This is the chicken house we built 2 years ago. Since then, we have built 2 more. A Summer House (which has turned into a year round house) and a converted playhouse. We have 3 chicken families in the 3 houses with their own rooster and flock of hens. (more than one rooster is hellish, that is another post!)
The things to remember when building a house for your chickens are many and varied. First, though, it should be cute. You will be looking at it summer, winter, sun, rain, mud.. etc. Make sure it kind of melds into the landscape around. My cousin gave us some left over green metal roofing from his house. I had some cedar slabs that I used for siding. It is rustic, but blends in well with the surroundings.
It should be bigger than you think you need because, depending on where you live, they don't really need warmth so much as air circulation and space. This chicken house has 2 windows that are covered in hardware cloth ( a tough wire mesh) and shutters to close completely during the cold, windy nights in winter.
It needs roosts, laying nests, (one for every three hens) and an escape route if a predator gets in during the day when the run door is open. (We once had a skunk get in there, it ended badly) We leave the "people" door open during the day specifically for this reason. It also helps with cleaning out the chicken house to not have a door jam threshold.
The run should be secure on the bottom as chickens will dig under anything and undermine the fence line. I had some old iron slabs that had been lying around on the property for years. I left some of the chicken wire laying on the ground (about 8 inches) and put the iron slabs on top. They can't dig under that. I also put some deer netting over the whole top of the pen, as we lost a chick to a raven that first year. It keeps the chicken hawks out, and the bantees in.
They love to have a dry area to dust bath in (necessary for keeping mites and fleas at bay) so having a good deep overhang on the roof works well to keep some of the ground dry. A full on veranda is planned for them, but, low on the list.
Make sure the door and any windows are very secure at night. Bears can get into almost anything so the harder it is for them, the longer you have to get out there and rescue them! And remember, a weasel can get through a 1 or 2 inch hole, and wreck havoc in a chicken house, so make sure there are no holes anywhere.
There should be a feed area where their water and feed dishes are not under the roost or in front of the door and run hatch.
Permaculture ideas for the chicken house are- One: having the kitchen compost pile as part of the chicken run. They will work and dig the compost for you, making it process amazingly fast. And they think they are having a party every day when they see you coming with the bucket! Two: having a rain barrel for the chicken house roof, using that for watering them and for any plantings near the area.
Happy chickens make lots of good eggs so make sure they are well protected, and you will have a happy flock.