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.
Weather is a prime factor in shingle life span. U.S. Inspect notes that in hot climates, such as in Florida, asphalt shingles often deteriorate in 12 to 14 years. And, in northern states, such as Massachusetts, asphalt shingles on houses with high, sloped roofs and an eastern and or northern exposure can last 25 years.