We started with chickens this Spring, in East central MN (by Pine City). The temperature has varied between +104 in summer and -30 F in winter in my experience over 5 years on this site.
Our coop was somewhat over engineered, perhaps...
We re-built an ugly, (cheap) used 10'x10' shed into a coop. Here's what arrived- No insulation, doors that did not close, sheathing popping off. A good roof though-
http://i559.photobucket.com/albums/ss31/Bert2368/photo-133.jpg
We fixed the exterior and doors, added windows, an automatic pop door, 2" of foam insulation, an infra red reflective (aluminized) vapor barrier/building wrap under the roof and outer walls, made the exterior very tight with caulking and trim over any gaps or cracks throughout.
Then we provided ventilation of the space between INTERIOR insulation and OUTER WALLS & ROOF.
We put vents under the walls, at eaves and at the peak of roof. We left an air space between the outer sheathing and the IR reflective layer everywhere. This allowed air to rise between the outer walls and insulation all around, flow through the space between the outer roof and ceiling insulation, then escape through the vent at the roof peak. During the summer, it was never any warmer inside the coop than outside, and generally it was slightly COOLER. We were pretty happy with that! No heat stressed birds were observed.
Then it got cold. We had 2 windows and the pop door for interior ventilation with the man doors closed, all these were on the same wall. The tops of windows were all below upper roost level- Our Dorkings wanted to roost as high as possible and we obliged them...
Experienced people are now shaking their heads at our newby failure to provide a good INTERIOR ventilation system.
The interior of the coop was paneled with a white plastic sheeting of the type used in wet areas of commercial kitchens- Floor, ceiling and walls. We used the included binder strips at the joints and filled all the grooves with silicone sealer as we installed this plastic. The inside of our coop would hold WATER, it was so airtight. Our intent was to be able to pressure wash the coop interior without fear of water entering the insulation behind the interior paneling. We succeeded-
The temperature dropped to -21 F a couple of nights last week, daytime highs below 0 F. The interior of the coop was draft free and about 30 F warmer than outside temperatures, with no heating beyond the 24 birds body heat and the covered, insulated water bucket. But I found some frost bit tips on the combs of a couple of roosters- And when I put a temperature & humidity sensor in the coop, relative humidity was around 70%... My glasses fogged when I went inside.
Cracking the windows and opening the pop door helped very little, especially at roost level where all the humid, warm chicken breath was.
I spent a few unpleasant hours outdoors in the snow at subzero temps with power tools. We now have a vent at the peak of the interior, and another vent at the opposite side about 8" above the floor (we use wood shavings as deep litter, so vent is above highest observed level of litter).
The new vents are aimed to avoid draft on perch areas. Coop interior now has cross ventilation, air goes in at base on one side and out at peak on the opposite side. The humidity and interior temperature both dropped, we are now below 25% relative humidity and only about 10 F warmer than outside temperature at night. I give the chickens extra black oil sunflower seeds and cracked corn, they're going to need more fuel now... They yum it right up!
Birds are much happier, they sit on the perches and fluff themselves up, lay down to cover their feet and some tuck their heads under a wing and snooze... They look like a row of feather balls!
I'm building new perches with built in poop/sand boards under. I'll extend this all with some pictures when I have more time-
