Shower Door Dimensions

Shower Door Dimensions I am in the middle or a master restroom renovation. I’m replacing the actual shower fiberglass surround along with tile. I’m confident with the actual tile and waterproofing component but I’m having a difficult time finding a solid response to the simple question of how broad to make the shower opening for any specific door width.

The actual shower area is 36″ across. I’d like to install a 30″ frameless glass door. Beyond the shower the wall sticks out and will only permit clearance for a 30″ doorway. (the previous door had been larger but I presented the depth of the bath by 6″).