Starting from scratch, building from the ground up is one option. Another option would be to convert an old garden shed into a dry, easy maintenance coop. When considering retro-fitting a garden shed into a chicken coop, there’s a few things to consider:
Flooring – Wood flooring should be covered with either: a thick layer of straw/shavings, vinyl, rubber or sheet metal (to prevent moisture absorption into material). A tight silicone seal along the edges would be beneficial as well, to keep all the moisture on top.
Walls – Our Winnipeg weather in winter can be ferocious. Although it’s not mandatory (heritage breed’s are quite a bit more resilient to the cold than you might think) insulating the walls isn’t a bad idea. Most consumer garden sheds post-70’s era have metal or vinyl walls. Metal studs can be used here to keep insulation batted in. That, or reflective foil insulation can be placed between your outer walls and your inner liner (plywood, panelling, sheet metal, etc.).
Roof – Hot air goes up, pushing the ammonia fumes to the top of the coop. The fumes need a place to escape. Install ventilation panels in the uppermost part of your shed, either in the top of the wall if your shed looks like “|” or across the arch of the roof, it it looks like this “/”. Be sure to install some heavy screen in your venting though, as to prevent critters from trying to sneak in.
Friends with 5 gallon pails – are invaluable. Take 4 pail lids, bolt them to the wall. Cut out the bottom of 4 pails, and stick then to the lids. Instant, easy to clean nesting boxes! Also, cut 2″ holes all along the bottom of a new pail, attach the pail to a slightly wider metal garbage can lid. Instant feeder!
Doors – If you’re dealing with those flimsy sliding metal doors that come with some sheds, I’d highly advise removing those doors, building a wall to cover that section and build your own doorway for your chickens and a human body to come and go through.
Roosts– Probably THE easiest thing to setup for your whole coop setup. All you need are a few broom/shovel/hockey stick handles to span across two walls for your chickens to sit and sleep on overnight. Many urban farmers have mentioned that this is where their chickens do the majority of their defecation while sleeping/roosting, so it might be a good idea to setup some type of trough to gather their droppings.