Good pick up Dave. I didn’t take notice of that…
lazy way not to have to cut into the valley…
http://www.extremehowto.com/xh/hotprod_images/asphroofdiagram11.jpg
A closed cut valley is installed over a heavy-duty valley liner or metal roll flashing. Shingles are then overlapped. Do not nail the shingles within 6 inches of the centerline (as already stated). Then a straight line is cut through the top layer of shingles 2 inches away from the centerline of the valley. The 2-inch offset prevents the majority of the water runoff from flowing directly over the seam.
Good link David.
That’s what they were TRYING to do.
Yes, indeed. Until they started drinking or drugging on the job.
The steeper plane should overlap the shallow pitch plane…?
nice images David! good catch…
I agree with James
Barry,
Please tell everyone how you wrote this particular installation up?
OK, now I’m confused. Can someone document whether height or pitch governs overlap?
Mfg. instructions are the best guide, but in this case it’s obvious this is a crap install no matter how you look at it
My comments
- The shingle’s intersection at the valleys are improperly installed at numerous locations.
- The steeper pitch shall overlap the lesser pitch roof section to avoid water migration under the shingles, which is occurring at this time and presents a greater opportunity for lessened shingle life and future leakage.
- No moisture intrusion was seen or metered from the attic in these areas at this time (see attached attic photos of all valleys).
- The starter course, shingle tabs installed perpendicular in the valley is improper, this is trapping moisture under these shingles at these locations and may lead to premature failure (leaks).
- The valley runoff discharge does not align with the gutters, soil erosion and pooling is occurring under these discharge impact areas.
- Unable to verify proper installation of the required additional valley underlayment flashing membrane or metal materials at all valley locations. These may be present but are not installed the entire length of the valleys in question.
- Advise that a qualified roofing contractor shall make any of the necessary repairs to the current building standards and material manufacturer instructions.
*]Tear off and replacement of absent or improperly installed materials is most likely required.
Larry is right
I kind of agree with Ken too, but the photo could be decieving. If both roof planes are at the same pitch it should not matter what laps over the other. I have this style valleys on my house with no problems
ROY
My friend had an addition and roof like this put on and it had to be ripped off because it leaked everywhere inside the ceilings and out the light switches.
If they are both the same pitch it doesnt matter, if they are not the same rise it dose.
left is 9:12 smaller surface area
right is 6:12 larger surface area
hope this helps
That is called a California Open Valley, which has an architectural shingle run up parrallel to the center of the valley. As stated previously, the open side should have been done on the higher pitched run off side.
This is one of the alternate specs from Tamko for installing the valley materials, but the top corners are supposed to get clipped so that an angled top edge can potentially diflect the downhill flowage of water away, rather than allowing it to run under the bleeder run up the valley.
The pitch versus volume debate needs to be decided at the time of installation, from experience speaking, as there are no direct guidelines governing that aspect.
Ed
Which side overlaps has to do with runoff velocity and square footage. As a roofer, you do your best to keep water out of the home. There aren’t always handy rules of thumb. Never heard of cutting to 6" one side or the other of center. What would be the purpose?
Larry caught a good one with the gutter!
Kenton,
It’s not 6"…it’s 2".
And that basically prevents the majority of the water runoff from flowing directly over the seam area.