Question about angle of shingles at sides of valley

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Old 06-15-12, 03:55 PM
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Question about angle of shingles at sides of valley

Re-roofing - Iím going to replace old close-cut valley with an open valley. Iíve already run ice & water shield and placed 20Ē wide galvanized on top of that.

But, when it comes time to shingle Ė donít I want to run the valley shingles ďlevelĒ (on a plane parallel to the eve)?

If you look at my photos you can see that folks who laid the original sheathing (1x8 boards; 50yrs ago) Ė ran the boards on the left, parallel to the horizon, but the boards on the right side of valley "seem" slightly diagonal:

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Is this normal?


I think I can understand why they ran the right side diagonally instead of the same angle as the boards on the left. I guess they did that because, otherwise, the bottom board would have been an odd cut-out size (maybe that could have been addressed with a small custom cut piece of plywood; angled at the bottom parallel at the top).


So, when it comes to shingling, shouldnít the angle of the shingles on the right be adjusted to match the angle on the left (which is parallel with the eve) - the right side just seems a bit too steep an angle to me?

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When I tore off shingles, the boards on the right seemed fine, but Ė still isnít running the shingles on the right side diagonally asking for water and snow to get underneath them? Then again - I guess this is always part of the challenge of a valley?


Still - maybe this is more about optical illusions (see the photo of the bottom layer - red shingles); should I just "go with the flow" and lay the shingles on the same angle as before and just be sure to cut the hidden corners at the leading edge of the bottom - at a 45 and use asphalt to seal beneath the edges?.



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I guess the angels do seem geometrically pretty equal, so maybe this is normal?
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Just shingle with the same pattern?


Also,I guess I should make an effort to line up the rows of shingles on left and right (or intentionally off-set them)? This is the front of the house. Maybe this is what I need to concentrate on - shingle alignment across (valley & hip) the front of the house?

thanks
 
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Old 06-15-12, 10:02 PM
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If you want an open valley, your new shingles will be laid in exactly the same fashion as your photo, where you have the caption "open-cut valley".

Also, W-valley (which has a 1" ^, or peak, in the center of the valley is superior to standard valley which is a more like a V. With no W, water coming down one side of the roof may be more likely to go up and under the shingles on the other side of the valley.

Additionally, many old-time roofers used to clip the top edge of shingles that lap over valley flashing so that water would not catch the top corner of the shingle and run horizontally under the shingle. They'd just cut an isosceles triangle off the upper corner of the shingle that's 6" long or so.
 
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Old 06-16-12, 07:27 AM
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I don't see what you are describing at all. The sheathing boards appear to to be laid parallel to the ground to me. If you look at where they meet in the valley, the boards line up perfectly on each side. This means the angles on the ends of the boards are equal. A perfect bisection of the total angle to create a 90 degree angle. The bottom layer of shingles appears to be run properly to me as well.

Seems like you are off to a good start with what you have already done to your valley. If you are still not comfortable with what you have done, run another strip of the water and ice shield along the edge of the valley flashing. Have it overlap the flashing and cover the nails heads you used to nail it done. As long as it isn't exposed to sun light, you are in good shape.
 
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Old 06-17-12, 09:04 AM
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"If you want an open valley, your new shingles will be laid in exactly the same fashion as your photo, where you have the caption "open-cut valley".

Thanks XSleeper

"Also, W-valley (which has a 1" ^, or peak, in the center of the valley is superior to standard valley which is a more like a V. With no W, water coming down one side of the roof may be more likely to go up and under the shingles on the other side of the valley."

I thought about that, but I would have had to lap it (edit: comes in 10 feet lengths). My valley is only 12 foot long, so I went with a single piece of galvanized steel. I etched with vinegar; primed with acrylic-based exterior Zinsser primer; and a few coats of latex exterior. It's currently sitting in the valley with a section of heavy metal pipe holding and "molding" it in place. Eventually I will run a bead of silicone (I don't think Tri-Flex does well, long term, with asphalt - issue with solvents) along the edges and tack in place with roofing nails along the edges (not penetrating - just the heads to hold in place so it can move with contacting and expansion).

edit: - I just realized that, because metal is 20 inches wide and "valley" will be no more than about 6 1/2", I will end up nailing outer portions of the metal when I nail shingles (there goes some of that "float" temp adjustment).


"Additionally, many old-time roofers used to clip the top edge of shingles that lap over valley flashing so that water would not catch the top corner of the shingle and run horizontally under the shingle. They'd just cut an isosceles triangle off the upper corner of the shingle that's 6" long or so."

I came across this youtube video that seems to do a pretty good job of explaining the trimming of corners in a valley (if it violates rules - I apologize - please remove):
Valley Installation with Shingle - YouTube

thanks
 

Last edited by AccidntlTourist; 06-17-12 at 11:28 AM.
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Old 06-17-12, 09:08 AM
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"I don't see what you are describing at all. The sheathing boards appear to to be laid parallel to the ground to me. If you look at where they meet in the valley, the boards line up perfectly on each side. This means the angles on the ends of the boards are equal. A perfect bisection of the total angle to create a 90 degree angle. The bottom layer of shingles appears to be run properly to me as well."

Thank you drooplug.

I guess you are right; didn't trust my eyes.
I'll follow the same pattern.
 
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