The ThermoShield R-42 attic hatch consists of a box made of chipboard 5/8'' thick and a finishing edge MDF with weather stripping foam. The door is made of 1/2'' chipboard laminated on 11'' thick expanded polystyrene. R-42 insulation complies with current requirements. Stable polystyrene insulation doesn't absorb water, while regulatory dimensions make it easy to install the attic hatches between trusses. This product meets the new energy efficiency standards of the RBQ building code.