That's informative.
Watching my boys in action, I would have thought that a low roof would impede them. I guess they're more adaptable than I'd thought.
My Australorp rooster is about 18" tall -- 45 centimeters. He stretches to at least 2 feet when crowing.
That's an excellent way to work out what's needed for specific situations.
That would defeat the purpose of separating them into breeding groups since they would mate outside their group...
How tall are your chickens?
The rooster has to be able to stand on top of the hen's back in order to breed her. In a low pen this will be impossible for him to accomplish.