# Tying new roof into old.



## Clutchcargo (Mar 31, 2007)

I've added an addition to my home, basically just a bump which joins the old roof at a right angle. I used valley boards for the new roof built onto the old. I removed the shingles where the valley boards are and built the new roof on the underlayment. 
Now, I need to figure out the layering and shingling of the valley.
My plan is to remove about 2 feet back on the old roof around the addition.
Cut the underlayment right at the edge of the new roof.
put down a 36" wide IWS at the valley directly on the roof deck.
Lay the old underlayment, that I pulled back, back over the the IWS.
Put new shingles back on the old roof and run up the new roof. 
For the shingles on the new roof, I'm going to cut at an angle to follow the roof line up. (Done this way to match the current dormer.) 

Questions:
Does the plan for the underlayment at the valley sound correct?
How far should the shingle extend up the new roof?
For the drip edge, do you overlap or butt seams?
The IWS on the old roof is double wide and extends up the roof about 60".
This layer I cannot pull up so how do you layer with the existing IWS?

TIA


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## Clutchcargo (Mar 31, 2007)

Trying again...ttt


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## tinner666 (Mar 14, 2005)

For the shingles on the new roof, I'm going to cut at an angle to follow the roof line up. (Done this way to match the current dormer.) 
*Make the cut 2" out of the valley center, and clip the shingle tops.*

This layer I cannot pull up so how do you layer with the existing IWS?
*Don't worry about it. If you roof it right, no water will get to it.*

How far should the shingle extend up the new roof?

Use the relevant answer.
*Cross the valley no less than 12". No joints withing 12" of the valley center. No nails there either.*

*Extend the tie in as far as necessary to get under undamaged old shingles.*


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## tinner666 (Mar 14, 2005)

Guess which leaks.


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## Clutchcargo (Mar 31, 2007)

tinner666 said:


> Guess which leaks.


I can see the problem, but even with the metal flashing water got into the house?


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## tinner666 (Mar 14, 2005)

Not until the first rain.


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## tinner666 (Mar 14, 2005)

This pic is of a 40 year old valley. The tops were clipped. The valley is of 12" metal, no hemmed edge. No I&W. No felt. Nothing under it. The lines highlight how the shingles were clipped. Notice the water flow tracks. Never leaked.
We sometimes had 18"+ snows sitting there too.


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## tinner666 (Mar 14, 2005)

It's all about guiding the water. Your choice. On down the roof, or under the roof. The roof installion is important. Not the underlay.


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## tinner666 (Mar 14, 2005)

Sorry. I re-read my last post. It sounded harsh and was not meant. Ed has the gift for gab, I don't. I just have the gift of posting pics of what did or didn't work.


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## Clutchcargo (Mar 31, 2007)

I didn't read it that way, so no worries. 
On the right edge of your last pic (the open valley), it does look like water was being wicked up. I surprised that there wasn't any roof sealant on the bottom edge of the shingles. At least none is evident 
I'm doing a closed-cut valley and am planning on only using IWS in the valley. Is there any reason to add a layer of aluminum too?


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## tinner666 (Mar 14, 2005)

If you're talking about the metal valley, no sealant was used. Never needed.
The white shingled valley doesn't need any either.
In hurricane country, on the beach, I'll put a tiny dab, 1", on the metal of an open valley to prevent the wind from lifting the shingle. 

I took the one pic showing the cut, before I came back and added dollops along the valley, out of sight, and out of the water flow.
In the next pic, you can see where the water went. It leaked with all that glue, and 2 layers of I&W.
Here's her comment:
"
It has rained for several days now and NO Leaks. We really don't even think about it like we use to when it rained. This is the first time we have confidence in the work. If we lived in a perfect world we would have found you in the BEGINING and had a Roof done right the FIRST TIME. But like they say "better late than never". 
Say hello to your wife for us and again Thank you for a job well done."

The lady even climbed out there during a night storm to watch the valley perform!


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## tinner666 (Mar 14, 2005)

I should have mentioned. I had to learn how to do it the way roofers did it before I&W, and even caulk. I had to know how to do it without felt, I&W, or caulk.


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## Clutchcargo (Mar 31, 2007)

Thanks, I guess the moral of the story is "no nails within 12" on each side of the valley."
Edit: I'm out there now trying to delicately pull up shingles from beneath other shingles. Any tricks to do this? I'm finding that they easily tear.


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## tinner666 (Mar 14, 2005)

I use either the Malco I-beam 'Rooster Bar' and/or a round ended trowel made for modified bitumin roofing. Some times/brands work easier in cold and when stiff, other times/breands seem to work easier hot. Go figure. 
If ou pull any material off an existing shingle, replace it too! Even if it means going to the ridge! Damaged ones will leak.


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## Clutchcargo (Mar 31, 2007)

Thanks Frank,
I spent the day carefully removing a path of shingles on each side of the new roof only to discover that the color, weathered wood, from 4 years ago isn't quite what weathered wood is today. I've decided to redo the entire side of the hip roof down to wood. The patched in look would drive me nuts every time I look at it and it's only an extra 3-4' on each side of the path. Hindsight 20/20, it will probably end up being faster in the long run and give me a lessor chance of leaks at the valley.
Too bad you're not in my neck of the woods, I'd hire you as a DIY helper.


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## tinner666 (Mar 14, 2005)

Thanks for the kind words. I'm elated that I was able to help in an understandable way. I have trouble with that sometimes.
I can't seem to explain roofing any better than I can explain how I breathe. But I can do both, it seems.


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