I applaud you for being proactive rather than waiting until something goes wrong and you are back on this forum asking for help after a bathroom disaster.

I'm just a homeowner, not a pro. There are a lot of pros on here who can help you if you will post the language of the bids.

I was in your position about 18 months ago, gathering bids and getting ready to remodel a master bathroom. I didn't know exactly what a "moisture sandwich" was, but I had heard of it and knew it was bad. So every contractor I met with I said "whatever you do, you need to properly waterproof my shower and not create a moisture sandwich." What I should have said is "put into the contract that all materials and work will adhere to the TCNA and industry standards, and manufacture's instructions." (or some such proper contractual language like that).

What I ended up with was a contractor who "waterproofed-the-hell-out-of-it" meaning that they installed a double vapor barrier (poly behind and red guard on top). That's a moisture sandwich - 2 vapor barriers. They actually wrote the moisure sandwich into the contract and I didn't realize it.

Long story short, they did a bunch of other stuff wrong (no pre-slope; holes in the pan; spot-setting the tile which is dangerous, etc.). When we asked questions, they quit the job rather than answer questions or finish the job, and we had to get another contractor to re-demo and re-build everything. I read the entire 2016 TCNA handbook. It's a good education just to read that manual.

You are doing the right thing to reach out ahead of time, so that you don't end up like me. In the end we got everything worked out and we have a very nice, waterproofed bathroom, but I wish I had been more proactive like you are doing now.

There are training/certificate organizations for tile pros. I think NTCA and others. Maybe a pro on here can weigh in on those so that you can find someone certified in your area.

You are already more on top of it than I was. Good luck on your project!

- SS

Thanks ssdarb and Mr. Memes! For both showers, one of the shower walls is an exterior wall, so what should be use between studs and cement board? And for the interior shower walls, is cement board over stud and RG over cement board acceptable?

Would a real pro weigh in here please? This homeowner is doing the right thing by asking ahead of time. Most OP's post after a disaster.

The homeowner should educate themselves so they know what questions to ask and what to look out for (which OP is doing), but a homwowner should not tell the contractor what products or methods to use. That's just asking for trouble.

If you’re considering solid surface shower walls rather than tile, read the installation instructions. You’ll probably find that waterproofing is not needed. I’m planning to use Kohler Choreograph walls and they get installed directly on cement board. I also plan to use a cast iron or acrylic shower base and neither require separate waterproofing.

This will provide you with the questions to ask. https://www.ceramictilefoundation.org/homeowners-guide-to-hiring-qualified-tile-installer

You want your contract to state all tile work to be in accordance with TCNA, ANSI standards and manufacturers instructions.

Thank you everyone for all the good comments. I don't know what material facing I have for the exterior wall, I guess I will know when they gut the bathrooms! But don't do moisture barriers on both sides, got that! I will also wait for the contractors to tell me their methods but at least I know when I should be concerned about if I hear certain things from them!

@beaniebakes The shower walls will be solid surface, but the shower floor will be tiled, with big tiles to minimize grout lines.

@Creative Tile Eastern CT Thanks for the link, I will study that! The first contractor will be coming this Saturday, trying to schedule another one. And I want to get at least 3 quotes, if not more, to compare.

This is great - I'm following because I will soon be in the same position. @yeh_yeh, have you selected the quartz slab maker/color for your shower walls? I have been looking at porcelain slab and quartz slab for this.

Also - I have learned here that sometimes "solid surface"is a specific term that refers to a specific material (Corian maybe?), so sometimes when people say it they don't just mean "one big slab instead of tiles all over the wall."

don't any tile setters do 'old school' mud anymore? My guys did it in my shower. (that back wall is exterior)

this is all they used to do in the old days and those tiled showers held up for 70+ years. A good mud guy can do those walls in the same amount of time it takes to hang CBU and waterproof it. Plus, w/the mud, they can screed it so that it's perfectly plumb/level, unlike your CBU on your studs.

You'll find that in Calif most of the guys use hot tar for the shower floor. (at least down here in So Cal they do)

When things go wrong, people always ask to see in-progress photos so be sure to take photos of every step.

One contractor came and he said he do the following for waterproofing:

1. Vapor barrier

2. Hardie Backer

3. Kefir Schluther cloth

4. "Dragon skin"? (I think that's what he said"

Do these add up as "mold sandwich"? It just sound like a lot of layers.

Another one said he does:

1. membrane

2. concrete board

I am trying to call a couple more contractors but that's what I got today. Do they sound right?

Thanks!

Siena/Omega Products

Siena Dragon Skin is a liquid-applied, fast-drying, high-performance, easy-to-use water-proofing and crack-isolation membrane, formulated to produce a high-quality elastomeric barrier. It is easily applied using a trowel, roller, paintbrush or sprayer. It changes color from light purple when wet, to a dark purple when dry. Dragon Skin is IAPMO Certified and complies with the requirements of ANSI A118.10 and ANSI A118.12. www.siena.omega-products.com

the first guy w/all the layers is way too much. Click on the Sienna link and read what it says about using it's product. it will prob tell you no barrier behind the cement board.

here's the Schluter Kerdi system. you don't need any of those other things if using this.

If using Hardie or Durock cement board, it's either a vapor barrier between it and the studs, OR a waterproof membrane (like Redgard) on top of the cement board. You don't do both or else you will make a mold sandwich.

I've done many with vapor barrier behind the CBU, proper taping and mortar and no membrane painted on the board. It's perfectly fine.

And don't use large tiles for the shower floor. 2" is preferable. Remember, you're tiling a "bowl" and can't do that with big tiles. 4" is absolute maximum unless you are using a linear drain with one slope...

" Remember, you're tiling a "bowl" and can't do that with big tiles. 4" is absolute maximum unless you are using a linear drain with one slope..."

Correction:

Outdated innacurate advice. very common to use large tiles and envelope cuts today. round, square and linear drains too.

OK....you CAN use larger tiles, but it frequently requires that you cut them up into triangles and such....not something the average homeowner/DIY'ers are comfortable doing. A pro can certainly do this, but my advice remains.

I'm just a homeowner, not a pro. But my tile pro is here right now building one new shower and re-tiling floors and shower/tub combos in 2 others. He doesn't use the cement boards. If you look up the Laticrete Hydroban Board instructions he does that, 100%. You can look at their videos and read the manufacturer's instructions online. There are area reps that you can contact if you have questions. You can also buy a download of the TCNA handbook for about $40 and read the shower sections of that. Very helpful to prepare you to know what questions to ask and what to look out for. There are other companies such as Schluter, Wedi, etc. Laticrete is just what my pro chooses to use. Contractors have their own preferred products and methods based on their experience, availablility, etc. It's good if they go to training sessions, seminars. conferences, etc as my pro does. That's always a good sign.

NOT stating that it's "bad advice." Just that it may not be a technique that many HO's are able to do....and I've been doing this for over 40 years....

I'm not a pro or anything approaching one (just someone about to have two bathrooms remodeled), but I thought smaller tiles were preferable because it will provide a less slippery shower floor.

You are correct, Patti.

Thanks all for the advise! It never cross my mind to do any of these by ourselves, we are hiring a pro. I might be a pro at something else (maybe at spending money =p) but definitely not DIY Remodeling!!

If I was getting a tiled shower done today I’d use one of the waterproof foam backer board wall and floor systems from Schluter, Laticrete etc. or I’d use solid surfacing for the walls and a pre formed shower receptor.. Make sure you follow local code and the manufacturers instructions and that your contractor is experience with the shower system. Don’t mix and match products or systems.