I have raised/open air coops and I use hay in all of them. It's so much easier to clean. All I do is pick up the hay and poop on the hay put it in the compost pile, sweep out any poop that may have fallen out from the chickens scratching and put more hay down. The girls love it. I only pay $3.00 for a bale of hay. It's not expensive at all.
Here are pics of 1 of my raised coop with and without hay.
With hay:
Without hay:
Here are pics of 1 of my raised coop with and without hay.
With hay:

Without hay:


