They like to perch high up and about wood about 2" wide with curved edges is best for them. B&Q do some called CNS I think or CSN cant remember now but its ideal. Put the curved edges upwards for them to grip and make sure you have something to enable them to get there. We have hutches in the shed and they use them as nesting areas and as a way of getting to the perches by degrees. Some chickens are not good at flying straight up there, silkies for instance. We also have rows of crisp boxes with a round hole cut in the front and a little bedding there for additional nest boxes and a safe place for broodies to sit. It is easy to keep them clean as we just burn them and replace them periodically.