Coop drawings are finished.

Here's my experience:

In addition to two 12" gable vents, I also have 8 four inch soffet vents and an 8 ft. ridgecap vent. My coop is 6x8, walk-in with only 4 chickens. When it gets REALLY cold (like well below zero - I KNOW you know what I mean), I close up the two gable vents and rely solely on the ridgecap/soffets. It does get a bit stinky and stuffy inside, so this is only temporary until the temps return to "normal," usually above zero. I leave the soffet/ridgecap vents open year-round.

I would not recommend relying on windows to ventilate in the winter time. It's just too cold and you don't want that cold air blowing anywhere near your chickens.

Don't know how many chickens you're going to have -- your coop is pretty good sized... I think that Pat recommends 1 sq/ft-ish of ventilation per chicken. She knows of what she speaks.

My advice would be to add some more vents that can be opened/closed upon your desire. Options are nice.

 

My avatar, not the image but the real bird, just flew low over the house, could probably take anything he/she wanted that is lighter in weight but no birds are out yet. And I think the bald eage was hunting fish in the rive anyway.

 

buy two dryer vent covers place them over two small holes, have sliding door on the interior that you can adjust the size of the opening. the dryer vent covers keep strong wind from howling through but allows the air movement to be ajusted by sliding open a little door. Put one on each end of the coop. I would put them in north and south. and being in hot climbs I would put in the ridgevent all else fails put in a coopala.

 

Take a look at my "passive ventilation" roof that I designed on my BYC page - so far it's working GREAT! Don't know if it would work in Michigan! I'm going to have to start leaving a heat lamp on in my coop at night cuz we're getting into the teens here in North Texas, but so far the girls are happy as clams!

 

Here's something that's working pretty well in my coop in Ohio. My coop is 32' by 12' with about 6' of one end sectioned off for feed and equipment storage. Standard shed roof about 7' tall in the back(west) and about 10' in the front(east). This coop was built in the 60's of tongue and groove pine, with a tin roof. One window, and one man door, on each short side, and four windows down the front.
When we bought this place about eight years ago the coop had been empty for years, except for the coons, possums, and the ground hogs, who had a good start on a full basement under the cement floor. After patching and coating the roof, splicing in some sideing to repair rot and varmit holes, and paint, I had tight, sound coop. And there lies the problem, it was too tight, built with no vents. I suppose they had used the windows to try to cotrol moisture and condensation, but I could never find the sweet spot, water dripping off the ceiling, respiratory issues with the birds.
I came across the idea in an old poultry book. I installed a (whirlygig) turbine vent in the roof, close to the front wall(high side), about center of the long side, spaced to fall between windows. Below the vent I built a plywood "duct" about 16" square from the ceiling to about a foot above the floor, using the outside wall as one side, and open on the bottom. At the top of this shaft I hinged about a 20" piece of the plywood that would fold flat up against the ceiling, allowing the hottest summer air to draw out the vent. Come winter, close the flap and draw the cooler air off the floor while retaining most of any heat generated by the birds. I installed three modified dryer vents as cool air inlets spaced along the top of the back wall, carefull to avoid placing them above any roosts. This helped alot, but calm nights were a problem. As my coop had electricity, I found some garage sale fans that would fit my purpose. I mounted an older window fan on a slide directly below the vent for the warm flap up weather. I mounted it on a slide for ease of removal for maintenance, about every 30 days I take it out, brush off the feathers, blow it out with the compresser, oil it, (about a 10 minute job). For cold weather I mounted a heavier attic fan near the bottom of the duct, remove the upper fan, close the upper flap, and this keeps a good air mix that has eliminated condensation and respiratory problems.This setup does require power, which has not been much of an issue,(short of Ike last year).
I realize Michigan experiences worse weather(and college football) than Ohio, but this has worked well for me.

big medicine