the difference between a political and a physical boundary is that a physical map shows geographical features like mountains and rivers while a political map shows boundaries.
Standard Weight. Standard asphalt shingles generally weigh about 190 pounds per 100 square feet, based on information from U.S. Inspect, a property inspection company. The weight of asphalt is especially important if you want to install a new layer of asphalt roofing over an existing layer.A roof measuring 1,600 square feet that has two layers of standard asphalt shingles on it is holding about 6,000 pounds of shingles..S. Inspect indicates that dimensional shingles can be 50 percent heavier than standard asphalt roofing. Therefore, they could weigh about 285 pounds per 100 square feet. Heavier shingles reduce the chance the underlayment will wrinkle, according to the National Roofing Contractors Association.
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. Asphalt Shingle Installation. The under layer for asphalt shingle is usually roofing felt with a course of ice and water shield covering the lowest 3 feet.eavier shingles (up to 350 pounds per square) generally last longer than the lighter shingles (200 pounds per square). The heavier shingles tend to be of the architectural style, with several layers of material.