We are building my tractor as I type this, so anyone who can answer this now, would be most appriciated. I'm planing on having the acess to the outside drop down fron the floor, the coop part will be 18inches to 2 feet off the ground. What is the minimum the whole should be cut for heavy birds? I have Faverolles and Sussex. Also what is the minimum opening for the entrence to the nesting boxes. I plan on 12 in X 12 in boxes with a 6 in board across the bottom to stop any (or most) of the litter from coming in but I'm not sure how far up to go for the top slanty board thing. I hope I explained what I meant, right. thanks Ray