My son has a home and the kitchen sink base cabinet had to be replaced as a result of the 3/4" copper water entrance failing under the slab. After the demo and restoration was completed the cabinet company came to install the new sink base. They cut the existing 2" SCH 40 PVC drain, which rises vertically out of the concrete slab, to a height 1" above the floor of the new cabinet, then set the new cabinet over the 2" stub, with a hole in the bottom of the cabinet just slightly larger than the 2" pipe. The cabinet is now mounted, the counters are in, the double bowl sink is installed. While attempting to replumbing from the vertical stub it was recognized that where the cut was made the outside of the pipe has glue residue all over it not allowing for a clean surface to glue on a 2" coupling.

Under this circumstance we are trying to figure out how to join the existing pipe and ensure a good connection without cutting the bottom out of a brand new custom sink base. We have learned that joining the pipe with a 2" FERNCO is one option. My question is 2 part, " Could a 2" X 1.5" SCH 40 Glue reducing bushing be used to make a quality connection point? The inside of the 2" drainpipe presents with a clean surface. This would leave an 1.5" opening that will accept a 1.5" SCH 40 PVC pipe. Can we plumb back from that point to a double sink bowl, 1 each? One of these traps would be coming from the bowl that has the garbage disposal mounted to it which also accepts the dishwasher's drain line.

To summarize can 2 sink bowls, one of which has the dishwasher connection, be drained into a 2" drain line that has a 2" X 1.5" reducing bushing installed before those fixtures join the 1.5" drain line? The point at which they join the 1.5" drain line would occur within a maximum 12 to 16" behind the bushing.

the outside diameter of a 2 x 1 1/2 bushing is the same size as the 2 inch pipe???

to answer your question. code requires a full size cleanout for that 2 inch pipe. so reducing at floor level will not pass inspection.

Yes a 2” x 1.5” reducing bushing slides inside the 2” drain pipe and once set would then accept a 1.5” sch 40 pvc pipe. So the outside diameter of the bushing is 2” the inside diameter of the bushing is 1.5”. They are a $1.48 at Home Depot. But I understand what you said. The bushing mounts at the termination point of the 2” pipe. You are saying that a clean out access to the 2” pipe has to be the full diameter of the 2” drain line. I then presume that the drain can reduce in size after the clean out access or how would you get a trap arm to attach.

Just sand off the glue residue.

something doesn't make sense. the outside diameter of a 2 inch bushing is exactly the same size as 2 inch pipe.
it is meant to go inside a fitting not inside the pipe ??

I would remove the glue residual either chemically or mechanically or both.

PVC primer usually will soften and loosen paint, adhesive and such on a pipe before joining.

Products like GOO GONE or GOO OFF are quite effective. Try emery cloth to sand it off as well.

As Packy stated you can't physically fit a 2X1.5" bushing INSIDE a 2" pipe. The 2" end of a 2X1.5 bushing is meant to fit inside a 2" fitting hub, so to make such a connection you need a coupling which again, will require mating the the outside of that 2" pipe that you have adhesive residual on. Besides, you cannot decrease pipe sizes "downstream". So follow the water as it drains out of your kitchen sink the pipe sizes can only be maintained or increase but no reduction. A 2" cleanout should be installed upstream of that 2" pipe sticking out of the cabinet floor unless trap adapters are used that can be taken apart easily.

There is something called an "internal pipe coupling" that is along the line you are thinking, they are meant to be inserted inside a pipe, for some emergency temporary repair situation or for pool/spa/irrigation or other pressurized applications but not for drains.

If you are unable to remove the adhesive for some reason (like it is not a regular adhesive but it's epoxy fused onto the plastic which still you can sand smooth), a Fernco PROFLEX is a good alternative.



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Help me understand this....I thought a 1-1/2" drain was perfectly OK to service a double kitchen sink with DW tee and disposal. I get that you are not supposed to reduce pipe sizes going toward the street, but if you connect a 1-1/2" trap assembly that feeds into a 2" pipe you are INCREASING pipe size as you head toward the street, not reducing it, correct?
Easy fix would be to clean up the outside of the pipe, glue on a 2" coupler with a 1 1/2" reducing bushing and a trap adapter. The issue then becomes installing the trap assembly correctly with enough horizontal run into the drain pipe to avoid creating an "S" trap.

Trap and traparm can be 1 1/2", but as soon as you get to the vent, you no longer have a "traparm" and the drain needs to be 2" (unless local code states otherwise).