Thinking about your last post, I have a few suggestions...
Also, I’m in the city and there’s a serious rat issue, not to mention not a lot of space, so that’s why I went with a raised hutch.
I don't have a rat issue, but I do have a raised chicken coop. I think it helps to cut down on potential predators. Nothing wrong with a raised hutch.
I think I’ll put a solid floor in the hutch and try the pellets bedding.
I advocate for using any free source of litter you can get. I have tried free wood chips, leaves, and dried grass, but my current favorite bedding is shredded paper. I shred all our household paper and cardboard using shredders I buy from the Thrift Store at less than $5.00 each. The used shredders don't last forever, but they pay for themselves in terms of how much coop litter I can make before they die. Well, that, and I shred my bills, etc... anyways.
Nothing wrong with mixing different types of litter. If I am short on shredded paper, I'll mix in leaves, wood chips, or dried grass to get the depth of coverage I want.
If you have to buy litter, I do hear pellets are good. You might also want to consider pine shavings. I just encourage you to consider using free resources because it will not only cut down on your expenses, but in my case, it reuses sources of material that previously I used to bag up and send to the landfill.
I need to think about how to keep the rain and rats out of an aviary, and the ground from becoming a mudpit. Maybe bury wire, then layer gravel and dirt mounded a little, then bedding. Perhaps siding for rain that can come off in the summer. Further suggestions welcome.
There are a lot of people who advocate using a wire apron around the run. They say if you lay down wire on the ground, maybe 18-24 inches out, that digging animals will give up trying to dig a tunnel into the run. It run contrary to a digging animals nature to dig a long tunnel where they could trapped. So, they attempt to dig a tunnel next to the run wire and discover the wire apron and give up. Using a wire apron laid on the ground is a lot easier than trying to bury wire 18 inches deep. If you don't want the ground wire apron to show, you can cover it with dirt and let the grass grow up through it.
After my chickens ate all the grass and pulled everything out to bare dirt in the chicken run, I converted my entire chicken run into a chicken run composting system. I dump all my wood chips, leaves, grass clippings, and used coop litter into my run. My run never gets muddy. All that litter breaks down into Black Gold compost which I use in my raised bed gardens. It's just a win-win for me.
You don't need a lot of litter to keep your birds out of the mud. Maybe only a few inches. Because I compost everything organic on my property in my chicken run, my run litter is almost 18 inches deep this time of year, full of leaves. Over winter, it will break down and fall to about 12 inches deep.
But I remember back when I first started that only a few inches of litter were enough to keep my birds up and out of the mud. Again, I have access to lots of free organic resources to use as run litter.
Every year, I harvest hundreds of dollars of Black Gold compost that I use in my raised beds. If you garden at all, that used litter into compost is the best. If not, at least organic litter in the run will keep the birds up and out of the mud.