@electrycmonk You may have covered this earlier in your build thread so if you did I apologize for asking, but why didn't you use purlins under your lean to roof?
That's a good question. I don't believe I said anything about purlins as they are -to my limited knowledge- used as supports that are 90° to the rafters. Correct?
Well, the serious storms that had been occuring (see pics earlier in thread on post #30) doing serious damage to neighbors barn/shed caused me to rethink plans. I wanted the metal roof panels to have as close to 100% hold down on the long overlapped sides. If you look at post #53 above, you can zoom in and see the 26" wide panels and screwed in an avg of 3-4" spacing all the way to the peak on the rafters.
The fence top bar & the middle 4x4 posts with the dual 2x6" support beams allowed me to maximize the length of the 2x4x12's for the rafter strength. There is a bunch of construction calculators on the web for finding out a beams maximum load and span rating depending on what type of wood and where it's harvested. As well as for metal beams too. The math I found was very, very helpful as I knew that the roof load was only the metal roofing panels and rain/wind/snow loads. The span for the 12'ers was ~11' with "x" load. I put the 2x6's on both sides of the 4x4's the make the load span about 9'. Then when I was looking at the point of supports on the west side of the coop I realized that the 11' was getting too close I experimented with cutting a 2x4 to be a vertical support that transferred the load to the frame of the coop at the roof/wall point. Then I added some cross beams to reinforce them.
See last picture in post #4? It's the frame of the coop BEFORE the roof rail mod to the run.
Post #7 has the "cleaned up redrawn" pics at the top of the post
Post #8&9 have images showing the rafter rails and the 2x6's and rafters spaced with the roofing panels
Post #9's last picture -if you zoom in- you can see the ~18" tall 2x4 that I had the specially cut 4 angles to them for fitment that required a soft tapping into place before being screwed in.
Post #14 inside the coop will show you that ~18" in the upper right corner (the styrofoam is cut right up to it for visual aid)
Post #17 picture#1 & 5 specifically give you very good view of the ~18"we and the area it's used in. The other pics give good followed up but, obviously hide that key part from view.
Post #27 & 50 has a couple pics to zoom in on as well.
How's that for an answer? My dyslexic brain took a while to write this, I hope it was clear & concise enough.
Upon reflection, one could say that I used the fence top rail, the 2x6's and a few parts on the coop frame as "under side purlins", eh?
Penny for your thoughts?
