Roofing felt or tarpaper is the first layer applied to a new roof of asphalt shingles. Roofing felt comes in 15- or 30-pound weight. The heavier-weight roofing paper is used primarily in northern climates where ice build-up on the roof’s edge can be a problem. The roofing felt is made up of a paper base impregnated with asphalt. It can be secured to the wooden roof deck by staples or short roofing nails.
Roll the felt a few feet and attach another fastener to the lower edge. Keep the lower edge of the roofing paper aligned with the lower edge of the long side of the roof. Continue rolling the felt to the other end of the roof. Stretch the felt tight and align the lower edge with the lower end of the roof decking. Then secure the felt to the deck with fasteners every 3 to 5 inches along the lower edge.
Secure the middle area of the felt in a repeating-W pattern, with nails every 9 to 10 inches or staples every 3 to 5 inches. Cut the end of the roll with the razor knife.
Start another course by laying the roll over the secured paper with a three-inch overlap. Note that there are white lines printed on the paper. The first line from either long edge will be 3 inches. Align with the aid of the white lines.
Secure the roofing felt in the same manner as described for the first course. Continue in the same manner until all areas of the roof are covered. Cover the peak of the roof with a double covering of roof felt. Overlap the peak of the roof equally with the top rolls of felt. Trim all overhanging edges with the razor knife.