I agree, insulate.
But here is another concern to think about:
Quote:
You will have one heck of a time (transl: it will require extensive engineering of hooded and possibly ground-warmed vent openings) ensuring adequate ventilation of that small a coop without getting harmful subfreezing drafts.
The problem is that in such a tiny space (both in terms of footprint and in terms of height) there is nowhere for incoming air to go EXCEPT straight at the chickens. And you MUST have adequate ventilation -- you cannot shut it up tight, especially in such a tiny space -- because chickens give off a whole big lot of moisture and you will have severe humidity problems and the chicken health woes that accompany them (frostbite, respiratory disease etc).
If you are really intent on overwintering your chickens in a Michigan climate in what is basically a tractor-sized coop, you need to plan now, in the design stage, for how you will buffer and possibly warm the incoming air so that you can have respectable airflow through the coop (thus keeping the coop from getting all damp and ammonia-y).
jm$0.02,
Pat