# Roof valley incorrect overlap on shingles? **URL:** \ **Category:** Roofing Inspections\ **Created:** [March 17, 2026, 6:42pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932 "2026-03-17T18:42:58Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![sanfinsen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/sanfinsen/32/385607_2.png) [@sanfinsen](https://forum.nachi.org/u/sanfinsen)\ **Post date:** [March 17, 2026, 6:42pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/1 "2026-03-17T18:42:58Z")
I did an inspection this morning and ran across a roof valley that didn’t look quite right; it looks like the overlap is on the uphill side of the shingle rather than on the downhill side. My concern is that as water is flowing down the valley, it will flow under the shingle rather than on top of it. I may be looking at it incorrectly. But, I thought I’d post the images and see what all you fine folks have to say about it. ---
**Author:** ![sanfinsen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/sanfinsen/32/385607_2.png) [@sanfinsen](https://forum.nachi.org/u/sanfinsen)\ **Post date:** [March 17, 2026, 6:45pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/2 "2026-03-17T18:45:05Z")
And before everyone starts lighting me up for not posting the images, I’m still trying to figure out how to do that; I’ve only posted once before. ---
**Author:** ![sanfinsen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/sanfinsen/32/385607_2.png) [@sanfinsen](https://forum.nachi.org/u/sanfinsen)\ **Post date:** [March 17, 2026, 6:47pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/3 "2026-03-17T18:47:56Z")
![IMG_8301](https://global.discourse-cdn.com/internachi/original/4X/4/5/b/45b3fe39784e522bb9c9a26efac7ec3f9e4aa3d5.jpeg) ![IMG_8300](https://global.discourse-cdn.com/internachi/original/4X/a/e/3/ae3162daba0254083509008257139eb7055f91b8.jpeg) ![IMG_8299](https://global.discourse-cdn.com/internachi/original/4X/4/2/a/42a2feda20757e549c5642abc5252b479650602b.jpeg) ---
**Author:** ![lkage](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/lkage/32/347658_2.png) [@lkage](https://forum.nachi.org/u/lkage)\ **Post date:** [March 17, 2026, 7:05pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/4 "2026-03-17T19:05:13Z")
[![](https://global.discourse-cdn.com/internachi/original/4X/8/1/f/81f6f205c7de70a183796c026a848e40e0e6c5aa.jpeg "Roof Valley Types Explained | Woven, California Cut & W Valley Metal") ](https://www.youtube.com/watch?v=81nVV8FQGXI&t=55) ---
**Author:** ![wjones18](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/wjones18/32/397367_2.png) [@wjones18](https://forum.nachi.org/u/wjones18)\ **Post date:** [March 17, 2026, 8:05pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/5 "2026-03-17T20:05:19Z")
> [@sanfinsen](#): > > it will flow under the shingle Well I can not see what section of the roof is higher than the other or if that’s a dormer. The lower side of a roof needs to always go under, unless that’s side has a steeper pitch. If both sides meet at the ridge it really doesn’t matter, but usually the cut side or top side will be the larger of the roofs. But also wind direction can also determine what side should go over, if you are in n a high wind area the cut side should be in the usual wind direction, that way high winds do not pick up the shingles and tear them off. ---
**Author:** ![sfetty](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/sfetty/32/331195_2.png) [@sfetty](https://forum.nachi.org/u/sfetty)\ **Post date:** [March 17, 2026, 11:55pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/6 "2026-03-17T23:55:53Z")
> [@sanfinsen](#): > > see what all you fine folks have to say about it. Some manufacturer’s include this detail in the installation instructions, here’s one from [GAF (Timberline):](https://www.gaf.com/en-us/document-library/documents/installation-instructions-&-guides/timberline-layerlock-installation-instructions-trilingual-restl622.pdf) ![image](https://global.discourse-cdn.com/internachi/original/4X/3/6/0/360d5bbd996978b7c776722f155e3f5f39245ffb.png) There are three key points to this detail, the minimum 2" gap (looks about right in your photo), the clipping of the top corner (we called it the ‘dog ear’ in my roofing days) to direct water flow into the valley and sealing the valley shingles with mastic/roof cement. Their metal valley graphic shows the dog ears a little bit better: ![image](https://global.discourse-cdn.com/internachi/original/4X/5/0/3/503e014055b2696e1cad42cb11e23e48d5e23e7c.png) It was explained to me many years ago without cutting the dog ear water will hit the top point of the shingle and travel along the top edge (instead of down the valley) resulting in potential roof leaks. ---
**Author:** ![yzhang](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/yzhang/32/57038_2.png) [@yzhang](https://forum.nachi.org/u/yzhang)\ **Post date:** [March 18, 2026, 12:43am UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/7 "2026-03-18T00:43:42Z")
That’s a California valley, nothing to see here ---
**Author:** ![ryoung7](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ryoung7/32/188798_2.png) [@ryoung7](https://forum.nachi.org/u/ryoung7)\ **Post date:** [March 18, 2026, 12:53am UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/8 "2026-03-18T00:53:41Z")
[California Cut Valley](https://hinarratives.com/reference/roof/asphalt-shingles/types-of-valleys/) ![cal valley](https://global.discourse-cdn.com/internachi/original/4X/e/0/6/e06ecf6d3c43054ca70e7229b6cd0cff3d6a18b1.jpeg) ![valley error](https://global.discourse-cdn.com/internachi/original/4X/c/2/5/c254b0f2d1678d1768fccec962b1ca3d02a885b4.jpeg) It appears the short side shingles where not cut long enough or cut at an angle. Water can flow under composition tabs. Poorly installed California Cut Valley. Refer to a licensed roofer for further evaluation and repairs where required. Act upon any recommendtions therein. ---
**Author:** ![sanfinsen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/sanfinsen/32/385607_2.png) [@sanfinsen](https://forum.nachi.org/u/sanfinsen)\ **Post date:** [March 18, 2026, 8:30pm UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/9 "2026-03-18T20:30:54Z")
Excellent information! Thank you to all that responded. It just didn’t look right so I noted it for further review. Thanks again! ---
**Author:** ![kshepard](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/kshepard/32/59504_2.png) [@kshepard](https://forum.nachi.org/u/kshepard)\ **Post date:** [May 22, 2026, 5:37am UTC](https://forum.nachi.org/t/roof-valley-incorrect-overlap-on-shingles/265932/10 "2026-05-22T05:37:02Z")
It’s called a california cut valley: [Types of Valleys – InterNACHI Inspection Narrative Library](https://hinarratives.com/reference/roof/asphalt-shingles/types-of-valleys/)