realize he is using USG fiberock. My understanding is that this is not a cement board (Durock is the cement board and I want to use that). I argue this with him and he yelled back to me saying this is cement board and I am not respecting his expertise.
Am I wrong here?