We are renovating a shed that is preexisting in our yard to be our coop. It is an 8x8 with about 8 feet of vertical space with a gable roof. We currently have 4 chickens. We would want to get 2 more max. Is 64 sq feet too much for winter for 6 chickens? We live in the Salt Lake Valley in Utah. The lows are typically in the 20s with the few days in the teens. Would the chickens get too cold in that much space? We will also have a run and option to free range the garden.