I am moving in with my finance, but the problem is we both own 2 bedroom houses. I plan on renting my house out (who really wants to buy a 2 bedroom), and moving into his house, but his house is even smaller than mine. Instead of buying a new house, we've decided to add on to his ranch style house. We only need to add a master bedroom, but we are not sure how much it will cost us. We're looking for a ball park figure.