I think you would need about 40 square feet to be safe but I used many in Europe that where even smaller.

A few B&B's we stayed at had Curbs at the doorway to the shower and the little room 20-30 square feet was all shower with the toilet and sink getting wet with every shower.

That's a bit small for my tastes but I'm sure it could work in a pinch...

Put up some pictures and more details and you will get more options.

we are rebuilding our house and are doing exactly what you are talking about. We plan to have no shower door and the shower is about 4x5. It's just in the framing stages still and we're still deciding what tile we're going to use but leaning toward carrara marble and glass tiles. We put the shower head on one of the side walls so it doesn't spray directly out the shower entrance.

I just finished having a walk in shower installed in my master bath. My shower is the same size as gryane is building, 4x5. The partial wall is 5 feet tall. I didn't want any glass either, and after a week of using it I don't think I'll need to. If I use the regular shower spray, 99% of the water stays within the walls. If I use the shower massage spray, some of the water bounces out over the partial wall. Since I use the shower massage spray very infrequently, it's not worth it to me to put glass above the wall.

I think open showers are AWESOME! First of all they are very modern. Second of all ... no glass to clean!

I think gryane hit on the important thing: you need to orient the showerhead so that it's not spraying out the open part.

The only possible negative I can think of with an open shower (assuming you don't have water spraying out of it) is that it might be a little cooler. You know how in an enclosed shower, even one that's not a steam shower, the steam sort of builds up and makes it warm in there (and then you open the door to get out and its freezing)? You wouldn't have that with an open shower. Small potatoes, I say.

Oh, and this is coming from someone who loves glass showers and is about to put one in our house. Still, open showers, done correctly, are awesome.

The 4x5 is making me feel a bit better. Without any major modification, I only have about 4x4, but the tub would most likely be right next to the shower and splashing into that area wouldn't be a problem. The shower currently angles into the closet and we were already looking at taking that angle out. I might be able to steal another foot or so there, especially if we change the sliding doors into the closet (that foot would be into the door now). That creates a balance issue I will have to look into, but I just had another idea and will have to go look at that. Worst case, frameless glass will be a lot better than what we have now. But no door at all appeals to me even more.

Oh -- cooler is not a bad thing here most of the year. We are in the Houston area and the bigger issue is showering and being able to actually dry off the rest of the year. ;-)

I have an open shower and I do not like it.It is drafty. I like for the steam to build up,but that is just my opinion.

Well, I suppose the nice thing about it being open is that you can always add some glass and close it in.

We have an open shower and I LOVE it. In the winter, it is a little cold for the 2 seconds when I turn off the water and grab my towel but I can live with that. I think our shower is 5X5 but there is also a narrow "walkway" where there is a half wall with glass block on top. The glass block doesn't go all the way to the ceiling so it blocks the water from coming out but still gives an open feeling. In the shower we have a handheld, a rain shower and four body sprays. The only time we come close to getting water outside the main shower part is when we use the body sprays.

I am rereading this and it sounds kind of confusing...I can email you a picture of what we did if you would like. HTH

We will have a small master bath with a shower only. I was planning glass blocks up about 5 feet and then stepping down to the open threshold. A closed off doorway would become a seating alcove. The measurements will be something like 36 x 60.

We're planning a rainhead which will mostly be a softer fuller shower, and then a handheld with a longer hose, but mounted on a shower bar. If this handheld, which is more forceful, is closer to the glass block wall, it should direct water more into the corner away from the threshold. Or so I'm thinking. Is my reasoning backwards on that assumption?

Asking advice here: would a frameless glass wall be better to use than the glass block? It would take up less space but it would not give any privacy.

And as far as an open shower experience making you feel too cool, there is the option of a heat lamp on a timer which would counteract that. I prefer the heat lamps to bathroom heaters built into the wall. But then I've not lived in really cold climates.

We will be selling this house next spring, or I'd consider adding infloor heating under the new tilework.