The Run

Along with a coop for the chickens, they also need a spacious area outside for them to roam. There are three options for an outdoor area for the chickens. You can either let them be free roaming in the backyard; you can build an enclosed run attached to the coop; or like me, have an enclosed run attached to the coop and a more spacious fenced off area around the coop/run. A enclosed wire run with a roof is much safer than letting your chickens roam freely, but the more room the chickens have to roam and scratch around, the happier and healthier they will be. So it's up to you!


If you do decide to have a run, then consider this:
-Size. If the run is not big enough for the chickens, they will start hen pecking each other because they are bored. Hen pecking is when chickens will peck each other pulling the feathers out and causing the skin to bleed, this can then result in cannibalism. To prevent this, make the run as big as you can possibly afford. The more space they have, then there is less chance of them having problems like hen pecking. I think a good rule of thumb is to make the run at least 4 times bigger than the coop. I also made the run tall enough for people to walk in, to make it easier to clean.
-Perches. I have two perches in the run so the chickens can have a break if they're getting picked on.
-Treats. If your chickens don't have access to grass or foliage, then I recommend giving them plenty of fresh veggies, fruits, seeds, etc, so they can get the nutrients they need to be healthy and have healthy eggs.
-Ground. The chickens will need dirt in the run so they can take dust baths. I give them mowed lawn clippings (fertilizer/pesticide free), fallen leaves from our sycamore trees, and wood mulch-which are all great ground coverings. I also use the run as a compost. I put in all our leftover garden greens, weeds, fruits, veggies, etc, which will make the dirt rich with nutrients to use for your plants or garden. Never use hay/straw (it attracts mites/lice and gets moldy), gravel, or sand as the main ground cover. 
-Wire. Welded wire or regular chicken wire are good coverings for the run. I have welded wire since we've got predators like bobcats, coyotes, and raccoons. You can either lay chicken wire across the run around one foot deep and attach to the sides of the run (then cover with dirt); or insert wire, wood, concrete, or cinder block a foot deep vertically on the sides of the run. So predators can't dig under.
-Roof. Many people will put a roof on the top of the run instead wire, which is great. I think this is a good idea if you live in an area that snows/rains regularly. Since I only have wire, I put plastic over the top of the run when it's raining.

The fencing I use surrounding the run/coop is regular chicken wire 3ft high (but I think it's best to use at least 4-5 feet high fencing). I have to clip their wings so they don't fly over. Though letting the chickens roam freely is more risky safety wise, it makes them a lot happier to have more space to move about and be chickens. And it also keeps them very occupied throughout the day so I don't have to worry about them being bored, which will lead to problems. Make sure you don't have any poisonous plants in the chicken area. And make sure the chickens won't be able to easily escape under the fencing.