nest boxe size for larger sized hens(Heritage RIR)

[stevin]

what would be the minimum size for a nest box? especially the height of the box for the hens to enter.....
would 12" high opening be enough?
the nest box i'm constructing is 16" front to back, 48" side to side but i'm stumped with the height...doh!!!

 

[Happy Chooks]

I think mine's 16 inches high. Are you going to have a lip on the front? I do, so that takes away some of the height, but keeps the poopy shavings out of the nesting boxes.