Question - Freestanding Tub Drain over Floor Joist

[amcculidis]

We would like your feedback on options to modify plumbing for our bath remodel (2nd floor). We have this specific location for a small 53x 30 acrylic freestanding tub (w/ integrated overflow). Predictably its center drain is directly above the floor joist. Moving the tub away from the wall by 4 inches would solve the issue; however, this will also require moving rough-in plumbing for the existing double bathroom sink & toilet.

I would like to know if we can add a "plumber's box" and have a drain and p-trap right under and center of the tub? If so how should waste pipe connect to the existing 2" waste line - crossing a double headers or along right side floor joist? We are not sure if this solution is more cost effective and practical than moving both sink and toilet plumbing or not.

Thank you for your time. Have a great day!

 

[Breplum]

First, compliments on your sketch-up drawing. Best I've seen!
2nd: I don't understand "waste & vent" arrow on lower right.
That aside, if you head off the problematic middle joist, you must double joist both the main left and right joists, and , you don't normally have to double the headers the way you drew it, but because you would be drilling a hole high up in the header, it might be a good idea on that header.
Use a long sweep 2" 90 at a convenient spot in the first joist bay (away from the joist hanger that you will use).
If needed, you can add a 1/16th or 1/8th bend to head over to c/l of the tub, but the trap may swing far enough.
Support the trap with solid blocking and strap too.

 

[Sponsor]

 

[wwhitney]

A few comments:

-If you have access to sister some of joists, you may be able to sister the interfering joist and install your plumbing without cutting into the sister.

- If the two headers in the floor system are each within 3' of a bearing wall below (unlikely), then you could use single trimmer joists (i.e. no need to sister if you make the opening). https://up.codes/viewer/north_carolina/irc-2015/chapter/5/floors#R502.10

- Wouldn't moving the tub 2" be enough, and can you do that without interfering with your vanity and vanity plumbing?

- Much as am I am not a fan of it, if your drain is located away from the middle third of the span of the joist, you are allowed to notch the joist up to 1/6 of its height, in case that helps provide enough clearance. I wonder if there's something like a 45 degree tub drain, the way there are 45 degree toilet flanges. https://up.codes/viewer/north_carolina/irc-2015/chapter/5/floors#R502.8

- You could also consider rotating the tub to move the drain left or right, but that looks like it would require a fair amount of rotation.

Cheers, Wayne

 

[amcculidis]

Thank you very much for your comments and feedback.

1) As for doubling the joists I interpreted that trimmer joists don't need to sister since the prosed header span is less than 4'. Maybe I'm misunderstanding (but I understand that sistering is the safest way)?
https://up.codes/viewer/north_carolina/irc-2015/chapter/5/floors#R502.8


2) As an option for not cutting the interfering floor joist - Our new tub has at least 4 1/2" clearance under the drain. Would something like using a tub drain shoe will be acceptable (although I will have to angle to avoid the metal footing)? I see the same set up for our old garden tub but that includes the overflow pipe. The similar types of less costly acrylic freestanding tubs all come with a cheap flex horse with 90 degree bend, which obviously we are not using.

Thanks again

 

[wwhitney]

1) My interpretation of R502.10 is that single trimmers are only allowed if (a) the header span does not exceed 4' and (b) the header is within 3' of a bearing point of the trimmers. Together those ensure that the load from the header and the moment arm of that load on the trimmer are both on the low end, so that the moment induced in the trimmer (the product of the two) is low enough to not require doubling. But if either one is not true, then the moment in the trimmer from the header will be greater, and doubling would be called for.

2) What type of connection is that on the tub drain? The diagram you posted would be allowed, it's akin to an Ikea sink waste arm or half of a double sink. But if you can use (2) 45s instead of (2) 90s, I think that would be better, even if it required notching the joist 1".

Cheers, Wayne

 

[amcculidis]

Wayne - Thank you for responding to my follow-up questions.

2) I was thinking something similar to the standard PVC tub drain except for the tee and overflow/stopper assembly.

Thanks again.

 

[wwhitney]

Sorry, on (2) I was asking about your tub, not your diagram. It's got a metal threaded (?) connection right now sticking out, and I assume there's a stopper assembly already there? So what type of connection can you make to the end of the drain?

Cheers, Wayne

 

[Jeff H Young]

precise measurement I think the joist barely needs shaving , but you must determine you've got sheeting plus the thickness of tile. I can't see how far off floor bottom of tub is or if a skirt covers around there? does if it have exposed legs and you can look under and see the tub shoe
wait now I see it just a simple hook up self explanatory. joist isn't an issue

 

[amcculidis]

I disassembled the pop up drain, which is threaded and has a washer and brass lock nut. I do not know what connections can be used. I haven't been able to find good resources for "hard plumbing" acrylic freestanding tubs. They kindly supply a flexible drain hose, which is not usable. The picture of this tub is not ours but it looks identical except their hose looks slightly nicer (!). I have GCs and plumbers giving me inconsistent explanations. We are hoping educate ourselves before altering floor joists or spend additional money on unnecessary plumbing work.

Thanks!

 

[Jeff H Young]

use a standard solvent weld tub shoe, abs or PVC to your liking. and ditch the junk supplied with tub, just make sure it fits before proceeding

 

[wwhitney]

Since it's got an integral overflow, it needs a tub drain that will receive, like on a typical vanity but larger, correct?

And then hopefully that will accept a (street if appropriate) 45 elbow, and the elbow will miss the joist or just kiss it a little, requiring a small bevel

Cheers, Wayne

 

[Jeff H Young]

Since it's got an integral overflow, it needs a tub drain that will receive, like on a typical vanity but larger, correct?

And then hopefully that will accept a (street if appropriate) 45 elbow, and the elbow will miss the joist or just kiss it a little, requiring a small bevel

Cheers, Wayne

I guess it might have an integral overflow as a lav usually does, perhaps his picture he has the fitting turned 90 degrees not showing the slots, If that's the case then use what he has and get some kind of 90 that will fit correctly, I think avoiding butchery of joists can be accomplished

 

[wwhitney]

I guess it might have an integral overflow

Picture 2 (in the thread) shows the overflow on the inside, and picture 3 shows the cast integral channel connecting it to the drain location just like a lavatory.

Cheers, Wayne

 

[Tuttles Revenge]

I've done the same offset of the plumbing.. blind lining up your offset to your trap is going to be the hardest part unless you can access the drain from below.

The easiest install would be to do whatever is necessary to change the framing and add this drain body directly where the center of the drain needs to be. At final install you basically drop the tub on this fitting and you're done.

 

[Jeff H Young]

I've done the same offset of the plumbing.. blind lining up your offset to your trap is going to be the hardest part unless you can access the drain from below.

The easiest install would be to do whatever is necessary to change the framing and add this drain body directly where the center of the drain needs to be. At final install you basically drop the tub on this fitting and you're done.

his tub drain has a flexible connector doesn't look like it works with the connector you show Tuttles.
Actually could be easy but with that dumb flex hose it looks like one could get back fall on it if not super careful

 

[Tuttles Revenge]

his tub drain has a flexible connector doesn't look like it works with the connector you show Tuttles.
Actually could be easy but with that dumb flex hose it looks like one could get back fall on it if not super careful

The kit I show I think comes with the proper Tubular to fit that tub drain.

Here is the LINK . The kit comes with a flanged tubular tail piece that should thread to the drain on the tub.

Below is another kit that shows more of what is in the kit.

Doing the offset above the floor will work too, but if the final connection isn't accessible from below, it becomes a glued blind set where you Hope your connections are made up... and then you're stuck if a glued joint is glued, but leaky.. you can't remove the tub drain from atop.

The drain kit allows you to drop that tub into an gasketed connection and remove it if necessary later.

 

[Jeff H Young]

Tub comes with a special drain assembly it has a built in overflow, similar to a lav tailpiece assembly I don't see that in your link tuttles? standard waste and overflow won't work

 

[Tuttles Revenge]

The drain assembly that comes with the tub has 1.5" threads that accept the nut and flanged tailpiece provided with the drain kit.

 

[Jeff H Young]

The drain assembly that comes with the tub has 1.5" threads that accept the nut and flanged tailpiece provided with the drain kit.

my bad that's right that's right! I looked right at it

 

[amcculidis]

Good evening. I was too busy to check the forum yesterday. I surely appreciate your time responding to my post! The tub drain has an integrated overflow and looks just like a large lav drain assembly. I initially purchased the tub drain kit as pictured and ended up returning once we encountered the plumbing uncertainty. It's good to know that some of you recommend it.

Not sure which method we end up choosing but we are happy that there is no need for modifying the "entire" bathroom plumbing despite the floor joist.

Thank you for all your suggestions.