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Thread: Venting through metal roof

  1. #1
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    Default Venting through metal roof

    I have searched for this, but have not found a answer .
    I have a house in northern VT.
    I have a metal roof,6-12 pitch,3" vent going through.My friend is a plumber and installed when I wasnt there.He now has a broken leg in six places and I have to fix.
    He put it about half way up the roof,I wanted it up towards the top more ,but it was too late and what happened is what I feared would happen,The ice and snow slid down and mowed right over and broke the vent lines off.
    I now have to replace a peice of the metal roof as it is damaged.I know it wasnt anchored well inside and was looking for the correct way to anchor the vent line in my attic so it will not do this again.I will replace metal and move vent up the roof alot more.
    What I would like to do,Is go out the gable end wall towards the top of wall and exit and not compromise my roof.
    But I have read thats not legal.My house is spray foamed on roof and walls of attic,Could I vent out through my end wall?If not how can I anchor correctly so vent will not break again?
    Thanks alot in advance.

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default vent

    It should not have broken in the first place, but just use a different material, steel or cast iron, and it won't break.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    Default

    Parts of New England this winter had record snows...easily over 100". Obviously, not all of that was on the roof, but compress some, freeze, thaw cycles, and what is there often decides to come off the roof in a violent manner...not something those in Arizona are used to!
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    Master Plumber Redwood's Avatar
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    Default

    While it would have been best to put it up high, you can install snowgards or, snowbars that break up the avalanche as it comes down into smaller pieces that will not take out chimneys and vents. It is probably in the interest of safety for those who may be on the ground below as well. You can also install a vee-shaped wedge above the vent to deflect the snow.

    The other option would be to move the vent higher.

  5. #5
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    Default

    The 3" pvc did not break ,but bent over enough to ruin metal roof and broke off all connections below in my attic.
    What Im looking for is the correct method of securing the pipe before going thru roof.I know there is a cast iron round clamp that could go onto pipe before exiting thru roof.
    Could someone show me a link or photo,diagram of the correct method?

    So its not legal or to code to go out high on the end wall to exit vent?And not compromise roof.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    If the vent terminates high enough and is big enough in diameter, functionally, it should be able to exit there...most people don't like the looks...not sure if it is to code or not.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    DIY Junior Member
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    You should replace the piece of the metal roof if it is now damaged before doing some venting on the roof. You also need to have a snowboard to protect it from snow. I hope you had it repaired by now especially that the amount of snow expected to cover the place is unusually greater than before. Roofing Companies
    Last edited by ricaroofers; 02-18-2010 at 06:57 AM.

  8. #8
    Test, Don't Guess! cacher_chick's Avatar
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    Default

    To secure the pipe I would use a riser clamp secured between the 2 roof trusses and another between the floor/ceiling joists in the attic. A little blocking would do a lot of good.


  9. #9
    Moderator & Master Plumber hj's Avatar
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    We had snows in Chicago when I grew up there. I am not sure HOW your pipe penetrated the roof, but if the opening UNDER the metal was the proper size, (I am assuming there is a substructure of wood, or something under the metal, and not just the metal layer), the pipe could not have moved in ANY direction.

  10. #10
    General Contractor dx's Avatar
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    Default

    You can use any method you wish to secure the vent pipe. U bolts, U straps/clamps, wood blocking, etc. The best method depends on what's in the attic: trusses, rafters and joists or other structural members. It's best to secure at two points far apart (as suggested, at rafters and joists for example) so that the pipe cannot pivot as it did before.

    As far as going out the gable wall, call your local building department and ask if that is acceptable per local code.

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