The drawing shows the rig I use to keep shingle courses aligned when shingling a simple (no hips or valleys) roof. Instead of snapping chalklines, I scribe layout marks on the drip edge and use them to guide a stringline. The stringline has clips made of scrap aluminum at each end. On one end, the clip connects to the string by way of a loop of four or five heavy rubber bands. They supply enough tension to keep the string taut over the length of the roof.
With the bottom edge of the clip set on the mark, the string is 1/4 in. above the course I am putting down. When I finish a course, I slide the clip on that end up to the next mark, go back to the outer end of the roof, slide the other clip up and carry on.
Peter E. Rosenfeld, Charlotte, VT
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