For comfort and safety, a shower seat should be 17”–19” above the shower floor and at least 15” deep.
Waterproof material should cover the wall surrounding the shower at least 3” above a showerhead. If you are considering a steam shower, waterproof materials are necessary throughout. The standard bathtub is 5 feet long x 30 to 32 inches wide.
Switches should not be installed within wet locations unless part of the bath and shower assembly. GFCI receptacles should be located at all electrical appliance points*.