Rats can get in through a hole 5/8" or larger, mink can get in through a 1" hole, etc.
I suggest you figure out what predators you have in your area and then research to find out what you need to do to avoid them getting in.
The end caps they make (and that I now have) completely fill the corrugations, so there will be nearly zero gap--about a millimeter, or less. In my area, I know I have hog snakes, rat snakes, black snakes, copperhead, timber rattlers, rats, and least weasels. I probably don't have mink, but it's possible. I do have skunk, opossum, raccoon, black bear, bobcat, coy-wolves, red fox, gray fox, and various aerial predators. I'm probably forgetting some, such as feral dogs and cats. The least weasel is probably able to get in a smaller crack than most rats. And it's a weasel, so I could lose the entire flock in one night.
I'm sure I'll have losses, but the strategy is basically (1) surround the poultry pasture with a good enough electric fence that very few of the predators will get through it at all, (2) keep the coop tight enough that none of the above can get in, and (3) use a solar-driven door to shut the flock in at night. The poultry pasture is about a half acre right now, planted with various chicken salad. It might expand, over time, and I might let the flock out of the pasture to free-range during the day, when I'm present.
If I'm missing anything else, please let me know.
And thanks!
