The ideal ceiling height in a steam room is 7-8 feet. When seated in the steam room, most people's heads are roughly 4 feet off the floor. Since heat rises, the more space you have above where you are seated, the cooler the temperature is where you are.
Now that's not to say you cannot go taller than 8 feet, but do consider the effects when making that decision. Read more about steam shower ceiling height here...www.steamsaunabath.com//catalog/all_about_steam_rooms_ceiling.php#ceiling