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Cut valley roof shingles


palmettoinspect
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The valley isn't perfect. It's a closed cut valley and the larger roof should drain onto the smaller roof...just opposite of the installation shown . The cut should be 2 inches above the centerline of the valley. I'm not sure how the roofer managed to lose the course alignment but it looks like crap.

Will it leak? Probably not. Is it wrong? Sure, and it should be documented.

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The above pictured valley is how we typically see them around here. As long as there is no leakage or staining noted in the attic, I would call it functional. As the others day, any time that you can not access the attic and see the underside of the roof, make sure you document that in your report.

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The above pictured valley is how we typically see them around here. As long as there is no leakage or staining noted in the attic, I would call it functional. As the others day, any time that you can not access the attic and see the underside of the roof, make sure you document that in your report.

Matthew Steger, CRI

Hi Matt,

There are a lot of things that can be done wrong in a closed cut valley and some of the most important things are the ones you can't easily see: are the tops of the shingles cut off @ 45 degrees and is the top layer bedded in mastic?

On a roof where there are obvious egregious installation errors like the one shown in the picture, calling it "functional" would be a pretty risky assessment.

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I agree with Chad. The roof with the greater watershed should overlap the roof with lesser watershedding ability.

Here's a page from CertianTeeds' shingle applicators manual.

There's no way to tell when or even if that valley would leak or not, but the odds are greater when it's installed improperly.

Tony

Download Attachment: icon_adobe.gif Closed cut valley.pdf

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Hi Gary,

The NRCA website will have a pdf on woven valleys. However, in your location I feel an open metal valley with a W shape would be a better choice to encourage snow shedding. If you have a steeper roof, say 10/12 or greater it's not as much an issue. Even with a woven valley I urge you to use ice and water and 24 inches of metal beneath the shingles.

Don't brake the metal, instead, lay it centered in the valley, attach one side with a few staples or nails and then lay a roll of felt in the center which will create a nice smooth radius for the shingles to follow from one roof plane to the other.

Lastly, if your roof pitches aren't the same, it's more difficult to get a woven valley to look nice. Be carefull to keep the valley centerline from creeping; you'll need to make corrective double course weaves occasionally.

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Originally posted by hausdok

OK,

Now I see it. Chad's right, just reverse the arrows.

OT - OF!!!

M.

OK, educate me here. So, for closed valleys, Certainteed really wants the field with the more surface area (draining more water) to extend past the valley and terminate into the field with the lesser water drainage. Correct? In their diagram, the larger field of roof (more water drainage) should be the portion on the left and smaller field on the right?

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Originally posted by msteger

Originally posted by hausdok

OK,

Now I see it. Chad's right, just reverse the arrows.

OT - OF!!!

M.

OK, educate me here. So, for closed valleys, Certainteed really wants the field with the more surface area (draining more water) to extend past the valley and terminate into the field with the lesser water drainage. Correct? In their diagram, the larger field of roof (more water drainage) should be the portion on the left and smaller field on the right?

No, disregard the size of any given portion of the roof in the sketch 'cuz it doesn't mean a thing. What's important is which side they've designated greater watershed versus lesser watersdhed. The lesser watershed is not cut and it passes through the valley and angles onto the other roof plane. The the greater watershed laps over the top of that and is trimmed 2-inches back from the centerline of that valley and adhered with mastic. The sketch is correct, they just mislabled the two vertical lines that designate the centerline of the valley and the cut line. Those arrows should be reversed.

OT - OF!!!

M.

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Ok, so let me see if I follow you correctly. We're talking about either cutting shingles along a line parallel to the valley versus interweaving shingles from one field into shingles of another field at the valley. Is this correct?

For some reason, I think I am missing something. You are saying in the top photo from the book that the "cut shingles back 2..." and "valley center line" arrow are the reversed ones? Looking at the corner of the fascia below it, I agree.

What are we considering (forget the drawing in the Certainteed book) on a typical gable roof with a dormer window sticking out towards the north. The main gable roof who's fields face north/south. The fields of the dormer roof face east/west. Take the west valley where the dormer's roof meets the main roof field. Forgive me for asking again, but, to clarify, how should the shingles in this valley be installed? You say to not worry about which field of roofing has the larger field and thus, probably, has the higher water shed.

Am I making you feel as though you are hitting your head on the wall? Sorry..

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Oy!

Originally posted by msteger

Ok, so let me see if I follow you correctly. We're talking about either cutting shingles along a line parallel to the valley versus interweaving shingles from one field into shingles of another field at the valley. Is this correct?

Yes, the whole thread, and the text from the Certainteed manual refer to a cut valley; not a woven valley.
For some reason, I think I am missing something. You are saying in the top photo from the book that the "cut shingles back 2..." and "valley center line" arrow are the reversed ones? Looking at the corner of the fascia below it, I agree.

What are we considering (forget the drawing in the Certainteed book) on a typical gable roof with a dormer window sticking out towards the north. The main gable roof who's fields face north/south. The fields of the dormer roof face east/west. Take the west valley where the dormer's roof meets the main roof field. Forgive me for asking again, but, to clarify, how should the shingles in this valley be installed? You say to not worry about which field of roofing has the larger field and thus, probably, has the higher water shed.

No, I said not to look at the size shown in that picture; I wasn't referring to all roofs. In the example that you cite the main roof is the greater watershed area and the shingles from the roofs on the gables must curl against and lie flat on the plane of the greaterh water shed, the shingles of the greater water shed overlaps those, and the shingles of the greater water shed (the main roof in your example) are cut two inches out from the center of the valley and adhered with mastic.
Am I making you feel as though you are hitting your head on the wall? Sorry..
Yep. [:-banghea
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