When we moved to our Homestead 16 years ago, there was an existing old potting shed on the property, unused for many years. The flock we brought with us moved right in, and that was their "coop" for the first 5 years.
They endured -35F temperatures in the winter, and 105F in the summer. They never complained. But I felt guilty.
Where I live, building permits are not an issue unless you're building a new human residence. But depending upon where you live, even if keeping chickens and building a coop is permissible, a lot of times a local building permit is required for "new construction". However, "modifying an existing structure" usually doesn't require any official paperwork.
So my "modification" of my potting shed resulted in none of the orgiinal structure remaining, and the chickens got a palace.
I've always been a fan of Popular Science's "Wordless Workshop", so I'm going to post these basic construction photos, and any questions are welcome. I have lots more pictures, but these are the basic ones.
A few additional notes.
The coop has OSB exterior and 1/4" interior plywood paneling. It's insulated with fiberglass bats. Even in a sub-zero climate like mine, I've never found a need to heat the coop. The water will remain unfrozen even with outdoor temps in the mid-20's.
The doors are full sized, salvaged ones because I'm not the size of a chicken, and I wanted full access for my wheelbarrow, and other tools.
It's spacious enough I store all my feed/bedding in garbage cans (rubber) in one corner, and have shelves for chick feeders, lights and other hardware. Many times during severe winters I don't let the flock outside, and they still have enough room inside for me to scatter scratch on the floor for them.
I built it with 3 nesting boxes since my actual laying flock is always around a dozen hens, so the 5:1 hen-to-box ratio is maintained.
When the days get short, I use a dusk-to-dawn light switch (orinally made for outdoor Christmas lights) to give them a full 14 hours of light. They need that for maintaining a laying cycle, and it often prevents them from going into a winter molt.
Anyway...on with the show.
Laying out the floor joists for the expansion. 2x6 timbers on concrete piers.
Adding wall studs and 2x4 rafters.
Remains of old potting shed being disassembled.
"Nursery" gate latch
Exterior door to yard latch. (in keeping with the K.I.S.S. theory)
Exterior access to nest boxes, at my wife's request.
Railroad ties keep the chickens in and the skunks, raccoons and foxes out. The outside
shelter provides shade, And gives them a place to get out of the rain, or the threat
from aerial predators. We have 4 species of "chicken hawks" here, and the occasional
Bald Eagle looking for an easy lunch.
Hope you enjoyed the tour. Any questions, please ask.
(In Montana we have a saying: "Pretty and functional aren't necessarily synonymous.")