I'm in the process of planning the reconstruction of barn that will be used as a garage. The original barn was a common rafter frame with 12' 8” sidewalls, 30' tie beams connected at the top plate and supported by one post mid span. There were 7 bents. The rafters are 4-6" diameter poles placed 28" on center with a 12/12 pitch. There were rafter ties on every other rafter pair that are about 13' long. There was no ridge board.

I didn't see the original structure before it was disassembled, but it appeared to have a problem with the sidewalls bulging out. The pictures I have are poor, but it looks like steel tie rods were added along the tie beams to hold the walls together.

I want to reconstruct the building as a 30'x40' structure with the same common rafter design (with a 12/12 pitch). I plan to cutoff the original tenons and use timberlinx connectors with the tie beams lower on the posts (9'6"). I'm planning 4 bents, with the same H-design, post mid span.

My main concern and the reason for this posting is that I am concerned about the common rafter design. Should I add a ridge board to keep everything in line with these rough rafters? Should I add a ridge beam to carry some of the roof load?

Thanks