The drain pipe for my new tub is the same diameter as a sink drain pipe so it fit into a standard sink trap kit. The drain pipe extends through the subfloor so all connections are underneath the subfloor.

I used a sink p trap kit to drain the tub and it seems to work fine, but does it need to somehow transition into a bigger line? The p trap kit would allow removal and replacement of the trap if clogged. it is accessible via a simple panel and is over a garage. Or does this need to be a permanent solvent glued trap arrangement?

Next, due to tight location of horizontal 2 inch drain line parallel to and on the other side of a floor joist,is it acceptable to run the trap arm into a sanitary tee (1.5 x 2 x 2)? this would all be horizontal with the flow of the tee facing the proper direction. If i need to install a 1.5 wye it will require a bigger hole or maybe even a slot in the joist.

all advice appreciated

i have had to use a sanitary tee in a horizontal drain when the structure dictates. it is not the end of the world to do so..
as for the 'toy' trap, they are not allowed under my (MA) code..

is the reason the toy trap is not code because typically a bathtub trap is inaccessible (without some demolition)? this trap will be accessible just like a sink with a cabinet underneath.

I was more concerned about the function of the sanitary tee versus a wye. But the drain is flowing fine and I have tested it with a full tub of water.

One more added question, I used 2 rubber couplings to splice in the new 2 inch drain pipe with the sanitary tee. Same as the trap, all accessible. Is this allowed?

Thanks

Even IF the trap is "accessible", I would NEVER take it apart to clear the tub drain. It is much easier to do it from inside the tub, (you do not need to stand on a ladder), and the "backed up water" helps flush it when the line is cleared.

Good points. Wasn't fun on the ladder to do all the work in the first place. If it ever clogs I'm good with cleaning it out from the tub drain side.

I'm just trying to make sure that functionally the drain system works. Between the trap kit, the sanitary tee, and the rubber couplings, all is dry and flowing well.

I had read that using the sanitary tee in a horizontal application was not code. Not sure why, maybe it clogs easier than a wye. But with the tight location, the tee was a better installation fit.

A wye and 45 can keep the hole in the same spot unless it is within about 3 inches of the floor joist. A poly p-trap is a bad idea because if it needs cabled, a snake will normally bust a poly trap and all the water will be on top of your car, and a snake spinning around taking little swirls of paint will make a nice little scratch-scratch-scratch sound that you will wonder 'What is that noise?' when it happens. Use schedule 40 pipe for your replacement.

Unfortunately the drain pipe is within 3 inches of the joist. I can rebuild the trap with schedule 40 parts easily enough.

don't worry anout the san tee. you can't comprimise the integrity of a floor joist over a small issue like " T vs Y "..

I like that wording. It will impress the wife

I can improve the trap materials. The rubber couplings are OK in this sort of situation?

Thanks for the advice



Edited 1 times.

Usable, but not approved.

In my opinion if it doesn't leak and drains and you aren't a plumber then leave it alone . You can access and it has a trap so it doesn't stink.