how much does it cost to add a floor and renovate home
John Young, Agent, Bethesda, MD. If you are talking about raising the roof and adding a second floor with a bathroom you are probably going to spend at least $100,000.It's not easy or cheap to add a second floor.emodel & Renovate in 20901 Question Details. how much would it cost to add a 2nd floor 400 sq foot loft to an existing 920 sq ft house in silver spring, md?