I have also used poultry staples when I know I won't need - or want - to modify what I built in the future. Poultry staples are very cost effective, and extremely sturdy as you hammer them in. Their drawback for me has been when I needed to remove them to do an upgrade or modification. That's...
I just put a new corrugated steel roof on the poultry complex run this spring. Gilbralter utility gauge panels , used the Teks roofing screws, has a 3:12 pitch. No plywood needed, the purlins were built on the red numbers. Corrugated panels on a frame built to spec will have plenty of support...