Modifying Bathtub Drain and Overflow Kit

Hi -

I'm in the middle of a bathroom remodel and I've removed the floor down to the joists. I tore out the old cast iron tub and am in the process of replacing it with a Kohler acrylic tub. I realized too late that the drain on my new tub is centered almost exactly over a joist. I absolutely do not want to cut or modify the joists. I'm putting down natural stone so I'm concered about the stability of the floor. The tub is in an alcove, but I don't want to bump out the tub since then I would have to drill the joist for the drain pipe, which would then be located on the opposite side of the joist, and I dont want to do that.

The custom overflow kit I bought for the tub is copper pipe. I figure I can cut the two sections of pipe (the drain and the overflow) and solder in a few 1 1/2" 45s to jog them off to the side of the joist, connect to the brass sideways "T" fitting that came with the kit, and then drop down to the P-Trap.

I know that there is such a thing as a "side discharge" drain kit. I actually looked at one today in the plumbing supply house, but it costs $70. I don't want to spend alot of money on a solution to this problem since I already paid alot for the custom overflow. Plus, I would really only need the base fitting part of the side discharge and I would still have to make room for the drain pipe under the tub.

Is my plan advisable or am I just asking for trouble putting any bends in the drain line before it reaches the "T" fitting? Assuming the bend isn't a problem, is this plan otherwise ill-advised for any reason?

Thanks in advance for any help

If you ever need to snake the drain of a tub, it is usually done from the overflow. WIth extra angles in there, that may be impossible.

Is it the tub shoe or the vertical drain that is over the joist?

cacher_chick said:

Is it the tub shoe or the vertical drain that is over the joist?

Click to expand...

Thanks for the replies. The tub sits parallel to the joists - they run the length of the tub, so the tub shoe and the vertical drain would both be almost directly over the joist.

What KIND of drain is it? If it is a "trip lever" you could NOT offset the overflow pipe. Your drain is NOT the same size as 1 1 1/2" solder copper 45s, so you would have to use "slip joint" 45 degree "offset" tubes.

It's not a trip lever. It's the pop-up, toe activated kind. The overflow/drain kit that I bought is the one that is required for this tub. The tub has an oval shaped overflow opening as opposed to the traditional round opening - hence the need for the custom kit. The overflow part of the connection actually has a flexible ball joint type connection where the pipe meets the oval shaped overflow fitting. This feature permits the overflow pipe to move a few degrees to either side during installation - but not far enough to solve my problem. I'm not sure why this feature exists, other than perhaps to provide some flexibililty during installation.

What's your plan for soldering DWV-size copper pipe attached to an acrylic (=plastic!) tub? That requires
substantially more firepower (i.e. plastic-melting heat) than does supply-size copper tubing. It's hard to
imagine getting the required precision if done off the tub. The standard thing would be to cut and header
off the offending joist. You're not putting stone under the tub, are you?

I decided to go with this fitting, which I found at the local plumbing supply house.