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.

This type of level change is very dangerous. The brain can easily discern a level change of two steps, or about 12", but has a very hard time picking up on one that is one step 6" or under--even when the materials on the two levels are different. You are setting yourself up for a tripping hazard. I doubt it would be allowable by your local code if you need permits for your project, and you would also be setting yourself up for a lawsuit by someone who trips and injures themselves.

After speaking to the pros they didn't feel double plying and ditra (a water proofing un coupling membrane) would prevent cracking. I had a contractor out to talk about shoring up the flooring to remove deflection. He didn't feel it was really needed unless we laid marble. You need to find new installers. 1-Double ply doesn't do squat for the deflection we're concerned about. There are 2 types of deflection- generally when we speak of deflection, we are speaking of the joist deflection. This is stiffened by adding joists, sistering joists or reducing the joist span. Adding plywood to the surface, or blocking between the joists does nothing to help. There is also between joist deflection. If your joists are 16" on center, 5/8" BC plywood would be the bare minimum when laid with the face grain perpendicular to the joists. 3/4" is better. 2- Natural stone requires two layers of plywood installed in a specific manner we can cover later. This is to decrease the between joist deflection. You still need to meet the L720 joist deflection for natural stone. Sounds like the guys you talked to are confusing the two, or at least don't explain things well enough.

Durock's website says to install on wood. But I found this info... Manufacturer Recommendations James Hardie Industries, makers of HardieBacker®, and USG, makers of Durock®, indicate that their respective cement backer boards should not be installed over concrete. James Hardie: HardieBacker specifications specifically exclude concrete as a base for installation. USG: Durock does not expressly exclude concrete, but the material is specified only for minimum 5/8-inch exterior-grade plywood or OSB. One source reports that USG will not officially validate the Durock-to-concrete attachment simply because they have not tested it. The lack of testing may be simply because so few customers express a need for applying Durock to concrete. There is no problem with the two materials being compatible. The issue, as Bud Cline of The Floor Pro says, is more about how to attach the cement board to the concrete. A powder-actuated nailer is out of the question since nail depth would be impossible to regulate. Concrete screws, Cline says, have heads that are too small to hold down the cement board. His recommendation: Work with the concrete surface so that it is strong enough and porous enough to accept tile mortar. Portland cement-based fillers can take care holes and cracks. Painted concrete can be sandblasted, sanded, or ground down to bring up a nice, porous surface. Most tile professionals, including John Bridge, concur: Attaching cement board to concrete is not an acceptable way to surface the concrete prior to tile installation. Thin-set alone will not help the cement board stick to the concrete slab. Screws are the only logical way to do this, but it would entail an extremely tedious and time-consuming process of drilling pilot holes before sinking the screws. Additionally, you would be fighting against the thin-set bed under the cement board when drilling the holes and driving the screws. The View of Tile Professionals But the manufacturer prohibitions or omissions are warranty issues. The questions remain: Can you effectively pair two cementitious products—cement board and a concrete slab? ************************************ I went to Wedi's website, and the foam panels CAN be used on concrete for floor tile. Installation over concrete subfloors Floor application for wedi Building Panel All wedi Building Panel sizes and thicknesses can be used as tile underlayments over concrete subfloors. Modified thinset mortar, combed through with a minimum 1/4” x 1/4” notch trowel, will then provide a ribbed bed into which the wedi Building Panels will be laid. All joints should be staggered so that no seam continues throughout the length of the floor. Apply weights (i.e. tile boxes) onto the surface and where transitions are located while the mortar is setting up. After the mortar has set, wedi alkali resistant fiberglass mesh tape, or wedi Sealing Tape or wedi Joint Sealant should be applied to all seams, then tiling can begin. So Wedi panels may be easier and faster for us to install after the marble tile is gone. I also found a new floating porcelain tile product that Dal Tile started selling. It is like installing laminate flooring or vinyl planks. Dal Tile Revo Tile - they said I could install it over the marble as long as I level the floor with self-leveling compound, including where the missing tile is. I still need to follow requirements per tile industry as to x " per 10 ft. I can't remember ... 3/16" or something like that. https://www.daltile.com/revotile $4.50 sf plus $25.00 for tools, $58.00 for 9 lbs of grout. Underlayment $54.00. Adhesive tape for seams. $542.00 and I can install it. I am calling We Ship Floors tomorrow to see if their floating Supercore Extreme Vinyl Tiles can be installed over my marble once the floor is leveled. And if I can install over Wedi panels. For someone who works with mud day in and day out, I am sure it is much cheaper, but I am afraid that I can't do it. Three more tile guys today told me wrong installation procedures for backerboard on the marble and for the tub surround, so I will not be calling them back. Just because they owned a trowel doesn't make them an expert on tiling,