can I box in the roosting poles for added warmth?

I think if they can get on top of it that's where they would sleep.

Try to think of it not being the temperature that is the problem but rather wet and wind chill.
As long as they are protected from drafts and won't get wet when windy rain they will cope with some pretty low air temperatures quite fine. They are designed to hold warm air round their bodies themselves, that's why they get all puffed up in the cold .

So as long as you keep them out of winds so it isn't ruffling those little puffed up air pockets they can keep themselves warm quite well.

 

I’m not sure where you are located. What type of temperatures are you talking about?

I’ve seen chickens sleep in trees in zero Fahrenheit weather. These chickens were not roosting on a dead branch overlooking a bluff, squawking in the teeth of a raging blizzard. You’d see that in a cartoon, not real life. They were in a protected valley, in more of a thicket, and could move around behind the tree trunk to get out of the wind if they needed to.

But those chickens did not freeze to death and did not get frostbite. They were acclimated to the weather and they had great ventilation. With them sleeping in trees, their body heat did not warm up their environment. They just fluffed up and let their natural down coat insulate them and keep their body heat in.

I think their ability to move to get out of a direct wind and them having plenty of ventilation was really important. Ventilation is important to carry moisture away, but in your nice big coop and with a small flock, ventilation’s probably not all that important for you. In that volume, moisture would build up slowly. You would not need much of an opening up high to take care of it. It’s when you pack a lot of chickens in a small space it becomes more important.

I have no idea what kind of cold you are dealing with, what is cold to you when you walk from a heated building or what is truly cold to a chicken wearing a down coat and used to living in it. If you are where it is truly cold for chickens, where it gets well below zero Fahrenheit, you can try building a hover. That’s a not too large relatively shallow box with an open bottom. The idea is that they get under it and their body heat is trapped so it keeps them warm. But, yes , they will probably sleep on top of it if they can get to the top. If they can’t get to the top don’t be surprised if they don’t sleep under it and move to someplace more comfortable to a chicken wearing a permanent down coat.

Where are my manners? Welcome to the forum! Glad you joined us.

 

You could add a 2x4 wide side up about 8 inches above that shelf and that would get them off the poop pile.
They are probably going in the barn because it's out of the wind. They should always have access to a dry place out of the wind and secure from predators, especially at night.

Brahmas have pea combs, they are pretty small and great for your climate. Golden comets usually have single combs.

 

+1

I understand your logic with the bookcase to create a more confined area to create a warmer area via self generated heat. Outdoor dog houses often follow this logic and they are built just large enough for the dog to turn around but has the confined benefits for self generated heat. I would not confine a roost area since they poop there and need the space and fresh air. Birds will do well with a roost area that is draft free, sheltered from the elements, easy to access, and has plenty of room for them to move about. You may consider a poop bench/shelf under the roost bar and add straw under the bench. They can choose to sit up on the bar or snuggle in the straw below bench during extreme cold.

 

One thing some of you may not have though about is how much easier germs and diseases spread from bird to bird inside of tight and warm roosting coops. Warm air holds more moisture than cold air and hence more disease organisms. Diseases are especially easy to spread were chickens are forced to sleep cheek to jowl. Mega ventilation, like wide open sleeping quarters in an old peach tree seems to equal healthier birds.

I still have two pullets out of 11 who are roosting 40-50 feet up a tree. When they get hungry enough I will lure them into an empty pen and that will be how I catch them. Yes some birds have lost the tip a toe, and from time to time there are a few with frost bit combs but it seems such a small price to pay for the other health benefits. But then again my chickens can fly better than a wild turkey and they preen themselves like ducks. Even though they have a chicken house or shed with roost poles eight feet off the ground and a nice dry roof overhead, every year 80-95% will still take to the trees at dark.