Yup, 2" per foot for the ceiling... ...porcelain over natural stone... ...and for the generator, different generators can be placed in diffeent areas. Some need to be co-located near the shower, others can be 10, 20, or 50 feet away. The generator also needs to be sized for both the physical size of the steam shower and the thermal characteristics of the six sides of the cube that make up the shower. You;ll find info on most manufacturer's websites. You want a VAPORPROOF membrane...not just waterproof, but vaporproof...behind the tile on all six sides of the shower cube. And all plumbing penetrations should be sealed to the membrane. You want your lights to be vaporproof too. You usually won't have a vent fan within a steam shower, it'll be located just outside the shower. Were you to have a fan within the steam shower, steam vapor drive can do nasty things.

Steamshowers, you mentioned Kerdi, when I do Kerdi it's over cement board. Not Hardie. Durock is my first choice, Wonderboard my second. You'll need to Kerdi all six sides of the shower cube. Ceiling too. And you'll want to gasket the shower valve hole and the shower arm hole with Kerdi so moisture doesn't escape into the wall from those openings. You mentioned recessed lights in the shower. Look for "vapor proof" lights. Not just "damp" or "wet" proof. Vapor proof lights are gasketed and sealed to prevent moisture vapor from getting in to the housing and trashing the light from within, or from getting through the ceiling hole and into your framing bays. They can be expensive. Speakers within the shower. Same thing. They have to be able to withstand the steam environment. Ventilation, the same. Some put a "standard" vent outside the shower just above the shower door to keep things simple. Music? If you don't already have a set-up, look in to Sonos. It's my whole-house (and outside in my yard) music system. I love it. You can gradually expand it to other parts of you house should you desire. And there's an app for your android. I recommend porcelain tile in the steamer. Leave natural stone out due to moisture issues. Steam condensation can drip down on steam users. Some slope the ceiling to help avoid that. Grout lines can act as drip points. Just something to be aware of if you're not already. Good luck!

Zagyzebra - I can see that with yours on an exterior wall plus three windows that you would need a more powerful system. And yes, a steam shower that does not get hot enough would be sad indeed! But the ability to vary it to a cool setting is wonderful too. Those small windows sound great. Natural light in a shower is such a nice effect but especially while still allowing privacy like it sounds like yours does. The onyx I am using is a very subdued pattern and color and just a few dramatic accent areas. It is very traditional, classic and formal in an older home, but not near the age of your place. I love the feel of an older homes. They have a unique feeling and charm. Yours is about 50 years older than mine and I bet it has classic beauty. I worked with some builders in new construction a few years ago when the Tuscan look was very popular, and the back lit onyx was just starting out. It was very dramatic but we also did it a lot of that, so I guess I grew tired of it so I wanted something different for myself, with a more subtle color scheme for my area. I was not even looking for onyx when these slabs just jumped out at me at the stone yard and was 'the one' for my Master. We used book-matched slabs which creates a symmetrical pattern from two matched adjacent slabs, that when lined up and cut properly, can meet in the middle for a mirror image from the center, which creates beautiful classical proportions. The natural light is on the front and not the back which reminds me of the delicate hand painted old book inside covers of feathered paint (can't remember what that is called). Anyway, it is very serene and classic which is the feeling I was after and the color scheme is similar to your marble only darker. The Calcutta sounds great and I'm sure it will be beautiful. I love the subtle veining and the warm 'glow' it gives off. I bet you have all the precautions covered but if you don't mind me mentioning just a few that I've read about here on GW recently about white marbles specifically. These have mostly been regarding these marbles on the shower floors. Most came from a combination of or single problems of 1) installing directly on the mortar bed instead of a membrane (presumably like you have on the walls and ceiling), and the translucency and delicate nature shows darker if it remains wet underneath, and usually in an uneven pattern (darker = hidden moisture underneath), 2) sealing the tile with a traditional sealer (on tile and grout I believe) that holds in moisture and will not evaporate properly) and 3) using the typical grey thin-set instead of the white, so since it is translucent, will show darker than it really is. I was going to attach a link to one of those posts on the shower floor problems, but can't find them now. It was either Bathrooms, Flooring, Remodeling or Building a Home forums. Gee, I guess I'm reading too much GW! I tend to do too much research, but then again, it sure comes in handy!! These forums are a wonderful resource! Although they caution using a regular sealer that causes moisture retention, we needed one for the high calcium stone (limestone and the onyx which marble is too), so we researched and tested A LOT to find one that would protect the grout and stone while allowing both to evaporate any moisture behind the stone. The membrane of the steam shower with the water proofing as well as vapor proofing made this more critical so this would not cause a 'vapor sandwich'. Your project may differ and you may need nothing or something else. If you are interested, it is called Stain Proof from Dry-Treat. Smaller molecules or something and my engineer DH was even impressed with the tech behind it. And no, I don't work for them or anything. Just passing along what took us weeks of research and testing to learn. I would not have felt comfortable without seeing the samples myself. How far along are you? I know once I've gone over every decision and actually decided everything, then I'm anxious to see the final results! But I must be patient to get the best installation to match what's in my head. Hope yours will be or is going well. Monicakm - I have the chromatherapy in my bathtub as well. I got to try this also when traveling so knew I would like it. It is always nice to know you have even though it has lost it's usefulness for you. You could always use the color(s) to perk yourself up on a dreary day! You know, with everyone having problems deciding which features are important, or not, for bathtubs, (or showers for that matter) wouldn't it be great to have several hotel chains have different ones installed to use for real, so we could try out various tubs (and showers / steam showers) and see the sizes, configurations and special features!

(rewriting as I didn’t see my post) Hi everyone thanks for sharing your very helpful thoughts. They used orange schluter kerdi board (pic below) everywhere inside the shower. They then added mud on the ceiling that covered it up (not sure why - level?) One thing that bothers me is that they added these 2 inch screws to hold up the tile and I thought that was weird. Those screws must be penetrating the vapor barrier, no? I can’t change the shower head. Is this orange board okay? What to do at this point? I think they need to replace the kerdi board that’s penetrated. But then again, how to tile it while maintaining a 2” slope per foot? Should they tile from the shower head away to the surrounding margins of the shower? Thanks!