That is such a cute coop! I'm sorry you're having problems. I think making a sturdy screen door out of hardware cloth would work, especially as a temporary measure and for summer use.
If it was my coop, I'd add a big vent on the back wall, at the top, also. That way you'd have cross ventilation, as well as more ventilation. If you did that, I'd think about lowering the roosts a little, to keep the chickens out of a draft in cooler weather.
We have very hot, humid summers here and can have both temperatures and humidities in the 90s. Our 8'x10' garden shed style coop has a pair of windows at one end that have a combined size of 4'x4'. All of the windows on that coop swing open, so the ventilation opening size is the same as the window size. It has two smaller windows that are 18"x24" on the opposite wall, on either side of the door. A third 18"x24" window is on one of the sides and makes a corner breakfast nook for the girls to look out of.
If it was my coop, I'd add a big vent on the back wall, at the top, also. That way you'd have cross ventilation, as well as more ventilation. If you did that, I'd think about lowering the roosts a little, to keep the chickens out of a draft in cooler weather.
We have very hot, humid summers here and can have both temperatures and humidities in the 90s. Our 8'x10' garden shed style coop has a pair of windows at one end that have a combined size of 4'x4'. All of the windows on that coop swing open, so the ventilation opening size is the same as the window size. It has two smaller windows that are 18"x24" on the opposite wall, on either side of the door. A third 18"x24" window is on one of the sides and makes a corner breakfast nook for the girls to look out of.
