# Low slope valley



## neolitic (Apr 20, 2006)

Let's hear what you guys think.
Customer has a valley, one side a 2-1/2 pitch 
and the other a 3 pitch.
I can't raise them, so I will ice and water 
the whole roof.
As thick as these dimensionals are,
if the valley is just a straight cut, 
I'm afraid there will be enough of a 
hump on the high side to make a problem.
I'm thinking that I might be better off 
using a "W" valley, no nails in the metal, 
cutting tight to the center, and bedding 
both sides in mastic.
Am I over thinking this?
Better ideas?
TIA


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## seeyou (Dec 12, 2008)

neolitic said:


> Let's hear what you guys think.
> Customer has a valley, one side a 2-1/2 pitch
> and the other a 3 pitch.
> I can't raise them, so I will ice and water
> ...


Not much difference in a 3/12 and a 2.5/12. I'd just use a "v" valley, but hem and clip it down - no nails in it as you mentioned. But I'd show the metal. If you shingle all the way to the center, the ends of the shingles are too far away from the last nail in the shingle if you don't pierce the metal. Mastic will likely not last as long as the shingles. 

If you're really concerned about water running up under the shingles, use a Tamko valley if the dimensionals have the adhesive on the bottom. 

Or use a metal roof valley detail - see below.


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## MJW (Jan 27, 2006)

What we would do is I&W, then put the W valley down, then I&W on top of the valley leaving the W part exposed (1/2 roll on each side). Then run the shingles up the valley and do a California (I believe the guys are calling it) valley. This will seal the shingles to the valley. Every one that I have seen that has a "cut" valley on a low slope always leaks unless they sealed under the shingles to the valley tin. Recommend to the HO to periodically clean out leaves, pine needles, debris etc.. or hire you to do it for them. 

You can just guess what the metal guys will say.......pretty much the same thing, but using metal sheets.


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## seeyou (Dec 12, 2008)

*Recommend to the HO to periodically clean out leaves, pine needles, debris etc.*.

That's why I recommend using an open metal valley w/o the raised seam. It'll flush all that crap into the gutter and stop it up so you can sell them gutter guards.:whistling

*Then run the shingles up the valley and do a California (I believe the guys are calling it) valley.*

That's what I'm calling a "Tamko" valley. We need to take a vote and name that detail one name. It's so confusing.


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## neolitic (Apr 20, 2006)

MJW said:


> What we would do is I&W, then put the W valley down, then I&W on top of the valley leaving the W part exposed (1/2 roll on each side). Then run the shingles up the valley and do a California (I believe the guys are calling it) valley. This will seal the shingles to the valley. Every one that I have seen that has a "cut" valley on a low slope always leaks unless they sealed under the shingles to the valley tin. Recommend to the HO to periodically clean out leaves, pine needles, debris etc.. or hire you to do it for them.
> 
> You can just guess what the metal guys will say.......pretty much the same thing, but using metal sheets.


That's what I was getting at,
except actually cut and clip each
shingle, "old style."
That is kind of the "Tamko valley"
with metal. 










I let them do the metal on
my roof that way, (with a normal open slot)
but it's 12/12.


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## neolitic (Apr 20, 2006)

seeyou said:


> ...................
> That's what I'm calling a "Tamko" valley. We need to take a vote and name that detail one name. It's so confusing.


Agreed! :thumbsup: :laughing:


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## We Fix Houses (Aug 15, 2007)

I'd be very hesitant on these suggestions unless 4/12 or greater.

Neo, your concern and idea is valid. However a remodeling carpenter (like me) will view it different than most roofers.....Modifying the weakest point.....don't know about that ? 

I would cut the overlap neatly and seal it down. I believe the remodeling carpenter and roofer could agree that dim shingles cya on a lot of stuff in recent years both remodel and new.

Addl - I'd do double coverage paper and weave before I'd paste in a valley on low slope.


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## neolitic (Apr 20, 2006)

We Fix Houses said:


> I'd be very hesitant on these suggestions unless 4/12 or greater.
> 
> Neo, your concern and idea is valid. However a remodeling carpenter (like me) will view it different than most roofers.....Modifying the weakest point.....don't know about that ?
> 
> ...


Not sure I followed that, but
I'm thinking, with ice and water, and
hemmed "W" with no penetrations,
I am making it as bullet proof as possible.
I clip my top corners, so with the center
ridge, washing under would be minimized.
Bedding the ends in mastic is mostly
to keep the ends from lifting.

I have worked on more leaks
in "woven" valleys than any
other kind.
That doesn't mean they can't be
right, just that I don't often see 'em.


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## Grumpy (Oct 8, 2003)

Be careful ice shielding a whole roof, I have had major condensation problems with at least one project, and have heard many others complain of the same.


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## katoman (Apr 26, 2009)

Any reason you don't just use the I&W shield and weave the valley?


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## OldNBroken (Feb 8, 2008)

Neo, you are on the right track. CU's detail (including cleats) is the best way to go, give yourself a good 6" endlap and seal the lap w/ butyl tape if you have it. Dunno what he calls for in size but 12" is proper. Snap a line 4" from center and just cut your shingles to that line. Don't go mucking things up with mastic. If done right there is no need for mastic OR ice/water. I'm with Grumpy, ice/water shield is way overused and abused.


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## neolitic (Apr 20, 2006)

Grumpy said:


> Be careful ice shielding a whole roof, I have had major condensation problems with at least one project, and have heard many others complain of the same.


Just this section where the
slope is so flat.
It will actually be vented for
the first time in over 50 years.
But it has mostly been leaking
and smeared with multiple layers 
of tar for most of that time.


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## neolitic (Apr 20, 2006)

Renegade said:


> Neo, you are on the right track. CU's detail (including cleats) is the best way to go, give yourself a good 6" endlap and seal the lap w/ butyl tape if you have it. Dunno what he calls for in size but 12" is proper. Snap a line 4" from center and just cut your shingles to that line. Don't go mucking things up with mastic. If done right there is no need for mastic OR ice/water. I'm with Grumpy, ice/water shield is way overused and abused.


Planning on 24" "W" with 
the hemmed edges.
I really can't see any detail
in CUs detail... :laughing:


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## seeyou (Dec 12, 2008)

*I really can't see any detail
in CUs detail...

* I was trying not to be a bandwidth hog....


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## neolitic (Apr 20, 2006)

I see now.
I have a hard enough time
reading the comics pages
without a magnifying glass!


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## OldNBroken (Feb 8, 2008)

I don't have a detail I can post here at home but mine isn't quite that complicated CU. Same principle though. 24" stretch with pitch break in the middle obviously. 1/2" open hems on the sides and a 3" offset cleat hooked onto the hems and fastened to the deck. Simple, low-profile, and good coverage. It's actually metal roof detail but does work for shingles too. With or without the "w" bend in the middle. Depends on what kind of mood I'm in that day.


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## neolitic (Apr 20, 2006)

Renegade said:


> I don't have a detail I can post here at home but mine isn't quite that complicated CU. Same principle though. 24" stretch with pitch break in the middle obviously. 1/2" open hems on the sides and a 3" offset cleat hooked onto the hems and fastened to the deck. Simple, low-profile, and good coverage. It's actually metal roof detail but does work for shingles too. With or without the "w" bend in the middle. Depends on what kind of mood I'm in that day.


I'm getting pre bent W
just like you said.
24" with 1/2" open hems.
I'll make my own cleats.
I know how to run a bullet proof
valley, it's just the freaking low
pitch that worries me.
I don't want her calling me 
in a couple of years....


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## Tom Struble (Mar 2, 2007)

that double hem in cu's post would be easy to put in the off the shelf flashing your getting neo,thats a nice detail:thumbsup:


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## neolitic (Apr 20, 2006)

I wonder if the rental joint
would let me break two pieces 
in their shed?


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## Tom Struble (Mar 2, 2007)

tell em you want to test the brake first:shifty:


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## neolitic (Apr 20, 2006)

The last time I had it, I almost 
gave up on loading it back up
at the end of the day.
I'm sure it was 50 lbs heavier than
it was in the morning.


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## red_cedar (Mar 30, 2005)

It would be tough to form that in a regular brake particularly if your you havent done it before. Its not bends, its closing the locking hem more.
Wonder where CU got that idea?


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## seeyou (Dec 12, 2008)

red_cedar said:


> It would be tough to form that in a regular brake particularly if your you havent done it before. Its not bends, its closing the locking hem more.
> *Wonder where CU got that idea?*


I've been using that detail for copper roofs for years. So long in fact, I don't remember who showed it to me or where I saw it, so I can't give due credit. Before I started using that detail we used to solder a cleat to the valley on each side to lock the roof panels to.

I don't think I've ever made it on a portable brake, but you're right, it would be tough. If the lock bend was stretched out from 3/4" to 1+" and moved closer to the center, it might be doable.


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## red_cedar (Mar 30, 2005)

seeyou said:


> I've been using that detail for copper roofs for years. So long in fact, I don't remember who showed it to me or where I saw it, so I can't give due credit. Before I started using that detail we used to solder a cleat to the valley on each side to lock the roof panels to.
> 
> I don't think I've ever made it on a portable brake, but you're right, it would be tough. If the lock bend was stretched out from 3/4" to 1+" and moved closer to the center, it might be doable.



I pretty much knew how, just being a bit sarcastic.
Standard valley attachment for metal. :thumbup:


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## seeyou (Dec 12, 2008)

red_cedar said:


> *I pretty much knew how*, just being a bit sarcastic.
> Standard valley attachment for metal. :thumbup:


Figured you did. But did Neo?


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## neolitic (Apr 20, 2006)

seeyou said:


> Figured you did. But did Neo?


Not with a portable brake.
I will just settle for the hem anyway.
That has to be a help
to keep any stray water
on the metal.


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## OldNBroken (Feb 8, 2008)

Come on over and you can play with my Schechtl Max.


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## neolitic (Apr 20, 2006)

Idaho would make me raise my
commute rates.


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## Tom Struble (Mar 2, 2007)

that in copper you could crush closed in a pro2 no problem


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## Tom M (Jan 3, 2007)

I was thinking the same as katoman, ice the whole deck double cover paper then weave the whole valley.

Done no issues. no metal or sealing. Dont forget any water that could get in a crack in the seal wont get out and on a flat roof lay there.


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