Moving vent Stack

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by nelsonba, Nov 10, 2007.

  1. nelsonba

    nelsonba New Member

    Messages:
    116
    Location:
    Minnesota
    I need to move a vent stack. I'm having a plumber come out to reroute it, but I need to cut it off to make room for a header.

    1) Can I just cap the roof opening and leave the flashing? If so, what would I use to cap it off?

    2) If I support the vent stack at the floor with riser clamps set on floor joists, can I cut the stack with a reciprocating saw?
  2. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.

    Yes you can but I would still let a plumber do the work. I would not use a reciprocating saw it takes to long.
  3. Herk

    Herk Plumber

    Messages:
    547
    Location:
    S.E. Idaho
    I would remove the flashing and re-shingle over it.

    You don't say what kind of pipe - if it's plastic it's a breeze to cut with a recip saw - if it's cast iron, you need a special, expensive blade or a cast iron cutter.

    [​IMG]
    Last edited by a moderator: Jan 20, 2008
  4. nelsonba

    nelsonba New Member

    Messages:
    116
    Location:
    Minnesota
    Cast Iron

    Sorry. It's a cast iron pipe. There is also a joint halfway up to the roof. Could I take it apart there instead of cutting it and then take it apart at the floor? Here are a couple pics.

    http://picasaweb.google.com/barryjamesnelson/VentStack

    If so, what is the best way to disconnect the joint?
  5. nelsonba

    nelsonba New Member

    Messages:
    116
    Location:
    Minnesota
    Anybody?

    Will a torch do it?

    And back to the flashing... It is the metal type with the piece that slides down from the top. Do they make caps for these? I don't want to mess around with patching the roof.
  6. frenchie

    frenchie Jack of all trades

    You can't cut that pipe with a sawzall. Well, not without a whole lotta misery, anyways. And a few hundred blades... seriously, you'll be there all day.

    I'd wait for the plumber; with his chain cutter, it'll take him less than a minute.

    Cutting it is also kind of dangerous. That stuff is HEAVY and somewhat brittle. If it isn't supported, the top bit may come crashing down on you. Or though the ceiling below...

    It's a job best left to the relevant specialist, as well as a risk best covered by someone else's insurance.

    You could take that joint apart, I suppose, with a torch, and a lotta time, but then you'd still have to LIFT the top section out of the hub. It's HEAVY, and the bottom of it would be covered in molten lead while you tried to do this...
  7. nelsonba

    nelsonba New Member

    Messages:
    116
    Location:
    Minnesota
    I'm not afraid

    That minute would cost me $200 though. Looks like I can rent one for about $20. I once watched my brother carry a full keg of beer (140-170 pounds) into his house at chest level by himself. I'll get him to help. His labor is $0.
  8. frenchie

    frenchie Jack of all trades

    Okay, just... BE CAREFUL. Make sure the stack is securely supported, above and below, before you cut it.

    It might take an hour or so to set up some temp bracing, but it's worth it to avoid broken bones; a trip to the ER costs a lot more.

    On the other hand, chain cutters are way cool: there's nothing quite like cracking a cast iron pipe so precisely, and so easily, for sheer tool-use satisfaction...

    :)
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,515
    Location:
    Cave Creek, Arizona
    pipe

    It is not completely clear what you are doing. What is the header for? If it is a door way, then you are going to have to do more than just offset the vent, at least it appears that way from your pictures. You don't have to worry about supporting the lower section because that is already supported. All you have to worry about is cutting the pipe, which also does not need supporting, and pulling it out.
  10. MG

    MG New Member

    Messages:
    160
    Location:
    Illinois - Near St. Louis
    I have cut through cast iron w/a sawzall just recently - its time consuming but if you're in a tight area where you can't easily get a snap cutter in or if the pipe is questionable then its not a bad way to go.

    The blades aren't that expensive - I paid about $3 apiece for them. I bought 6 of them but didn't need all of them. Mainly I bought the extras as I needed to cut out the horizontal section in pieces to get it out easier.

    You have to support a vertical stack w/riser clamps or you're taking a huge risk...I supported mine in two places - one in the attic where I shored up the support w/a double layer of 2" x 6" boards that were attached to the joists w/4" lag bolts, and another on the floor below that. Probably overkill but lag bolts are cheap. You have to get the riser clamp completely tightened around that pipe before you do ANY cutting.
  11. nelsonba

    nelsonba New Member

    Messages:
    116
    Location:
    Minnesota
    The vent takes a 90 degree turn just under the floor, so it's already supported. I do have some risor clamps I could throw on it though. The header is to support the rafters where I'm removing a wall. I plan to cut out the elbow in the vent under the floor and run it straight over to the kneewall and out the roof from there since it would otherwise be right in the middle of the new room. Should be plenty of room for the proper slope.
  12. MG

    MG New Member

    Messages:
    160
    Location:
    Illinois - Near St. Louis
    A $5 riser clamp and some bracing will go a long way toward peace of mind and not worrying about that stack coming down, especially if you're cutting that elbow out.
  13. Ian Gills

    Ian Gills Senior Robin Hood Guy

    Messages:
    2,777
    Location:
    USA
    I just cut through a cast iron pipe of the same dimension with a hacksaw. It took an hour, but it wasn't that hard.
  14. TMB9862

    TMB9862 New Member

    Messages:
    206
    You can cut cast iron with a sawzall. The difficulty comes down to the pipe you have, old cast has all different wall thicknesses, some is harder then others, and some is more worn then others. I've cut 4" in less then two minutes using regular metal blades. I've also spent forty five minutes using a diamond blade. Fifteen minutes and one or two blades is about average.

    One of the best methods I have for removing cast iron that isn't going to be re-used is smashing the tub. Literally take a lump hammer and beat the hub until it cracks and no-longer exists. Then the pipe will come right out. You will need two guys, one to hold the upper pipe so it doesn't fall. It should also be obvious this is inherently dangerous, swinging a hammer with a second person in close proximity, flying shards of metal, and a heavy pipe that could fall if you don't aim your hammer and work the pipe correctly. Of course if you plan on ever using the pipe again this is a bad idea.

    I wouldn't use a torch. Lots of work, smoke, hot pipe and molten lead for no reason.
    Last edited by a moderator: Nov 13, 2007
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