Our coop is walk-in height, and is built off of our deck, in an "open plan" construction. This means that, until I winterize and close in the third wall, the back wall of our chicken coop is the railing of our deck. For a roost, we have a single 2x4, installed at approximately 36''. All of my hens (approx 6mo old) are able to get up and down from the roost easily, with the exception of two. Since changing from a multi-level roost to a single 2x4, my Wyandottes have been sleeping on the deck, against the railing that looks into the coop. They can see into the coop, but aren't IN the coop. Does this sound like a roost construction issue? If so, what is the recommended measurement for a lower beam ?