Are you installing asphalt shingles correctly? Check out JLC’s Field Guide to installing them next time you take this task on.
There are four basic patterns to laying out three-tab shingles: straight-up method, half-pattern, 4-in. offset, and 5-in. offset. The 5-in.-offset pattern provides the best all-around protection.
Alignment Guides. Most shingles include 1/2-in. alignment slits across the top edge and half-slots along the edges. Use these to line up adjacent shingles and successive courses. In addition, shadow marks may run the length of each shingle near the top of the slots. These are meant as an aid to horizontal alignment.