. I did not draw a proper roof pitch on the nest box - due to the exterior height it will have to be top opening and we'll go with a steep pitch so I don't push water into the nest box when I open it in wet weather.
Top-hinged nests are notorious for leaking at the hinge. If you can get a large roof overhang above them it will be a useful safeguard.
installing a removable sill to keep bedding in.
This is a great option.
What are your roofing plans?
We found metal roofing installed over purlins incredibly easy to work with.
Putting the joists up with hurricane ties instead of birds' mouth joints allows you to add soffit venting to the Monitor venting for even better airflow.
I hadn't finished this article the last time I posted on your thread: https://www.backyardchickens.com/articles/repecka-illustrates-coop-ventilation.77659/