Thank you very much, ABC, that is what I have been very worried. Since we are not professionals we don’t know this but from my research I see that he is on the wrong track. Can he slope the first layer of cement and then add the waterproofing? What is your preferred waterproofing? Thank you so much!

Thank you. The GC’s plumber confirmed that the pan has to be sloped.

You may want to reference industry standard build methods in your conversation with the contractor. A copy of the TCNA Handbook on the table will be helpful for that, as it is the industry standards in writing. It is difficult to navigate though, even for pros. But just it’s presence lends some weight in a conversation.

https://www.tcnatile.com/products-and-services/publications/218-english-publications/188-handbook/983-2022-tcna-handbook-for-ceramic-glass-and-stone-tile-installation.html

Thanks Linda, a very good suggestion!!

Ignorant here of your local code, but waterproof is waterproof- as long as it is waterproof as well as properly sloped to drain. Sounds like you totally get it.

The pan you are talking about with integrated slope/drain flange sounds like a Kerdi/Wedi type system. Wedi stands out as a little different and I LOVE using it for its ease and sealant and especially how flat a plane it makes- great for tilling, it isn't inexpensive though. Wedi is a cement coated rigid foam board that's glued at overlapping seams with their sealant, no chance of leaks because you'd see it. That kind of pan goes right on top of the subfloor. Additional sloped panels can be easily added- and it's watertight enough for steam rooms. Kerdi and similar use a similar pan, but waterproof fabric over your walls/pan/wet area. Unless it's a very unusual space or design, I consider hand making a pan a thing of a bygone era. I believe Wedi was 1st to this shower pan type, used in Europe, then Schluter (kerdi), Laticrete, etc came after.

Perhaps I misunderstood, but if the contractor is using a PVC pan as a building base to build concrete slope on, you better cut him his last check.

Build your slope/ shapes, then waterproof, then tile.

Thank you so much Perfect Edge F! This is challenging as we are not experts and have lost faith. Are you saying the first layer of cement should be slopped, then put the waterproofing and then tile on the waterproofing? The GC is planning to put first cement flat, then the waterproofing (PVC shower pan liner from Home Depot or leadpan - now he knows it has to be slopped - not sure how you can slope a PVC pan, though?) with at least 6" going up on each wall and then concrete on top, then a layer of laticrete water proofing. Then the tiles. Also, I understand from your note that the Kerdi/Wedi system is excellent. How durable/reliable is the PVC shower pan liner? Or the lead pan? I just came across this post - do you agree with this comparison of PVC liner versus Kerdi/Wedi system? https://www.johnbridge.com/vbulletin/showthread.php?t=9251 Thank you so much. We don't want them to have it redo it twice.

Perfect Edge F, I forgot to add that our wetroom is 47 wide and about 64 long.

That forum is the best place to educate yourself- even 20yrs later, what I read looks relevant today. Sounds like the full-time tile pros there prefer kerdi or wedi to making decks/pans over pvc pans. It's surely only improved since then. Funny though, even the forum namesake pro himself said basically what I did- "You can look at it and tell it's not going to leak"

I have to admit, I know NOTHING about compatibility of PVC/concrete for shower pans (but since I literally work in all aspects of remodeling, I do know that PVC is one of the most difficult plastics to get anything to bond to. Most paint primers, for example, won't even stick) or how durable long term- to me that's an old-school way of doing it, a tile-only person may know more... I have never seen a lead pan, other than very old vintage- my ignorance of either doesn't negate their legitimacy however.

I don't like the sound of concrete + paint on membrane only. A proper hand sloped pan has a sand/mortar bed and a bunch of steps. You can't just make some hills and paint it. I don't see the point in building a shower with techniques that have hardly changed in millennia, when there are so many smartly engineered modern options. You can get a tile ready pan for like $500, and as long as installer doesn't screw up the drain, it won't leak or damage tile/grout. I'm curious why the need to make a pan. An odd drain location could make a manufactured pan impossible though.

As I mentioned, Wedi is pricey, maybe about $2000+ for that size walls/pan/drain/etc., check Wedi Fundo prices- that is the whole kit name I think. You can save $ by not running the panels to the ceiling and do the top half of the walls with a cheaper panel. But, for me, it is SO much less labor than hand sloping anything, and also faster/ less steps than Kerdi. I don't do tile all day everyday, but I am proficient- and a perfectionist and just knowing the planes are flat, surfaces are watertight out of the box, and there is no question about wall joints being sealed that I find the saved labor/ vs initial cost to be more or less a wash. Let me put it this way: a custom deck done by a master is probably done quickly and will be perfectly watertight forever. However, 10 custom pans/10 people who built them could have varying outcomes. Is this contractor the master, or one of the other 9? The other side of that equation is... 10 different inexperienced minions with caulking guns could glue together 10 Wedi showers and they would all be the same.

Your local professional tile supplier may have a demo shower for their pan system they sell, seeing the work that usually hides under the tile in person will illustrate perfectly how professional and waterproof one of these systems is.

Perhaps The contractor is using a system he is familiar with and confident in, or perhaps is just stubborn and unwilling to try "new" stuff. We all have our ways of doing things, and as in most things construction- there is more than one right way to get the same result, the cost is related more to how it works with our own businesses.

Thanks a lot. FYI, the apt is in prewar building with steel, brick and concrete. The GC said that the wetroom floor, after the plumbing, is getting a layer of concrete, then the PVC waterproof liner, then another layer of concrete, a layer of Laticrete waterproofing membrane (applied in liquid form) and then set the tiles. So if I understand it correctly, there will be two layers of waterproofing - the PVC liner and the Laticrete waterproofing. Does that make sense to you? And if I understand it correctly, they need to handmade the slope with the first layer of concrete, so that the PVC pan is also sloped and then the follow the slope with the second layer of concrete. The GC is not familiar with the Kerdi or Weti system. Our drain in the wetroom is in a very specific location - not in the middle and the room not a standard shower size- so unless the Kerdi or Weti can be adjusted it would not work. Thank you so much!

Thank you Millworkman. That is correct. Why is it a problem to have two layers of waterproofing? They are not on top of each other. Would it not improve it? Thanks!

OP, there are a *lot* of details that go into a project like this, and it sounds like we're already starting off on the wrong foot. Are you sure you want to be teaching your contractor how to do this?

There's really no good way to achieve an entire wet room assembly with a PVC liner system. Where I see contractors adding topical waterproofing overtop of their membrane system, it means they really don't understand how these systems work. Maybe they don't trust their products and hope that adding extra layers/complexity will somehow improve things. Especially in a high-rise scenario, you want to find the best tile setter you can.

The essential reason as to why you don't want multiple waterproofing systems is that it creates a "mold sandwich." In an older, traditional shower, there is a primary mud bed put on the floor. On top of that, there is a rubber liner that attaches up about 10" up the walls. On top of that, there is ANOTHER mud be to which the tile is adhered to. The idea here is that water will transmit through the grout to the membrane and travel down to the "weep holes" and out, It works well as long as the weep holes are open.

In a system such as Schluter's "Kerdi," there is only ONE mud bed that is properly sloped to their proprietary flange and drain. In this case, the water going thru the grout hits their membrane and never wets the mud...and it dries out quite a bit faster. I like (and use) this system as it is bulletproof and give it a lifetime warranty. What is "lifetime?" I tell my clients...It's until you die or I die........LOL

Why not just take out the tub and build a shower where the tub is in the main bathroom? A wet room is a poor idea for multiple reasons including the floor being slick when wet, and then having to wipe down all the fixtures in the room.

Perfect Edge F, I forgot to add that our wetroom is 47 wide and about 64 long.

Your half bath isn't even large enough to do what you are hoping the room will eventually do for you. If you have a walker, it will be difficult as your bathroom isn't even 4' wide. It will not work for you as you age.

May I suggest you post the floor plan as to what you think you want to do.

Thank you Stonetech! Does the Kerdi come in all sizes/can it be customized? Cpartist, thanks for your comments. My husband really wants a tub in the master
bathroom, so that is not an option. The wetroom/shower in the half bath is a back-up option.

Kerdi comes in 1 meter wide rolls of varying length lengths. Some tile stores will custom cut to the length you want if you need an odd size.

Thank you Stonetech!

My husband really wants a tub in the master

How often does that tub get used?

The wetroom/shower in the half bath is a back-up option.

It's a backup option that is unworkable. Especially if someone is on crutches or using a walker.

And nevermind the fact that anyone looking to buy the place when you sell will consider it a remuddle.

The tub is not negotiable for my husband and I am fine with it. We both like baths. We think the shower in the HB will work.