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Proper flashing for "Bermuda Triangle" intersection of roof-lines.

Proper flashing for "Bermuda Triangle" intersection of roof-lines.

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  #1  
Old 09-13-16, 11:14 PM
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Proper flashing for "Bermuda Triangle" intersection of roof-lines.

Here is a picture of the challenging intersection:
Name:  Roofing-intersections.jpg
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In the picture, please note that I've bent the drip edge back so I could remove the old, rotten, fascia. The old wood fascia will be replaced with PVC lumber.
Not seen in the picture is a valley from a hip roof that dumps runoff to that intersection. So we have water coming down the roof of the main part of the house (the roof on the right). Water coming down the roof of the addition (the sidewall of which you see on the left) dumps to that intersection. Water comes off a hip-roof that bridges the roof of the addition to the roof of the main/original part of the house.

My plan is to remove just enough of the shingles so I can install Grace shield to the seam where the original house's roof (on the right in the picture) abuts the sidewall of the addition. We've had leaks at that intersection in the past. I try to be careful when I remove shingles, but I always manage to tear shingles that I wasn't planning to remove.
I will also be adding a Kickout-Diverter.

In the picture, we see water damaged sheathing. I had already removed the fascia which was very rotted where it terminated at that intersection.

Aside from using Grace shield to cover the gap between the house's roof and the sidewall of the addition, what are your recommendations for effectively flashing that intersection? It seems that additional metal flashing should be used where the different roof-lines meet. I'd like to direct water away from the sidewall.

Any tips?
 
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Old 09-14-16, 03:28 AM
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Pictures of the entire roof system surely will help, as we really can't imagine what you have without them. I see where you have cut some of the OSB underlayment. Will that be replaced? If so, you need to install step flashing under each shingle and up onto the OSB and under the Tyvek. You can chase that with your flashing tape if you care to. We'll need to see those pictures.
 
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Old 09-14-16, 05:33 AM
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Main reason wooden fashias rot out on the end like that is, is no one sealed the cut end before installing, and the tapered end was installed to close to the shingles.
https://www.google.com/search?q=dorm...o0CiPSZuR2M%3A
 
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Old 09-14-16, 07:38 AM
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Thanks @chandler and @joecaption for your replies.
@chandler, if the rain holds off, I'll get up on the roof and take a few more pictures. Yes, I'm replacing the OSB sidewall sheathing with plywood sheathing. For sub-fascia, rather than the strips of OSB that were there, I'm using 2x6 PT for the rake that terminates at the intersection shown. The fascia will be PVC.

@joecaption, thanks for the link, there are a lot of good references there.
 
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Old 09-14-16, 08:38 AM
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OK. Here is a view of the roof-lines.
Name:  Roof-Long-View.jpg
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Old 09-14-16, 09:46 AM
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That step flashing needs to go all the way up the sheathing until it dies out to nothing. (Gets cut with tin snips to a sharp point, matching angle of roofline) This means it goes on behind the fascia and drip edge.

Then after the fascia is on but before the valley is shingled, the ice and water shield that is laid down the valley will fold over the edge of the fascia, which will counter flash the step flashing. Where the shingles reach the point of your step flashing, the left side of that shingle should get notched and continue up that slope about 12", as should all other courses... they run through the valley and up the other slope 12" or more. Metal edging that goes on the gable is applied on top of ice and water and the bottom of it sheds onto the shingle you notched.

As Joe mentioned, keep the end of the fascia up off the shingles. An inch allows it to dry out.
 
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Old 09-14-16, 10:18 AM
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Thanks @XSleeper. If I'm following you correctly, it sounds like I'll need to remove and replace shingles in the valley. Ugh. Too bad the shingles weren't older so I'd be justified in getting a re-roof done :-(
 
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Old 09-14-16, 10:23 AM
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I was describing what you would do on a brand new install. The main thing is getting the step flashing all the way up. At the bottom of the valley you can try to do the bare minimum, but thats where your leaks will occur so use your judgement. If you can slip under existing thats great but in real life I think it might mean a tear off. But its a very small area so not that big if a deal imo.
 
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Old 09-19-16, 08:26 PM
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Additional questions

Hello again,

I'm wondering about the detail where the rake fascia meets the roof deck of the adjacent section of the house. I know that Joe cautioned that the fascia itself should not touch the roof deck. In my case, however, there is "spacer" lumber between the fascia and the sub-fascia. When I removed the old wood fascia, there was 1/2" particle board used as a spacer behind it. I'm going to use 2 x dimensional lumber (actual 1-1/2") as the spacer. That is causing me to do more shingle replacement than I'd like, but it will be a better look.

So, what's the right thing to do with respect to the spacer, the flashing, and fascia? Here are a couple of pictures of mock-ups I put up to look at the possibilities.

Name:  bt1.jpg
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In the picture above, both the spacer (which is 2 x pressure treated) and the fascia (which will be PVC) terminate above the flashing. I do intend to flash to the tip of the triangle. In this case, the vertical leg of all the flashing is up against the sidewall. The white paper is only there to show contrast between the flashing and the wall.


Name:  bt2.jpg
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In this picture, the spacer (2x PT) terminates at the roof deck. One step of the flashing is attached to the spacer. It's difficult to see in the picture, but the vertical leg of the next lower step of flashing is up against the sidewall (1-1/2" recessed from the flashing above it).

So, what's the better way to go? Is there a better option than either of those pictured?

Thanks in advance for your help.
 

Last edited by PJmax; 09-19-16 at 09:01 PM. Reason: enhanced pictures
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Old 09-19-16, 09:02 PM
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SturdyNail.... I combined your threads into one and enhanced your dark pictures.
 
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Old 09-19-16, 10:22 PM
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I have read this several times and still don't really understand what you are asking. The step flashing should go directly on the wall sheathing. As you add one or two more step flashing (top pic) you will take a tin snips and trim the top edge to match the roofline... so that metal flashing continues all the way to a single point, and that point should get pushed into a roofing adhesive like Geocel 2300 as you shingle up to that point.

You will then put your spacer on top of that, overlapping the step flashing. If you want to put another step flashing on top of the spacer, and another dab of sealant, it might be a good idea. That would make it double nice. The spacer and fascia do not need to terminate as high as you have them pictured. One inch above the finished layer of shingles (around 1 1/2" above the decking) is sufficient... so lower than shown in the 2nd picture unless that is 1 1/2". (Hard to judge measurements)

I'm at a loss as to what the pictures are supposed to be depicting, unless you are trying to ask whether the step flashing goes behind or in front of the spacer. It goes behind. If you want to add another single piece of step flashing on top of the spacer that's fine, but step flashing should go directly onto the wall sheathing the entire way until it reaches a single point first.

Also when you lay grace membrane down the valley, leave it long enough so that it will fold over the edge of your spacer and spacer step flashing. Then apply the fascia, then apply the roof drip edge. If your underlayment can't leak (even before you shingle it) then you did it correctly.
 
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Old 09-20-16, 12:01 PM
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Thanks @PJmax for combining my threads--that makes good sense. And, thanks for the picture enhancements. It gets dark so early now, that, by the time I get home and get my tools out, it's already dusk.

Thanks @XSleeper for your reply. Considering that you didn't understand what I was asking, you did a very good job answering my questions
Basically, I didn't know if the spacer (with consideration for it being PT) should contact the deck. And, particularly if the spacer did contact the deck, would it be considered part of the wall and, therefore, would the step flashing be applied directly to it.

It's too late for me to leave the Grace membrane long since it's already adhered, but I can add another layer near the top. Are you suggesting that I use the Grace membrane to form a sort of rubber boot for the end of the spacer? I'm trying to visualize that.

So far, my underlayment does not pass the "no leak" test. We had some heavy rains over the weekend that put it to the test. I suspect the area that you refer to as the "single point" as being a culprit. I can barely get my finger in there, but there seems to be a small opening in the sheathing at that point. The suspected hole is approximately above where the soffit begins--although, the way it's tucked in, it seems that water would need to flow upward to get in there. I'm not sure. I'm still looking. I may need to get into the attic crawlspace over the weekend and have someone run a hose on the roof.

Thanks again.
 
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Old 09-20-16, 01:56 PM
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The spacer and the fascia should be spaced 1 1/2" above the sheathing... If you put another step flashing in front of the spacer, it will cover the gap. Then leaves will only get stuck under the tail of the fascia.

I was assuming you might have decided to reroof the valley above this area. If you did, you would run Grace down the valley instead of valley tin, and let it drape over the edge. Or add a piece if you have to. Make it waterproof!
 
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