Oh, and I would use wood shavings for the floor of your coop. It keeps the smell and moisture down as the ammonia smell can be hard on the airways and could cause illness. If you use the "deep litter" method in the coop, (4 inches of wood shavings) and then turn it occasionally, you wont have to...
I don't know your locale, however I have the same conditions here in my garden for my chickens, all dirt. I have a dry climate. So what I do is spread a grass hay all around, (Burmuda Grass Hay, I get from the feed store by the bale,) and this gives them something scratch around in and eat since...