In my area code allows me to keep my 1 1/2 inch drain for new shower which I thought would save a lot to not have to cut out the stack and replace the wye to the toilet and present bathtub drain etc. having a dedicated vent only 28 inches away from the new shower drain makes even the extended 1 1/2 inch drain work. Funny I had 2 plan review guys at RBD say I could not use a reducer on the drop pipe since most of the tiling pans have 2 inch pipe, but finally the chief inspector came over and said no problem. However I have recently seen a reamer that would allow me to ream out the 3 inch stack coupling that currently has a 3 to 1 1/2 inch adapter, and since I already have most of the subfloor up anyway to replace water damage and move a floor heater duct into the wall etc, another 2 feet (where the tools are) would not be a huge deal if they work as intended. Would it be an advantage to increasing to a 2 inch drain and can I expect the reamer to do what it’s supposed to so I am not stuck with cutting out the stack? Showing the new extension which of course will be installed below the joists. enter image description here

  • I recently researched this quite a bit, but did not ended up having to use one. If you buy a quality one, I think you will have no issues. The videos of people using them on the web convinced me they will work.
    – Evil Elf
    Commented Apr 25 at 11:36
  • Hope that floor decking, with edges meeting in space between joists, is just a temporary work surface!
    – FreeMan
    Commented Apr 25 at 12:01
  • To be clear, you plan on reaming out a 1 1/2 " adapter and installing a 2 inch...correct? FYI, I have installed many a shower from where a tub was and adapted the 2" shower drain flange to the 1 1/2" pipe with no problems from inspectors or the function.
    – RMDman
    Commented Apr 25 at 12:03
  • FreeMan, yep only temporary work surface. RMDman, yes the idea would be to change it to 2” from stack. All the 1 1/2” stuff will go back to HD if I do. I expect if I tried to have a flow reduction between the p trap and stack there would be an issue with inspection, but not in the drop pipe.
    – Billyboy
    Commented Apr 25 at 12:31
  • Good question and already a good answer but I'm still struggling to see how the photo helps. :) If there is a 3x3 fitting with a 1.5 reducer in the photo, I don't see it. I guess the pipe in the foreground shows where the new shower will be?
    – jay613
    Commented Apr 25 at 13:11

1 Answer 1


Yes, the "socket-saver" or "hub saver" or "plastic pipe reamer" tools work.

As with all tools, there are better and worse ones, and generally the better ones cost more. I would see if you can rent a good one from a tool rental place rather than spend a lot on a tool you will probably only use once; or spending not much on something from the folks that sell cheap stuff that looks vaguely like it will work but actually ends up costing you more because it doesn't cut properly, isn't the right size, etc. and generally doesn't actually work.

Hmm. I think there's a prior question where there are pictures of various versions. Let me see...here we go. As noted there, the cost of a good one you'll only use once may well be less than having a plumber come by to do that part, if you could even get a plumber to come by and do just that part. But rental would be preferable.

As for 2" shower drain .vs. maintaining 1-1/2" grandfathered, I tend to think that there's a good reason they changed code, when they bother to change code, so it's preferable to follow current code when you can, even if the inspectors would let you use the grandfathered size. 1-1/2" pipe has 56% of the hole that 2" pipe does (that r-squared factor for area of a circle...)

  • Ecnerwal I was going to buy this set which will also hep minimize the cutting and recoupling of 1 1/2” vent piping. Has good reviews and it is not a huge expense in the scheme of things. I doubt these are available to rent anywhere. amazon.com/Reamer-Aluminum-Pipe-Plumbing-Extreme-Fitting/dp/…
    – Billyboy
    Commented Apr 25 at 12:39
  • You might be surprised what your local tool rental place has, if you check with them. Those look good in a picture, though you'll have to be careful about lining them up as the pilot section is quite short.
    – Ecnerwal
    Commented Apr 25 at 12:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.