9 out of 10, but the pop door opened a bit last night and the water was frozen solid and I could see my breath in the coop this morning. It was 24 degrees F inside and 20 below outside. After fastening the pop door and turning on a 250 heat lamp, the temperature began to climb slowly up to 30 and then warmer. Several Rocks shivered on my legs and I put my arms around them with palms on their backs and they warmed up and began to forage. We're in a cold snap - it was minus 38, but much better now.