We are doing a bathroom remodel, and I removed the vanity and found some pipes I did not expect to find. This is a second story bathroom, and the wall pictured is an exterior wall.

The pipes are nowhere near the downstairs kitchen or bathroom, nor are they near the laundry room. Above the bathroom is the attic. Directly below it is our living room, which does have a gas fireplace (although I believe it vents elsewhere).

The vanity has a normal looking drain connection just above the photo. Not pictured. Perhaps that's what one of these are for?

Anyone have any idea what the heck these are? Or how I'd put a new vanity in on top of these?

Unknown pipes

  • Do you have a direct vent heating system? Dec 6, 2020 at 23:04
  • 1
    Is there anything sticking out the wall on the outside of the house? Was it a double vanity - is there a pipe above each running into the wall below where the bowls of the sinks were? Do you have a basement or other place where plumbing is exposed below? Have one person put an ear on the pipe, and have someone knock on every pipe they can find down below with a screwdriver - you should be able to hear the sound travel very clearly through the pipe when it's being hit, but muffled at best if your hitting one next to it.
    – FreeMan
    Dec 6, 2020 at 23:07
  • @JeffWheeler Yes, but the vent is on the floor (not pictured, to the right) Dec 6, 2020 at 23:08
  • @FreeMan I'll go have a look at the house. Single vanity. The drain pipe is roughly centered between the two pipes. Also it's hard to make out, but the pipes are different sizes. Edit. I will try your trick, from the crawlspace Dec 6, 2020 at 23:09
  • Drain is connected to atmosphere and pipe going to roof
    – user263983
    Dec 6, 2020 at 23:46

1 Answer 1


Drain and dry vent, most likely. Rip some drywall you won't have to do a fussy repair job on because it will be hidden behind the new vanity if you are overly curious and want more info.

You'd put a vanity on them the same way the vanity you took off them was - they are running in the "toe kick space" between the floor of the cabinet and the floor of the room.

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