Closed cut valley install?


#1

A friend is doing my buddys valley closed cut. My ? is this…when you lay down the shingles that cross the valley then lay down the other side that lays over should you go all the way down that joint with tap or sealant or should the upper layer just lay on top ??

If it just lays there what stops water from going under the edge ??

Any pics of how they are layed down and if the lower layer really crosses the valley ?
Thanks


#2

I was just looking for info on this and found the following link which might help.
roofcalculator.com/roof_valleys.htm
I’m trying to figure out how to keep the edge joints out of the valley while still maintaining the constant offset from row to row?..davb


#3

The back of the shingle wrapper explains on how to install a closed valley. Just read it and you will be ok. Or go to the website for further instructions.


#4

[quote=“cvcman”]A friend is doing my buddys valley closed cut. My ? is this…when you lay down the shingles that cross the valley then lay down the other side that lays over should you go all the way down that joint with tap or sealant or should the upper layer just lay on top ??

This would’nt be “a friend” in the metaphorical sense, would it?[/quote]


#5

Hi,

If both sides are the same pitch and it only rained on one side of the valley then water would run up the other side.

The force of the water from both sides meeting in the middle offsets most of the force. The steeper side has more force. This side should be done first

Laying the shingles in roof cement is good insurance.


#6

[quote=“Lefty”]Hi,

Laying the shingles in roof cement is good insurance.[/quote]

I agree, and cutting the points is a must, the lower side always goes under unless the other is a greater pitch.

Actually, I’ve been doing the closed valley’s for 30 years, had contractors try to get me to tear them out because they didn’t know what it was.Points cut and valley sealed , there isn’t a better valley, looks or performance.


#7

[quote=“Lefty”]Hi,

The steeper side has more force. This side should be done first
[/quote]

I thought the instructions I've read say to do the lower pitch first and cut the steeper pitch over it? .daveb

#8

so only one side is cut acc to the we site. It seems I remember someone here saying NOT to seal in the overlapping side with tar or sealant ??

He only has 2 valleys to do and they are both the same pitch. I tried to check mine because I also have 2 on my roof with Archect shingles but both my roofs are pitched the same.

Mine do NOT seem to be sealed down the length of the valley ???

Oh well


#9
I thought the instructions I've read say to do the lower pitch first and cut the steeper pitch over it? .daveb[/quote]

You know what he meant


#10

[quote=“cvcman”]so only one side is cut acc to the we site. It seems I remember someone here saying NOT to seal in the overlapping side with tar or sealant ??

He only has 2 valleys to do and they are both the same pitch. I tried to check mine because I also have 2 on my roof with Archect shingles but both my roofs are pitched the same.

Mine do NOT seem to be sealed down the length of the valley ???

Oh well[/quote]

I did complaint jobs for GAF back in the early 70’s and they required them to be sealed then and have always done them that way. Maybe someone will enlighten us on the real way to seal a closed valley. I can count the roofers who will cut the points in valley’s on one hand too.


#11

I use the greater area of runoff method.
Cut the side with the most area.
If there are different pitches involved I change it up sometimes, it is a judgment call…


#12

Axiom, do you think I should seal my valley with roof cement under the cut edge or just leave it the way it is ?? It is 12 yrs old cut closed valley and has never leaked but I dont believe it is sealed down

???


#13

[quote=“cvcman”]Axiom, do you think I should seal my valley with roof cement under the cut edge or just leave it the way it is ?? It is 12 yrs old cut closed valley and has never leaked but I dont believe it is sealed down

???[/quote]

It should be fine.
You would probably do more damage trying to lift the valley.


#14

Ok I will leave it. I remember asking the guy when he did mine and my neighbors and he said they do NOT seal them down, I cant remember why…

Wouldnt the seal strips still seal them somewhat ??

I think he used Ice and water in my valley with metal and rolled roofing too. I really cant remember 100%

Do all roofers seal the cut edge down now days ??

Thanks

The guy doing my buddys is not sealing his either this is what got me on this


#15

[quote=“cvcman”]Ok I will leave it. I remember asking the guy when he did mine and my neighbors and he said they do NOT seal them down, I cant remember why…

Wouldnt the seal strips still seal them somewhat ??

I think he used Ice and water in my valley with metal and rolled roofing too. I really cant remember 100%

Do all roofers seal the cut edge down now days ??

Thanks

The guy doing my buddys is not sealing his either this is what got me on this[/quote]

Most in my area don’t.
Or, I don’t tear off many done that way.


#16

You know what he meant[/quote]

Ha, Don’t confuse me, I’m having a hard enough time sorting this stuff out. I thought the idea was to not cut the shallower pitched side? But now I’m not sure :>)


#17

We don’t use ice and water sheild in our valley’s so leaks show up when the points aren’t cut and /or closed cut valley’s aren’t sealed. If you have ice and water sheild it really dosen’t matter if the valley leaks or not .


#18

Hi Dave,

I was picturing a reverse A with a steeper pitch then the main roof. The reverese a ridge was a lot lower then the main ridge.

Most times the steeper side is done last. I am sorry for the confusion I caused.

It has to do with the volumne of water and how much speed it picks up till it hits the valley.


#19

Everyone has said what needed to be said but i would like to summarize.

The lower pitch goes under the higher pitch
or the smaller section goes under the bigger section
or the shorter section(ridge height) goes under the higher ridge section.

Points must be cut back if doing a open valley.
I have never installed a open valley on a shingle roof.
Open valleys should be reserved for non flexible material. Tile, metal, shake. Its not a rule or a law though, its just the way i do it.

You dont have to cut the points back on a closed valley. I never have and i never will.

I agree with axiom that trying to cement your closed valley after it has been installed would do more damage than good.

I install about a 6 inch strip of 1/8 thick cement in my valleys no closer than 6 inches from the center of the valley.

In a closed valley, the purpose of the cement is not for waterproofing. The valley will not leak because you didnt cement it. The cement there is for hurricane protection.

Closed valleys leak because you have a seam or a nail too close to the center of the valley.


#20

Ok guys, Thanks for the clarification( Lefty up in Pa. and Roof-lover, you guys have a good and safe day). With all the good advice I’m feeling that I can do this job, not fast like a real roofer but hopefully before winter :>)
Regards, DaveB