The sliding door; although never as tight as a swing door, can be used in a steam room quite effectively provided it is designed for that purpose. Most sliding doors have bumper stops on each end and a gap between the doors which makes them unsuitable for a steam application.
Here is a Sliding Door
specifically designed for steam rooms. The 500S door has unique vinyl sealed “pocket jambs” on each end and a vinyl seal in the gap between the doors. One thing to keep in mind with the sliding doors is the width of your shower. You will only have 50% of the opening to enter the shower so a minimum of about 48” is good.
Frameless Siding Doors are not currently available for steam but there are some beautiful Frameless Swing Doors which can be modified for steam. The advantage here is that the door swings both ways but you still must be mindful of the toilet. For more information on the frameless doors, call a Steam Shower Specialist