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  1. #1
    RobertSmith's Avatar
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    Default vent flashing/valley

    Last edited by RobertSmith; 12-20-2007 at 12:54 PM.
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  2. #2
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    Default Re: vent flashing/valley

    This vent is located to close to a valley to be properly flashed. Although there is no evidence of a leak at this time, a leak could occur later.
    Recommendation: Move vent away from the valley when, the roof is replaced or, a leak does develop.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  3. #3
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    Default Re: vent flashing/valley

    The valley cannot be properly flashed, or you would see the flashing on top of the vent flashing.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: vent flashing/valley

    Thank you Clay

    The biggest challenge I have as an inspector is reporting what I see/think.
    Once again I have given an incomplete description.

    The way the valley is now. The valley flashing is one long piece from top to bottom. With the vent flashing placed on top of and cut into the valley flashing.

    What I'm saying is it should be is:
    Valley flashing is two pieces.
    The lower piece of valley flashing comes up just above the vent opening.
    Now place the vent flashing over the lower valley flashing.
    Then the upper piece of valley flashing goes on top of the vent flashing and extending below the vent flashing.

    Kinda like step flashing, each piece overlaps the piece below it.

    So when I said "you would see the flashing on top of the vent flashing"
    I was refering to valley flashing on top of the vent flashing, not an open valley.


    "The flashing for the vent looks okay."
    I don't think that it is OK

    "The problem is when you nail the vent base flashing down, the nails could puncture the underlying flashing for the valley because"

    That is why I said it is not OK. Also any water that gets into the valley above the vent, will now be under the vent flashing. And the valley has this great big hole in it.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  5. #5
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    Default Re: vent flashing/valley

    Most valley metal is 16" wide. When properly placed down the center of the valley, the valley metal extends 8" to each side of the valley center (I know, that's just simple math - but let me finish ), that vent looks to me like it is right about where the edge of the valley metal is. Meaning its okay to be there.

    That is, without measuring and knowing for sure that the vent is not cut into the valley metal - we just do not know for sure how far the edge of the vent is to the edge of the valley metal, but ... to me ... it looks 'just about as close as it can get and be okay'.

    That said, the valley metal is now presumed to be 'okay'.

    Now, we are at the flashing around the vent, and if 'might not be' nailed through the valley flashing, the roofer 'might have had enough sense' to know not to do that ... nah, that'll never happen ... but, let's *assume* he did (for once, anyway). Now, there really is not much wrong with that flashing either.

    Without actually measuring the vent, I would hesitate to condemn it outright.

    It's much better to say 'when the roofing contractor is on the roof making other repairs, have roofing contractor verify the vent flashing is not too close to the valley flashing and make appropriate repairs as necessary.

    1) You are covered as you wrote it up.

    2) You did not condemn something which very well could be okay.

    3) The roofing contractor "bought it" whether or not they make any repairs. If they make a repair, they bought it. If they do not make a repair, they 'are accepting it as it is', and they bought it.

    4) You did your job of reporting it.

    Jerry Peck, Construction / Litigation Consultant
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  6. #6
    Richard Rushing's Avatar
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    Default Re: vent flashing/valley

    Quote Originally Posted by Jerry Peck View Post
    Most valley metal is 16" wide. When properly placed down the center of the valley, the valley metal extends 8" to each side of the valley center (I know, that's just simple math - but let me finish ), that vent looks to me like it is right about where the edge of the valley metal is. Meaning its okay to be there.
    .
    Errrrr.... Nope. That would be 16"/side, off center. Which would be a 32" wide metal strip. The valley metal is 24" inches wide, centered-- with a 4" inch/ per side minimum extension under the shingle.

    24" + 8" inches(4/ side, minimum under shingle)= 32" inches.

    That's 16" from center, which that certainly looks like cuts into the flashing of the valley for the composition shingle.


  7. #7
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    Default Re: vent flashing/valley

    It looks a lot closer than 8" to me, I'd say 4"-6".
    I base that distance by comparing be diameter of the vent to the distance of the vent from the valley center (what looks like the center).

    If it is 4"- 6" from the valley then it did have the valley flashing cut. If the valley flashing is cut then it is not properly flashed.
    That is why I said:
    "This vent is located to close to a valley to be properly flashed. Although there is no evidence of a leak at this time, a leak could occur later.
    Recommendation: Move vent away from the valley when, the roof is replaced or, a leak does develop."


    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  8. #8
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    Default Re: vent flashing/valley

    Quote Originally Posted by Richard Rushing View Post
    Errrrr.... Nope. That would be 16"/side, off center. Which would be a 32" wide metal strip.
    Not any place I've been. It's been 16" wide, 8" to each side of the valley.

    Talking *metal* here as in "valley metal".

    For open valleys, 24" width is required, but for closed valleys, the metal only needs to be 16" wides. And that is not an open valley.

    The cut valley 'cut line', though, is centered in the valley and should not be, it should be pulled back 2" from the valley center.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: vent flashing/valley

    Quote Originally Posted by Rick Cantrell View Post
    It looks a lot closer than 8" to me, I'd say 4"-6".
    Guess my calibrated glasses need to be re-calibrated, because it sure looks closer to 8" than to 4", I might be able to be convinced it is between 6" and 8", but without a ruler up there, I'm sticking with what I said: "That is, without measuring and knowing for sure that the vent is not cut into the valley metal - we just do not know for sure how far the edge of the vent is to the edge of the valley metal, but ... to me ... it looks 'just about as close as it can get and be okay'."

    I base that distance by comparing be diameter of the vent to the distance of the vent from the valley center (what looks like the center).
    Same here, and trying to compare the ridge caps (which are 12" wide) to that space, but they are 'bent over the ridge' (making them less useful for this) and at too far away.

    Without a ruler up there ...

    Jerry Peck, Construction / Litigation Consultant
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  10. #10
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    Default Re: vent flashing/valley

    Around here a closed valley, woven or cut, may not have a metal flashing at all, instead it there is a layer of 3' wide roll roofing or ice&water shield.

    So unless you can determine what's installed by lifting shingles at the eaves, you are best off assuming 18" from the center.


  11. #11
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    Default Re: vent flashing/valley

    Quote Originally Posted by Michael Thomas View Post
    Around here a closed valley, woven or cut, may not have a metal flashing at all, instead it there is a layer of 3' wide roll roofing or ice&water shield.

    So unless you can determine what's installed by lifting shingles at the eaves, you are best off assuming 18" from the center.
    Actually, you are "best off assuming" what is used in your area.

    "Assuming" that the valley flashing *not* metal and extends out 18" in the areas I've been would have you "assume" terribly wrong.

    If 'you know' what your areas "typically uses", then that is what you start off "assuming". But those "assumptions" will not be valid for every area.

    Jerry Peck, Construction / Litigation Consultant
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  12. #12
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    Default Re: vent flashing/valley

    I thought it was clear that "this is what you see in my area" = "in my area you are best off assuming this may be what you will find."... that's sorta' the point of the post...

    Last edited by Michael Thomas; 08-06-2007 at 06:50 AM.

  13. #13
    Richard Rushing's Avatar
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    Default Re: vent flashing/valley

    Quote (JP): "But those "assumptions" will not be valid for every area."

    That would be correct... Here is what Haag Engineering illustrates;
    (see attachment illustrating 16"/ side)

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    Default Re: vent flashing/valley

    and the plywood people say

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    Default Re: vent flashing/valley

    Quote Originally Posted by Richard Rushing View Post
    Quote (JP): "But those "assumptions" will not be valid for every area."

    That would be correct... Here is what Haag Engineering illustrates;
    (see attachment illustrating 16"/ side)
    Richard,

    I hate to be the one to point this out ( ), BUT, that shows "Valley metal 24" wide at ridge". Says nothing about " 16" " --- Oops?

    Also, that is a preformed valley metal with a center diverter for open valleys, which require (as I stated before, and as you just confirmed) "For open valleys, 24" width is required,", HOWEVER, the valley in the photo is not an open valley, thus does not need as wide of a valley metal - i.e., 16" ... unless your local code requires something different or does not allow metal (which, for the life of me, I cannot figure out why it would not allow metal). When *not of metal*, yes, the valley flashing must be wider - are we talking about a metal valley flashing or a valley flashing of another material? That's an assumption we have to make based on what is allowed/used in our areas as it is not shown in the photo.

    Jerry Peck, Construction / Litigation Consultant
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  16. #16
    Richard Rushing's Avatar
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    Default Re: vent flashing/valley

    Reading skills a must--

    the 24" is definately at the ridge. However there is also a 4"/ side (as previously stated) shingle overlap--each side, totaling 8" inches.

    8+24= 32" inches

    1/2 of 32" from center to end of (one side) flashing is.... 16" inches.

    RR


  17. #17
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    Default Re: vent flashing/valley

    Quote Originally Posted by Richard Rushing View Post
    Reading skills a must--
    Could not agree more ...

    "Valley metal 24" wide at ridge; 4" minimum extension under shingles"

    24" wide valley metal, this means 12" to each side of the valley center, with shingles covering a minimum of 4" of the valley metal on each side, which leaves a maximum of 8" of exposed valley each side of center.

    *Typically*, that 8" is at the bottom, with less exposed at the top. The open valley typically has the shingles closer together at the top and further apart at the bottom, this is to allow for the build up of water in the valley as you go down the valley. With a center diverter as shown in the photo, this is not as critical as with regular flat rolled valley metal.

    "Reading skills a must--" Absolutely!

    Jerry Peck, Construction / Litigation Consultant
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  18. #18
    Richard Rushing's Avatar
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    Default Re: vent flashing/valley

    Sure is... go look at the diagrams posted.

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  19. #19
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    Default Re: vent flashing/valley

    Quote Originally Posted by Richard Rushing View Post
    Sure is... go look at the diagrams posted.
    *I* *DID*.

    *Did you?*

    See attached drawing to see why *I* did and *you* must not have.

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