Sounds like a good idea to me. Before, when I only had 4 chickens, I housed them in the garage during the winter. So much nicer not to have to go thru the snow and wind to go take care of your chickens.
I built a small outdoor coop that Im not sure how water-proof it is and wont know for a while yet. Im thinking in the really bad weather I might let Chickie and Roo stay in the garage. I know it will be boring for them (not having access to the outdoor pen area off their coop) but then again, if the weather prohibits hunting bugs outside anyway....