we are planning on having a small run that is very secure and has plastic roof over it and then when im home the chickens will be allowed in a big connected run area that does not have a roof on it. does this sound all right? will they fly out if their is no roof? its about 6 ft and if they can fly out of the run then when they free range will they fly over the fence to the neighbors yard? does aviary netting last through lots of snow?