Plumbing Double Vanity

[Goodimike]

Hi everyone, I am trying to figure out DWV plumbing layout in a 2 x 4 wall with the least amount of holes in framing members. The plumbing is for an upstairs bathroom with a double vanity where the drain/wet vent is already plumbed to the far right of both sinks (instead of in between). I am under IPC. The drain/vent is about 6'4'' from the furthest sink which means it is just 4” too far to have a 1 1/2” interconnecting trap arm run between the two sinks "911.2 Connection at the same level. Where the fixture drains being common vented connect at the same level, the vent connection shall be at the interconnection of the fixture drains or downstream of the interconnection.". I am hoping the interconnecting trap arm can still work if I can run a re-vent between the two sinks (Pic #1)?. I have another layout that I believe works and might be preferred (Layout on Pic #2), but this layout requires a lot of holes in the 2 x 4 wall. I included some alternative layouts that I thought could possibly work which require fewer holes. Layout #3 was suggested to me by an experienced, but non-licensed plumber. Do any of these layouts work? Any other changes/recommendations? Every 2 x 4 stud is already doubled and regardless of the layout chosen I plan on using 1/2 or 3/4'' plywood across one side of the entire wall for shear strength. The wall is load-bearing in that it will be a small 5' x 10' loft/upper room in a kids bedroom. Thank you.

Pic #1: interconnecting trap arp w/ revent
Pic #2: I believe works, but requires a lot of holes
Pic#3: Recommending by plumber (unlicensed).
Pic #4: use of double fixture fitting or double San-tee with AAV attached above.

 

[Reach4]

IMF_9929.jpeg is not right. The right-sink needs to be vented before dropping.

Similar is Long or medium bend on the left with trap adapter. Combo (OR alternate) with trap adapter for the right lav. Both in the horizontal plane. Between those is a santee on its back connecting to the AAV. This minimizes penetrations. So this is equiv to IMG_9940.jpg, but using an AAV to reduce penetrations. Not using AAV is better.

https://terrylove.com/forums/index.php?threads/i-need-to-vent.90139/page-3#post-647579 talks about a similar situation and even pipe sizes..

 

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[Goodimike]

IMF_9929.jpeg is not right. The right-sink needs to be vented before dropping.

Similar is Long or medium bend on the left with trap adapter. Combo (OR alternate) with trap adapter for the right lav. Both in the horizontal plane. Between those is a santee on its back connecting to the AAV. This minimizes penetrations. So this is equiv to IMG_9940.jpg, but using an AAV to reduce penetrations. Not using AAV is better.

https://terrylove.com/forums/index.php?threads/i-need-to-vent.90139/page-3#post-647579 talks about a similar situation and even pipe sizes..

Thank you Reach. Can I keep the horizontal pipe 1 1/2” all the way or do I have to upsize to 2” after the second vanity?

 

[Reach4]

Thank you Reach. Can I keep the horizontal pipe 1 1/2” all the way or do I have to upsize to 2” after the second vanity?

#52 on that thread says everything can be 1.5.

You will want stud shoes, because you plan to drill 2 inch holes into 3.5 inch studs.

Putting in the non-AAV vent would be the better idea IMO. I am not sure that a second hole in a stud weakens it much more.

 

[Goodimike]

#52 on that thread says everything can be 1.5.

You will want stud shoes, because you plan to drill 2 inch holes into 3.5 inch studs.

Putting in the non-AAV vent would be the better idea IMO. I am not sure that a second hole in a stud weakens it much more.

Thank you. I will use double stud shoes and tie in to the vent.

 

[Cfelice]

Hi everyone, I am trying to figure out DWV plumbing layout in a 2 x 4 wall with the least amount of holes in framing members. The plumbing is for an upstairs bathroom with a double vanity where the drain/wet vent is already plumbed to the far right of both sinks (instead of in between). I am under IPC. The drain/vent is about 6'4'' from the furthest sink which means it is just 4” too far to have a 1 1/2” interconnecting trap arm run between the two sinks "911.2 Connection at the same level. Where the fixture drains being common vented connect at the same level, the vent connection shall be at the interconnection of the fixture drains or downstream of the interconnection.". I am hoping the interconnecting trap arm can still work if I can run a re-vent between the two sinks (Pic #1)?. I have another layout that I believe works and might be preferred (Layout on Pic #2), but this layout requires a lot of holes in the 2 x 4 wall. I included some alternative layouts that I thought could possibly work which require fewer holes. Layout #3 was suggested to me by an experienced, but non-licensed plumber. Do any of these layouts work? Any other changes/recommendations? Every 2 x 4 stud is already doubled and regardless of the layout chosen I plan on using 1/2 or 3/4'' plywood across one side of the entire wall for shear strength. The wall is load-bearing in that it will be a small 5' x 10' loft/upper room in a kids bedroom. Thank you.

Pic #1: interconnecting trap arp w/ revent
Pic #2: I believe works, but requires a lot of holes
Pic#3: Recommending by plumber (unlicensed).
Pic #4: use of double fixture fitting or double San-tee with AAV attached above.

I have a similar situation where I am connecting a double vanity (two sinks) to a drain that vents to the right of the sink to the right. I didn't quite understand the answer to the above thread and am wondering if the fourth picture with the AAV above a double fixture fitting would work. The previous set up was a smaller double vanity set up that drained fine with a double fixture fitting that fed into the 1 1/2" horizontal drain. The vent stack is behind the wall on the right and I don't have access to it, but it does run vertically through the roof. Appreciate any advice.