I want to remodel a small bathroom to add a double-sink vanity. Currently the layout looks roughly like this, with a single-sink vanity:

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I've looked at keeping everything on the "west" wall, but there's no great way to expand the vanity due to the space required around the toilet. The best configuration I could think of is this:

enter image description here

I found some larger vanities online and verified that they would fit the space with enough room for the door, trim, and so on. However, the following facts make me nervous:

  • The "south" wall is an exterior wall, and the sink plumbing would have to run through that.
  • I can't remember ever seeing a bathroom laid out like this.

Is there a reason I shouldn't lay out my bathroom like this?

  • 1
    you might be able to still run the pipes in the west wall, depending on what's under the sinks. I've seen the same layout in hotels, so it probably makes a smaller space seem bigger.
    – dandavis
    Jan 17, 2018 at 3:12
  • I have seen this layout in a friends house (his door opened inward and he had more space your door opens outward - which is the odd part for me. If you don't have space in the south wall for pipes (some houses don't - they have 1 inch spacing between wall and outer masonry) - Cheat connect them on the west end of the vanity at the west wall - where they already exist . Just remember the down slope for the drainage! Make the vanity drains like a double kitchen sink drain. You can hide the pipe on the back of the vanity as well if you desire.
    – Ken
    Jan 17, 2018 at 9:18
  • 1
    You could replace the outward swinging door with a pocket door.
    – d.george
    Jan 17, 2018 at 13:15

1 Answer 1


Water supply pipes on an exterior wall have a greater chance of freezing.

We do this all the time where I live, but we make sure the building insulation is on the exterior side of the water supply lines. Make sure the bottom and top of the insulation batts are turned so as to keep cold air from seeping into the cavity.

You’re not moving the lav that far, so venting, pressure drop, etc. is not an issue.

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