From Gene Logsdon (1985)
Garden Farm Skills
A backyard henhouse for only a dozen or so chickens year-round should be commodious, a minimum of around 5 square feet of floor space per hen, which is much more than a commercial poultryman can afford. My henhouse design, based on what I’ve learned so far by building three coops of my own, differs from the standard designs in a few other ways, which you might find interesting to think about when building your own.
1. Predator Proofing. I would have preferred that my latest chicken coop be built on a concrete footing to make it more or less predator-proof. But pole construction was cheaper and easier. The bottom wall boards are of treated wood for rot resistance, and the wall is sunk into the ground 6 to 12 inches. Cats will not dig that far under to get in, and cats have always been my most troublesome predator—not my own, though, which I train not to bother chickens, but feral cats. I keep the dog tied next to the coop for further insurance.
2. The Size. I knew that for part of the year I would house approximately forty-five to fifty chickens, although there would be less than twenty year-round. Every year we buy six Rhode Island Red chicks and about thirty White Rock broiler chicks, the latter for meat, the former to add to the laying flock. The broilers are butchered when about ten weeks old, and later on I’ll butcher some old hens as they quit laying, so that the flock dwindles to around fifteen through winter. We buy chicks in June so have no need for brooder facilities. (The first few nights I might use a heat bulb on the chicks.) Anyhow, by my own idea of space requirement, a 10 by 20-foot building is more than ample. And it is tall enough so I can walk inside without hitting my head, as I did in the old coop.