Relocate vent to accommodate sink move

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Jadziedzic

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I would like to relocate a vent line so I can move a bathroom sink to the center of the counter instead of near one end where the builder located it. If you look at the attached photo, my plan would be to cut the left-hand 2" PVC pipe (the vent) a few inches above the bottom plate, use a 90 degree elbow to run it to the next joist space over, then add another 90 degree elbow to go straight up through the top plate. I'd replace the existing drain stub tee with a tee pointing to the left, through the stud, then out through the wall with a 90 degree elbow. The red lines show the proposed drain/vent piping runs.

The vent lines in the attic above are easily accessible and run along the rear of the house (behind you, when looking into the photo). There should be no problem making the connections there.

If it matters, the vent (left-hand pipe) runs from the laundry room below this bathroom, where the washing machine drain box and the drain from this bathroom (right-hand pipe) tie into the vent with a double tee (is that the correct term for an "X"-shaped tee?). The shower (behind you when looking into the picture) ties into the right-hand pipe just below the subfloor; there's a separate vent line for the shower that ties into the vent running inside the ceiling joists above.

The ceiling joists tie into the main beam that runs from right to left in the ceiling behind this wall (you can see the column that holds up that beam if you look through the second from the right stud space). I'm not sure that I'd call the wet wall here load-bearing, but do I need to double up the 2x4 that I'll drill in three places to accommodate the new drain/vent runs? (Obviously I'll run the 1/2-inch copper supply lines through that stud as well.)

Is there a better way to accomplish this, without running drains inside the cabinets? I'll be removing the sheet rock from the wet wall to add a pair of sconce lighting fixtures so the entire wall will be accessible.

Thanks,
Tony
sink_pipes.jpg
 

hj

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That will work, although there might be an easier way to do it, by "offsetting the vent as far back as possible, and then running the sink drain in front of it, depending on whether those pipes are 1 1/2" or 2". And you do not have to run the "offset" vent up to the ceiling, all you have to do is route it around your new drain line.
 
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Jadziedzic

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Thanks much for the comments. That's an interesting idea regarding the offset trick, but as these are 2" pipes there won't be enough room in the 2x4 walls to run two pipes across each other. (I can't fur out the studs to gain extra depth because the room is already a bit small, and losing an inch or so for the furring would have an impact.)
 

hj

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In that case, just make a sideways "U" around your sink's drain. The 42" high before you turn horizontal rule does not apply to that left hand vent riser.
 

Jadziedzic

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A related question on glueing PVC pipe: All the recommendations I've read say to twist the fitting (or pipe) a quarter-turn to spread the solvent cement fully in the joint as the pipe and fitting are joined. Is there a "trick of the trade" that applies to that sideways "U" section I'll be constructing? No matter which order I follow, at some point I'll have to make one connection where the pipe/fitting cannot be rotated because the receiving fittings are already glued to another section of pipe. Do I spread both receiving fittings apart, apply cement to the pipe and both fittings, and then insert and rotate the pipe? Does the solvent cement have that much "open" time so I can get a good joint? Do I need a helper to simultaneously glue one joint as I glue the other? Or do I just exercise extra care to get a full coating of cement on the non-rotable pipe and fitting?
 
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hj

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Install the two horizontal pipes, assemble the "U" section, and then slide it onto the two pipes after applying the cement. If you apply the cement to the pipes properly, twisting is NOT necessary. In fact, with some glues it is almost impossible to twist the fitting once you push it on.
 

Jadziedzic

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Just to close the loop, I used the sideways "U" suggestion for routing the vent, had no problem with glueing the two joints simultaneously, and the rough inspection passed, so I'm good to go. Thanks for the help!

Tony
 
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