Thats what we did at the house my cousin bought down the road. It had a small upstairs with slanted sides. we completely tore it all off and rebuilt it and gained huge amounts of space. it went from a 1 bedroom and 2 small closets to 2 big rooms, bath and 2 closets.we also completely gutted the entire house and are in the process of finishing it. if you ever need any extensive work like that done and you dont plan on doing it yourself let me know, ill put you in touch with the right people and get you a deal, same goes for roofing, landscaping, and plumbing