I had two A-Frame 8 ft. long coops with about as much ventilation as you have and they didn't have enough ventilation. But I had 20 small birds in there only to sleep (ranging in garden all day). There were only supposed to be 10 in each coop but they insisted on sleeping together in one of the coops.
I disassembled the coops that I had made and turned them into range shelters.
Your coop looks great but you might need to put a long strip of ventilation along the length of it, with some sort of overhang to keep the rain out. I'd actually get in there with the chickens /door shut and see if it gets stuffy.
VERY decorative coop and good job! As for ventilation, I don't think there is enough ventilation there unless the coop is for a couple of chickens.
OK I did a search and found a pic of what I was thinking of: scroll down to mid-way and see the rectangle they cut near the roof (yours wouldn't need to be so wide) - hardware cloth 1/2 inch is good to line it with:
just a suggestion!
Edited by ChickensAreSweet - 8/6/12 at 5:00pm