I would be concerned enough to ask him for more details as to why he gave you that guidance. Can he explain his thought process, or provide building codes for your areas that would demonstrate his reasoning. Repost with what he says; then if his advice turns out to not be right you probably need to work with someone else. that being said, curbless showers are still pretty new so if this is a contractor you like and trust and has other good experience, then you might still go with him. My contractor is my stepbrother and I knew he would do an excellent job, as he had done alot of work on my Mom's house and the quality was excellent. Plus, he would have heard about it every Xmas, Thanksgiving, etc if he messed up the job. But, curbless was new to him...still I had confidence that he could learn how to do them and do a good job...and he did.

Thanks for your nice comments! The vanity is just about 60", I love the space... Looking at doing a master bath remodel, and would hate to have two sinks in that space. The showers inside dimensions are 55 inches on the 2 long walls, 26 inches on the two shorter walls, with the opening 33 .5 inches. We did this for a roll in seated bath chair, which fit perfectly, and I think would work great for bathing assisted shower. Unfortunately my father in law passed away, so we never did get to use the shower for its intended use.

Mongo, Tundra, Thanks to the both of you. Part of my concern was how to accomplish the slope with concrete. I'll be blunt, my concrete skills suck and pouring a sloped pad was likely to be well outside my skills range. Tundra, thanks for the pictures, they clarified a great deal. It's true that a picture is worth a thousand words because I don't know how you could describe what you did without at least some drawings but the pictures tell the tale just fine. Above is a piss poor rough drawing of the floor plan of my bathroom. As you can see my intention is to install the drain at the far side of the shower enclosure. My wife has requested that she be able to spray down the whole bathroom with a hose. I'm guessing that to allow for that would make the bathroom "wet"?? My current working thought is to pour the pad in two stages. The first would be about 2 to 2-1/2" below the existing grade. The other would be 2" below that. The demarcation like would be the beginning of the shower enclosure area. The purpose of pouring it so low is so that I could use deck mud to create a dual slope from the edges to center and from right to left (as seen from diagram). I was thinking 1/8" per linear foot of drop for the primary bathroom area and somewhere in the range of 1/4-1/2" drop for the shower proper. I would mud out the preliminary slope with it all rolling into the weep holes of the drain assembly. I would then membrane the whole thing. I'd membrane the walls in the primary bath area up to the 4' mark since that's how high my tile is going to go. I'd membrane the shower area all the way to the ceiling since that's how high the tile will go in there. On top of the membrane I'm planning to make a final deck mud slope that I would then thinset the tile to. I'm using 3/4" pennyround mosaic for the floor and ceiling so adjusting to the slope won't be an issue. As I said, that's the current mental formulation, pending feedback and ideas. As with all battle plans it's not likely to survive contact with the enemy. Mongo, don't fret about rambling. As you might have noticed I'm a bit on the verbose end of things myself. To Mongo and Tundra, thanks again for your prompt response and insightful advise. It was, in part, your commentary on other threads that led me to post this question on this forum. Cheers.

Before you go with that type of shower, I strongly urge you to spend a few nights in a hotel in the handicapped room. I used to live in hotels traveling around Texas with a crew of guys. We would roll in and take all the suites for a month or more at a time. The guy who got the handicapped suite ALWAYS complained about his bathroom being wet everywhere after taking a shower. But we learned quickly to ask for a normal suite and not the handicapped one. I suppose you could save the cost of the hotel by calling and asking about their handicapped room maintenance. Or you might talk to the head housekeeper.