Brooks has given you the clue that can help avoid so many of the problems with chickens coops.
You can build a lovely looking coop. There must be hundreds of the in the BYC Coop Articles section. Many will look lovely in the garden. Some have little ventilation chimmney pots, others little cubby holes inside to store the coop cleaning kit. Many are built on the ground with quaint windows, carefully cut planks, shelves, in fact every sort of design imaginable and I don't doubt the many are the object of jealousy amoung the neighbours whose house isn't so loveling constructed.
Some work well for years and then one day the mites move in. Hundreds of the little bleeders. They sneak in behind every carefully fitted upright, between those tiny gaps on the poop shelves, burrow behind the wall mounted nest boxes, climb into the rafters, hide behind the the steel plate joiners, crawl in between the floor planks.
If the coop is built on the floor it doesn't take long for word to around the local rat population. They dig in under the coop and then bring their friends over for supper.
Your lovely $5000 coop build suddenly turns into a rodent and pathogen haven for the homeless and no matter how many evection squads you send in you can't get the pests out.
One acknowledgement of reality and five simple rules will help avoid this nightmare.
The chickens don't care what the coop looks like!
1) leave the frame outside and clad the interior.
2) use sheet material not planks or T&G
3) make everything you want to put in the coop like nest boxes removable
4) build the coop at least three feet off the ground and mesh the underside on the outside.
5) learn how to clean your coop with a blow torch. A 400 degree centigrade flame kills everything, mites and their eggs, everything!
Here is such a coop. Yep I know it's ugly, but it's secure, reasonably cheap, weather proof and easy to clean properly.
