how much does a square of roofing weigh
You need to be aware that most jurisdictions allow only two layers of shingles to be applied to the roof due to the load considerations. For example, a 15-square area of roof with two layers of average 250-pound shingle has a total weight of covering of 7,500 pounds, or nearly 4 tons of weight. The under layer for asphalt shingle is usually roofing felt with a course of ice and water shield covering the lowest 3 feet.