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  1. #1
    Join Date
    Sep 2012
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    Default ZIP roof sheathing, standing seam steel over, no felt

    Huber crows loudly that no felt is needed between their taped-joint coated OSB and roofing.

    So who has experience with standing seam steel going on it, no #30 felt between?

  2. #2
    Join Date
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    Quote Originally Posted by IamTheWalrus View Post
    Huber crows loudly that no felt is needed between their taped-joint coated OSB and roofing.

    So who has experience with standing seam steel going on it, no #30 felt between?
    I've used the ZIP roof product, no way would I not use another underlayment.
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  3. #3
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    I leak tested taped zip roof and it came through the nails. So my opinion would be to add some redundancy.
    "First we finish the game, then we’ll deal with the Armada!"

    Sir Frances Drake

  4. #4
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    We've used it under comp and I still like the idea of underlayment.

    We had one house where I taped the roof and then worked in the pouring rain before the roofer got there and we had two spots where there were leaks.

    When I found them, they were where I had dragged a sheet across the tape, so its good to tape all at once at the end of the sheathing/nailing process. Although for steep pitches this might not be advisable.

  5. #5
    Join Date
    Dec 2005
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    Michigan
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    In order to seal, the nails have to go through an elastic membrane of some sort. Anything not flexible will not seal at the nail holes. Kind of obvious, but it bears repeating.

  6. #6
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    Jun 2004
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    Holley, NY
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    507

    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    In this case the underlayment also serves as a buffer to isolate any nails or staples left slightly proud of the deck. Most steel failures I've inspected have been from the bottom side up.

  7. #7
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    Chad, can you clarify that a bit? Not sure what you're saying.

    OSB serves as a buffer??? Isolating nails from what? I don't get it.

    And those failures 'from the bottom up', what exactly does that mean? Steel rusting on the bottom side?

    Love your brevity, but you lost me there.

  8. #8
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    Jun 2004
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    Holley, NY
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    Sorry about the brevity.
    Even if I used Zip systems, I would still use felt below steel. The underlayment helps prevent abrasion of the steel's very thin protective plating.

    I've inspected steel roofs less than 5 years old that were rusted through from the bottom up. The expansion and contraction cycles wiggle things around enough to wear the steel wherever there is contact with abrasive stuff.
    Last edited by Chad Fabry; 04-15-2014 at 05:29 AM.

  9. #9
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    Ah, OK. But Zip is not bare OSB, it has a surface coating that (to my half-educated judgment) is less abrasive than most underlayments. And certainly less abrasive than OSB. It is very smooth.

  10. #10
    Join Date
    Apr 2008
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    SF Bay Area (East Bay)
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    Quote Originally Posted by Chad Fabry View Post
    In this case the underlayment also serves as a buffer to isolate any nails or staples left slightly proud of the deck.
    It's not the board (OSB or Zip) he's talking about, it's the nails.
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

  11. #11
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    Jul 2008
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    Suburbia (Washington, DC area)
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    I am one more on the side of using underlayment.
    Per Joe L: "all metal roofs leak"...in my experience, this is pretty much true (though usually only at complicated intersections, low slopes, or in heavy winds).
    I would actually prefer using high temp peel-and-stick under a metal roof because of the constant minor leaks I've seen.

    Regarding Zip, the tape is pretty good, but not perfect. And there are all those nail holes. We decided that we want another layer on top like felt or wrap, even though the taped sheathing is great for air sealing, for during-construction, and probably for long term as well.
    Last edited by ThingOfBeauty; 04-23-2014 at 12:12 PM.

  12. #12
    Join Date
    Jun 2004
    Location
    Georgia
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    Default Re: ZIP roof sheathing, standing seam steel over, no felt

    Quote Originally Posted by Chad Fabry View Post
    Even if I used Zip systems, I would still use felt below steel. The underlayment helps prevent abrasion of the steel's very thin protective plating.

    I've inspected steel roofs less than 5 years old that were rusted through from the bottom up. The expansion and contraction cycles wiggle things around enough to wear the steel wherever there is contact with abrasive stuff.
    Yes, but the felt itself requires fasteners, so you still have the problem.

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