Thank you, Leahs Mom! I really appreciate this and my chickens will soon.You can get a big bag of peat moss from any home type store. I got mine at Menards. I think any place like Home Depot, etc., that has a garden center will have it.
I did use sand for awhile - and at one point just dug dirt from the garden. At this time of year, if the ground isn't too frozen to dig the dirt, it would be holding a lot of moisture so you might have to let it dry out before putting it in the box. They didn't like the sand as well as the dirt or peat moss.
The WOOD ash helps prevent lice and mites. You only use a very little of it percentage wise in the whole box. You can get that from having a bonfire with wood or from someone that has a wood burning stove. Just ask them to save a bucket of their ashes for you!