In this video I show how to build a top cover for a beehive. This is a telescoping cover with a ventilation notch to match the ventilation notch that I put in my inner covers. If you want to use Styrofoam insulation in your cover just add the thickness of the insulation to the 1 3/4" width that I use. The drip groove that I cut helps to keep water away from the boxes during a slow drizzle or snow melting condition. It is not perfect, but every little bit helps.