We are seeing more and more ineptitude when it comes to shingled valleys.
Shingle Valleys on Asphalt Roofs have long been installed with the closed valley system. There was a system years ago passed down from expert to journeyman that included careful valley construction for leak proof service. The careful installer knows that nail placement must be kept out of the valley. The careful and knowledgeable installer knows that butt joints are staggered, cut back and installed to not only keep an open joint away from the valley, but to form a valley with whole shingles.
Something has been lost in the asphalt shingle trades when it comes to shingled valleys. The simple concepts of valley construction seem to have been lost in the last generation, or so. Shingle manufacturers don't offer specifications that make sense and the young roofers are left to their own devices. Although a completed shingle closed valley may look perfectly fine, hidden flaws often show up after a couple of seasonal changes.
Above: Shingle Valley construction has shingle staggered too close. This brings the butt joint too close, along with the nails, etc.
Above: Same Shingle Valley construction has shingle staggered too far away from valley. This causes not enough shingle to form proper valley.
To the left: A Shingle Valley is constructed with the shingles too far into the valley. Nails are placed everywhere, even at the very bottom watershed area. A common void is left at the bottom intersection of the valley at the watershed area. Water will be channelled under the shingles and onto the underlayment.
After the valley is run, what we call "dubbing" the points of the shingle-over side is carried out to prevent build-up of debris on the points of the shingles. Pointed cuts can cause lateral water flow and leaks. This procedure is often left out also. An image below is provided to show the "dubing" technique.
Who is to blame? Manufacturers are to blame. "Roofers" are to blame. Inspectors are to blame. Homeowners beware! Yes you must check out the quality of the installation because no one else will do it for you! Do not deal with the low ball bidder! You even have to watch the big names in the industry. Factory certified roofers are the worst! Factory certifications mean nothing but that you are dealing with a volume roofer.
The next time you are in the market for a new roof or a repair, please call us. Many new age roofers do not know what they are doing. When they look to the manufacturers for answers, the specifications offered by the "experts" lead to problems like those shown above. Trust the "Old World Craftsmen" for your roofing needs.