One more detail to think about, an attic hatchway can be another source of large air leaks when not properly sealed and insulated. The large block of SilverGlo insulation in this picture fits over the hatch. It is lightweight and infused with graphite powder to improve its insulating value. Now this attic is properly insulated in a way that will keep temperatures down which will prevent melting snow on the roof and, consequently, prevent ice dam formation.