It may also have something to do with the number of days of extreme heat where I am. 105 degrees in the shade is a cool summer day here. We have temps over 110 degrees for extended periods. It has already been in the 90's here this year. It's only mid-February. The hoop coop is not in the shade. The chickens in the hoop coop spend most of their days gathered in the shade around the pond, or under the deck of the house on the hottest days. We also have extreme winds associated with thunderstorms. The microbursts can rip a tarp to pieces in no time. They can come from any direction.
I have a billboard tarp but made the mistake of getting a new one. It does not have grommets or a pipe sleeve, and I have not been able to successfully secure it. It is extremely thick. The shipping weight for the 16' x 16' tarp was over 70 pounds. It might last longer than the other tarps I've been using, but it does me no good if I can't put it up. I can change out a regular tarp by myself in under an hour.
You can buy grommets and tool for large grommets fairly cheap. Double your layer at the end where you will put grommet in and it will hold better.
You can also buy a plastic insert that fits in a ring but they may not work if they are that thick.
I have grommets and a grommet tool. Problem is the tarp is so heavy I can't maneuver it by myself to put them in. And I haven't been able to sweet-talk any friends into helping with that project. Wonder why?