Addition above Carport/Garage

BR area - a hand full of houses in our neighborhood have additional bedrooms above the garage/carport- in my current lay out I have a back office that in my mind we could go with stairs and turn that into a office/mud room and put two rooms above the carport even if they they have to turn it into a garage. There's a full bath right outside of this bedroom so no plumbing needed up stairs.


Any idea on someone to talk to about this/ball park on price?