I am planning my new (and first) chicken coop and run. It is based upon the Wichita style coop, but I am going to make it a little bigger overall. I was curious what would you all consider to be a good height for the area directly under the coop? I was thinking 18" would be enough. but then I started thinking that some big birds are pretty tall. I am going to have a mix of Brahmas, Sussex and Wyandottes most likely. No more than 6 hens and no rooster. I want to make them as comfortable as I can.