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Thread: DWV Vents Through Roof (NYC)

  1. #1

    Post DWV Vents Through Roof (NYC)

    I'll be having a complete roof tear off and replacement done shortly, and was wondering what to do about the two aging galvanized vent stacks. The roofing contractor suggested now would seem to be a good time for replacement.

    I've been gradually ripping out much of the 55 year old galvanized DWV and replacing it with copper DWV... expensive I know, but I refuse to use cheesy PVC or ABS which wreaks amateur in my opinion. Since I'm not ready to replace the entire vent stack yet - that'll be replaced when the kitchen and master bath is eventually redone - I'd like to just replace the section that extends through the roof. I plan on cutting the old galvanized vent below the roof, and joining the new vent with no hub couplings.

    The question is, what kind and size copper should be used through the roof? It seems DWV yellow wouldn't be sufficient. Would type L be acceptable, or would K be needed? This is NYC. Perhaps CI would be needed.

    Any advice would be greatly appreciated!

    Thanks!

  2. #2
    Plumber Cass's Avatar
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    I think you should check with a plumber who is up on NYC codes.

    I'm not sure if there is one on this board or not.

  3. #3
    Questions from readers Guest's Avatar
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    Not to seem like I'm being argumentative...
    Copper is metal, metal corrodes...turns green after a few years...but it beats the heck outta galvy any day of the week.
    PVC doesn't corrode...but it has two disadvantages...it's noisey, it expands when hot water passes through it...if packed into tight spots it'll creak in longer lengths, stacks.
    ABS...still noisey, but doesn't expand when heated.
    Cast iron...quiet, no expansion, though it rusts over long periods, (I've seen it hold well over 50 years on remodels) I'd take it over copper any day.
    On a final note....stubbing copper through a roof to the weather extremes here in the nor'east...have ya seen lady liberty lately?

    Grumpy Plumber

  4. #4
    Jack of all trades frenchie's Avatar
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    I'm pretty sure that all DWV pipe in NYC is required by code to be cast iron? I know PVC & ABS aren't allowed; and I've never seen anything else than cast iron coming out of a roof before.

    The guys behind the counter at any small plumbing supply shop will be able to tell you whether copper's also allowed.

  5. #5

    Thumbs up

    Thanks for all the replies!

    Here in NYC you won't see plastic coming out roofs on commerical, but you'll see it all the time on resi. NYC approved PVC for resi fairly recently it seems, but I still won't use it.

    Just as an aside, NM (Romex) cable in resi is now OK by code in NYC - though nobody I know is using it, mostly because they fear inspectors won't be too happy seeing it as old habits die hard. Many local supply houses don't even carry it. I won't use NM either.

    I guess it can't hurt to go out of the roof CI then transition with no hub to copper (with the appropriate no hub fitting on the copper end).

    Haha, the supply house has been telling me to use PVC and thinks I'm crazy to be fooling with copper in resi... "PVC is cheaper!"

    Many thanks!

  6. #6
    Licensed Grump GrumpyPlumber's Avatar
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    Joe, not just cheaper, it lasts longer.
    But, CI is the best of the best when it comes to noise and expansion.
    Charlotte touts their CI as "The quiet pipe"
    More expensive than PVC, but not nearly as expensive as copper

  7. #7
    Jack of all trades frenchie's Avatar
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    Dang - I've been working in Long Island for the last 2 years, and haven't kept up with the last code cycle in NYC. I'd heard about the new code changes vis-a-vis NM; but I'm amazed that they changed the rules on PVC pipe as well! That's under the fire code, and if you want to talk about entrenched bureaucracies resistant to change... zowie. I am truly amazed.

    Grumpy - are you sure PVC lasts longer, even when exposed to sunlight?

  8. #8
    Licensed Grump GrumpyPlumber's Avatar
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    Quote Originally Posted by frenchie
    Grumpy - are you sure PVC lasts longer, even when exposed to sunlight?

    In theory PVC has a shelf life of 100 years, but we'll have to wait another 40-50 years to know, it has only been around since the 50's.
    As far as sunlight affecting it...You might be thinking of PEX (cross linked polyethylene) which does degrade when exposed to sunlight.
    "The biggest regrets we have in life are the chances we never took."

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    In the Trades kordts's Avatar
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    Sunlight affects pvc as well. But the 12" above the roof is just the terminal, and it's just a vent.

  10. #10
    Licensed Grump GrumpyPlumber's Avatar
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    Quote Originally Posted by kordts
    Sunlight affects pvc as well. But the 12" above the roof is just the terminal, and it's just a vent.

    I'll buy that...the PEX I was sure about, in fact it's written on most MFG's packaging....the PVC I wasn't aware of
    "The biggest regrets we have in life are the chances we never took."

  11. #11

    Talking

    I don't like plastic pipe because I've seen enough of them come apart... all with expensive outcomes. CPVC seems to be the worst at coming apart on domestic water - you sure don't see that with copper joints. And PVC and especially ABS on DWV doesn't always seem to like being snaked aggressively. I cringe at the thought of ripping apart expensive Italian marble because a cheapo plastic fitting got undone.

    Grumpy, I sure agree with you on CI though, it is indeed the best. Problem is, I never learned how to pour lead, and that's truly the best way to join CI in my opinion. Many of the CI jobs I've seen on small commerical projects around the NYC area are done largely with no hub. The CI pipe will be around almost forever, but the rubber no-hub fittings certainly won't stand the test of time.

    Frenchie, my understanding too was the FDNY was the biggest opponent of PVC because of the toxic fumes potential in a fire. The compromise I believe was structures no more than 3 stories were permitted to use PVC (DWV only) - anything larger must go with metal... CI, copper, galvanized, brass.

    As for electrical, though MN is approved in NYC, I don't believe the plastic boxes are approved however (could be wrong though) - you still must use steel. I still use MC or BX though. Heck, it could be worse, in Chicago ALL electrical must be run in PIPE - even on resi jobs. You can only use Greenfield on short whips. It's amazing though how those Chicago sparkies can run pipe like it's nothing... they can probably run it fast as the guys up here to MC, BX or NM.

  12. #12
    Jack of all trades frenchie's Avatar
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    That sounds probably right, about the compromise - I know it's what they did with the electrical; anything over 3 stories, or that's not a detached house, still follows the old rules.


    ... the bit about the Sparkies in Chicago... you hang out in a few other forums, don't you? JLC? BT? I've read that paragraph before, somewhere else.


    BTW, I've seen some pretty old no-hub, holding fine. Better than old PVC, anyways ...
    Last edited by frenchie; 06-25-2007 at 05:18 PM.

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