Can I Fix up my basement that is part of a Condo and turn it into a new unit?

[Raj Tirur]

Hi everyone, first time poster here and somewhat of a novice investor! I am part of a condo association with 3 other people. My basement is unfinished and is shared with my neighbor. My thought is to buy his share from him and then put some money into it and turn it into a 1 bedroom apartment, sell it, and add it to our condo association. Other than getting permission from the others in my association, is this something that is even legal? Would I need to consult the town first? Appreciate any help I can get!