I am so happy that I have avoided all these pit falls my first year of chickens.
We built a small 8x8 fully insulated (including human and chicken door an double pained windows with 4 inches if air space). I ended up with 25 chickens so the coop is tight but in the winter (and we get -40 without windchill here in Canada) the small space stays warmer. My only supplimental heat was the water buck that hovered just above freezing but kept the inside of the coop at -25C or warmer. The hens even kept laying to my surprise.
We built a small 8x8 fully insulated (including human and chicken door an double pained windows with 4 inches if air space). I ended up with 25 chickens so the coop is tight but in the winter (and we get -40 without windchill here in Canada) the small space stays warmer. My only supplimental heat was the water buck that hovered just above freezing but kept the inside of the coop at -25C or warmer. The hens even kept laying to my surprise.