My coop is 6x8 foot. It has two large canopy windows on the front, they are about 20"x20" each, maybe 18"x18" (I've never measured them. The back side has two 12x12 slider windows. When I put the metal on my roof I kept it several inches short of reaching the peak. I put hardware cloth over that opening and then put my ridge cap on, so I have ventilation all the way down the roof ridge that is about 5 inches. Plus I leave the eaves open on each side and they are just covered by hardware cloth, so there is a lot of ventilation there. Here are some pics of the vents. I bought a gable vent to put in above my walk in door. but I haven't done that yet, maybe once it warms up.