To help keep my chickens warm during the winter, I practice the deep litter method in my coops. I typically clean out my chicken coop twice a year, once in the fall and once in the spring. The litter from over the summer goes in the compost so it can be ready for the garden in the spring.
I start off by adding approximately 3” of shavings to the floor of my coop. The shavings will need to be stirred every week or so. You can do this manually or you can throw some scratch in the bottom and the chickens will do it for you. If the coop gets stinky or you notice that your chips are decomposing, add more wood chips. The point of this method is to make sure everything stays dry and odor free. The buildup of ammonia gasses can do more harm than good, so you want to make sure you do your weekly maintenance. By the time spring is here, there might be 6+ inches of litter in the bottom of your coop.
Many people throw food grade Diatomaceous Earth (DE) in the wood chips so when the chickens scratch and peck around and possibly dust bathe, they are getting that added benefit. Diatomaceous Earth is good for worming and keeping skin parasites at bay. Additionally, it is added protection against moisture in the coop. Be certain to only use food grade DE (carried at farm supply stores), not the kind at your hardware store for pest control. The non-food grade DE can cause respiratory irritation.
In the spring, when the temperatures are warm, I clean out my coop again and repeat the process. I try to not let the chips get as deep in the summer because we need to keep the coops cooler. Sometimes I do change the litter out midsummer if there is a great buildup.
A word about using the litter and chicken manure in your garden as compost: It is very important that the poultry manure have time to decompose at least 6 months. Also, it needs to be kept moist, mixed with plenty of plant material and turned more often to facilitate the decomposition process. I water my compost bins when I water my garden.
I really like the deep litter system because the natural decomposition of the chicken manure helps keep the birds warm over the winter. I also like it because it cuts down on cleaning. The loose wood chips and stirring keep everything dry. There is no scraping up caked up poultry manure when you clean out the coop at the end of the season. I just take the wheel barrel and flat shovel to my coops and have them cleaned out in no time. Another benefit is that you can put the litter in your compost for fertilizing your garden. I highly recommend this deep litter method for backyard chicken keepers.