We currently have snow and temperatures of 0 degrees centigrade. This morning the door of my small coop (like a rabbit hutch) was frozen solid and I couldn't open it. Pullng only moved the whole thing! Eventually I managed to open it using a hammer and screwdriver but am worried about damaging it and making it worse. Has anyone got suggestion to stop this repeating itself every day? (The wood has been treated so I thought it would be weatherproof.)