Wow, our seramas must feel abused. We have only A's and B'a, we kept them outside almost all winter, it got down to 0 degrees and they were fine, just had a nice tight coop for them to be in out of the wind. When it dropped below 0 I moved them into an uninsulated building that had a small heater in it, kept it around 25 degrees....and ours are silkied....they can handle colder temps than most people give them credit for, but with any bird, when you start getting into extremes, you may lose one or two that arent the hardy ones....but for good hardy, vigorous stock, breeding from only the hardiest birds will give you good hardy birds...I know its not the most popular idea but a tried and true one...