Raise the lav drain for a new vanity

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Enrique Montar

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House was built in 79.
Removed the vintage toe kick attached vanity.
Want to install a new free standing vanity.
The bottom of the 1.5" ABS drain pipe coming out the wall is at 15-3/4" from grade..
The bottom of the existing trap is at 12-3/8" from grade.
The bottom of the access area for the new vanity cabinet is 13" above grade.
To the right of the old/new vanity is the toilet, and to the right of that is the shower.
I removed some sheet rock (about 2-1/4" wide and 1-1/4 high) above the 1-1/2 ABS and saw that the ABS has a 90 going to a horizontal drain line which I assume connects to a stack by the toilet. But I don't know.
To install the new vanity I need to raise the ABS coming out of the wall by a bit. I was thinking of tearing into the wall, cutting off the existing 90, add a new 90 going up, then add another 90 to allow me to raise the drain coming out the wall sufficiently to raise the trap.
Lots of work and not sure it meets code.
So Options are to:
Tear into the wall and do the plumbing
Buy the vanity and cut the bottom drawer and bottom of access area to allow for room for trap
Buy a different vanity
I noticed that there is plenty of flex in the horizontal ABS.
I believe from past work in the house this non load bearing wall is 2' on center on the studs.
The flex in the ABS allows me to raise the ABS and the trap so the bottom of the trap is at 13-3/4 or about 3/4 higher than the bottom of the access area in the new vanity, based on the spec drawings for the vanity on the company website.
From previous work on hanging some cabinets in the laundry area on the other side of the wall, I know that this is a "false wall"? or a "plumbing chase"? (don't know the terminology). Anyway, the studs are placed face to the wall not edge to the wall. The wall is non load bearing as the joists/rafters (one and the same on the one story low slope roof here in AZ). BTW, on the other side of the wall behind the clothes washer is a clean out cap down near the floor. I expect this is near the stool/toilet and the stack going up and where the lav drain line drains to.
There is a 2x4 immediately to the right of the drain that comes out the wall but the ABS is not connected to that 2x4 as far as I can see as it is loose behind the face of the 2x4. The next 2x4 is 24" away based on the stud locator gizmo.
The photos show the ABS as is, and as it could be pushed up. At the top of the hole is a 2x4 running horizontal, I expect to hold the water lines in place. I could easily (hopefully) take some plumbers strap and strap the ABS to that horizontal 2x4.

Question is:
Is it ok to have that much flex in the ABS? It would be the easiest way to solve the problem. It seems to easily flex without much pressure or force. I could easily prop up or fasten somehow the 1.5 ABS (by plumbers strap as mentioned above) and then have plenty of clearance for the trap in my new vanity.

Any comments?


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