I looked through the pictures on my iPad (others were on my phone) and found this one with lighting that shows the underpinnings of the roof.
I think my rafters are 16” on center, purlins are in that ballpark. I am actually not sure if the rafters are 2x6 or 2x8. In any case I am fairly sure it is over-engineered but I am happy to err in that direction, especially given that the snow sliding off the metal barn roof will sometimes back up in quite a deep pile on the aviary roof before finally giving way and continuing its slide to the ground.
One thing mentioned in a previous post that I disagree with is about whether the intersections of panels need to line up with a rafter. The roofing doesn’t touch the rafters as it sits on the top surface of the purlins, 1 1/2” above the rafters, so it is only fastened to purlins. I don’t believe there is much danger of a predator ripping it apart between fasteners; the overlapped ridges make it quite rigid.
I did put sections of 2x3 between the 2x3 purlins on top of the end rafters to seal that gap between rafters and roofing.
I think my rafters are 16” on center, purlins are in that ballpark. I am actually not sure if the rafters are 2x6 or 2x8. In any case I am fairly sure it is over-engineered but I am happy to err in that direction, especially given that the snow sliding off the metal barn roof will sometimes back up in quite a deep pile on the aviary roof before finally giving way and continuing its slide to the ground.
One thing mentioned in a previous post that I disagree with is about whether the intersections of panels need to line up with a rafter. The roofing doesn’t touch the rafters as it sits on the top surface of the purlins, 1 1/2” above the rafters, so it is only fastened to purlins. I don’t believe there is much danger of a predator ripping it apart between fasteners; the overlapped ridges make it quite rigid.
I did put sections of 2x3 between the 2x3 purlins on top of the end rafters to seal that gap between rafters and roofing.
