Unless you have some special "exotic" breed there is no need to bring chickens into the garage/house at 25 degrees. If you kept chickens in a heated coop all the time then threw them into freezing temps they would have a problem. If you allow them to live in the natural temps to your area they will adapt and be fine. There are plenty of people on here who live in Canada with coops that are not heated. Some have open sided coops with only three sides closed in. Keeping the water from freezing is important though.
