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  1. #1
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    Default Skylight flashing (extra?)

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  2. #2
    A.D. Miller's Avatar
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Andrew Kolar View Post
    What is the purpose of the extra piece of metal type flashing shown here at the top edge of these skylights?

    http://i303.photobucket.com/albums/n...A090218003.jpg

    http://i303.photobucket.com/albums/n...A090218002.jpg
    Andrew: It appears to be serving no purpose other than to elicit questions.


  3. #3
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    Default Re: Skylight flashing (extra?)

    I suspect the intent, as feeble as it was, to be for the purpose of stopping water running down the roof from splashing up underneath the other flashing and the skylight itself.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  4. #4
    Ron Bibler's Avatar
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    Default Re: Skylight flashing (extra?)

    Basketball flashing...

    Best

    Ron


  5. #5
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Ron Bibler View Post
    Basketball flashing...
    That's what the Harlem Globetrotters do ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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  6. #6
    Gary Anglin's Avatar
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    Default Re: Skylight flashing (extra?)

    My roofer just retrofitted those to a skylight he put in last year. Said it would help prevent ice daming - which had forced ice up under that upper edge - causing a leak at the top of the interior.


  7. #7
    A.D. Miller's Avatar
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Gary Anglin View Post
    My roofer just retrofitted those to a skylight he put in last year. Said it would help prevent ice daming - which had forced ice up under that upper edge - causing a leak at the top of the interior.
    Gary: Roofers everywhere are like an army of diddling babblers moving over the landscape in search of a real profession. But, I have to give yours credit for originality. That is the first time I've ever heard that B.S. - ice dam - yeah, right.


  8. #8
    Gary Anglin's Avatar
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by A.D. Miller View Post
    Gary: Roofers everywhere are like an army of diddling babblers moving over the landscape in search of a real profession. But, I have to give yours credit for originality. That is the first time I've ever heard that B.S. - ice dam - yeah, right.
    Well - this roofing company is the only one to touch the house since I bought it in 1990. Actually they have treated me pretty well - and the "repair???" was free. But you are absolutely right - roofers drive my industry nuts also with the stuff they come up with.


  9. #9
    Ted Menelly's Avatar
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    Default Re: Skylight flashing (extra?)

    I think Jerry had it right


  10. #10
    Frank Suchodolski's Avatar
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    Default Re: Skylight flashing (extra?)

    Maybe that is how they install Backpans in Iowa? Maybe it's a spoiler so the house is more aero-dynamic?
    Also, the actual back pan, unless it is a one piece soldered unit, doesn't look right to me. Back pans usually extend 3" past the edges of the skylight.


  11. #11
    A.D. Miller's Avatar
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Gary Anglin View Post
    Well - this roofing company is the only one to touch the house since I bought it in 1990. Actually they have treated me pretty well - and the "repair???" was free. But you are absolutely right - roofers drive my industry nuts also with the stuff they come up with.
    Gary: Seriously though, there are some competent roofers out there. Problem is, they are no longer in the business.


  12. #12
    Brandon Chew's Avatar
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    Default Re: Skylight flashing (extra?)

    Jerry has it right, except for the "feeble as it was" comment, and Gary has it right, regardless of Aaron's opinions about roofers and ice dams.

    Its purpose is to keep rain or melting snow/ice from jumping the curb in the joint between the head flashing and the window sash.

    If done right, the head flashing and that U shaped portion are actually formed from one piece of metal. Your typical head flashing, instead of ending at the top of the curb, is folded back down and then up again to create the U shape. It's done wrong if that U portion was a separate piece that was simply tucked between the head flashing and the counterflashing. You can't tell from your pic if it was done right or wrong.

    Here's some details from a major manufacturer which shows a profile of that that type of head flashing. Go to this link and then download the pdf for "Section 6: Roof Windows and Skylights". Refer to the vertical sections on pages 6-2 through 6-6.

    Andersen&#174 Online


  13. #13
    A.D. Miller's Avatar
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    Default Re: Skylight flashing (extra?)

    regardless of Aaron's opinions about roofers
    Brandon: Maybe roofers are differently abled in NY than in TX. I see at least one roof each year that is installed according to the instrcutions on the back of the shingle package. How many do you see?


  14. #14
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Brandon Chew View Post
    Jerry has it right, except for the "feeble as it was" comment, and Gary has it right, regardless of Aaron's opinions about roofers and ice dams.

    Its purpose is to keep rain or melting snow/ice from jumping the curb in the joint between the head flashing and the window sash.
    Brandon,

    I realize that is its purpose, however, as that one is installed, the protective flange will also act as a funnel flange and catch water, directing it right into where you are trying to protect it from.

    When that water which has collected there, added to that the snow which will collect there, will simply cause the same ice lifting effect.

    That is like using an umbrella turned upside down to keep rain off you, it will work to a point, then it makes matters worse.

    You will notice the one in the Andersen link ( http://www.andersenwindows.com/servlet/Satellite?blobcol=urldata&blobheader=application%2 Fpdf%0D%0AContent-Disposition%3A+inline%3B+filename%3DSEC6_Skylights _Roof-Window.pdf%3B&blobkey=id&blobnocache=false&blobtab le=MungoBlobs&blobwhere=1192555326847&ssbinary=tru e ) is installed facing the other way. See bottom of page 6-5.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  15. #15
    A.D. Miller's Avatar
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Jerry Peck View Post
    Brandon,

    I realize that is its purpose, however, as that one is installed, the protective flange will also act as a funnel flange and catch water, directing it right into where you are trying to protect it from.

    When that water which has collected there, added to that the snow which will collect there, will simply cause the same ice lifting effect.

    That is like using an umbrella turned upside down to keep rain off you, it will work to a point, then it makes matters worse.
    JP: Thanks for rescuing me from this impromtu lynch mob of roofer mavens. I see silly stuff like this flashing installed all of the time. I belive I will take the time to start posting all of them. If the other inspectors in my area will do the same, everyone can get a better view of the fine professional MF's we have here in the residential roofing community in North Central Texas. No bueno.


  16. #16
    Brandon Chew's Avatar
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Jerry Peck View Post
    Brandon,

    I realize that is its purpose, however, as that one is installed, the protective flange will also act as a funnel flange and catch water, directing it right into where you are trying to protect it from.

    When that water which has collected there, added to that the snow which will collect there, will simply cause the same ice lifting effect.

    That is like using an umbrella turned upside down to keep rain off you, it will work to a point, then it makes matters worse.

    You will notice the one in the Andersen link ( http://www.andersenwindows.com/servlet/Satellite?blobcol=urldata&blobheader=application%2 Fpdf%0D%0AContent-Disposition%3A+inline%3B+filename%3DSEC6_Skylights _Roof-Window.pdf%3B&blobkey=id&blobnocache=false&blobtab le=MungoBlobs&blobwhere=1192555326847&ssbinary=tru e ) is installed facing the other way. See bottom of page 6-5.

    Jerry,

    I'm not following your comments about "protective flange" and "funnel flange" and your reference to the bottom of page 6-5 makes me think you are referring to what Andersen calls an "Auxiliary Water Deflector". That is not the flashing that I am talking about.

    I am talking about the one-piece head flashing that is shown in the vertical sections on pages 6-2, 6-3, 6-4, 6-5, and 6-6. It has an edge profile just like I've outlined in yellow on the original poster's pic. The Andersen details and the flashing in the pic are both oriented in the same direction with respect to the ridge. Its purpose is to keep water that runs down the roof from jumping over the curb (blue arrow) at the head flashing.

    The installation in the original pic could be fine ... if this is one piece of flashing with a profile like I drew in yellow. At least one manufacturer cranks them out of the factory with that profile, and a competent tin man could bang one out too.

    If it was two pieces instead of one piece that was folded back on itself to make the U, and the right edge of that projecting U portion was just tucked up under the counterflashing, then it won't do what it is intended to do, and water can still flow up over the curb. We can't tell from the pic whether it is one piece or two pieces ... the area in question is beneath the counterflashing and is not visible.

    Aaron - we have our share of poor roofers here too.

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    Last edited by Brandon Chew; 02-21-2009 at 09:13 PM. Reason: proofreading

  17. #17
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    Default Re: Skylight flashing (extra?)

    Quote Originally Posted by Brandon Chew View Post
    Jerry,

    I'm not following your comments about "protective flange" and "funnel flange" and your reference to the bottom of page 6-5 makes me think you are referring to what Andersen calls an "Auxiliary Water Deflector".
    Correct, I was, I thought that's what you were referring to.

    See attached for the "funnel" I am referring to. The angled surfaces will serve to catch water and direct it right to where the flashing is trying to direct it way from. Additionally, snow will build up in that "funnel" and the ice will do the same thing that flashing is trying to avoid.

    That is not the flashing that I am talking about.
    I am talking about the one-piece head flashing that is shown in the vertical sections on pages 6-2, 6-3, 6-4, 6-5, and 6-6. It has an edge profile just like I've outlined in yellow on the original poster's pic.[/quote]

    The drawing on 6-2 shows the same angle but used with a different skylight which has deflector angles to keep water out of that angled out flashing. The original posters photo does not show that.

    The drawing on 6-3, 6-4 and 6-6 is somewhat like the original photo except that the skylight flashing as a returned lip which seals that additional piece, the original photo simply shows a break lip angled outward.

    Drawing 6-5 shows the same detail as 6-2 except it now has an angled cover flashing over it (which would not work well for the operable type sashes shown in 6-3, 6-4 and 6-6).

    The Andersen details and the flashing in the pic are both oriented in the same direction with respect to the ridge. Its purpose is to keep water that runs down the roof from jumping over the curb (blue arrow) at the head flashing.
    Understood. But that flashing will also catch water - see attached.

    The installation in the original pic could be fine ... if this is one piece of flashing with a profile like I drew in yellow. At least one manufacturer cranks them out of the factory with that profile, and a competent tin man could bang one out too.
    Andersen shows it as two pieces and that photo looks like two pieces.

    If it was two pieces instead of one piece that was folded back on itself to make the U, and the right edge of that projecting U portion was just tucked up under the counterflashing, then it won't do what it is intended to do, and water can still flow up over the curb. We can't tell from the pic whether it is one piece or two pieces ... the area in question is beneath the counterflashing and is not visible.
    Looks like two pieces to me. Too nice and neat of a break job on that "second" "outer" piece to match the 'not as clean wrap' around the corner.

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  18. #18
    Frank Suchodolski's Avatar
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    Default Re: Skylight flashing (extra?)

    Now I know why I have never seen a flashing like that before. This "OPtional Head flashing" would be required with the ski jump back pan, with a regular back pan, single break not rounded, and 6" high curb for the skylight, water will not go over the curb (not that I've ever seen). I have seen lots of leaks like that with poorly installed EPDM (rubber) loose laid back pans. You want the water to hit the back pan with a sharp corner. Water quantities, unless you have 100" of roof slope above the skylight, will never come over the top. If skylights exceed 3' in width then backpans/curbs should be raised accordingly (approximately 1/5 of the width, so 40" wide backpan should be 8" curb).

    Last edited by Frank Suchodolski; 02-22-2009 at 12:19 PM. Reason: Correction

  19. #19
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    Default Re: Skylight flashing (extra?)

    Brandon is spot on, that is exactly what it is, optional shingle flashing, that's the normal for the head flashing. You'd see the same on tile roof optional flashing except lower profile. Yes it is an *extra* or option to use this flashing/counterflashing system, it is a good thing in IA with a moderate to steep pitch tab roof.

    Perhaps they're not as familiar with their southern no-snow, low slope roofs and their hurricane rules they're probably more familiar with curb flashing, relying on sticky membranes for flashing, or offset installations. We can't use curb flashing with steeper slopes and snow/ice loads. We don't need to use an offset flashing if the roof has sufficient slope.

    We see this in northern tornado alley all the time with other than flat or low-slope roofs. Actually we sometimes install strip above entry door and window locations above the icedam zone in the tab asphalt roof with a slope to divert rain flow also. We don't usually bother with A's auxiliary gutter where we have rain storms raining buckets, normally have ice and snow in the winter and occasionally have hail, they don't usually survive a full climatic cycle with more than a few midwest thunderstorms or single microburst or blizzard.

    Last edited by H.G. Watson, Sr.; 02-22-2009 at 12:43 PM.

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