We used this "coop" design for almost 2 year with up to 15 hens. It was built under a 36" deep 42" high workbench that was built across the back wall of a 10x16 shed. The hens were free-ranged in my fenced backyard, so they were only in the coop to lay eggs and at night. They were locked in at night, and during any blizzards, but otherwise were free to come and go. I never had any issues due to overcrowding, and consistently got 12+ eggs a day.
This would be an easy design for someone who has an existing shed in their backyard, and doesn't want to have a separate structure for the chickens. It is also very discreet, as it does not look like a chicken coop. Assembly costs were super cheap - a few 2x4's, some hinges and latches, plywood, OSB and insulation. I would estimate the total cost was well under $150.
I do not have any step-by-step photos of the construction, but I can tell you it was super simple. Basic framing with 2x4's and faced with plywood. We did insulate the interior walls of the coop with foam board, and lined them with thin OSB, and it did help maintain a more comfortable temperature in all seasons. The front wall of the coop was not insulated, and only consisted of the plywood you see in the pictures. The doors/access hatches were only plywood, they were not reinforced with any other wood. They were lightweight enough that the hinges had no trouble supporting them, and they swung freely.
Instead of building a door for the chickens, we purchased a doggy-door from Lowe's and installed it in the coop. We removed the weather flap from the door, as the chickens weren't keen on walking thru it. The door does simplify things, as the install is nothing more than cutting a hole and drilling 4 holes for screws. The kit comes with an easy-to-use template. The only downside is that you have to manually open/close the door, it cannot be done remotely. But it does lock closed securely and 100% predator-proof.
Ventilation in the coop was accomplished via the large window on the back wall, and the fact that the front doors of the shed were left open in all but the worst weather. I fashioned a predator-proof screen door to fit the opening by using a cattle panel cut to the correct dimensions, and attaching chicken wire to it. This was all held in place by 4 eye bolts and double ended snaps. I do not have a picture of the completed screen door, sorry. In the summer, I would attach a box fan to the large center door opening, to move more air.
Roosts were made using closet hanging rod/shelf brackets and a wooden closet rod, cut to size. Nest boxes were stacking bins. Everything could be accessed via the 3 doors/hatches. I was able to clean the coop by opening the large center door and scraping/shoveling everything into a wheelbarrow I had pushed into the shed.
If I find more detailed photos, I will post them....
View of the coop under the workbench. Main access door in the middle is the full height of coop, the 2 side hatches were only ~18" tall. All were hinged to open outward.
View of the front of the shed, looking back to the coop in the rear. These doors were open except in extreme weather - I made a predator-proof screen door to cover the opening yet allow access.
A shot inside the coop.
