How can I extend the rough-in drain away from the wall?

Question

I installed a new bathroom vanity and sink, and the sink is a slightly different size than the old one. As such, the tailpiece for the new sink doesn't line up with the existing drain line coming out of the wall (I have to move the sink back another half inch or so in the picture below).

I've got to move the drain away from the wall by about an inch. Normally, I'd just cut off whatever is there and redo it, but there is not much pipe left behind the p-trap to glue things to.

How can i reposition the drain so that the tailpiece from the sink fits?

Answer 1

Yes, the solvent welded elbow above the trap does makes things challenging. How excited are you to completely remove the old trap and elbow?

It's likely the connection can be made using the existing trap. Swing it a little to either side, cut the old riser short, and use a pair of 45° elbows to make a jog in the riser to align with the new sink tail piece. Or, use a flexible section rather than fixed elbows.

If completely removing the old trap and elbow is your preference it can be done mechanically or with heat.

The mechanical method is to cut off the elbow at the base of the socket. Next, grind or sand away what's left of the elbow on the pipe. Take care not to cut too deeply. A rotary tool such as a Dremel works well.

The heat method is to warm the fitting with a heat gun. At some point the PVC makes a transition from solid to rubbery. When it reaches that point it can be massaged and tugged with a wrench or maybe a gloved hand. This breaks the solvent-weld bond between the fitting and the pipe inside. The pipe temperature will not lag far behind the elbow temperature, though, so it takes some care to work the elbow off without deforming the pipe too.

Answer 2

Honestly, I would replace the whole thing. Otherwise, replace the top portion that screws onto the p- trap and goes into the wall, being certain to cut that pipe long enough to reach the new drain. Much simpler that rearranging the drain.

Alternatively, there is a flex adapter that will allow for awkward installs and give the added length needed to reach the tailpiece.

UPDATE: I’ve literally just changed out the plumbing in my pedestal sink in the fashion I’ve suggested. The wall adapter was installed at an awkward angle and was an eyesore. Without cutting into the wall or re-installing the pedestal sink, I replaced the standard p-trap with a flexible one.

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