I'm sorry, I did not read all the previous posts. SO if I'm repeating something that was already said, well, then it must be important LOL!! Hehe,
*I hate chicken wire. Predators can rip chicken wire apart.
*Wire spacing must be smaller than 1". Snakes can fit through 1" and kill chicks & eggs. Even large chicks--if the cannot eat it, they will just spit it back out. You will have a poor dead half eaten chick, with a slimy stretched out neck. 1/2" hardware wire is good. In fact, no holes anywhere that are larger than 1/2". (My personal preference.)
*Reinforce the floor of the run. If not, Predators can dig under and get your birds.
*Door latches must be secure.
*Make the floor easy to clean from the start. This is a must if you want clean birds. A Wire floor, or dry deep bedding is good. If the bedding gets wet though, it will dirty up your birds.
*Don't use staples to attach wire to wood. Use screws, bolts, or a heavy duty staple gun (the kind you attach to a compressor.) Not the hand-held staple gun--dogs can rip the wire right off the frame if you use weak staples.
*If your birds are valuable, remember there are human predators too. Find a good lock.
All of these recommendations are from my own errors. In fact, we just had a dog attack 2 weeks ago. I lost my favorite pet chickens, including the one in my avatar. I lost some that I've had for 4 years. I thought my pen was secure, as we've had dog attacks before. I thought I had everything just right. 4 years, sigh. However, they found a weak spot in the chicken wire, and now I am at a loss. The chicken wire had 1" wide wooden stakes nailed over top for added security, but the dogs ripped the stakes off the house, then ripped the chicken wire off.
If you live out in the country, you will have to deal with more predators than usual. So my advice--go overboard with your safety measures. Make it so nothing can break into your coops--from a tiny snake to a large strong dog. The worst predator attacks we've had were from stray dogs. They will kill everything in sight, and just leave it there.
So I am remodeling my broken coop, and I will be using my own advice.