I live in SE Texas. Last winter had some very cold days (for down here), and the same is expected this year. After removing the mower, and other gas related items, I plan on setting up my portable coop in the garage, so I can bring them inside when it's too cold. My outside coop/run is under a roof, and I have a tarp stretched overhead too. I have 2 Partridge Silkies, an EE, and a BR. At what point does a coop/run need to somehow insulated? How cold should it be before I bring them inside?