I have a 1 and 1/2 story house with two bedrooms and a bath upstairs. The house was build in 1910 so there is no insulation in the walls and only R-19 in the rafters. I live in Minnesota so it gets very cold but we also have days above 90 during the summer. The rafters have drywall on them so I am looking for the best cost vs benefit of adding insulation. As of right now I am looking at pulling down all the drywall, having someone spray closed cell insulation and then installing new drywall. Our rafter bays have been furred out to 2X6 so if we got 5 inches of closed cell foam that would be about R-35. Is that benefit worth the cost? My estimate is the ceiling is about 1300 sqft and we would install the drywall ourselves. Might have a finisher come in to tape and mud. We have not had issues with ice dams that I know of but we have only been here for less than 2 years. It gets pretty warm up there when the temps rise and especially if the sun is out. I am going to convert a half bath upstairs into a full so if we decide to do this project I would like to do it before the bathroom is done.