And from this site: http://www.poultry.allotment.org.uk/Poultry/Start_Keeping_Chickens/chicken_coop_check.php
Perches
There needs to be a perch for the birds to sleep on at night, with a minimum 20 cm of space per bird (30 cm if you have large birds). The width is 4-5 cm and slightly rounded at the sides for ease of grasping. Ideally the perch should be placed higher than the nest boxes so that the chickens are not encouraged to sleep in the latter. If there is more than one perch they need to be arranged in such a way that chickens are not directly below each other. The perches should be easy to remove for ease of cleaning.
There needs to be a perch for the birds to sleep on at night, with a minimum 20 cm of space per bird (30 cm if you have large birds). The width is 4-5 cm and slightly rounded at the sides for ease of grasping. Ideally the perch should be placed higher than the nest boxes so that the chickens are not encouraged to sleep in the latter. If there is more than one perch they need to be arranged in such a way that chickens are not directly below each other. The perches should be easy to remove for ease of cleaning.