I have an unfinished basement and am looking into creating an office down there as my current office space in the loft is looking to be turned into a fourth bedroom. Can I wall off and create an office room (lit, heated, finish floor, finish walls, finish carpentry, as if it was any other room in the house) while leaving the rest of the basement unfinished? Or must the entirety of the basement have work done to it (subfloor, framing, etc) in order to create a single room down there?

Will the proposed office room legally classify as a "living space", and will I be bound by building code for its construction?

Thanks.