Question on open valley technique

I had a new roof put on a few months ago, and I wanted open valleys.
I like the way he ran the shingles along the valley on each side first.
But that doesn’t seem to be what most do. I’m curious why most don’t do the open valleys like that? Most seem to overrun the valley, and then cut the overlap off to create the open valley.
Cutting the shingles to create the open valley seems like it’d be more work to get it looking good and straight the whole way?


That’s called a California cut valley. It’s a shortcut, but a good shortcut. Some guys don’t like them and don’t use them.

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That way of doing valleys is not wrong, I see it more on closed valleys. On open valleys, We run the shingles into the valley up until the top of the exposure hits your cut line. Then put a dub, or back cut, on an angle from where the top of the shingle interests the valley metal about 2-3" down towards the open valley. This eliminates horizontal water travel.

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Thank you both - combining your two replies now it makes sense to me :slight_smile: So it’s a California cut on an open valley. That’s probably why it looked different to me. Like MPA said, they’re usually done on closed valleys, which is what most all of the pictures I see are for California cut valleys. Just finally had to go up their for the Christmas lights, so I was poking around a bit to see what it was like from top view.