I am the second owner of my home. The original owner had the contractors rough in a bathroom (no copper or anything) in the basement but it was never completed. I am in the process of finishing the bathroom but the drain in the slab for the alcove tub has, I guess, strange rough in dimensions.

The tub is a right hand drain (2" drain) tub with the following dimensions (all measurements to the center of the drain):

  • 2 1/4" off the right wall
  • 15 3/4" off the back wall
  • 57 3/4" off the left wall

Most of the tubs I have looked at expect the drain to be around 8 1/2" off the right wall, although I did find a brand (A2) that has a tub that expects the drain 2" off the right wall but it expects the drain to be 18" off the back wall.

I have had a handful of people tell me that I am going to need to break open the concrete and move the drain because it was roughed in "wrong".

My questions are:

  • Is there some brand of tubs that are designed for drains roughed in 2" from the wall? What I have seen at Home Depot and Lowes so far is the drains are expected to be 8 1/2" from the wall.
  • I have a radon system and I have read that if I break open the concrete it messes up the Radon system. What precautions do I need to take to make sure the radon system isn't impacted?
  • Is there some other way to get this installed that doesn't require cracking the cement open?

EDIT: Photos Drain1 Drain2 Drain3 enter image description here enter image description here enter image description here enter image description here enter image description here

  • I guess I wanted to see the whole room. Who framed the walls? Maybe the layout was misinterpreted by them. Could be that is actually a vent (that should've been in the wall) and there's a shower box in the floor somewhere.
    – isherwood
    Commented Aug 6, 2020 at 14:12
  • What do you see below that cap?
    – isherwood
    Commented Aug 6, 2020 at 14:13
  • 3
    It's probably going to be a LOT easier at this point to move the wall than to move the drain.
    – jwh20
    Commented Aug 6, 2020 at 14:15
  • @isherwood sorry about that. I have posted pictures of the whole room. The bathroom was roughed in by the builder (picture of the floor plan is up there). The dimensions of the the basement bathroom are the same as my second upstairs bathroom, the layout is just reversed.
    – dparsons
    Commented Aug 6, 2020 at 14:26
  • 1
    Most tub drain and overflow kits run the tub drain out to a tee (with or without the annoying remote stopper that will jam and become useless) that's near the wall, straight down from where the overflow connects to the end of the tub. It sounds like you're trying to drain straight down from the hole in the tub, given your "usual dimensions" and that does not compute for any tub install I've met.
    – Ecnerwal
    Commented Aug 7, 2020 at 2:32

1 Answer 1


Our home has a drain system similar and we did not have to break the floor. We went to a GOOD plumbing supply company to buy the shower unit. The floor pan is elevated 4 inches so the plumber was able to do PVC pipe under the pan that ran to the exhisting front drain. That was probably 5 years ago and we have had 0 problems. We now have a center pan drain.Ours was a remodel so the unit came in 3 pieces. But on my invoice is reads KDS 3460 AKER RHS 142042-R-000-002.Maybe that will help you find a unit you can use. Good Luck!

  • This. There are tubs with an extra 3" clearance underneath specifically for bathrooms on concrete so you don't have to have the drain perfectly lined up Commented Aug 10, 2023 at 17:30

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