Thanks, that's super helpful.
I've been a little concerned about ventilation in the plastic coops too but I figured I could always drill extra holes?
Unfortunately,  rats are something I do have to worry about! I'm truly sick of the little buggers. Two days ago, I watched two younger rats emerge from under the dust bath - not 2ft away from me and in full view - and saunter over to a feeder. They then started eating right along side Clara, who barely glanced at them! Had Gladys been there, she'd have been in full kill mode and I might have 2 less rats. Last week we caught 8 rats in one trap! 
