I have a 24 x 40' shop with a bonus room upstairs. The roof is sagging in the middle, and one of the walls is bulging outwards. It has 2x10 rafters nailed to a ridgeboard 24" OC, and notched and nailed at the wall plates (2x6 walls). The collar ties are 2x8's, on every other rafter, and no ceiling joists, as the walls are 4' high in the upstairs room. The home was built in 1978, all lumber is nailed, no ties or mending plates or anything. The bottom ends of the rafters are pulled away from the ridgeboard about 1.5" at the worst in the middle. And they have slid off the wall plate a few inches as well . I tried lifting the ridge with a bottle jack and got it level, but the rafters need to be pulled in. How can I do this? My understanding is that without ceiling joists, there is nothing holding the bottom of the roof from spreading outwards from downward force, but putting joists on top of the walls would be right at chest level in the room. So could I reinforce the roof enough with other methods to not need joists at the wall plate? I'd appreciate any advice. To a new homeowner trying to finish a man cave.