I don't have a roof on my run. I have had a possum come into the coop/run but that's cause the door was open since my chickens free range too. The run does get wet and my chickens don't mind, it dries out well and I keep their feed inside the coop but have numerous waterers outside. If I had an issue with flying predators then I would add some netting but having an open run is fine with me!