Asphalt shingle roofing is the most common residential roofing system due to cost-effectiveness and adequate performance for residential buildings. Asphalt shingles consist of a fiberglass mat or organic felt substrate coated with asphalt and covered with mineral granules for UV protection and color. Shingles are typically 12 inches wide, 36 inches long, and weigh 2.5 to 3.5 pounds per square (100 square feet). Quality varies by weight; heavier shingles generally last longer. Most common asphalt shingles are rated for 20 to 30 years; premium shingles may last 40 years. Installation begins with preparation of the roof deck, which is typically plywood or OSB sheathing. Roof underlayment (synthetic or felt) is installed over the deck to provide additional weather protection. Felt underlayment is 15 pounds per square and provides some moisture protection. Synthetic underlayment provides better moisture resistance and tear resistance. Eaves flashing (metal) is installed at the edge of the roof to direct water into gutters. Shingles are installed with nails or staples from bottom to top in overlapping courses. Each shingle is attached with 4 to 6 fasteners. Fastener placement is critical; fasteners must penetrate the roof deck but not protrude through it. Proper fastening is essential as high winds can cause shingle blow-off if fastening is inadequate. Ridge cap shingles cap the roof peak and are also nailed in place. Proper ventilation of the attic space extends shingle life by reducing heat and moisture buildup. Ridge vents or soffit vents provide air circulation. Gutters and downspouts manage rainwater runoff. Regular maintenance including removing debris and cleaning gutters extends roof life.