Howdy, It's getting cold at night--down to 40 or 45 deg. at night here in the front range, and my 18 week old girls are hunkering down on their roost at night. I'm wondering what I need to do to keep them comfortable as fall (and winter) sets in. I have three girls in an A-frame coop. The top of the A has a 9" x 9" cutout for ventilation on each side, but unfortunately, the girls roost is close to the window. Seems like a cold place to sleep, so I have a couple of questions: 1. what is "too cold" for a barred rock and a couple leghorns? 2. do i need to cover at least part of the ventilation windows? 3. do i need to insulate the roof of the a-frame? Right now it's just 1/4" thick OSB board 4. should I heat the coop with an outdoor heat lamp? any advice is appreciated!