I have my 4 month olds in an unheated 6x 10 "tack room" attached to a run in. There are 23 birds in this space. We've had over 3' of snow this week and it's supposed to get cold..single digits an the next few days. They don't go outside and don't have a run yet. I was thinking about putting a chainlink panel over the run in opening and letting the out there during the day. My concern is how draft free should the coop part (the 6x10) be? The eaves are open with chicken wire over them and there's a 2' space above the wall with only chicken wire as well as a hay feeder as the top half of the door to the run in. I was thinking of covering all of that with a tarp. Should that be enough or would they also need a heat lamp? I have chickens in a seperate coop. They free range during the day and get loacked up at night. I only put the heat lamp on for them if temps fall below zero. Most of them don't have large combs or wattles. (Sumatra and sumatra mix).