Parking is, quite often, a requirement for people unable to walk. A therapist will also need room for storage (towels, products and other equipment - depending on the type of therapy he/she practice) and, obviously, room for a couch and at least 60cm clearance around it. Also, 2 chairs and a small table, for the consultation, and, possibly, a sink. Although some therapists have their own couch, it is good practise to have a room with a good quality, height adjustable (pedal operated) couch.
I hope this will help>