bicoastal, Unless it's detailed with a full vapor barrier from the start, it's very difficult to turn a "regular" shower into a steam shower with just a little remodeling. Traditional showers are normally built with a drainage plain behind the tile/cement board...it might be tar paper, it might be polyethylene sheet plastic...but it's usually "lapped for drainage" instead of being fully sealed at the seams, and it's usually a partial wall installation instead of being floor-to-ceiling and ceiling. Or there might not be any barrier at all. Just tile over backer board over framing. A steam shower can drive moisture through natural stone, through grout, and into the wall. If there's not a fully inclusive vapor barrier on all six sides of the steam room cube, then moisture vapor can be driven through the wall and into the wall cavities. When warm moisture vapor cools, it'll condense...wetting and saturating the insulation and/or the wood framing. Not good. That's why with steam showers it's best to have a fully integral vapor barrier on all sides of the cube. A small yet important point, is that "waterproofing" does not necessarily mean a "vapor" barrier. You can use a waterproofing membrane, and it'll shed liquid water. That's good enough in a traditional shower. But vapor can pass through some waterproofing membranes. Again, that's not good in a steam shower. Moisture vapor would destroy your green board over time, green board is moisture resistant. Not waterproof. Not vaporproof. It's been recognized for at least the past 20 years by good tile mechanics that green board is an inferior tile backer in wet areas. Building codes finally caught up to common trade knowledge and banned green board as a tile backer in wet areas in 2006. That said, in a typical shower green board can perform fine or 30 years or fail in 3 years. In a steam shower it'd be a short-lived installation due to repeated vapor drive. The nice thing about having a topical vapor barrier applied to the face of the tile backer board (between the backer board and the tile) is that the only thing that can get "wet" in a situation like that is the tile and the thinset. The membrane stops the moisture from penetrating into the backer board. With no deep wetting, the steam shower can dry more quickly than otherwise might be possible. While there are several materials out there that perform fine, you'll see Bill and I mention Kerdi. It's not the only material that can do the job, but it's a warm-fuzzy for me. It's been my membrane of choice since way back in the 20th century. Wow, that's over a thousand years!

I don't understand the last post to this thread? Thermasol offers a 5-year replacement warranty on all their controllers. Why would you pay to replace it? Maybe you had it more than 5 years? If so, then it's too bad it failed but how long do you expect it to last? I doubt you could expect a car to last reliably with no problems longer than 5 years, so why expect that of your steam shower. I have a PRO-395 that I installed 14 months ago. It just failed tonight. Not sure if it is the controller board or the heating element, but it stopped producing steam. Called tech support and they are shipping me a new replacement unit tomorrow and paying for the install, all at no cost. I am going to call them tomorrow to talk to them about the fact that it failed so soon. They are supposedly the best and charge a premium for their product. I am curious how they will explain that it failed so soon. Will update this post if they say anything interesting. Update: Spoke to them this morning and they are sending me a new unit, and pay for installation charge. One other thing. Someone in the tread above talked about making their shower with a 10 ft ceiling. Don't do that! That is just dumb, and will affect the experience of a good steam. If you ever want to make your steam shower bigger, do it in the length or width but never in the height. My house has 10 ft. ceilings, but my shower has a 7.5 ft up to an 8 ft. ceiling and that is plenty high enough. The 7.5 ft part is over the bench so the fact that it is lower there makes no difference because you are sitting down.

I have to second Thermasol and their customer service. We had a problem with installation (plumber's fault) and Thermasol sent out a tech who repaired the problem with no cost to us. If I ever get my dream to re-do our master bath, I will be adding another Thermasol. The current steam shower is in our guest bathroom - makes it hard to kick guests out!

I have been looking for a steam shower unit and there are so many out there (ie, Royal, WMK, Ariel, Dreamline, etc.) However, unlike most other things on the market, I cannot find any reviews for different brands. This is a major investment, and I hate to order something without actually knowing the quality of it. Does anybody have any experience with these types of units and any recommendations?