Need some advice. Here's my coop. No ventilation at top so I always keep a window open (4 nesting boxes are in the back). 2 birds (brahma & sultan) sleep in a nesting box in the back (because the roost is slightly higher than the roosting bars inside - now I know why this isn't the best coop) and my cream legbar perches herself up in the rafters (she's 6 months old and can fit). I live in Ohio and have had my flock of 3 for 6 months. They have been doing well in this coop so far, it has gotten down in the 20's at night. Tonight is supposed to get down into the teens. How cold can they handle it before I need to roll them into my garage? Brahma is 8 months old and cuddles my Sultan Roo (also 8 months) under her wing. My 6 month old cream legbar just lost her cuddle buddy last week but she perches up high so she's probably good. I usually close one window and leave one open, because there is no other way to get air exchange. I have closed both windows before but I don't like to. Their breath has created condensation inside so I stopped doing that. Any opinions on the temperature they are ok to outside?