What kind of flashing

Malcolm

I am going to use a closed valley. I was wondering what kind and size flashing should I use underneath. I was just going to form 20" roll flashing. Is this the size and type you guys use. I am also going to use ice and water underneath the flashing.

Ed the Roofer

With the Ice and Water Shield, you will not need any sheet metal at all. Especially the light weight crap rolls you would buy off the shelf at a HD, Lowes, or Lumber yard.

If you decide to have a proper W-Valley flashing made and installed, I would still use I & W shield under the Sheet Metal Valley liner.

But, then it should be an open valley versus a closed valley.

Ed

P.S. If you have a bunch more questions to ask. Put them all in one post and number them to get a more expedoted answer, instead of one at a time.

Malcolm

It was the one at lowes. The codes say to use metal or rolled roofing under the closed valley. I want to make sure it is up to code. They sell a galvanized thick roll of metal that is $47 for a 20in by 50 ft. Can you tell me what to ask for at ABC supply tomorrow. Is 20in sufficient? I know it is by code standards, but I want to make sure this thing doesn't leak. This is my first roof. I was hoping you could get me through it.

Ed the Roofer

Usually, when we use Sheet metal valley liners, we get the color coated Pac-Clad or Copper. Regular galvanized will eventually show off its rusting abilities, even though it is not supposed to.

24 " wide metal comprised of either 24 Guage steel or if you choose aluminum instead, then order .040 mm thickness for sturdiness and less chance of puncturing accidentally.

Theree should be an upside down "V" in the center to prevent water flowage and migration under the opposite side of the valley shingles, which becomes more important the steeper the pitch is.

An open valley will not clog up with leaves and pine needles as readily.

The side edges should have a hem bent in them and you are supposed to use sheet metal cleats to hold the metal in place versus nailing through the metal valley to allow for expansion and contraction from thermal schock.

I don't buy into that premise, unless you are doing an entire metal roof. After all, the nails from the shingles are going to penetrate the sheet metal anyways.

If, per chance you go with the copper valley metal, buy one or two pounds of copper roofing 1 1/4" nails to nail the valley shingles in with. Otherwise you will have the corrosion by electrolysis problem discussed previously, for sure.

A slight bit of roofing cement from a caulking tube under each of the end edges of the final valley shingles will assist in preventing water back up under the edges of the shingles.

I believe the code you referenced would allow lee-way, as an either/or situation regarding the ice and water shield versus the sheet metal valley liner. I personally would prefer only the ice and water shield method, especially for someone who does not have any sheet metal experience. You will see what I mean at both the bottom of the valley at the inside corner and at the to edge of the final piece of valley metal.

At that point you will be asking additional questions. Visualize it and you may realize what I am implying.

Ed

RooferJim

They should update there codes. its stupid to spend $ on metal only to bury it. with I&W and good workmanship it is not needed. If you do want metal then bend it in a brake or it wont sit right and will bump up your shingle causeing a potentle leak or blow off.