I don't think there are absolute alwayses and nevers, just things that you will rue more vs less
Less obvious things that can be hard to change, or may not be obvious til it's too late, include:
-build on high ground, preferably not too windy a location, preferably with some shade available in summer if you're in a hot climate
-it's nice to have the roof slope some way that it does *not* dump water and snow right on top of people doors or chicken popholes.
-it's nice to have the pophole high enough on the wall (like 12" ish) to prevent lotsa litter from getting kicked out every day.
-it's nice to have more ventilation than you need and simply not have it all open all the time, as opposed to having to trudge out there in a winter storm after they've already started getting frostbite (which is encouraged by *humid* air, and sometimes solved by more ventilation, perversely enough)
-don't rely on chickenwire to keep predators out
-remember raccoons can reach through 1" mesh and grab parts of chickens that are within reach and yank them out to eat
-remember raccoons, and some other things as well, are superb climbers and can scale everything short of a blank wall (and some of those, too). Also they open most latches short of a padlock.
-if you're building a tractor (moveable little coop), add up the weight of the materials in the proposed design and see if it seems plausibly moveable before you build anything
-there is no such thing as too big a coop (no, not even up North); there is no such thing as too much room per chicken.
-you are almost certain to want more chickens than you initially expect
Good luck, have fun,
Pat
).Trying to avoid some newbie mistakkes as we design our coop.
