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My neighbor had a new roof put on and I noticed that instead of exposed flashing that I normally see between the slopes where different sections of roof meet, they continued the shingles un-interrupted over the "valley" where flashing used to be. Is this some new method, or is it a way to save money and time by the roofers? I would think the shingles would sag and fail quickly in that area.
Thanks for any info!
Location: Shoveling snow from my driveway into your driveway.
Posts: 8,312
I'm no expert but from the way you described the roof shingles, the flashing seems to have been omitted or installed incorrectly. It may have been installed under the shingles.
If this is asphalt shingles flashing a valley is actually quite uncommon. The most common way to address shingles in a valey is a weave that overlaps each row below the next row.
If I understand the method you described it is called a 'California cut'
The shingles are laid completely up one side of the valley,then the opposing side is laid just up to the valley center,being cut to give a clean appearance.The water has to flow over the shingles below,never getting to the bottom of the valley(under the shingles).
Yes,this seems to be a strange way to shingle being as the 'old' methods show a valley.
New building practice is to eliminate the need for metal in those valleys,as they used to fail often enough and then repair was to remove the adjacent shingles and replace an entire valley.
This method is accepted by all manufacturers (along with the 'weaving' method described above) for new roofs.
What you are describing is the shingles are 'laced' or 'weaved' across the valley. This is done quite often in some areas. It is still a good idea to install valley flashing in the valley prior to installing the shingles. Standard practice used to be 'standing seam' valley flashing or exposed valley flashing. Another method is the 'cut valley', where shingles are ran from one side across the valley and lap onto adjacent roof area. When the shingles are ran on this adjacent section they overlap and are cut along the line of the valley.
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