I'm from Michigan and used TWO BALES of straw during cold weather in a pretty small coop (8'x8' approx.). I shook it out and it went almost up to the base of the roosts. The chickens spent time pecking about in it and it kept them busy for quite a while getting it all mashed down. Sure, it's sort of heavy to clean out in the spring, but a pitchfork and shovel do the job all right.
The only thing I dislike about using straw is the dust.
