Minimum spacing between rafters for roof structure.

[Prashanth0206]

Hello all. Recently i started working on roof structure and while working on it inner rafter and outer rafter were colliding with each other. So i know thst we can move them apart but don't know the minimum distance to maintain between the rafters. So what should be the minimum distance between rafters? Thanks in advance.

 

[JStephen]

From experience long ago, we'd figure about 8" (200mm) center-to-center. This with nominal 4"/100mm or 5"/125mm wide rafters.
Rafter chair details may limit spacing.
If rafters are to be painted after construction, the spacing becomes more critical. In that case, limiting the amount of overlap lengthwise will also help.
Where our theoretical layout resulted in two rafters falling at exactly the same location, we'd simply shift them apart at that point, so they were slightly non-radial. But on a low-slope roof, that wasn't objectionable.

 

[IFRs]

API is silent on this question, therefore is it only a field fit-up, welding or painting concern.