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Thread: Converting single vanity into double

  1. #1

    Default Converting single vanity into double

    Read a bunch of threads that a search pulled up, found a lot of answers, but lack the answer to a specific question or two that I have.

    Currently have 1-1/2" iron waste line running up from slab into wall, T to the sink, and continuing up to vent. Wall is interior 2x4. I understand that if I were pulling a permit, I probably shouldn't run this pipe horizontally through 2x4 studs as it might weaken the wall too much. I think that the size is OK to support the 2 sinks.

    Question 1: Assuming I run a leg to the right and left for the two sinks, will the center drain and vent be appropriate? I can't think of a better way without breaking into the slab and running separate drains and vents for each sink - something I really don't want to do here.

    Question 2: Assuming I drill or cut through the studs anyway (looks like I'd need to go through one additional one on one side, two on the other), what is the preferred method of maintaining structural integrity: notch on one side and put a metal strap across, or insert a header above and below the horizontal pipe run creating essentially a window inside the wall?

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default sinks

    Technically, 1 1/2" pipe is not proper for your application. Drill the holes, install the pipe, place protector plates so you do not drive drywall nails or screws through the pipe, and then install the sheetrock. The studs will not be weakened enough to require reinforcement.

  3. #3

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    Looks like I was mistaken - the drain is 2" iron and 1-1/2" galvanized vent extending up. I didn't notice that the iron below the current T was larger.

    Any problems using a PVC or ABS double santee to make the "cross" for the left and right drain runs? Going with iron would be a pain to find locally and the notches for the horizontal runs through the 2x4 studs would be larger.

  4. #4
    Master Plumber nhmaster's Avatar
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    Default

    Quote Originally Posted by rhosch View Post
    Read a bunch of threads that a search pulled up, found a lot of answers, but lack the answer to a specific question or two that I have.

    Currently have 1-1/2" iron waste line running up from slab into wall, T to the sink, and continuing up to vent. Wall is interior 2x4. I understand that if I were pulling a permit, I probably shouldn't run this pipe horizontally through 2x4 studs as it might weaken the wall too much. I think that the size is OK to support the 2 sinks.

    Question 1: Assuming I run a leg to the right and left for the two sinks, will the center drain and vent be appropriate? I can't think of a better way without breaking into the slab and running separate drains and vents for each sink - something I really don't want to do here.

    Question 2: Assuming I drill or cut through the studs anyway (looks like I'd need to go through one additional one on one side, two on the other), what is the preferred method of maintaining structural integrity: notch on one side and put a metal strap across, or insert a header above and below the horizontal pipe run creating essentially a window inside the wall?
    So are we to assume that you will not be pulling a permit for this?

  5. #5

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    That would be a pretty good assumption. I should probably add that this wall is the the back of a closet from another room so there are lots of structural support in this area, as well as the roof being constructed from prefabbed trusses that are capable of spanning the width of the house without needing weight bearing walls for support. So I'm not too concerned about losing a 2x4 or two, though I'd like to restore as much strength to them as possible just to "play it safe."
    Last edited by rhosch; 12-31-2008 at 03:51 PM.

  6. #6
    Master Plumber nhmaster's Avatar
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    Default

    In that case, best of luck.

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