BTW the house my "one" feral female cat lives in, just off to the side of the deck, I had an Amish man make it for me. Saw how he could build dog houses and rabbit houses, so we combined the two, it has two doors, for ease of escape should a night creature come around, walls are thick about 3 inches. It is up on legs to meet the same level of the deck. But, its getting old, about 8 years now. Going to have to get a new one for next winter. My neighbor likes to build things out of wood, and he is retired, might ask him if he can, then draw out what I want. She the cat is the last hold out that will not come inside. Even her mother comes in side and uses the cat door well. Anyway, in the cat house is an adult heating pad, plugged into an outdoor extension cord so its out of the way of being exposed to weather etc.