That's the opposite way of the most effective use of the foam pad. Defeats how most inflatable pads work by heating air in the pad and reflecting the heat back to you. The foam on top blocks that from happening and does nothing to help protect against punctures. Running it under the air pad gives better pad protection and helps insulate the air pad from the ground making the air pad much more efficient.i put mine on top for more insulation. as many others do i carry a 4 ft sit pad that is a quarter inch thick and i also have a half incher for colder weather.