I would look askance at anyone that rejected the TCNA handbook.

He is semi-correct, in that boatloads of water do not pour through tile and grout and saturate whatever is behind them every time you shower. But some moisture can and does seep through. If the cement board gets wet, it dries out and doesn't mold, but if it gets through to the studs it's attached to, they can mold and rot.

What you want to avoid is a moisture sandwich. You need a single waterproof barrier. It can be a sheet of plastic stapled to the studs behind the Durock. Or a coat of Redguard over top of the Durock. You DO NOT want both plastic and Redguard because moisture will condense in between them, get trapped and have no way to get out. But a waterproofing barrier on either side of the cement board does not trap anything.

While the TCNA now requires a waterproof membrane to be applied over Durock, it wasn't the case for many years. So I can sympathize with some of the old timers who followed a certain process for years with no issues. I work with numerous contractors and only a few started using Redguard within the past few years. I've never gotten a call about a waterproofing failure and some of the tile installations I designed are over 15 years old (tile on Durock).

Having said that, you won't know there is a problem with the waterproofing until it fails. So if your installer follows the TCNA guidelines, at least you can be assured he's adhering to current protocol and systems.

Ha!!! That's hilarious!

When hunting for a tile pro I heard all kinds of excuses used to soft-bully me into not getting a competently built shower. Such as:

“I have a great handyman who does our tile. He’s never had a call back.”

“It’s important that the drywall is really flat. Then you put thinset and the tile on that. The grout is the thing that makes it waterproof.”

“You don’t really need anything because you have central AC; that’s basically like waterproofing because it keeps your house dry.”

“A sloped floor is nice but not really needed.”

Read this:

https://www.gardenweb.com/discussions/5725013/what-to-do-when-a-project-goes-completely-south#n=66

If you read that you might be able to avoid a huge problem this lame fake-pro is trying to sell you!

Hunt for a real tile pro:

https://www.ceramictilefoundation.org/

https://www.tile-assn.com/

Keep looking. You have not found your tile pro yet.

You said this is your builder, so you might be in a situation where you already have a contract, and you don't have control over who the builder hires to do the waterproofing and tile installation. That is the rub. I have never ever been able to figure out a way to get GC's to hire competent pros. The only times things have gone right at my house is when I've been able to hire the real pros. I had 2 big project with issues, and those were the only ones with GC. I guess it's the same deal with builders. They hire cheap, unqualified subs to boost their margin at the expense of the homeowner who ends up with crappy work.

Go to a shop that sells ONLY tile (no pallets of tile, no tools, no grout) and ask them for the names of their "preferred guys". Expect to wait 6-8 weeks for the install...and expect the labor cost to be substantially higher than your current guy is charging.

This is her builder, not a tile contractor. New construction?

If a proper barrier is installed behind the cement board and overlaps the presloped pan liner which extends up the walls 3" above the finished curb then that would be an approved method. If no barrier is behind the board in this manner then your builder has been doing things wrong for 40 years. Ask how the curb is to be detailed. If he says cement board goes on it then you have a problem. For the moment lets assume he is doing things properly. Post pictures and details. You can simply insist work to be done according to TCNA details. The handbook is composed of approved methods not recommendations.

If you can't run the shower without tile then it is not constructed properly. Simple.

weedyacres, Thank you. That makes sense to me. I wonder if there is any truth to his claim that tile doesn't adhere well to Redguard?

The Cook's Kitchen. Thank you. I'll lose a lot of money if I fire him now. Of course I'll lose more money in the future if he does it wrong. This reno has been a huge money pit. I chose the wrong contractor.

Have you had other issues with this contractor/builder? What's the scope of the project?

Is this a remodel or a new build of an entire house?

Rachel, my tile is sticking just fine to the Redguard. Next up is watching him use a spot setting technique and listening to that wrong explaination.

He used some classic lines on you

That makes sense to me. I wonder if there is any truth to his claim that tile doesn't adhere well to Redguard?

My tile setter in my old condo used Redguard on the shower walls. That was 10 years ago and the tile is still sticking fine. I know that because the condo just sold.

He is semi-correct, but has given you the incorrect reasons. If you use cement board, you either put a vapor barrier behind it (between the studs/cement board)

OR you apply a waterproof membrane to the cement board and have NO vapor barrier. If you use both, you're creating a possible mold sandwich. So technically you can use cement board and no waterproofing membrane like Redgard if you have the vapor barrier behind it. I've had showers in my house done like that (before Redgard was a thing) and they held up just fine.

As for the tiles not sticking to the redgard, that's just bull. He obviously doesn't want to go through the expense or the hassle and is trying to sway you. But as long as he does the barrier, it should be fine. Even by TCNA standards.

Sal DiBlasi gives you every step of the way https://youtu.be/rsubb1HuLks

Kristin Petro Interiors, Inc.Hi Kristin. Thank you!! We're renovating most of the house. Which is why I feel trapped in the contract. They are almost finished, except for this bathroom. We haven't paid much for the bathroom yet. We paid for Ditra heat mats and related labor. They haven't been installed yet. We've had a few other issues, mostly cosmetic. Most of the problems relate to the bathroom: a questionable subfloor under the whole bathroom, and no slope in the shower preslope. And I already purchased marble for the shower floor and walls. I wish that I hadn't now, since it makes it even more important to install everything correctly.

Is he using a qualified tile professional or is he doing the work himself? If the latter, maybe negotiate with him to bring in a 3rd party tile professional for the shower.

Yes you need pro help and that guy is not it.

I can assure you that cement board has to be waterproofed. We just ripped out a decade old shower (mainly for layout issues, small master that was half Jacuzzi tub...) The shower had a rubber pan liner with cement board walls. The walls had no waterproofing either topically on the cement board or plastic behind. The framing was fine for the area covered by the pan liner and above that was furry- black with mold where water was migrating through the cement board to the wall cavity. Not pretty.

I have a whole Idea Book that has pics of improperly waterproofed showers that are being torn out and replaced. What the pics don’t have is Smell-O-Vision. The smell of a swamp and dead creatures in it rotting.

https://www.houzz.com/ideabooks/120393851/list/bad-wet-areas-and-mold

See if he’s open to hiring a CTI for the bath job. It may cost you more. That’s less than it will cost a year later. https://www.ceramictilefoundation.org/find-certified-tile-installers

Thank you everyone for trying to help. Much appreciated.

The Cook's Kitchen My GC won't hire anyone else. I asked him. Since I won't let him move forward, he may let me give up this part of the job. I'd take a financial hit, and need a good replacement. It's hard because the contract was for the whole house, so costs are difficult to separate. I'd definitely lose money. A designer gave me 2 reputable installers, but they're too busy to be interested, and aren't calling me back. I would love to get a rough estimate from a good installer, so I know what I'm looking at.

Your damages are exactly the amount it will take to hire a real pro. That same amount is what gets deducted from the GC's paycheck, If the GC didn't charge enough that's on him. It may be time for a lawyer.

agree about our guy Sal Diblasi . Only one on youtube that always does it right. The mans A legend in the trade

"The bathroom and shower walls are waterproofing not to protect them from leaks but to prevent condensation from penetrating under the tile"

Huh?