Most asphalt shingles used in residential work are known as three-tab shingles (Figure 2). Three-tab shingles weigh about 240 pounds per 100 square feet of area and they are typically available with a 15 or 20 year warranty. Heavier, more durable asphalt shingles are also available. But if you want to purchase an asphalt shingle product with a 30 or 40 year warranty you will have to buy laminated shingles, also called architectural shingles (Figure 3). These type shingles are solid across their entire length and width. They consist of multiple mats laminated together within each shingle. They are installed so that three to