We decided to do some testing of our own on the Thermocore MO 6 1/2″ roof panel and we were very surprised with the results!! 3/4″ deflection with a car that weighs 4400 lbs. and the panel goes right back to its original height after pulling the car off!!! There is no lumber embedded in the panel…just 7/16″ OSB and 5 1/2″ of polyurethane closed cell foam. Now, would you try this on your conventionally framed roof??