Let me explain a bit how I set this up. There are three 3" screws holding the small boards to the cross member. The 2x4s spanning the width are set up at about 15 degrees, so the rain won't accumulate. We don't get snow here, save for maybe an inch once in a while. The corrugated roofing panels are also not heavy at all, so the load bearing upon the three screws is minimal.
I did give consideration to the loading when I started building it and given our particular weather here, I didn't see a need for a tremendous amount of support for the roofing panels. As for the wind, the coop is quite well-protected from it due to it's proximity to the tall woods next to it. Even when we had very high winds a few weeks ago, nothing in or around the coop was affected. My Big Foot cutout was blown over, but it's not secured to anything, and a couple plastic chairs were knocked over, but that's it. The winds were high enough to warrant a tornado warning too, so it was a good test of the coop.
I will be looking at it more closely once it's complete to see if it needs to be shored up anywhere, but so far, it's very strong.
Thanks for your concern!! I really appreciate it!!