I wish I'd known that my chickens would fly/glide off their roost instead of hopping straight down. My top roost is about 4 feet off the floor and about 5 feet from the wall. Sometimes a chicken (mainly the larger ones, like my rooster) hits the wall on their way down. Not pretty.
Build it so you can collect eggs, open/close door, and add food and water without entering the chicken area. I LOVE my little feed room area that's just 2x4 feet but keeps my shoes clean when I step in to do chores.
Think about feed storage--where are you gonna put those five 50 lb bags you just bought? How are you going to keep mice out of the stored feed?
Isolation room--what about when a new animal needs to be quarantined, or a sick one needs rest, or a broody wants to hatch some chicks?
If you're a gardener then consider the deep litter method. I love it for these reasons: 1. amazing compost happening right in my coop--sometimes I see steam rising as they scratch. 2. warmer in winter, 3. soft cushion when hopping down off their roosts, 4. totally free bedding--I rake up leaves and grass, dry them, then store it in big bags, add a 3-4 inch layer every 4-6 weeks as needed, 5. minimal effort, just one clean out in the spring, 6. no smell--sorry, but poop boards holding fresh, uncovered poop up in the air sounds pretty smelly to me. If a chicken poops on the window sill in my coop I can smell that one poop very strongly, whereas there's no smell from a lot of poop falling in and getting scratched under the deep litter (hint: add table scraps to the area under the roost so your chickens will scratch and hence do the turning under for you).
Finally, build with flexibility. Consider semi-portable interior walls that can be adjusted over time as needs change. Good luck and have fun!
Build it so you can collect eggs, open/close door, and add food and water without entering the chicken area. I LOVE my little feed room area that's just 2x4 feet but keeps my shoes clean when I step in to do chores.
Think about feed storage--where are you gonna put those five 50 lb bags you just bought? How are you going to keep mice out of the stored feed?
Isolation room--what about when a new animal needs to be quarantined, or a sick one needs rest, or a broody wants to hatch some chicks?
If you're a gardener then consider the deep litter method. I love it for these reasons: 1. amazing compost happening right in my coop--sometimes I see steam rising as they scratch. 2. warmer in winter, 3. soft cushion when hopping down off their roosts, 4. totally free bedding--I rake up leaves and grass, dry them, then store it in big bags, add a 3-4 inch layer every 4-6 weeks as needed, 5. minimal effort, just one clean out in the spring, 6. no smell--sorry, but poop boards holding fresh, uncovered poop up in the air sounds pretty smelly to me. If a chicken poops on the window sill in my coop I can smell that one poop very strongly, whereas there's no smell from a lot of poop falling in and getting scratched under the deep litter (hint: add table scraps to the area under the roost so your chickens will scratch and hence do the turning under for you).
Finally, build with flexibility. Consider semi-portable interior walls that can be adjusted over time as needs change. Good luck and have fun!
And now I have chickens and I'm so happy playing with them ;P I still have things to build, I have no choice, so I will bite the bullet and get them finished. However, they are not as imperative as the coops were, so I can take my time 
