Bill V. Thanks so much for responding! I have been planning my purchases for this phase and waiting anxiously for a response to my floor questions :) So Bill V., regarding #5 question - I'm asking just about the plumbing rough-ins, like the hole for the toilet, and the "through the floor" tub plumbing pipes. I would think that the plumber would want to cut through the plywood and subfloor before the SLC is in. I haven't asked my plumber Kevin yet what he wants, and he is ultimately who will make the call. But if I could pour before he made his rough-ins it would be easier for me to not have to work around the extra plumbing and openings. Another question about the SLC - is the SLC not strong enough for the weight of the tub? I was going to install the tub after the SLC, I didn't even question this one. I have a standard tub, alcove type. So, I would think that when installing the tub, before SLC, I would want to caulk the tub at the floor to prevent the SLC from seeping in under the tub. I will have one end of the tub open, for a built in cabinet that will come after I tile the floor including this area. This cabinet will house the plumbing. I will need to create some sort of dam at this end. Staceyneil posted some time ago about how she made a successful SLC pour and described how she made a dam out of 2x's. Again thanks so much for your input.

I went through all of this. Mongoct and Bill V. are very helpful. Joist. you may or may not have the ridgidity to tile with stone. It requires a stiffer floor system than ceramic. Check the JohnBridge web site and look at their "deflectolator" to determine, roughly, your capacity. Subfloor. If you use cement board it has to be thinset inplace as well as screwed down. The thin set is not to glue in place but to fill voids that may flex and cause cracking of the tile system down the road. If you use plywood as the underlayment it needs to be screwed down on center every 6" not glued down. Ditra is a decoupleing membrain that goes down after your self leveling compound is installed. Check out my post on floor joist on the remodeling forum and here. There is a link to the remodeling forum that is very detailed and time consuming to read and interpret. I provide a link below. Check out Bill V's. post on frequently asked questions. bathroom tile FAQ's-bathrooms Check out Staceyneil's post on " Self-leveling compound & radiant heat: what I learned..." Mongoct has very detailed information throughout different posts. Here is a link that might be useful: Progress on floor prep for slate tile

Because your slab is suspended above a basement, you could float a plywood subfloor or adhere a subfloor to the slab. When we float a subfloor, it is usually two 1/2" or 5/8" plywood layers installed on a diagonal layout to the room with each layer staggered so no seams line up. The layers are attached to each other only. The plywood needs to be dry and reasonably flat. Garbage sheathing will not suffice. Since yours is such a large space, I would suggest you do a lot of research on different install options and consult with installers who have done solid over concrete slabs. One important thing to note is the fact that even though your slab is suspended construction does not mean it is entirely safe to assume it is dry enough to install wood flooring over without providing for some sort of moisture barrier or retarder. Concrete can take up moisture and emit moisture depending upon the temperature and moisture vapor content in surrounding air at any given time period. There have been remarkable advancements in adhesive technology with some adhesive manufacturers making the claim that now you can install a solid to concrete directly when using their product designed to do just that. I have not done that. Engineered wood flooring construction is basically a quality plywood with a veneer face that is the specie of choice. The veneers differ from product to product; some have a thin peeled veneer and others have a sliced (sawn) veneer. The unfinished Owens engineered is of the sawn type with a veneer that is almost a full 1/4" thick. I did an Owens unfinished over sheet cork over a slab where the product married to an existing 3/4" solid wood floor attached over a portion of the house that had a basement. You could not tell the solid from the engineered. Good luck with your searches.

^^^HA! Snap! Millworkman hits it on the head...AGAIN! Your 'dude' (sigh...I'm telling you the guy with 2 years of experience has yet to have a MASSIVE fail that costs him his HOUSE!) is not making allowances for the gap (vertical gap....between the old house and the new house = gap between the wood and the concrete). That gap is going to move. Actually it isn't the gap that moves...it is the WOODEN side of the house that moves. Wood expands and contracts in the presence of moisture. That means between the seasons that gap will expand (in the dry winter months) and contract (during the humid summer air). Tile is NOT happy with this type of expansion and contraction. There will be issues with tile in the breeze way. I guarantee it. I would get this in writing. It will say, "I, Joe Schmoe floor guy with 2 years of experience, hereby promise to remove and replace all flooring that fails because of my installation technique. I promise I will not leave the town, state or country upon notice of complaint. I will guarantee my work for five (5 years). After such time I will offer prorated discounted repair service for the next 10 years should this floor fail due to my installation techniques." I can guarantee the installer will not agree to this. Because several hundred square feet of failed tile work could bankrupt his little business. This only works if you FLOAT a wood over a FLOATING wooden subfloor like Dricore ($1.35/sf + $1.65/sf labour = $3/sf). This STILL REQUIRES the two floors to be leveled out. This is a MAJOR renovation to get your vision to work. Again, you've been given the limitations of your situation. What you 'want' is not something your budget NOR your installer can handle. Go ahead and get 3mm cork underlay over top of the wooden floor...now float a wood floor over the concrete and over the cork. You will have to leave drop in a T-moulding at the gap...and you are DONE. This is what the HOUSE is able to do. Just because you 'want it' doesn't mean it is feasible. You could spend $10/sf on this area. You could hire a TOP flooring pro - not a well meaning 2 year pro. You could also shrug your shoulders and say, "Nah. I'll just to it the way the HOUSE wants it done. It's easy and FULLY ACCEPTABLE in the world of design and flooring." Go ahead and ask your installer, point blank, if he can AFFORD to pay for a complete redo of your home's flooring WHEN his plan fails???? If he looks shocked and angry, you know the answer is "Hell Naw!" You can swim upstream against the current and curse it every time you have to paddle harder or you can float with it and end up on the other side without any physical (or financial) exertion at all...other than keeping your beer from falling off the inner tube! It's your call....but the house has spoken.