I'm not an expert in transoms or steam shower design, but I'm surprised nobody has yet said why they were invented, get installed, and are used. 1/ Steam machines make steam. More and more of it. Without new steam, the experience of a steam shower can be less and less enjoyable. New steam is needed. It actually puts pressure on the walls, and in 24hour commercial steam showers this is a big thing. But, even at home, where does all the water vapor go? It doesn't all become liquid (condensation) and go into the drain. 2/ :: Plan where it will go, otherwise it will go places you don't want it to go. A transom is a safety valve putting your excess steam into the bathroom, from where the fan exhausts it. 3/ :: Otherwise steam seeps into everything. Wall-ceiling junctions. Light fixtures. Into the attic insulation. Water vapor can penetrate anything, because it has time on its side, and the world's best solvent: H2O molecules. The opposite approach is "If you only use the steam shower for a short time and not often, who cares?" Anyone want to defend that point of view? I think there is no point building something that you "really ought not to let run". Some future user might want long steam showers, or frequent steam showers. Without a transom, you are guaranteeing that your escape route for water vapor will be confused, since it's unplanned, uncoordinated and unwanted, and your result will eventually lead to problems. As far as I know. Anyone reading this thread so far would be well advised to look more into it instead of concluding that transoms are just for fun. Many homeowners don't care much about codes or practices and will allow anyone to build anything for them. After that, it may or may not work as expected, and ultimately the homeowner may or may not be satisfied. This applied to all fields of construction. My writing this out is not to say that anyone here has been intending to do the wrong thing deliberately. Hth

There was a discussion about this in earlier -- I finally found the thread. Scroll down to where Chays starts posting. There you'll find some discussion of the "embedding" options + pictures of what Chays did. A truly beautiful bathroom. While it's not a steam shower, I don't see why there would be any problems. When our glass walls were being installed (with clips + silicone), I asked about the embedding option. The only issue the installer said he might have would be identifying leaks when they occurred. But he did not see that as a big issue. Hope this helps.

We have a semi-frameless, so there are cracks around the door and around the transom window above the door. But when we run the steam there's no noticeable escape. That said, I've never run the steam for more than 10 minutes (it's fairly new) and our bathroom is pretty large (10'x20') so take my experience with a grain of salt.

I have a steam shower, and yes, a teeny bit of steam escapes, but the shower is way more than steamy enough anyway. I'm thinking that maybe this is something they haven't done before? The door doesn't need an airtight seal in order for you to have a good steam.