Toilet Venting

[Kamil]

Hello,

I have a question regarding two toilets that are on the same horizontal drain pipe. The toilets are back to back in two separate bathrooms. As you can see on the picture toilet#2 is vented but I am not sure if toilet #1 needs a vent as well and if it does how would one do it while staying within the joist bay? The 3" drain continues horizontally picking up a sink and a shower downstream. Thank you very much for your help.

 

[Terry]

The one vent works for both toilets.

 

[Sponsor]

 

[SterileCuckoo58]

Would that 2" vent still work if the Y were rolled to 45º (with 60º bend) and run at 1/4"/ft for 4.5 ft, then turned up? (Under the UPC). How about if it were a wet vent receiving two lavs., perhaps 3" Ø.

I did put a 3" dry vent in place down stream of the D/S toilet (because I thought I could and there is only one way to know for certain), but it is >72-in. from the U/S Toilet flange. It will work for the D/S one, and for any future pumped Basement bathroom.

I assume the minimum distance from trap weir to vent is met because the trap weir is at the flange, but some other diagram may suggest it is from the D/S end of the closet bend. Then I am concerned I do not have 2 x D or 6-in.

As originally plumbed, it was 10-ft to the Y with the vent connection, and it ran flat 4-ft to the vertical vent.

 

[wwhitney]

Would that 2" vent still work.

Your diagram is a bit too busy to be clear to me, and your comment about 1/4" per foot with respect to an apparently vertical pipe doesn't make sense. However, here are a couple comments based on the UPC; I didn't check if MA has amended anything relevant.

For the UPC, the diagram in the OP is not allowed, because wet venting is limited to one bathroom group (and because the vent takeoff would need to be a wye or combo, not a san-tee on its back). As regards what I understand of your layout, you could wet vent your upstream WC with the double lav, and then vent the downstream WC with the 3" vent you show nearby, before that downstream WC drain joins the double lav and upstream WC drain.

Cheers, Wayne

 

[SterileCuckoo58]

Your diagram is a bit too busy to be clear to me, and your comment about 1/4" per foot with respect to an apparently vertical pipe doesn't make sense. However, here are a couple comments based on the UPC; I didn't check if MA has amended anything relevant.

For the UPC, the diagram in the OP is not allowed, because wet venting is limited to one bathroom group (and because the vent takeoff would need to be a wye or combo, not a san-tee on its back). As regards what I understand of your layout, you could wet vent your upstream WC with the double lav, and then vent the downstream WC with the 3" vent you show nearby, before that downstream WC drain joins the double lav and upstream WC drain.

Cheers, Wayne

Thank you Wayne,

Yes, 1/4" per foot vertically is nonsensical. The Copy/Paste/Edit Fail monster got me.

Not sure what the "diagram in the OP" refers to. But I fixed the tub drain vent (don't know yet if it is feasible).

In the context of wet venting one bathroom group, I think I only want to wet vent the U/S toilet with the two lavs (adjacent bathrooms) upstream.

I don't believe i put any SanTees on their back, although the 3" dry vent connection to the 3" trap arm from D/S toilet would be a SanTee, wouldn't it?

File revised and decluttered.

 

[wwhitney]

Your last drawing looks OK to me. Your 3" vents, both wet and dry, could all be 2".

Not sure what the "diagram in the OP" refers to.

OP = original post.

I don't believe i put any SanTees on their back, although the 3" dry vent connection to the 3" trap arm from D/S toilet would be a SanTee, wouldn't it?

As drawn, it would be an upright combo, not a san-tee on its back. If you want the drain to turn down directly under the vent, you can use a san-tee. But if I'm understanding correctly, you have everything that runs perpendicular to the joists located below the joists in a single (2% angled) plane. So that wouldn't apply to you.

Cheers, Wayne

 

[SterileCuckoo58]

Thank you again Wayne.

Kamil's OP looked a bit like what I hoped would have been feasible, but it wasn't built to be. (Of course it is possible to encroach the corner with a vent pipe, but that's way too much work and time). It seemed a good spring board for my variation.

So... a dry vent connected at the top (or 45º from top) would be connected with a Y and 45 (or combo)? I suppose that would allow it to become wet some day, perhaps a shower drain.

Keep well

 

[Jeff H Young]

Sterilecuckoo58, from top of closet flange measured along center line to inside edge of vent needs to be under 6 ft for code.

 

[wwhitney]

I suppose that would allow it to become wet some day, perhaps a shower drain.

Yes, the rule in the UPC is that any vent piping that is below the flood rim level of the fixture (including the takeoff) has to be of a drainage pattern.

Cheers, Wayne

 

[Kamil]

Thank you for all the feedback!