I live in Central Tennessee and Temps in winter is freezing or above with a few days below and sometimes in the teens. I have a 1/2 acre pond which did not freeze last winter. Their current duck house is 8'x8' shed with with three sides fence the back is enclosed. I am planning on using plywood to enclose all sides of the shed. The ducks are free range during the day and locked in the house at night. Any suggestions?