Think U with straight sides and put perches within it. I bought a house, must be about 13 years ago, but it has always been under cover. Painted with Culprinol and have heavy duty castors on it for easy moving. My house is on concrete as easy to clean unlike earth.
I have metal panels for the roof and guttering into a water butt, currently draining into polytunnel.
A useful run area is one which can can be divided, so they eat one side , then given the other side.
Hens prefer short grass.