Sure you can fix up the attached shed. That should be fairly easy actually since the basic stucture is already there. You need to make sure nothing, and I mean NOTHING can get in when the chickens are closed up for the night, IE coons, possums, skunks, dogs, anything.
You need 2x4 roosts. Chickens roost. Put some high, some lower, With 10-20 hens, then you need about 4-5 nest boxes. Best to have side open nest boxes, cuz some chickens will perch on open top nest boxes and poop in them. OR, you could have open top nest boxes but have a roof/shelf that goes over the top that the chickens can sit on and will catch poop instead, but I'd opt for side opne boxes. 5gallon plastic tote work nice. Leave the lids on, and cut a nice hole in the side that the girls can get in and out of, it'll keep eggs clean.
If using lights, make sure they have NO TEFLON. Teflon emits gasses that hurt the chickens/birds lungs.
If you can put windows in that open and close, do that.
If you have a cements floor, thats cool, cuz then nothing can dig under the wall and get in. If its an earthen floor, be sure to make sure nothing can dig under the walls to get it.
Use sand for the floors, or do a deep litter method.
How old are the chicks going to be? You will probably need to brood the chickes for several weeks with heat lamps. If they are already in coops, say 10-12 weeks, you could just put them strait to the new coops. They should feather out pretty good before winter comes. You don't need to heat the coop really. If they are old enough they should be fine, they will huddle together. If you heat the coop, they will get used to that, and if you have a power outage, you risk losing them because they didn't develop a winter feathering. My girls now seem to be getting a nice set of feathers.
Make sure you dust the coop for mites/flees/lice before you put your new birds in it. IF its an older barn, you risk those if you haven't done it first. ITS A REAL WITCH to get rid of mites. Mites can impair your birds and can lead to deaths.
You need atleast 4sq feet per bird of coop floor space. Are you planning to free range or use a run? if you use a run, you need 10 sq ft per bird of run space.
I am going to suggest too, that you get an Everything chicken, or chickens for dummies and read it cover to cover before you get chickens.
Other than that, welcome to BYC, and so many people here are very very knowledgeable and will help and offer the best advice, better than any book. But its always good to do your homework before you actually have the birds.
Oh, and make sure you get a heated waterer for the winter so the water doesn't freeze.
So, i want to know if i can built the coop as an extention from my barn (no animals in it save a friendly dog who will be trained not to harm and maybe a cow) I was looking at the barn and it had a small shed that had kind of fallen apart attached to it open on the inside. Can i patch it up, add air slits and ample light? How many nesting boxes should i have and where? How many beds? Where do chickens sleep??? See, i told you i was new at this
