Making it an L will make the coop harder to drag to new places. Leave it in one place, and they'll kill the grass in their run pretty quickly. This is my Dad's coop: Houses anywhere from 10 to 18 birds in a 70'x100' area. Flock size depending on how effective the dog has been at keeping the foxes out, how many random birds have joined the flock (happens from time to time in the country) and how the hens feel on nesting vs eating their eggs. The run is also home to two rabbits! They weren't invited, but have set up shop anyways.
Interesting. I guess that begs the question of whether or not I need the smaller run attached the the coop, or if I should just let them run around the entire area behind the garage. My ordinance says: "A covered enclosure or fenced enclosure shall not be located closer than ten (10) feet from a property line of an adjacent property nor shall it be located closer than forty (40) feet to any residential structure on an adjacent property." It might be worth having some fenced enclosure connected to the coop (which will meet the distance requirements) so I can make the argument that our yard fence isn't the enclosure itself. We have a bunny that spends a lot of time in our yard. I wonder if it will like the chickens.
We had chickens who constantly escaped from their run. Bear in mind that you have to get them back into the coop every night before sundown or every raccoon/coyote in the neighborhood will treat your yard like a buffet. We lost a couple chickens that way; another got injured, and then her coop mates pecked her half to death because what do you know, chickens are assholes. I had to kill that hen myself just to put her out of her misery, and it was a pretty messy experience. Anyhow. Chickens don't always get that they have to retreat to the coop. Which means you have to chase them into it. This is easy with a run. It is not easy without. It'll end up dominating your early evening, depending on how many chickens you're getting. To top it off, chickens don't fly far or well, but they can fly far enough to get over a fence, depending on how resourceful they are about finding the highest take-off point. Then you'll have to chase your chickens through the streets. Also, chickens obviously shit everywhere. And chicken shit is great for yards, but more by way of introducing it in an orderly manner via compost. If you just have chicken feces willy-nilly throughout the yard, it severely limits your ability to walk around out there, and if you have any kids who play in your yard, you have to worry a great deal more about salmonella and all that jazz. I once read that chickens are more likely to have salmonella in their poop if they've been eating rat turds; thus, if you're letting your chickens run around wherever the hell throughout the day, especially in an urban/suburban setting, they're more likely to find and eat said turds and again disseminate them throughout your relaxin' space as they please.
Ha. My cousin has like two dozen chickens, and they follow her to the coop each night like soldiers. She did lose a few along the way, and maybe it was for the best. I'm definitely not going to be chasing chickens down the street. If they want to strike out on their own, then I wish them all the best. I'd rather 2 obedient chickens than 4 rebellious ones. If it takes some selection pressure, I'm ok with that.
I'm on my phone and I'm super lazy - so we should probably talk on the phone about this... Chickens are dumb and awesome. The eggs are fantastic. When you get them, lock them in the coop for 2 days straight. This seems to reboot their brains and they go in there on their own every night. I never once had to chase a chicken. The closer it gets to sundown, the closer they got to bed. Seriously. So dumb. And so awesome. While they can and may hop/fly over that fence... I doubt they will. And if they do, they'll come back. Honestly - I'd chuck a cheap/temp fence up from the side of your garage to the back fence and let them roam that whole area. You can build/buy a simple coupe to close them in at night. Keep it simple. Keep it easy to clean. All the stuff everyone else said. Let em roam.
Maybe if you get chicks, they'll imprint. We inherited our chickens from our landlord- they owed us no allegiance.
Being able to contain them in a run comes in handy if you use your yard at all for non chicken activities. Some people (kids) think chickens are pretty neat, but others find 'em unnerving. Especially when they mob you because they're out of food. I quite like the chickens, but my sister hates being around them.