Metal flashing in valleys? 4 pitch roof

Well I’m putting a new roof on my house. I’ve done some roofing in the past but it’s been a long time. I was planing on using a 3’ strip of ice and water shield in the valleys and a 3’strip of roll roofing on top of that and then overlapping/weaving the shingles. Then I started reading books and most of them recommend metal flashing in the valleys. Do you pros always use metal flashing in the valleys? It will be some extra money But I’ll use it if necessary. If I use it what is the specific order of installation? Ice and water then metal flashing then roll roofing then shongles? Also the books seem to be all over the place about how close to nail to the center of the valley. I’ve read everything from 3" to 10", what is a good rule of thumb? So if you can’t nail close the the center of the valley do I just glue the shingles with roofing cement and leave it at that?

I know, lots of questions but thanks for any help.

Ice & Water Shield in the valley, metal is optional.
If you choose to use metal also install the metal over the top of the Ice & Water Shield.
Return the 90# rolled roofing to the store, it is worthless.

Keep all your nails at least 6" away from the valley center line.

I was going to tell you how to do it properly, but Axiom beat me.

If your nails are 6" from valley center, you shouldn’t need to “glue” anything. That and I have seen tar cause leaks because it wasn’t applied properly.

Good luck.

[quote=“-Axiom-”]Ice & Water Shield in the valley, metal is optional.
If you choose to use metal also install the metal over the top of the Ice & Water Shield.
Return the 90# rolled roofing to the store, it is worthless.

Keep all your nails at least 6" away from the valley center line.[/quote]

At least 6. Thumb to middle finger is 7.5 on me. I use that as my gauge when shingling.

if you are installing laminates , don’t weave them , if its 3 tabs fine

If you have valley that is contructed right…then go with the metal. follow Axiom’s instructions. Be sure to cut your corners (you probably have read that already). I use a 3-tab bleeder on each side of the valley.

Bleeder has two functions

  1. The tar line will give you 7-8 inches away from the valley center to place your nail.

  2. With a bleeder hieght, makes it a little easier to cut the shingle along the bleeder line and helps reduce scratching the surface of the valley metal with your knife.

If your valley is crooked or has lumps, it will prevent the valley metal from laying down properly. I would then do the 3-tab weave or the laminate with cut technique.

Ok, thanks guys. I think I’ll go with ice and water and also the flashing. I’d rather be safe than sorry. Yup these are regular GAF 3 tab shingles. None of that fancy stuff for me. LOL. This job is taking longer than I thought it would. I’m having to replace alot of decking along the eaves because the old roof didn’t have drip edge installed. Then since I had all the eaves exposed I decided to run wireing for low voltage lighting. Ha Ha, it’s always something!

Roofer Gee, a couple of questions. When you say cut the corners do you mean cut he corners off the shingles where they run up the other side of the valley? How much should I cut off? What is a bleeder? You mean something simular to a stater strip except placed at the valleys?

[quote=“skidstreet”]Ok, thanks guys. I think I’ll go with ice and water and also the flashing. I’d rather be safe than sorry. Yup these are regular GAF 3 tab shingles. None of that fancy stuff for me. LOL. This job is taking longer than I thought it would. I’m having to replace alot of decking along the eaves because the old roof didn’t have drip edge installed. Then since I had all the eaves exposed I decided to run wireing for low voltage lighting. Ha Ha, it’s always something!

Roofer Gee, a couple of questions. When you say cut the corners do you mean cut he corners off the shingles where they run up the other side of the valley? How much should I cut off? What is a bleeder? You mean something simular to a stater strip except placed at the valleys?[/quote]

The rotten sheathing at the eaves is probably from ice dams opposed to lack of drip edge.

See how the top of the shingle is cut in this picture?

http://www.roofing.com/images/topics/10312/img_1288873305.jpg

See Axiom’s pix…That is what I mean by cutting the corners.

Take a stater strip or a 3-tab (is what we use) and line it up with your chalk line. Then start shingling over it.

You have already read two reasons why I use the bleeder strip (**keep in mind that you still have to cut the corners off your shingle…not your bleeder though)**I you cut the valley w/o the bleder then your valley cuts will look crooked as you look from the ground.

For an estetic view, we use the bleeder to help guide our cuts. Then from the ground view your eye is geared more toward the straight line of the bleeder.

Does that sound clear or did I confuse you?

“Does that sound clear or did I confuse you?”

No I see what you are saying but in Axiom’s picture isn’t that what you call a cut valley? It looks like the shingles from the first roof plane were installed through the valley and several inches up on the second roof plane. Then the shingles from the second roof plane were overlapped and cut right at the center line of the valley. Right?

I’ve done it that way but on this roof I was planing on overlapping and weaving the valleys. I didn’t think you had to worry about the corners in a weaved valley.

“The rotten sheathing at the eaves is probably from ice dams opposed to lack of drip edge.”

It could be but I doubt it. I’m in OKC and it really doesn’t stay frozen long enough to cause much of an ice dam. We do get alot of wind driven rain though. 60-80 mph winds and 50 cent size hail is fairly common. Then once every 3-5 years we get the bad stuff with baseball and softball size hail. This is a old house with 1x8 sheathing and I’ll swear almost every knot in the old wood is busted through from the hail. I’m cutting galvanized flashing to cover over the knot holes. Just a bunch of little crap like this has taken more time than I expected.

Axiom’s pix is a cut valley…but he only displayed the pix to show the top-left corner was cut off.

Did you say that you wanted to use valley metal in an earlier post…well there is no sense in installing valley metal if you are going to weave your 3-tabs, and no need for any bleeder either.

I guess you could probably use the type of valley metal w/o the rib in the center…then weave your 3-tab over.

Thanks, I understand what you are saying now. This is 20" wide galvanized flashing , perfectly flat with no rib in the middle. The metal may be a bit of overkill but it’s not much more money and I shouldn’t have to worry about any leaks. Plus I can’t take it back now anyway cause I’ve used alot covering those damn knot holes. LOL

Axiom - Do you caulk in between each shingle too or just on the bottom?

I just put a thick bead of caulk in the valley as pictured, like it says on the package.

If you’re going to put metal down, why cover it up?

And a woven valley looks like doggy doo-doo once the shingles weather and shrink a bit.

I agree too…but if you are still going to use the valley metal then throw a strip of felt over it.

yeah…you probably don’t need to to but I would do it anyway just to cancel out any possible future condesation issue.

The reason for my statement above???

Because you chose not to resheet your entire deck…warm, moist air will flow through the gaps of your 1 x 8 boards and begin to warp the felt and shingles above it. This warm moist air may flow toward the valley and get trapped (w/o felt moisture could began to form)

Don’t let my reasoning befuddle you, if your going to add material you don’t need, then you should be aware of the dymanic affects it could have toward your roof.

[quote=“-Axiom-”]

I just put a thick bead of caulk in the valley as pictured, like it says on the package.[/quote]

Just curious. I see the pro and cons of both and the 3rd of leaving it alone.

“If you’re going to put metal down, why cover it up?”

Hmmm, to provide extra protection against leaks in the valley. Isn’t that the main reason for using metal flasing anywhere on the roof, for protection against leaks? I’ve never thought of flashing as something to be shown off.