Ok I keep my ducks and hens in a shed with a pen attached. The shed has a dog flap (my dogs used to sleep in it) but the plastic door cover would be useless at keeping animals out at night. Wondering if I would be better to remove the flap and make a inner and outer door, or try and keep the flap and build around it? I hadn't thought of this when I was building the pen at the minute each night I'm screwing wooden sheets on the inside and outside of the flap to stop predators but it's a major pain! Anyone have any ideas?