Letâs crunch some numbers. For example, RoofmeadowÂ® green roofs, engineered to be both lightweight and efficient, generally weigh about 6.75 pounds per square foot for each inch of media depth. Thus, the saturated weight of a 3-inch deep system is about 20 pounds per square foot, including a mature plant cover. Mid-range, 5-inch, systems weigh approximately 34 pounds per square foot and are compatible with wood or steel decks. Heavier intensive green roofs generally require a concrete supporting deck.