Copper Vertical Vent Pipe Question (Hopefully Simple, But Very Important)

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Bluegrass Picker, Dec 4, 2014.

  1. Bluegrass Picker

    Bluegrass Picker Member

    Joined:
    Jan 30, 2013
    Location:
    West Richland, Washington
    Hi,

    Single story home with basement. We're swapping out the old bathtub for a new Sterling tub.

    I will have to replace the old 1 1/4" trap with a 1 1/2" trap which means I'll need to cut into the vertical copper 1 1/4" vent pipe that extends from below the tub up through the roof to attach a new 1 1/2" T for the trap and for the outflow that goes to the drain stack in the basement.

    After I disconnected the tub drain, it appears that the vent pipe that goes through the roof is loose, in that I can move it slightly up and down as if it's not attached in the attic. Does the pipe generally in most situations move inside the vent stack that is attached to the roofing, or am I possibly making a potential roof leak happen?

    I ask this question because if I can cut the T out in the joist area in the basement below the tub and then grab and raise the vent pipe up about 6 or 8 inches or so, I can splice a 1 1/2" vertical pipe directly to the copper vent up in the bathroom wall which would leave me a 1 1/2" stub sticking down through the subfloor in which to attach my T and the new 1 1/2" trap. Space is extremely tight below that subfloor in the joists, so there's no room for a Fernco coupler below the subfloor and then a T. Basically the plan is to transition from the copper to PVC in the bathroom wall and then have PVC for the rest of the bathroom drain parts and pieces that eventually end at the main stack.

    Am I possibly going to damage anything in the attic or roof? (We are having freezing rain, so climbing on the roof right now is not an option, and there's about 2 feet of blow in insulation in the attic, so climbing around in there is not fun).

    Here's a couple of photos of the existing trap if that helps at all.

    LR-2855.jpg LR-2856.jpg

    Thanks in advance for any advice.

    Bluegrass Picker
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Is that blown-in fiberglass or is it blown-in cellulose?
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    You'll want to find a place where you can put some riser clamps on that vent line to take the weight off of the plastic you plan on installing underneath. OFten, that pipe goes through a rubber boot on the roof, and if you move it, you might end up with a fold in it that can let water run down the pipe, so whatever you do, you may want to finish up by checking that penetration when you're done and make sure it is still entirely intact and you've not dislodged or torn the boot or moved the flashing to it.

    You can find banded couplings designed to transition between copper and pvc...the ones typically found in a big-box store will be too big on the copper end to seal properly. To use one of those, you don't really need to slide the pipe up or down as you first take the band off of the coupling, slide it on one side, fold the rubber back onto itself, slide the new pipe up to it, then roll the neoprene rubber sleeve over it, then reinstall the banded coupling and tighten up the clamps.
     
  5. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    In the first place, that IS at least a 1 1/2" P trap, so if anything it only has to be relocated, which is NOT a problem for a plumber but could be for you. From your description, what I can make out from it, it looks like you are taking a minor revision and turning it into a project.
     
  6. Bluegrass Picker

    Bluegrass Picker Member

    Joined:
    Jan 30, 2013
    Location:
    West Richland, Washington
    Rockwool and then in later years, a layer of cellulose on top.
     
  7. Bluegrass Picker

    Bluegrass Picker Member

    Joined:
    Jan 30, 2013
    Location:
    West Richland, Washington
    Thanks for your reply. I hope I haven't done any damage already. I only moved it up and down no more than an inch just to see if it moves....

    Never heard of the banded couplings. That's why I like this forum and I deeply sincerely appreciate the information here and the time that persons take to help those of us who need it. If it turns out that I end up doing the project in the way I described, then I'll check the local plumbing supply house. Thanks.
     
  8. Bluegrass Picker

    Bluegrass Picker Member

    Joined:
    Jan 30, 2013
    Location:
    West Richland, Washington
    Thanks very much for your reply.

    I certainly don't want to make the minor revision into a major project since this bathtub replacement is major enough.

    Since posting my question here, I looked at the copper vent pipe and it says 1 1/2".... The confusion is that I tried a Fernco 1 1/4" coupler on the old drain pipe just above the trap and it fit. The Fernco 1 1/2 was too big and the new tub drain pipe is 1 1/2" PVC which is certainly larger. I'm expecting we are dealing with ID... Sorry about the erroneous info in the OP. I appreciate your catching that.

    My old tub drain was right next to a floor joist, and the new drain will be 1 1/2" so clearances are going to be extremely tight next to that joist. I'll be using a Watco flex setup so I can be somewhat flexible in the drain placement, but the existing 1 1/2" copper trap is too high being slightly below floor level (bottom of the tub) so attachment of a 1 1/2" drain pipe from the tub with a Fernco coupler to that trap is almost impossible due to height. The new PVC 1 1/2"tub drain 90 T extends too far below the 1/2" subfloor .

    I picked up a 1 1/2" PVC trap that is solvent weld on the ends and a large screw nut in the center. I've tried many scenarios of bending that trap around, but I cannot see how I can connect it to the horizontal copper that goes to the existing trap and then have the inlet of the trap be positioned properly for the tub drain.

    The distance between the joists is 11.5"According to the photos I supplied does it look as if the PVC trap should fit?

    Is it possible to splice into the horizontal pipe for the outlet and cap off the T where the existing trap connects to the vent T?

    Alternatively, can I cut the 1 1/2" copper right where it connects to the existing trap and attach a Fernco or other coupling right directly to the outside diameter of the trap fitting itself?

    I'm no stranger to construction and electrical DIY jobs, and my goal is always to do it right the first time and do it to last, but figuring the angle of the dangle of this trap problem is somewhat of a challenge because when that tub goes in, it's gotta be right the first time....

    What would your recommendation be? Any advice that I can receive is deeply appreciated, and if my best option is to call a plumber, then I'll do it if necessary.

    Thanks very much.
     
  9. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    I would lose the p-trap with nut on it; it's just one more thing to leak.
    Pick up a solvent weld trap. You have room there for a coupling to go from copper to plastic, and they make a copper by plastic coupling for just that purpose.
     
  10. Bluegrass Picker

    Bluegrass Picker Member

    Joined:
    Jan 30, 2013
    Location:
    West Richland, Washington
    Thanks very much for your reply.

    Do they make a 1 1/2" copper socket to 1 1/2" PVC coupling? I have a 1 1/2" PVC trap and it's longer than the existing copper trap. The socket to pvc coupling would theoretically buy me more space?
     
  11. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    I would stay with copper because converting to plastic is going to take up a lot of space and you don't really have any to waste. IF you cannot work with copper it would be an easy, and fairly quick, task for a plumber.
     
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