I looked at the diagrams for building a WOods-style coop. Q Are the spaced between the rafter left open for air movement? I'm rereading everything, hoping for one sentence that addresses this. I know the old building left them open for air flow, but not sure on the Woods design. WOuldn't the cold air come in and fall on the birds on their roost, or is the pocket of warm air enough to protect the birds??