Transition from roof to valley

I decided to use closed cut valley since I am using thicker architectural shingles. Per recommendations, first row is woven with larger roof course over the first smaller roof course over valley, then will stagger across the valley from the smaller roof. Basically it is garage roof coming to connect to main roof. Main roof has the drip edge, it is taller so it will have the cut shingles.

My question is this, for the very first shingle from main roof that will be woven, where do I terminate the butt edge of that shingle? In other words, how low do I go with that first shingle that will run perpendicular to the drip edge? Do I continue it until it touches the shingle on garage roof, do I terminate it before that point, or do I overlap it enough that butt edge BENDS onto garage roof plane? Bend would be more water resistant, but may be more likely to crack. I know, excessive detail, but want to make sure it is done right. I was able to fit about 2 inches of shingle up under the main roof facia board and shoved as many as I could under the main roof soffit. And then I used grace to connect Valley to the garage shingle so water can be expelled onto shingle should the valley shingles leak. I think I followed all the rules to a T, but confused on how to start first woven course before switching to closed valley system. Thanks in advance!

Forgot to mention, the next step I plan is to run the full shingle from garage roof up the valley onto main roof. Then weave one full shingle from main roof onto garage roof. And then continue garage roof with overlap onto large roof. So the only thing that made me quit for the day is not really knowing how much to overlap of the main roof woven shingle. Where does that butt edge go? How high or how low in relation to garage roof shingles? Thanks!

You are correct about running it lower with the bend in it. You want to run it down the hill as much as you can. You will need to high nail the top left of that shingle and not hit it in the standard nail spot. When running a closed valley a good general rule would be to have the tops of the shingles cross over by about a foot. No nails within 6" of the valley center is a good rule to live by.

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Thank you so much for clarifying this for me! So I basically place that shingle down with bend onto the garage roof and nail in the top left corner only, since the nailing strip will end up being too close to the valley and won’t meet the 6 inch guideline. Now the shingle from the garage will bend up first onto main roof, then I run the main roof shingle with butt edge bent onto garage roof. Now, RooferOhio, I can make it as low as I can. I literally can bend down that shingle many inches over, depending how low I go off main roof. What is the rule of thumb in terms of how much exactly to bend onto the garage plane? Just and inch or two or more? There is literally no limit to overlap, so I want to make sure I don’t end up under doing it or overdoing it. The valley coverage for the bottom does not worry me much, since the woven shingle from garage will provide its coverage for the valley bottom. Then the main roof shingle will double cover that end in a woven pattern.

By the way, when that garage shingle bends up onto main roof, it will end up overhanging slightly over the drip edge at the very end of the shingle. I guess the angle will push it out a bit. I was planning to simply cut off that overhang so that the shingles from that roof will be the only ones neatly overhanging the drip edge by 1/2 inch. Am I on right track there as well?

I would get that shingle down 2-3". It’s a field fabricated detail so there is not an exact spec to follow. Don’t forget to nail the side that crosses over as well.

Your thoughts on the over hang are correct.

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So here is an example of shingle overlap of about 2 to 3 inches, with higher main roof on top of first valley row of garage roof. Not much space to nail there when trying to stay 6 inches away. The other side has plenty of nailing space, but small piece on main roof only has top left corner to offer. Hopefully won’t get loose in high winds. Does this look right?

I almost feel like if that first main shingle went BELOW the first woven garage shingle, it will be more secure since the garage shingle will support it better against wind. But most sources recommend overlapping main roof over smaller roof for the initial weave. Is that true or can this rule be bent in this circumstance? I truly appreciate all this advice, I know I am overreacting over a tiny detail, but valley’s are so prone to leaks, I want to avoid one.

Here is what I mean overlapping it the opposite way, with garage weave over the main roof weave. Does it not look more secure from wind, since garage shingle will get many more nailing spots on both sides and can probably even be nailed into the OC Strip? Thank you, RooferOhio for all this advice!

I would do it the way you posted it in the 3rd pic.

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Agreed. The rules can change when the valley is not at the bottom of the roof.


I appreciate you both for assisting me with this. I will do as you suggested, place main roof’s weave course underneath the garage overlap, that way the longer garage overlap can provide better wind resistance support. I don’t think it will in any way reduce water shedding capability of the roof. Frankly, that valley is tiny, so volume of water should not make much difference. I Graced it over first with Grace overlapping the OC underlayment on the bottom of valley, then added another small piece of Grace to valley bottom so valley is connected ONTO the shingle below so any leaks will be taken out onto shingles instead of underlayment. With shingle below valley actually squeezed 2 inches into valley gap, that entire surface coming off valley is well water proofed, even for wind-driven rain. But this extra uncertainly bothered me, so I appreciate you all putting me a peace and giving me good feedback on shingling this particular valley.

It will be fine. It looks to me like you are WAY over thinking this area.

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Almost finished tonight before the darkness set. Hopefully will have that valley completed on one side by tomorrow before I begin the main roof.

One more thing - I know I am overthinking another thing, so please go easy on me. The guidelines recommend overlapping shingles 12 inches up the major roof. So I measured 6 and 12 inch lines from the center of valley and am a bit confused. If I overlap by 12 inches for the top part of shingle as I did in photo below, the bottom of shingle ends up being about 16 inches above that centerline, since that edge goes higher with the roof angle. The issue then is that the butt edge on the smaller roof will then only have 10 to 11 inches from valley center. My question is this - which part of shingle overlaps 12 inches? Top, center, or butt edge? It is overlap measured from shortest distance to valley or along the length of shingle itself? If I do opposite and overlap the bottom by 12 inches as shortest distance from valley, then top part will only overlap by 6 inches. NACHI image has measurement for at least 12 inches for the top side as I did below, then the remaining part on smaller garage roof seems inadequate, especially as it has to deal with more water volume coming from the main roof. In the grand scheme of things, does that detail even matter? My thinking is to caution of leaving more shingle on smaller roof and overlapping less onto larger roof, since it will have double coverage. The bottom is the one that now accepts all that water rushing from main roof, right? Am I losing it?

Just keep thinking about it while you lay shingles. You are doing well.

Personally, I would aim to keep the center of the surenail strip in the center of the valley. I realize with the pitches of the two sides of the valley it will be impossible to do that with every row (because of your shingle staggers). Its okay to vary it one way or the other, just try to keep it as centered as possible and when it starts to get too much up the smaller roof just stagger your next shingle back to reset the pattern. Hope this makes sense.

Oh and one other thing. From your pics it looks like the drip edge has a sharp edge against the shingles. Perhaps its an elusion but if its not you should trim it. It can cause a hole in the shingles over time.

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Looks good, I try to keep it roughly half and half on equal pitchs. minimum for me is 12" measured at the middle .

What I end up having to do is to add a piece of shingle (maybe around 12 to 18 inches long) to the last shingle on the garage roof prior to valley shingles, so I end up having nearly identical overlap for each shingle onto valley. Since the inserts also end up staggering, I end up being successful in keeping each joint at least 4 inches away from the joint in the row below, as required by OC. I have a full valley on the other side of roof, so I am wondering that maybe in order to avoid having to deal with inserts prior to valley, I should start the valley first and move away from it. The only issue there is that in order to maintain similar overlap for each course, I would have to stagger shingles about the same as the exposure to maintain that 45 degree angle of the valley - of exposure of 5 5/8 inches with about 6 inch stagger will provide same slope for staggering shingles. The only issue is OC recommends to maintain 6 1/2 inch stagger as they describe when you make starter shingles. Probably half an inch won’t make much difference, but these people can void warranty at a simple detail. Don’t know if it is best to try to limit joints closer to the valley and deal with inserts if necessary at the edge of roof - but frankly adding a staggered joint 2 or more feet from the valley is far enough that it should not make any difference so long as I maintain 4 inch difference for joint staggers. But for now, just about every row, I add part shingle so that the valley shingle lies in the middle of the valley consistently. If I didn’t insert 12 to 18 inch staggered shingles, my joints will either end up too close to valley or the overlap will be insufficient. You can see the insert on my last photo. But I will try to shift overlap to be approximately in the middle, as it is now slightly more on main roof with slightly less on garage roof.

I cut the drip edge in a circular fashion there to eliminate sharp corner. It is about 1/4 inch off the shingle below, but I may trim it a bit more to ensure that even if that section ever settles (shouldn’t but who knows), it won’t puncture the shingle at such a critical joint. Thank you for noticing this.

Annotated joints and distances I have so far. Keep in mind, I am measuring distances as the shortest 90-degree distance from the valley and not diagonally along the edge of shingle. If I should measure from the edge, then I have way more than 12 inches overlap both ways.


Measure along the shingles not perpendicular to the valley. What is that you do for a living again? And you are still doing well