I have a flat roof over the garage that has been covered with a rubber membrane roofing material. I would like to build a floating deck on top of the material but have concerns that walking on the deck will cause the stringers to flex and wear through the rubber membrane. Do you know of any material I can place between the rubber roof and deck to absorb the movement and eliminate the wear? Is it even necessary to do this or is the rubber resilient enough to take the movement?