Replacing rafters, but no ridge board
Okay. Like I said in my introduction, I've taken on a house in need of a lot of work. I've been working through the roof, and inside I've been tearing down ceiling where there is lath and plaster (partially because it's all that's left of the original construction interior walls from 1917 and the only place the lead tests are showing positive - side note, I've gone through the EPA lead renovation certification clase just for this purpose - other part of it is so I can insulate properly with rafter baffles.)
Anyway, the house was built as a 22 x 22 bungalow originally. Later, 10' was added on to the back. Seperate story, but this addition was not supported with any beams. I'll be working on that, but that's a story for later. Anyway, upstairs the rear bedroom was expanded and 2 dormers placed on both sides. The dormers have a shed style roof. Most of the house has 2x4 rafters on 24" spacing, which I'm presuming has been okay because they're supported by knee wall. The dormer rafters, however, are unsupported and have sagged. The previous owner felt that the way to fix this was by putting enough 2x4 boards on top of the 1x sheathing to support flat OSB. I feel that properly sized 2x10 rafters on 16" spacing is the better approach, and while I'm at it I'm extending eaves so I can put in soffit venting.
My question is this... The rafters are entirely without ridge boards! No, these aren't trusses... It brings to mind the question of what's up with that, but more improtantly is there anything I should be aware of or do because of this construction detail? Can I simply put in my own ridge beam for the section where I'm replacing the rafters as if I was starting from scratch? Unless anyone has a better idea, that's what I'm thinking of doing anyway. Any feedback would be much appreciated.