Green roofs weigh anywhere from 12 pounds per SF fully saturated to 60 pounds and up. The green roof industry has made big strides in lightweight technology and soil medium to make more green roofs possible despite many buildings low structural capacities. On average a green roof weighs 6.25 lbs per inch per SF fully saturated. So a 1” green roof weighs 6.25 lbs per SF. A typical extensive green roof of 4” weighs 25 lbs per SF.