My DH built me 2 raised coops with a covered deck in between because I told him that chickens don't like snow. They can also go under neath the whole set up. They never stay inside even when its brutally windy. Our lowest temp so far was 7 deg, and they still came out. Some of them charged the door when I open it, others lagged behind waiting for it to get a little warmer. I have to push my orps into the coop at night, so I can close the door. They hang out on the ramp and the deck, until I decide its time to go in. My EEs are in when dusk comes. I don't use a heater, but I do have winter hardy breeds.