Putting a roof on a chicken coop is not much different than that of a shed or house. The good news is that if you are going to have drafts or seams, having them at the top is much better than having them at the bottom. The bad news is that planning the roof requires some time with triangles, and putting on the roof will require ladder work, and goes better with at least two people.
One slope or two?
A roof with two slopes is called a gable roof. You may choose this for big structures, or just because you like the traditional “house” look. If you pick this version, you’ll put up trusses over the flat top of the wall frame.
A roof with one slope is much easier than two. You may even be able to cut out the step of creating trusses if you build the wall frame so that one wall is higher than the other. You can choose to have the roof slope forward towards the front of the coop, or towards the back. If your coop is up against your house sloping it so that water rolls towards the front (and away from your house foundations) is a good idea. Otherwise, if you slope the roof towards the back rain and snow will run off that direction, making the front entry clearer. A one slop roof is known as a shed roof.
Those triangular wooden frames between the walls and the roof are called trusses. You can either purchase these pre-made in common pitch heights, or create your own. I go into much more detail on how to build a truss on my website. However you choose, you will need a truss every 16-24 inches along the width of the house. Screw them in place with truss fasteners.
The roof itself can either be plywood covered with felt and asphalt shingles, or corrugated metal. This is a great time to call around roofing contractors or scrap metal dealers to find a second hand source for material. Fastening the roof to the trusses will depend on the material you use.
When the time comes to raise the roof on your hen house, plan ahead for safety. If you are on a ladder, it is a good precaution to make sure someone is close by. Use temporary braces to hold the trusses in place. Get a second person to lift the trusses from the bottom, and grab tools so that you don’t have to constantly go up and down the ladder. Take a water break if you find yourself getting overheated while shingling. The roof on your chicken coops will keep your hens safe for years. Take your time and follow precautions so that you are safe, too.