Change of status from barn to habital dwelling

Hello all, We are looking to buy a small 1 storey barn with door & no windows the roof needs to be raised 1mtr for regulation height at present there is no water or elect, the agent says he has been in touch with the commune & there is no problem changing the status to habital dwelling. My problem is,what utilities and/or building regulations (if any) have to be in place to get habital status. I do not want to hand over monies without written confirmation from the commune and it would have to be a condition of sale, any suggestions/advice will be gratefully received. thanks, Dido

Sorry to all who replied but I think I may have un subscribed by mistake as the mail has vanished. Mick

You must be bored of me now!!..I can get my Geometre to ask at your comune and clarify everything if you want..