First, our exclusive SilverGlo board foam is installed across your ceiling joists or existing plywood storage area. The Oriented Strand Board is installed over the SilverGlo with very long screws and 3" washers. To keep blown insulation away from the new storage deck, we install dams made of the same oriented strand board approximately 18" higher than the drywall ceiling. Then the attic is ready to have blown-in cellulose to be added.