There are some basic rules for designing and running a good healthy chicken shack:
1. Adequate floor space per bird.
2. Dry with good ventilation.
3. Temperature control.
4. Predator protection.
5. Keep it clean + fresh water/food = happy & healthy birds.
Many towns actually allow up to 5 chickens but no roosters. Check local rules on this if you plan to build. If you do get chickens in town, be courteous to the non-chicken majority so the rest of the city chicken people don't get punished through politics and zoning.
I submitted pictures of this coop to someone who was working on a coops book a while ago and they included a picture of it in "Chicken Coops, 45 Building Plans for Housing Your Flock." By Judy Pangman
Sources for my chicken knowledge:
"Building Chicken Coops" Gail Damerow
The City Chicken, http://www.thecitychicken.com/
Backyard Chickens Forum, http://www.backyardchickens.com/f/
FeatherSite - The Poultry Page, http://www.feathersite.com/Poultry/BRKPoultryPage.html
I recently posted another coop, a chicken outhouse with a beer can roof at diylife.com
Step 1: Floor Space, Framing, and Nest Boxes
I built this 18" off the ground to create a shady part of the pen underneath the coop.
The floor is 2x4s framed like a little porch 3 feet by 4 feet sitting on 4x4s attached with many 3" screws.
The walls are just under 4' tall and I used 3" screws to put together the 2x4s. 4' walls are a good dimension because siding and plywood come in 4'x8' sheets.
I framed in nest boxes here. I think a rule is one box per 3-5 laying birds. They like dark, comfy places to lay. Making the boxes the size of a 12" dust pan works great when cleaning the coop. Lots/all books suggest elevated boxes, but these floor boxes have worked great for three years now.
Avoid treated lumber inside the coop or where they perch; the toxic stuff can affect the birds (ie. sickness/death)