I have 2 coops: one is on a concrete pad I poured and the other was a reused cattle loafing shed on 1/2 on dirt and 1/2 on concrete. The concrete is the way to go IMHO. I attached the coop to the cattle shed, and built a 600sqft run attached to he coop. Although I free range most of the day (6am-8pm), they do use the run during bad weather or when there are a lot of predators around. I would suggest you have the contractor come out and take a look. Draw up a sketch of what you are wanting, and go over the specifics with him
We do the deep litter method for bedding. I put 5 bales of pine shavings in the coop then add organic matter (hay, straw, pine straw, etc) every week or so. after 6 months, I clean it out and start fresh. I've not had any issues with cold and concrete with my chickens. you won't need too many nest boxes. Of the 29 hens I have, they only use 2 of the 4 I have. Occasionally they will lay under the poop board in the corner or in one of my rabbit barns on the hay.
inside the coop before bedding. I suggest adding a poop board
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