"My question to you is are you recommending a membrane between the two layers of deck mud & then another topical membrane directly under the tile?"
No, my previous wording was probably a bit vague.
What I recommend is really a method that I consider to be a "best practice" for showers, especially those with natural stone. Starting with a flat subfloor, after proper prep you put a sloped later of deck mud on the subfloor with a flanged drain set flush into the deck mud.
Then on top of the sloped mud you put a topical membrane; Hydroban, Kerdi, for example. Those at the two systems that have flanged drains.
Then you tile directly on the membrane.
The thing I like about the flanged drain is that when compared to a clamping drain, the physical structure of the clamping drain creates a small 1/4" high dam where the membrane is clamped by the drain's ring.
That 1/4" obstruction shouldn't restrict drainage, because the weep holes should allow any moisture that hits the flange to flow through the several sets of weep holes built into the drain. In the above photo, you can see the weep holes to the left and right of the 6 o'clock position on the flange. There's another set in the bolt holes.
The clamping drain system should work fine. But sometimes it doesn't. And sometimes there is no logical or apparent reason why it doesn't give optimal performance.
Compare that to a flanged drain, where the slope of the membrane is smooth from wall to drain pipe itself. There are no vertical obstructions.
I have to consider myself fortunate that I've never had "wet ring" moisture issues like you, stacy, and threeapples, even when using clamping drains.
One other comment. I hadn't seen this thread for a while and I just noticed your tiler's response to you:
"I used dry pack. Thinset(no mastic) and hydro ban. Did pre slope. Water proofed, then pan. Then tile with thin set. I have no idea what could be going on"
The part that confuses me is the "Did pre slope. Waterproofed, then pan."
I don't understand the "...then pan" part that follows "Waterproofed...". Is it supposed to be "Waterproofed the pan."? That would make sense.
With Hydroban, you do a sloped layer of deck mud. Then hydroban over that deck mud. No "pan" goes over that waterproofing. You tile right on the Hydroban.
I don't know what kind of drain he used. If he used the Laticrete flanged drain (which is designed to work with Hydroban) your GC shouldn't have been able to get to any "drain pack", here are the layers he would have found during his excavation:
If your tiler used a clamping drain with Hydroban, which he probably did since your GC was able to remove some tile and "dig through some mud to see weep holes", then he probably did it using the "divot method".
You do a mud preslope, then carve out a bowl or "divot" around the clamping drain.
Then hydroban the sloped mud, the divot, and the drain flange:
Then install the top part of the clamping drain over the base flange:
Then thread the drain grate assembly into the drain base.
Add a small handful of pea stone (or other "debris") over the weep holes so mud doesn't pack into the weepholes and clog them. Then fill over the pea stone to fill the divot with mud, then tile:
Sorry I can't be of more help, but it's time for me to run. Hopefully you can get things figured out.
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How shower floor should be installed
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