2010 ADAS 608.2.2 Standard Roll-In Type Shower Compartments
Standard roll-in type shower compartments shall be 30 inches wide minimum by 60 inches deep minimum clear inside dimensions measured at center points of opposing sides and shall have a 60 inches wide minimum entry on the face of the shower compartment.
Citation according to 2010 ADAS. Check your state’s accessibility laws. Some states such as California, Georgia and Florida have additional requirements and standards.