Need help with roof rafters on my shed (measuring angle/birdsmouth)
I am working on rafters for a lean-to shed (a single slant from the back wall toward the front wall). I have watched some youtube videos and read up on speed squares and roof angles etc. I have a decent handle on that. However, all of that assumes perfectly parallel/squared off lumber. I did the measurements but that just doesn't work because each part of the roof is slightly off and not perfectly squared.
Partially due to my inexperience, the craftsmanship quality I am aiming for (low – this is small shed for just some knick knacks), and the poor quality lumber from HD, my 2×4's and the wall framing of my shed is far from perfect and have some warps.
When I measure rise/run from the left side and right side, the "rise" is different by about 1/4 inch. Additionally, there is a bit of warp down the middle. Instead of going with theoretical numbers/math, I decided to just mark with a pencil the birdsmouth by holding up the rafter on one side. It fits that one part well enough, but as I move it down the roof line it's clear that I will have to custom mark each rafter for each part of the shed thanks to the warp and my craftsmanship.
I know how to mark the birdsmouths for the left/right side, because I can just hold it on the outside of the plates and mark the lines. But I don't know how to mark birdsmouths in the middle of the roof because I can't actually hold it at the right angle and mark it, because of physics and everything.
Any tips for how to do this? Sorry if it's not clear, it's really difficult for me to explain in words but I'm happy to clarify any questions.
Submitted March 15, 2021 at 12:07PM by CaseLogic
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