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  1. #1
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    Default Cut valley opinions please

    Small plane surface area to the left is 9:12 larger right plane is 6:12

    This is being disputed by the in$urance provider they want the vallys redone even though two other independent roofers disagree and say this is OK.

    Moisture is present when cut tabs were lifted but nothing is showing in the attic YET. Last rainfall 04-04-08.

    Also the valley discharge over shoots the gutter end.

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  2. #2
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    Default Re: Cut valley opinions please

    Quote Originally Posted by BARRY ADAIR View Post
    Small plane surface area to the left is 9:12 larger right plane is 6:12
    Barry,

    I think the cut side should be on the steeper plane.

    Picture looks like the gutter ends short of the valley discharge.

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  3. #3
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    Default Re: Cut valley opinions please

    I have to agree with the insurance company (oh that's scary). The picture shows numerous bad practices.
    - the steeper roof shingles appears to run under to lower roof shingles; will always leak
    - the shingles don't appear to be woven together, it's looks like some strange straight cut on the lower shingle line to give a neat appearance; why wouldn't water want to run under those shingles.
    - maybe if they can prove there is a 3' membrane in the valley or the shingles are actually woven underneath they could get it to pass.
    - I just don't see anything that's going to keep the water from not running under the shingles ... which eventually will leak.
    If the roofers say it's OK, then they should have no problem explaining the 'physics' of it and drawing a diagram of how it works.
    That always shuts them up.

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  4. #4

    Default Re: Cut valley opinions please

    Markus,
    That is called a cut valley, and is very common in some areas.
    That being said, I think the cut is on the wrong side as well. - I say check with the manufacturers installation instructions-- most lay it out pretty well on which side to overlap, etc.


  5. #5
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    Default Re: Cut valley opinions please

    I know about the cut valley way. We don't usually do it that way around here much because it doesn't work well with our weather.
    Usually woven shingles or a cut valley with exposed copper, alu. etc

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  6. #6
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    Default Re: Cut valley opinions please

    The steeper roof slope should be the overlying layer, not the underlying layer, with the cut valley pulled back 2" from the valley center toward the steeper roof (overlying layer) side.

    That is all based on the theoretical amounts of water flow and the force of that water flow - the steeper the roof, the faster the water flows, with the water meeting at the center (for same slope roofs of the same height) or with the water from the steeper roof overshooting the center of the valley toward the lower sloped roof side.

    That said ... if you have a small steeper sloped roof and a larger shallower sloped roof, which roof is going to have the most water on it and which water is going to have the greater force behind it? Let's say the steeper slope has 5 feet head above that end of the valley, whereas the shallower sloped roof has 20 feet of head above that end of the valley ... which roof *should* be on top? The steeper sloped roof. Which roof 'should' be on top? The taller roof. Which is enforceable and has documentation backup? The steeper sloped roof being on top.

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  7. #7
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    Default Re: Cut valley opinions please

    Look closer in the valley, starter course was used, this isn't a cut valley by any stretch of our imagination.

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  8. #8
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    Default Re: Cut valley opinions please

    Quote Originally Posted by BARRY ADAIR View Post
    Look closer in the valley, starter course was used, this isn't a cut valley by any stretch of our imagination.

    You were there, so I trust your opinion, but I can't can't see enough detail in the photo to draw any conclusions.

    Dom.


  9. #9
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    Default Re: Cut valley opinions please

    Starter course would not have been as bad if it were installed correctly with the tabs cut off or installed upside down. Still not right but the way it is the tab cut at the middle of the valley directs water under the roofing. Think roofer needs to read the instructions printed on the bundle.


  10. #10
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    Default Re: Cut valley opinions please

    I'm sorry Vern but you are way off base. 'Read the instructions on the bundle'? As far as I know those bundles are written in english, I don't think there's much possibility of any reading going on.
    I know I'm a bad boy, I'll go back to my hole in the ground now.

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  11. #11
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    Default Re: Cut valley opinions please

    Quote Originally Posted by BARRY ADAIR View Post
    Look closer in the valley, starter course was used, this isn't a cut valley by any stretch of our imagination.
    Barry,

    I see it now, they *did not* cut the shingles at the valley, they just laid a starter course shingle up the 'cut line', then landed shingles on that starter course.

    I remember a couple of others here have posted similar photos of that in the past, and we didn't catch it at first then either.

    A closer look will reveal the slots/ends in the singles going up the valley making that 'cut line' are at an angle to the shingle tabs. Didn't pick up on that when I first looked at the photo, but I see it now.

    Jerry Peck, Construction / Litigation Consultant
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  12. #12
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    Default Re: Cut valley opinions please

    I'm sorry Vern but you are way off base. 'Read the instructions on the bundle'? As far as I know those bundles are written in english, I don't think there's much possibility of any reading going on.
    Nope, Spanish and English on all construction products around here, of course they still don't read it.

    Jim Luttrall
    www.MrInspector.net
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  13. #13
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    Default Re: Cut valley opinions please

    So this is what we are seeing? Or is if flipped over, with the tabs to the right?

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  14. #14
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    Default Re: Cut valley opinions please

    This is link to Certainteed Manual. Pretty clear installation methods. But the issue of which slope goes over/under and Watershed area didn't help much. They call what you have pictured a "closed cut valley" installation.

    http://www.certainteed.com/NR/rdonly...Manual8Ch6.pdf

    The above statements are expressed solely as my opinion and in all probability will conflict with someone else's.
    Stu, Fredericksburg VA

  15. #15
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    Default Re: Cut valley opinions please

    Barry, what was your final verdict on the shingle application? I reviewed the applicator's guide that Stuart sent (good job) and it mentions that 3-tab shingles shouldn't be used at all in the alternate closed valley.

    Hard to tell exactly, but were you looking at a 3-tab shingle on that valley?

    Re: Two differing pitches...

    This is from page 8 (pg 66) of the guide:

    Making decisions about cutting shingles in valleys often requires
    some careful thinking. Here are two “tough” calls:
    1. If a 10/12 roof section forms a valley with a 4/12 roof section, and
    the 10/12 section is one-third the area (water volume) of the 4/12
    section, you should cut the shingles on the 10/12 side.
    2. If an 8/12 roofing section forms a valley with a 10/12 roofing section
    and the 8/12 roof has one-third the area (water volume) of
    the 10/12 section, put the cut on the 8/12 side.

    Based on the photograph and my inept brain and the verbage above, the cut in a "real" cut valley (not what you inspected) would be on your larger 6:12 side. Am I right?

    Bruce


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  16. #16
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    Default Re: Cut valley opinions please

    OK, now that I've read my own post...

    The cut side should be on the smaller, steeper side. Right??????? Help, I'm sinking here...

    Bruce Thompson, Lic. #9199
    www.TylerHomeInspector.com
    Home Inspections in the Tyler and East Texas area

  17. #17
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    Default Re: Cut valley opinions please

    [FONT='Georgia','serif']On Page 8 of the [/font][FONT='Georgia','serif']CertainTeed[/font][FONT='Georgia','serif'] installation manual entitled “ALTERNATE CLOSED VALLEY APPLICATION “ [/font][FONT='Georgia','serif']Figure 6-18: Alternate closed valley application [/font][FONT='Georgia','serif']Shows this exact scenario. [/font][FONT='Georgia','serif']This application cannot be used with shingles that have cut-outs, such as a typical 3-tab strip shingle. [/font][FONT='Georgia','serif']CertainTeed apparently is not concerned with the pitch of the roof, but only the watershed area. If the right side of the roof as pictured is the larger water shed area then by CertainTeed this is an acceptable installation.[/font]
    [FONT='Georgia','serif'][/font]
    [FONT='Georgia','serif']http://www.certainteed.com/NR/rdonly...Manual8Ch6.pdf[/font][FONT='Georgia','serif'][/font]


  18. #18
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    Default Re: Cut valley opinions please

    Oops! Where did all that extra stuff come from? Let’s try again.
    On Page 8 of the CertainTeed installation manual entitled “ALTERNATE CLOSED VALLEY APPLICATION “ Figure 6-18: Alternate closed valley application Shows this exact scenario. This application cannot be used with shingles that have cut-outs, such as a typical 3-tab strip shingle. CertainTeed apparently is not concerned with the pitch of the roof, but only the watershed area. If the right side of the roof as pictured is the larger water shed area then by CertainTeed this is an acceptable installation.


    Link to CertainTeed http://www.certainteed.com/NR/rdonly...Manual8Ch6.pdf

    Richard Mobley
    Mobley Home Inspections


  19. #19
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    Default Re: Cut valley opinions please

    If the shingles that are tucked up under the ones on top go up that roof 24" I'd say it would be reasonably water tight. Now I have never seen a good roofer do one like that before. I think the whole issue is whether or not there are shingles from the one side going up under the other or if they stop under the shingle laid along the angle of the valley. Clear as mud?


  20. #20
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    Default Re: Cut valley opinions please

    The installation is quite common except on deciding which side the cut should be. We always used the higher side because there is a less chance of water flowing upwards to the top of the underside shingles. We also applied at least 6' wide tar bead down the starter course of the valley.
    But around here we are more common to use woven valleys.

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  21. #21
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    Default Re: Cut valley opinions please

    GAF calls that type installation a California Valley - Closed. There is also a California Valley - Open version. They spell out strict requirements for type of shingle allowed for this installation as well as other paramters to be closely followed or you will have problems. Also, they will not cover this installation technique under their premium warranty plan.

    See: GAF Materials Corp - Residential and Commercial Roofing and type California in the Search box.

    Which side should be the "cut side"? The steepest, unless it carries the least obvious volume, as Jerry pointed out.

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