I have a super secure run (thanks to some advice on here). It's against the side of my shed, and has 6 ft chain link (with privacy slats) on all other sides. Half is covered with a tin roof, the other with a sturdy welded wire (I think 2x4" or something like that) so it is totally enclosed and predator proof. (also has hardware cloth on bottom 2 feet and welded wire 'apron' to discourage diggers.) All that despite no evidence of predators, but it wasn't that much work to beef up the existing fencing so I figured why not. I also added 6x1 boards around the base (with gaps for drainage) and added 6 feet of sand to the entire run, as I live in Oregon and it's already raining more often than not. I'm very happy with the sand as it's super easy to keep clean. We built a plywood box all nice with ventilation and a ramp and all that good stuff and put it under the tin roof side...and they roost on top of it. They seriously only go inside to eat because I stubbornly put their food in there so they'll use it. This would be why I beefed up the run security so much, so nothing could get in and catch them in their sleep. I didn't like them roosting in their poop on the flat top, so I tossed an old pallet on top at an angle and they are happy on the middle slat of that, (top slat is a bit too close to the ceiling I think) and I have a piece of plexiglass under them that I scrape off once a week and rinse once a month or so. Now I am wondering, should I just get the big, bulky plywood box out of there all together and just build some nicer roosts? Right now I've got 4 hens and a not yet mature showgirl and I think the one middle pallet slat is already crowded, the showgirl sleeps on the bottom one altho that may just be a pecking order thing. I plan to get a couple marans in the spring so they will need to roost somewhere. The run is in a VERY sheltered area as my neighbors shop is close to my fence plus the privacy slats in the fence make it feel more enclosed and keep the rain out. So they are fairly cozy between my shed and his shop. We usually get maybe one snowstorm a year up here, it mostly just rains and rains and rains... I'm not sure they would smart enough to go in the hen house even if it did get really cold. I think if I do this I may cover the other half of the run with that corregated greenhouse stuff to help hold a little more heat in.
They most certainly are creatures of habit Make sure there is a secure place for the hens to lay their eggs and some sort of roost for them to perch on. It's funny; you can put a 2x4 right along the ground on end and they'll perch on it (just 3.5in off the ground), LOLz. That's about it. Sounds like you got it pretty well covered.
A friend of ours houses his chickens in roofed chain link dog kennels. He tarps the sides in the worst winter weather (which in North Texas is not that bad, but we do get down below freezing from time to time). He's been keeping chickens here for more than 25 years, so it's something that can work under the right circumstances. Chickens need to be able to stay dry and out of cold wind. So if your run is roofed, and you have the roost areas windblocked, it should work fine.
I also have a super secure run, electrified and fortified... My hens only use the coop for the nest boxes. When they decide it is too cold, and that has only happened once, they go inside for the night.
I also use chain link dog kennels with only a medium sized wooden doghouse in it. They lay eggs in the dog house and scratch up the hay in there sometimes but have NEVER gone in there to get out of the weather. They perched on top of it till I added a 2 x 4 roost about a foot above the top of the dog house and now they roost on that. I do have the kennels covered with metal roofing and will add a tarp to the north & west side again before really cold weather gets here, which worked well last winter.
a run with roosts and a nesting box is pretty much what i built. one end of it has 3 solid walls and a roof plus some ventilation. that's their "coop" part. the other side has 2 solid walls with all the open spaces covered in hardware cloth. the only thing i wish i had done different was roof the whole thing. turns out, the chickens don't really appreciate time in the sun and don't go down to that end until right before bedtime. i'd say for you, the biggest question is, how will they do on the coldest night of the year. if it's not so cold and they have solid shelter, then you might as well get rid of the unused box and give them some more space.
