For the next two shingling methods, closed-cut and Long Island valleys, I work out of the valley using laminated shingles instead of working toward the valley with three-tab shingles. Shingling both a closed-cut valley and a Long Island valley is the same for the first half of the process. Working on the smaller roof plane, I set a shingle on the first course line. I place the shingle so that one edge is 2 ft. away from the valley center at the nail line. I mark the shingle where the valley center crosses the top edge, and I mark the roof at the top outside corner of the shingle.
To shingle out of the valley with laminated shingles, lay a shingle down as a gauge and mark the corner at the bottom (left) and top (right) of the roof.
I then move the shingle to the uppermost course on the roof plane, line up the mark on the shingle with the valley center and again mark the corner. A chalkline snapped between this mark and the lower mark forms my guide line.
After snapping the guide line between marks, install the shingles with one corner on the line. Snap a chalkline 3 in. from the valley, and you're ready to complete the valley.
I always weave my first course. But after that I run the shingles up the valley, aligning the top edges with the course lines and the top outside corners with the guide line. I nail the shingles normally, except that I keep nails at least 6 in. away from the valley center. Now I'm ready for the other roof plane.
Closed-cut valley -- Even if I work toward the valley with three-tab shingles, cut valleys are faster than woven valleys hands down. With a closed-cut valley, there's no need to shingle the two roof planes at the same time. Plus, cutting the closed-cut valley shingles can happen after the rest of the roof is shingled.
I begin the second side (the side that will be cut) by snapping a cutline 2 in. to 3 in. from the valley center. Keeping the cutline away from the center of the valley creates a better watercourse for runoff and tends to hide discrepancies in the line after the shingles are cut.
Working out of the valley with the closed-cut method, snap the cutline (left), then step the shingle back from the line to eliminate the need for dubbing the corners. Here, the gauge shingle marks the guide line ( right).
Here's one of the big advantages of working out of the valley with laminated shingles. To establish a line to guide the placement of the shingles on the second roof plane, I place the lowest shingle on the course line so that the cutline meets the shingle 2 in. down from the top edge. In this position, there is no need to dub the corners of the shingles. As I did on the other side, I mark the location of the outside corner of the shingle on the felt, repeat the process at the top of the valley and snap a chalkline. I then install the shingles, lining the top edge with the course line and the outside corner with the guide line, letting the other edges run through the valley.
When the shingles are all in, I resnap my cutline. For protection, I insert a metal sheet between the shingles from both roof planes, and I trim the shingles one at a time with a hook blade in my utility knife. I finish the cut edge with a double bead of roof cement, the same as for the open metal valley.
When all the shingles are installed to the guide line, the cutline is resnapped (left). With sheet metal protecting the lower layer of shingles, the shingles on top are cut back to the line (right). The cut edge then is sealed with roof cement.
Long Island valley -- A young roofer from Long Island first showed me what I now call a Long Island valley. This valley looks the same as a cut valley, only it's faster to install. Although this valley system isn't entirely new, you won't find it described on shingle wrappers. However, it does seem to be a viable weather-resistant method. The only drawback is that Long Island valleys work only with laminated, random-pattern shingles. This method cannot be used with three-tab shingles.
For a Long Island valley, a row of shingles is bedded in roof cement (photo left) and installed with their top edge on what would be the cutline (photo right).
When I've finished shingling the first roof plane, I snap a chalkline 2 in to 3 in. away from the valley center, just as I did with the closed-cut valley. Next, I smear roof cement a couple of inches away from my snapped line. Then I install a line of shingles up the valley with the top edge aligned with my snapped line. The lowest of these valley shingles is cut back at an angle in line with the lowest course line.
Shingles go in with one corner butted to the valley shingle; no guide line is needed.
A small dab of roof cement seals each shingle corner.
I install the shingles for each course with the lower corner lined up with the edge of the valley shingles. The result of this layout leaves a small triangle of the valley shingle that is exposed on each course. From the ground, the Long Island valley is indistinguishable from a cut valley. The sealing is easier, too: Just a half-dollar-size dab of roof cement under each corner where it laps over the valley shingle is all that is required.
Article Source: http://www.roofer911.com
Article: "Four Ways to Shingle a Valley"
Author: Mike Guertin
Issue/Date: #152, December 2002/