I haven’t read all the comments, but no matter how well a fence is built, if it’s not a covered area, a raccoon can do such devastation to your flock. A spring loaded door in the pen works just in case your door is left unlocked. At least it’s closed. I have my chickens coop inside of a fully...
I can confirm with others to add sheets of plywood to the inside to eliminate drafts. I used just 1/4” hardwood ply and they’ve done really well even when temps dropped below 0°F. I even have their entry door open 24/7 leading to their closed in pen. Coop is only 4x8. They roost on the opposite...