I would not use hay/straw at all, ever. Not only will you have a slippery, mucky mess, but both those harbor aspergillus, which is toxic to chickens. I'd do a deep layer {at least 3 inches deep} of construction sand- it's got small rocks in it. You want it to drain the water down, which the sand will do if it's deep enough. You can add some sweet PDZ to it for the smell if you need to; no idea how long it would actually help being exposed to the elements.Ok everybody, I really need some advice. We are getting serious here lol. I have ordered my girls :yiipchick (8 hens) from a breeder, she keeps them til they are pullet stage. So I will be picking them up in September. Need some advice on the run floor. I live in the Piedmont Triad region just west of Winston-Salem. Our lot has a gentle slope where we are planning the coop, just enough for good drainage. However our lot is really rocky. I mean REAAAAAALy rocky . DH is not going to do any digging, it is impossible, so we are building up with cinder blocks over either welded wire fencing or hardware cloth to prevent predators. My question is what to fill the run with? Our dirt as you can see (pics below) is red, and gets really muddy. We are situating the coop back in the woods as far as possible to eliminate the red mud factor. I had thought sand, but read that if you have a lot of humidity it doesn't work so well. We thought about filling a bit with crushed run gravel then topping off with mulch or straw, want (as I am sure everyone does) what will work best at keeping the run as dry and odor free as possible. Our situation does not allow for full time free ranging, may be able to let them out a little when we are there with them but not much. Any suggestions appreciated, here are a couple of pics of our site, Nothing whatsoever grows on the mud on the side as you can see