You've gotten some excellent advice and info on this thread. Patandchickens is kinda our resident expert on coops, so if you run into a problem or question along the way, chances are you can find the answer in one of her posts.
A simple shed on that concrete, I agree, is the way to go. I personally like ones with a roof that slants all to one side because you can easily get plenty of good dry ventilation right under the roof at the high point of the shed, with a little overhang, where you need it to get the warm humid air out readily.
A couple of other points. Don't bother with external nest boxes. You'll find yourself going inside to check on things anyway, and they tend to be leaky affairs that let predators in. A metal garbage can is the simplest solution to feed storage. Nest boxes can be as simple as a few cardboard boxes or a couple of old dresser drawers, bins, or kitty litter boxes. They need to be lower than the roosts, anyway. You may, however, want them on a shelf or something that's high enough for the chickens to walk under. Increases the effective square footage for them when they're indoors.
And definitely get all 16 or whatever chickens from the start, rather than planning to add more. Fair chance you'll lose some, for one thing, but mostly, adding chickens to an established flock is at best a pain and at worst a disaster. If they're not newborns, it really should be done by first isolating the newbies in a separate coop far from the others for at least a month, then putting one of yours in with theirs for a couple of weeks, then housing them near but not with the current flock. Penalty for not doing this? The newbies can be a carrier for a disease that kills them all, or they can attack each other viciously, being the cannibalistic dinosaurs that they are. If you buy day olds to raise, you then need to house them separately until they are full size, and they need to be in sight of but separated from your regular flock. If you plan to keep at least one roo you can hatch replacements on your own -- if you're lucky, under a broody.
I have a 12'x18' coop for my 15, though I've had twice that in there, till they were ready for freezer camp. I've never regretted the extra space.
A simple shed on that concrete, I agree, is the way to go. I personally like ones with a roof that slants all to one side because you can easily get plenty of good dry ventilation right under the roof at the high point of the shed, with a little overhang, where you need it to get the warm humid air out readily.
A couple of other points. Don't bother with external nest boxes. You'll find yourself going inside to check on things anyway, and they tend to be leaky affairs that let predators in. A metal garbage can is the simplest solution to feed storage. Nest boxes can be as simple as a few cardboard boxes or a couple of old dresser drawers, bins, or kitty litter boxes. They need to be lower than the roosts, anyway. You may, however, want them on a shelf or something that's high enough for the chickens to walk under. Increases the effective square footage for them when they're indoors.
And definitely get all 16 or whatever chickens from the start, rather than planning to add more. Fair chance you'll lose some, for one thing, but mostly, adding chickens to an established flock is at best a pain and at worst a disaster. If they're not newborns, it really should be done by first isolating the newbies in a separate coop far from the others for at least a month, then putting one of yours in with theirs for a couple of weeks, then housing them near but not with the current flock. Penalty for not doing this? The newbies can be a carrier for a disease that kills them all, or they can attack each other viciously, being the cannibalistic dinosaurs that they are. If you buy day olds to raise, you then need to house them separately until they are full size, and they need to be in sight of but separated from your regular flock. If you plan to keep at least one roo you can hatch replacements on your own -- if you're lucky, under a broody.
I have a 12'x18' coop for my 15, though I've had twice that in there, till they were ready for freezer camp. I've never regretted the extra space.
