Shower vent question in bathroom remodel

[wwhitney]

Your drop measurement shows you have enough slope for the drainage, which is good: (3-5/8" + 7/16") / 149" = 2.7% > 2% minimum. But 12' 5" is way too long for the shower trap arm before the vent, and upsizing the WC doesn't help. You need to add a shower vent.

So go back and review the whole thread and consider the different options discussed for venting the shower. Pick whichever you think would be easiest to implement, and then you can follow up if you have more questions.

Cheers, Wayne

 

[Vinmassaro]

@wwhitney Ok, hopefully we are getting to the end here. This thread has gone a few directions so I’m having trouble with the best way. I understand the trap arm has to come off the 2" pipe at most 8 linear feet from the trap, so either of the first two bays in the shower area. I looked at post #9 of yours but am unclear if it is based on my bad photos. I finally got a photo of everything with wide angle on a new phone. Would you be able to mark this up with the best route, then I can ask some final questions on fittings. Appreciate your ongoing attention to my thread, thanks.

 

[Sponsor]

 

[John Gayewski]

@wwhitney Ok, hopefully we are getting to the end here. This thread has gone a few directions so I’m having trouble with the best way. I understand the trap arm has to come off the 2" pipe at most 8 linear feet from the trap, so either of the first two bays in the shower area. I looked at post #9 of yours but am unclear if it is based on my bad photos. I finally got a photo of everything with wide angle on a new phone. Would you be able to mark this up with the best route, then I can ask some final questions on fittings. Appreciate your ongoing attention to my thread, thanks.

View attachment 86852

Edit: Your markup on post #12 would need just moved to the right of this picture so your lav ties into the shower drain 8' feet or less from the shower trap. Then you'd have to come back up the wall, still the studs horizontally to back to your lav location or settle with moving the lav over toward the middle of the room more.

Or use that wall with the plumbing in it and tie a shower drain into it from below the floor and run an individual vent.

I would seriously consider moving this shower drain if your distances don't work out.

 

[wwhitney]

My thoughts:

- The limit on how far away your vent can tie in isn't just 8' along the pipe from the trap, it's also at most 2" of elevation drop from the trap outlet. If your trap arm is a perfect 1/4" per foot slope, those coincide, but from the earlier elevation measurements, it seems like overall the trap arm is a bit steeper.

So I suggest you set up your laser level again, measure down to the shower pipe just after the trap elbow outlet, and then measure down again at the 8' along the pipe point. If the difference is less than 2", you have a problem and need to add more slope. If it's more than 2", then your vent needs to connect sooner; find the point where the difference is 2" and mark that, your vent needs to come off there or closer to the trap, unless you reslope your trap arm.

- I think my suggestion in post #9 is the simplest way to vent the shower without moving the shower drain or changing the trap arm much. Although as John suggests, you may want to consider those options just to figure out which would be the least work. In post #9 you redo the double lav drains, so the right hand lav drains separately, and it needs its own dry vent that rises up and reconnects to your existing vent at least 6" above both lav flood rims. Then the right hand lav drain runs over to wet vent the shower.

Cheers, Wayne

 

[Vinmassaro]

@wwhitney and @John Gayewski

Thanks - I remeasured with the laser level and it’s just shy of 2in at 8ft along the pipe. I marked with a blue arrow where 8ft is. It drops off a lot at the last bay where it connects to the 3x3x2 reducing wye. I should be able make one or two holes a little bigger and then strap the pipe to get the drop to 2in.

I didn’t pick up that the suggestion in #9 was to redo the lav drain, thanks for clarifying. So I would cut and cap at the green line in the photo and then redo with the red. See new photo.

Are these the correct fittings to use?

1: 2” x 2” x 1.5” reducing wye plus 1.5” 45 elbow
2: 1.5” long turn 90 elbow
3: 1.5” sanitary tee
4: 1.5” short 90 vent elbow
5: 1.5” sanitary tee

 

[wwhitney]

Yes. (4) can be any kind of 90, and a quarter bend is maybe cheaper than a vent 90. (5) is conventionally installed upside down relative to (3), although it doesn't matter.

Since you'll be cutting back the copper at the top anyway, I'd suggest putting the san-tee at (5) at the same height as the horizontal copper vent. So then (5) would have its side inlet pointing downwards.

Also, you'd get a cleaner result if you just redo the PVC for the left hand sink instead of capping at the green location. The redo would just use a san-tee and a LT90, so not alot of fittings.

Edit: The rubber coupling at the end of the 3" PVC is the wrong style, that style is only for underground use. You need the style with the full stainless shield. Also, to install the wye at (1) you'll need some left-right play on the 2" PVC, so hopefully loosening that coupling will provide you enough play.

Cheers, Wayne

 

[Vinmassaro]

@wwhitney

Finally had a chance to work on this the other day but just dry fit, didn't get to finish up and just need to do some trimming to correct the slope at the top.

Thanks on the second point, I forgot to mention that I did remove that flex coupling for a shielded 4" CI x 3" PL coupling.