Our neighbor is giving us his old wooden chicken coop. It's 4 feet deep by 6 1/2 feet wide with the nesting boxes on an upper shelf. It's made of plywood with two upswinging doors in the back for egg gathering and cleaning. There is no ventilation in it currently. Can I add two small ventilation grills on the upper ends near the roofline? Also, is it advisable to add insulation covered by plywood on the inside for winterizing? We're in the Puget Sound area where it can get very cold.