we just moved our 50 cornish x to the coop at 1 week old, because we just could not stand the smell in the house any longer. we blocked off an area about 4 x 10 and put a thick layer of straw, 2 red heat lights, and plenty of food and water. i was nervous last night wondering if they would be warm enough, but this morning they were just as happy as clams - running and flapping around in their big new space. As they get bigger, we'll move the fence back to expand it more - it is about 18 x10 in all. they have really grown fast in 1 week - they are actually outgrowing their down and have bare spots along with their feathers coming in. don't know their weight, but quite a difference when picking them up - real heft to them they are still at a very cute age. so far am very pleased with the Cornish.