[Atlntabrvs86]

Hey everyone, I have what I believe is a horizontal valley(after searching around), and it is currently leaking. I know I have some damaged sheathing when I had the ceiling open during my kitchen reno. I am having trouble finding out how I should properly do the valley as I can't seem to find any setups like I have. And how to properly tie back in to the old roof that I'm not tearing off around it as it is fairly new. Any help is greatly appreciated.

 

[jlhaslip]

Your best bet would be to add a "cricket" roof over the existing horizontal seam in the roof. I will attach an image after my next comment showing what I mean exactly, but it is a false roof which will drain from the main roof down to the outlet. It would require stripping the roof, adding the cricket, then a membrane, and then the shingles due to the low pitch of the cricket, but the positive slope should eliminate future issues.

As an alternative, strip off the shingles and add a bituthane membrane at minimum to the existing slopes. Depending where you live, consider that the roof will hold snow and water, so run the membrane about 3 feet or more up each side if you go this route. My thoughts are that the first option is the better plan.

Cricket image here:

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[joecaption]

It's called a dead valley.
Poor building design and there always a leak issue.
Check out this video.
http://www.graceprosintheknow.com/dead-valley-roof/

 

[ParagonEx]

Poor design.

Remove three feet of shingles on each side. Install new EPDM (Rubber).

 

[craig11152]

I would remove shingles all the way to the ridge we can see. Do that all the way around at least Go even higher if needed to not have to piece in the close cut valley. With the close cut valleys piecing in is not easy. Its easier to redo them completely.
I agree a cricket would be best but as long as that dead valley has some positive flow a flat roofing product like an EPDM or SBS or APP would work OK without the cricket. Then just fill in the needed shingles again.

 

[Atlntabrvs86]

Here is another picture. I will take one of the other valley tonight. I thought I would have to completely redo those valleys to do it properly without the cricket. Should I flash either of those 3 valleys? And also is the close cut valley the correct way as well?

 

[craig11152]

How far up does the top valley go in that picture? Is it similar in length to the one we see? Or does it run a lot higher?

 

[Atlntabrvs86]

Also would ice and water shield yield the same result as the products you've mentioned?

 

[Atlntabrvs86]

Looking at the first picture the valley to the left goes up about twice as high as the valley to the right.

 

[craig11152]

Also would ice and water shield yield the same result as the products you've mentioned?

No. Ice and water shield is an underlayment that needs covering. It should go in the upper valleys and perhaps above the dead valley where it will be covered by shingles. The dead valley needs a flat roofing product. At that point ice and water shield is redundant. EPDM is one option. I would use an SBS mainly because I have used a ton of it and that is my comfort level and experience. In my nearly 28 years of roofing I probably did that repair 5-6 times easy.

 

[craig11152]

I would go at least that much and then piece out the rest of the longer valley.

 

[craig11152]

are you in snow country?
Heavy rain country? (Washington/Oregon)

 

[Atlntabrvs86]

No in Virginia

 

[craig11152]

does water flow down at all? Is it dry 24 hours after a rain?

 

[Atlntabrvs86]

Yes it does flow and is dry after 24 hrs. Pending I regularly keep the pine straw and leaves blown off

 

[Windows on Wash]

It may not leak now, but I can't imagine that design being leak free for the duration.

I wonder about architects sometimes and why a roofer would trust that to be leak free for any sort of extended time.

 

[Atlntabrvs86]

It does leak now. That is my reason for tackling the project.

 

[Atlntabrvs86]

If I go cricket method, do I then treat the new valleys as I would a standard valley and ice and water and flash it down to the bottom?

 

[craig11152]

The reason for a cricket is to get some positive flow of water. You already seem to have that. Your not going to get enough cricket to move away from a flat roofing product (FRP). So a cricket may not be worth the effort. Especially given the position of that plumbing vent stack on the long valley side. Its not good to get that stack too near a pitch change that a cricket would create.
The valleys in a cricket still need to be a FRP that needs to roll up the steeper pitches at least 16"-24". Then the shingles come down over the FRP 4"-6". If you were in serious snow country I would have gone up 36" but that is overkill in Virginia.
As to ice shield you can do all the exposed deck if you want but in theory its not needed under the FRP. That hinges on ice shield adhering to the top edge of the flat roofing product where the shingled valleys dump on to the FRP. Because shingles are a water shedding system rather than a water proof system its possible for water to get under shingles. That is where ice shield comes in to play as a product. FRP's are supposed to be water proof rather than water shedding and therefor don't need ice shield. But in your case you have shingles connecting to and pouring water on to a FRP so the rules are a bit jumbled.
There was a time when there was no such thing as ice shield and roofs didn't always leak.

 

[Atlntabrvs86]

Ok that makes sense. Thanks for all the great info everyone. I just need to research a little more on making the closed cut valley so I can redo the one after installing the FRP and properly splice back into the valley on the left side.