barge rafters on lean to

[ugabulldog]

I am building a shop w/ 2x6 rafters, 1' overhang, 2x4 purlins 2' OC for metal roofing. On my main roof I have 2x4 lookouts 4' OC notched in to gable end rafters  and face nailed into second rafter that are supporting the barge rafter. I also have a lean to barge rafter that ties into main roof barge, I plan to cut angles on the two intersecting barges where they meet and toenail together, also scab a piece of 1/2" osb on the backside of intersecting rafters to help tie together. The lean to barge will be supported on bottom by 2x8 gutter board (2x6 rafter + 2x4 purlin in why I am using such a big gutter board) Lean to barge is only about 12' long, will it be supported in the middle of the span enough by the 2x4 purlins on top? If not what do you suggest, I don't think I should notch into the end 2x6 lean to rafter since there is no wall supporting underneath (lean to open on the sides)

PS It will have an open soffit.

[akwoodchuck]

Nail some 2x8 blocking between your fly and main rafters, alongside every purlin, it'll add a lot of strength.

[Don_P]

I agree with ak, although I think the shed rafters and barge (fly) rafters are 2x6's so that would be the blocking. In heavy snow or wind country this wouldn't be enough but by your handle I suspect that is not a problem. I would cut the angles on the intersection of main to shed so that the shed fly rests on the main fly and then bisect the angles with the finish fascia boards that go over the flys if you are using finish fascias. (I usually build with 2x6 subfascias and cover them with 1x8 finish fascias). In theory, by physics, you can notch in the end 1/4's of span without strength loss as long as it is less than 1/3 depth but do bear in mind trees don't read books.

[ugabulldog]

Thanks to both, I think what ak meant was to use a 2x8 since I have 2x6 rafters plus 2x4 purlins, the 2x8 would hang down 1/4" but yes, I am using 1x8 fascia so this would cover it.