As Bruceha2000 says the perches should at least be 3-Inches round or I like the 2x4 planks for roosts with the flat side up. Thin perches are hard on the chickens' legs/feet and in cold weather like to have a platform perch to cover their feet with their feathers.
I use the flat 2x4s myself... I have one in the coop and I'm going to put a few under the stand and I hope to find a nice tree root system laying along the road soon... Grab that... Cut off the smaller roots leaving a chuck of the stump and roots for a roost in the yard... I saw someone else do that and it was sooooooo cool... :yiipchick happy chickens lol