Well, you should always listen to Mongo-- I did and I'm glad! We used the Laticrete drain and Hydroban on the floors and partway up the walls. Our shower is only 3 x 5 and the drain is on the far (long) shower edge. So we only have 1.5 inches of slope.

We did have the GC talk to the inspector and he agreed that was safer than having a half inch drop to get the 2 inches code specifies. It made out architect scratch his head because he knew he would not have been able to get that through in the plans. I think common sense indicates that a 5 foot long drain is a lot harder to plug up than a small central drain, but you never know if common sense will prevail. A slight drop that was not a full step would be much more dangerous, in my opinion.

Thanks Mongo and Lori for your replies. A few questions..

1. I understand the 2" drop requirement from the curb to the drain. I have poured over quite a few curbless shower projects on houzz and was wondering how some of them managed to put the drain on the long side of the shower (3' from the curb)? I was originally planning the drain on the wall with shower system (5' length providing a 1.25" - 1.5" slope differential, similar to Lori's). But I was worried about the small ledge created at the shower curb entrance due to the slope. Another issue in my current layout, was the impact of the floor slope while facing the shower, which would create different heights under my feet...

2. For topical membranes, is the preference Sheet membranes or Liquid? Since I mentioned using Hydroban on the walls, I am presuming Mongo's recommendation is to stick with Hydroban on the shower floor (and essentially eliminate an additional deck mud layer)

3. How does the transition look between the shower and flat bath floor for curbless? Does the Hydroban get coated on the concrete 6"-12" beyond the shower and tiled over?

4. ACO drain appears to be a popular choice at the plumbing store and the contractor. Any issues combining the ACO drain and Laticrete waterproofing method?

5. Where can I find more info on what is 'capillary break' and how to build/account for in the install?

Thank you.

1) And there's the rub. Sometimes code gets enforced. Sometimes it doesn't.

2) Sheet versus liquid. They're both good, and both do well for waterproofing a basic shower. Both have pros and cons.

If care is taken either will suffice and I'd say that liquid can be easier to apply especially on smother surfaces. You might need a little additional prep work though. With liquid, if the surfaces are fairly smooth you should be able to
achieve the advertised coverage. For a larger shower it might be
nice to have additional liquid on hand just in case.

On the sheet side, you know what your coverage will be when using sheet and sheet can cover rough surfaces and span cement board seams on the walls. With sheet you'll have membrane lapped over itself at seams and in corners. Thickness build-up due to multiple layers can sometimes be an issue.

Just like with painting a room, with liquid its all in the preparation. The actual application is very easy. With sheet it's more in the execution during application and solving installation problems as you install the sheet.

Overall I'd say liquid is probably easier for those new to the game.

3) Typically you have flat and level bathroom floor, a break in the tile at the threshold, and the tile transitioning to a flat yet sloped floor in the shower.

Yes, continue the waterproofing outside the shower floor and on to the bathroom floor for a couple of feet.

4) The ACO flanged drain is designed to be used with liquid or topical membranes. Should be no issues there.

5) Capillary break is a break in the thinset at or near the shower threshold, or along the sides walls of the shower where it transitions from "shower" to "bathroom". It can be as simple as a bead of caulk sandwiched between the tile and the membrane under the tile, or a manufactured capillary break.You want to separate the "shower floor thinset" from the "bathroom floor thinset".

The ideas is that If the thinset under the tile in the shower gets wet, the goal of the capillary break is to prevent moisture in the wet shower thinset from wicking out of the shower and into the thinset under the bathroom floor tile, essentially wetting the bathroom floor from underneath the tile. The water in the wet shower thinset can travel through the thinset and out of the shower via capillary action.

The capillary break is simply a small barrier that separates the thinset that adheres the shower floor tile to the shower membrane from the thinset that adheres the bathroom floor tile to the bathroom floor membrane/substrate.It can be as simple as a bead of silicone. Or it can be a manufactured barrier.

Just something to think about.

Mongo I talked to several experienced GC about the curb less and the two most qualified said they only do hot mop. Apparently their insurance doesn't cover the newfangled techniques/products.

So should I just have them hydroban over the stuff before tiling?

It took 15 GC screening to find two that have experienc and understood working with remodeling over a post tension slab. That was another pickle altogether.

I'll preface this by writing that being on the east coast, I'm not a hot mop guy.

If you have to use hot mop and you still want to use a topical membrane like Hydroban, then the hot mop should still be sloped to a clamping drain. You can do it the same as you have in the drawing on page 4 of your original proposal. Your sloped chloraloy liner will be replaced by sloped hot mop.

Do sloped mud (or sloped plywood base if that's what the hot mop guys do) to a clamping drain base piece.

Hot mop over the sloped deck mud (or sloped plywood) and onto the drain base piece. Install the clamping drain ring while protecting the weep holes (just in case).

Install the ACO linear drain using the gasketed hub to set it into the clamping drain.

Do a second layer of deck mud from threshold to drain, packing it around the ACO linear drain.

FWIW, prior to installing the ACO drain you can paint the outside and bottom metal surfaces of the drain that will come into contact the deck mud with liquid hydroban. The HB will stick to the stainless, and the deck mud will adhere to the HB. It'll give a slightly more secure installation than having deck mud coming in to direct contact with the stainless drain body. That's technique, it's not mandatory.

With the second layer of mud packed in over the hot mop, let it sit for several days while the moisture in the deck mud burns off, then Hydroban (liquid) from the bathroom floor, across the second layer of mud, and on to the flange of the ACO drain. And hydroban the walls.

Read the Hydroban installation pdf on Laticrete's website. If the work is neat, the HB can simply be applied to the surfaces to be waterproofed. If the prep work is a bit messy, they may need reinforcement fabric in the corners and over the wall board seams. It's fairly straight-forward.

Two coats of HB.

Tile over the Hydroban, abutting the tile to the ACO drain.

You'll want to use liquid hyrdroban instead of sheet. The liquid is vapor permeable, so if any moisture was to get below the HB, it can transmiss back out instead of getting trapped between two barriers.

Hopefully that makes sense. And again, these are techniques I'm offering. My way is not the only way.

Thanks Mongo. I'll talk to the GC about your recommendation. So far, every GC I talked to only does hot mop. I could have the tile guy do the work but I don't want to be the contact for the bathroom with the city over the post tension slab demo.

I have it all worked out with the city but I want a GC to handle it in case there's memory loss by the various city employees/inspector/engineers.