Oh its amazing what you find on hearth...
Our 5 just started laying, pulled a monster out just an hour ago.
I used standard lumber, jay i have no doubt yours will be heafty. Ours is 16 x 8 i wrapped all but the roor in galv wire, including the whole floor. On one end, i build a coop about 2 feet off the ground. I made it out of 3/4 subfloor, so it can hold up. We have a stair like roost for them, 2x2 work here as this is where the bulk of the manure ends up. Two story..nesting booxes on the other. We used the same 2x2s as roof perlins and corregated plastic roofing.
What ever you do make sure you can get in to clean. Make the run big enough for them. And give them stuff to climb on and roost. We made ours semi moveable so we can change it up and let them scratch in other areas
Layers stay clean, we had meat chickens, and they are tasty, just not sure its worth the effort.
Good luck, they are fun,and byc is a great tool like hearth. Ill try to get pics, hard with cell phone only.