We are now ready to begin laying shingles. An upside down shingle can be used for the starter run. A bead of tar one-quarter of an inch thick is required in high wind areas along the bottom edge.The starter shingle must have at least 4 nails [6 in high wind areas such as along the coast]. When applying the shingles you must alternate between the two bonlines [this is the reason for two vertical lines.] The raingrooves will then have a 6 inch stagger.
Fasteners [nails] are applied over each raingroove, below the tar line. Fasteners on the end of each three tab shingle must be exactly one inch from the end. In high wind applications, two nails are required over each rain groove, one on each side, no farther than one inch from the raingroove. When the top is reached, ridgecap is applied. Cut three tab shingles into one tabs. Start on side of house that receives least wind, and lay one tab over the other down the ridge, leaving a five inch exposure on each. Fasten tabs one inch from the end, also below the tar line.
Valleys can be laced in two fashions. I recommend the laced valley. When lacing a valley all the same principles apply as in a flat run, but make sure each shingle extends a full 12 inches across the valley. If the shingle does not reach the 12 inch mark a 1 tab will have to be added, slightly overlapping the full shingle. According to th slope of the valley different patterns will have to be used to keep the intersection point as close to the center of the valley as possible.
On a cut valley,one side of the valley is shingled and allowed to extend a full 12 inches across the valley. Then the other side is laid. The larger side is laid second. A two inch mark is made at the top and bottom of the valley, on the smaller side. Aline is popped between the two and the shingles are cut. A bead of tar should be placed under the cut edge of the shingles.
A steep roof should only be attempted by a professional and precautionary fall protection should be used no matter the height or steepness of a roof.