Chuckie chicken
Chicken Chucker
Most likely 2', I winged it. I built it last spring, and haven't been in Canada for almost 6 months, soenough photo there I can see what you did - 2x4s @ 2'oc, just like I framed my metal roofing, didn't see a call out for your purlins, or their spacing. 1x4s also 2' oc?
