You want us to temp fate?
No coop will be 100% perfectly safe 100% of the time.
I live in central california, it gets hot here, so I built a 3 sided coop/covered run combo. I tried to incorporate everything recommended here.
My coop is built like a tank, but a bear could still take it out. A mountain lion might be able to push through/break the heavy door or push in the hardware cloth eventually. Determined animals might eventually chew through the wood. I could forget to lock it.
I built with a thick cement pad, and covered wood seams with hardware cloth.
Used thicker plywood (3/4 inch), 1/2 inch hardware cloth on open end. 2 by 4's every 16 inches. Cross bracing.
I framed in the door with overlapping trim on the inside on the hinges and on the outside by the handles to close all gaps (the too small to squeeze into but maybe something could anyway gaps).
The egg box has a trim 'lip' that overlaps to prevent squeezing/chewing/reaching in.
I used hasp-like locks that have a key lock on them. 2 on the door and 1 on the eggbox.
I put trim on top of the stapled hardware cloth to keep it from being pulled up. The trim is 6 inches on the bottom to also help keep shavings in.
I used hog rings/fence joiners to secure the overlapping hardware cloth.
So far, so good. Knocking on wood now.
I will post pics if you want.
Have to agree. No coop is predator proof untill it happens to you.
We are as proactive as we can be on catching/trapping outside of the coops and runs.
Spent way too much $ to loose any of our flock(s) to a coon, stray dog, etc.
We have a no catch and release, take no prisoners policy. If its on our land/property and doing harm to us or our flocks its delt with in no uncertain terms. We have spent too much time and $ to be forgiving/gracious/petaish, etc...
Its our property and land after all.
I have a little different policy. Probably many different policies here.
Mine is, if it is wild and intruding on my property and doing damage and not protected by law, it is fair game. It's going to get trapped and turned over to animal control, or disposed of.
If it is domesticated, I think its not the animals fault and there is another way.
I would fence, electrify, charge the owners all costs plus a stupid tax, call the pound, call animal rescues to rehome the pet to more responsible owners (far far away), or rehome it myself to someone without chickens and with big strong fences.
As you can tell by my way too expensive, heavy-duty coop, I hope/pray to avoid these trials of conscience.
I inherited my runs. They are heavy gauge chain link on all six sides, from a wild animal training center and was strong enough to put lions, bears, baboons and what not in them. They are eight feet tall, eight feet wide, twenty feet long. There is a six foot by six foot double gated catch area between them. Lockable gates on all three doors. One has been lined on the inside with half inch chicken wire. That one run I consider predator proof, except for small rodents. We don't have a snake problem here. There is a skunk that lurks and will steal eggs from the other runs. The other runs are plain ol' chain link and any night a coon could grab someone through the chain link and do their damage.
We just took a shed and converted it into a chicken coop. The only entrance into the coop leads to a run we made by attaching dog pens to it. Any gaps on the bottom between the coop and the run was blocked so nothing could get in. We used big rocks on one side, there was nothing on the other side to reinforce. Nothing has ever moved the rocks yet (knock on wood). We have netting over the top of the run.
A lot of people would recommend you lay the dog kennels over chicken wire so that other animals can't dig under. And a lot of people would close the coop at night and not allow the chickens into the pen from dusk till dawn and another preventative measure. Some would also recommend to cover the windows with something small predators can't get though, such as 2"x4" welded wire. Some would also recommened adding chicken wire to the dog kennels to hinder snakes from getting in though the chain link.
We used to close the coop door at night, from dusk to dawn. But I really didn't like our chickens cooped up like that over night. In the summer, it would be impossible. So we only close the pen at night and let the chickens access the coop and run freely.
If you're going to leave the chicken coop door open, you might want to consider making a little auning (sp?) over the door so that it doesn't rain inside the henhouse. I have also seen some people recommend you cover part of the run with tarps to protect from rain and/or too much sun.
I put bird netting over the top to keep hawks ect out. (got it on ebay)Then I put up 6' welded wire fence & covered it with chicken wire to make the holes smaller Then I put up 4 srands of electric fence wire 1 really low & on up in wider steps. The electric fence keeps a bunch ov critters out. dogs cats foxes coons ect.I use traps on rodents or any other small animals. I put powdered sulpher around the coop & yard to keep snakers out . I will think of more after while & let you know