Installing peel-and-stick roll roofing on a flat roof requires a minimum slope of 1/2 inch per 12-inch roof run. Typically, a flat roof is a low-sloping roof with a maximum 10 degrees of pitch or usually having a slope of up to 3 inches per linear foot for adequate drainage. In this respect, peel-and-stick products are suitable for the majority of flat roof construction types and usually come with a 10-year warranty. Peel-and-stick roll roofing is a polymer and asphalt product, with a metallised or granular top coat and a self-adhesive underside, which purports to provide a faster installation time than traditional roll roofing materials.
Sweep the roof deck with a push broom in order to remove debris such as stones, leaves, twigs, moss and loose dirt. Use a degreaser to clean ingrained oily marks and dirt from the roof deck. Wipe the deck with a damp cloth in order to pick up any dust particles that remain.
Hammer raised nail heads into the roof deck to ensure a smooth surface for an effective installation of the peel-and-stick roll roofing. Read the roll-roofing manufacturer's instructions to determine if you need to apply an asphalt primer over the roof deck, because some peel-and-stick products adhere more effectively with a primer.
Align the length of roll roofing with the lowest edge of the flat roof and flush to the side edge of the roof. Pull back 6 inches of the release paper in order to position the start of the roofing sheet accurately. Smooth down the sheet with your hand to adhere the roll roofing to the roof deck.
Peel back the release paper and smooth down the roofing sheet as you go in order to prevent wrinkles in the asphalt membrane. Cut the roofing to size using either a utility knife or scissors, according to the roofing manufacturer's recommendations. Use a hand roller to firmly press the roofing length onto the roof deck after you position each course.
Overlap each preceding course by 3 inches to create an effective watertight lap for the flat roof. Overlap the edge of an end piece from roll to roll by 6 inches and stagger the laps between courses.
Run a bead of waterproof caulk along exposed edges of the peel-and-stick roofing to increase watertightness. Install the roll roofing in warm and dry conditions to produce optimum adhesive performance. Check your manufacturer's instructions carefully because some products require the application of an additional adhesive spray along the perimeter edge of the flat roof.
Take considerable care on the roof in order to prevent injury or death from falling off. Applying peel-and-stick roofing in cold weather severely reduces the efficacy of the adhesive. Do not install the roofing onto a wet roof deck because the adhesive will fail.