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Metal roof flashing help!

| Posted in General Discussion on February 8, 2001 09:40am

*
I am trying to fix a metal roof with a dormer. The dormer’s ridge does not meet up with the main ridge. (The dormer’s ridge is located a third of the way down from the main ridge) I am not sure how to finish the dormers ridge where it meets with two valleys. So far I have installed the W channel on both valleys and have been able to overlap the w channel. I am not sure how to install the ridge metal cap. Should it be bent to go up under the metal on the main roof? and if so how should I go about cutting it and fastening it to have a water tight seal. Is there a special piece of flashing that I need to cut to go over the ridge and under the main metal roof.

Katie

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  1. Mad_Dog | Feb 07, 2001 04:20pm | #1

    *
    Katie,

    I'm just a carpenter who does some roofing, and have been forced to be creative when flashing metal roofs. You're going to have to think creatively here unless you can find flashing made to fit this application.

    Is the metal corrugated? You may have to construct a sort of anvil in the shape of the dormer ridge and hammer out some flashing that will not only conform to the top of the dormer but bend back to fit under the main roof too. Not easy, you may have to cut slits to allow everything to bend, then reflash over that too. Could possibly rivet this together and install as an assembly.

    Happy flashing,

    MD

    1. davidmason | Feb 08, 2001 12:03am | #2

      *Katie, This has got to be the hardest part of metal roofing.Every time I get to a ridge like that I have to retrain myself.What I do is cut my ridge cap(r.c.) so that it tucks up underneath the metal on your main roof.I cut the r.c.wherever there is a bend or break in it so that it will slide up underneath. Sometimes I have to cut the metal back on the main roof so that the r.c. planes out , otherwise it could buckle it. Then I put screws where the r.c. tucks in and anywhere that needs it. I also use mastic underneath the metal roofing and r.c. anywhere that looks like it could leak, some people use silicon but I believe that it would seperate over time ,whereas mastic wont.Just make sure you don't get any on the outside of your metalroof,looks like crap (literally) I always wondered if there was a special flashing kit for these, like those flashing kits for skylights, the ones with the lead skirt? (just a thought) Good Luck,

      1. kkearney | Feb 08, 2001 02:16am | #3

        *Katie,I also run the "w" up and over the ridge and fold both sides. That leaves one small hole at the apex.Then flash this going under the main roof metal. I bend the ridge cap to go under the main. It is a coplaner bend so it leaves a dimple that only birds see. Use seam tape(mastic?) and Lexel caulk. Don't use acid cure silicone since it eats holes.KK

        1. K._Blackford | Feb 08, 2001 02:18am | #4

          *Thanks for the information Dave and MD. I ended up using advice from both of you. The ridge was a bit of a pain to install up under the main roof. Very time consuming work. It turned out better than I expected it really looks good and the owners are happy and I don't think it will leak. So Now I only have two more to reflash . I installed Cobra Vent (a mesh type ridge vent) under the ridge cap for a ridge vent. Do you think this will work? thanks againKatie

          1. davidmason | Feb 08, 2001 09:40am | #5

            *Katie, Well the best thing about having to do it two more times is that you usually have it figured out by the time you get to the last one.That Cobra vent should work ,just make sure that if you get snow and ice built up at the peak ,as in an ice dam, that it won't leak back into the ridge vent.Just a thought. Dave

  2. Katie_Blackford | Feb 08, 2001 09:40am | #6

    *
    I am trying to fix a metal roof with a dormer. The dormer's ridge does not meet up with the main ridge. (The dormer's ridge is located a third of the way down from the main ridge) I am not sure how to finish the dormers ridge where it meets with two valleys. So far I have installed the W channel on both valleys and have been able to overlap the w channel. I am not sure how to install the ridge metal cap. Should it be bent to go up under the metal on the main roof? and if so how should I go about cutting it and fastening it to have a water tight seal. Is there a special piece of flashing that I need to cut to go over the ridge and under the main metal roof.

    Katie

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