How you put the roof together is just as important as the materials you use. When framing and sheathing the roof, for example, how many nails you use and where you put them may determine how well your roof stays in place. Fasten your roof incorrectly and it may blow away in a high wind or collapse under a heavy snow load. The same applies to the roof covering itself. Whether you install asphalt shingles, wood shakes, slate, tile, or a low-slope membrane roof, the fastening details can make the difference between success and failure. Roofing details such as underlayment, flashing, and edge detailing must all be accomplished with care for your roof job to succeed. You must also be aware of underlying structure. Heavy materials like slate and tile need a beefier frame under them than lighter products such as asphalt shingles or sheet metal; so, be sure to have the supporting structure evaluated before reroofing.