Help with bathroom waste & vent hookup

[Billboe]

Hi All,

I'm hoping somebody can suggest a good option to hookup the vanity & washer (upper right of the image) into the 3" waste coming from the w/c to the main stack?

Info:
- w/c area has 2x8 floor joists (waste will be run underneath them)
- vanity / washer area has 12" open-web joists (waste will run thru them)
- hoping to use the vanity to as a wet vent for the whole group.
- i was planning to vent the washer separately (from my reading of code?!?!)
- the numbers on the on the bottom & right side represent approx. feet

Do I need to run 3" through the rim joist to pickup the vanity & washer? Or will 2" work?
Should I change the 3" 45 to a wye and do a long sweep 90 towards the vanity & washer?
I could also put a wye downstream of the 45 to pickup the vanity & washer.
Does wet venting thru the vanity make sense?

Thoughts? And THANKS!!!

p.s. I couldn't for the life of me find a good plumbing design software!!?!?\

 

[wwhitney]

For the IPC, which I understand Vermont uses:

The vanity and clothes washer will each require a dry vent takeoff (or AAV) at the height of their traps, which will be above the floor. Those dry vents could combine at least 6" above both flood rims to become a single vent through the roof.

If you keep the clothes washer and vanity drains separate, the vanity can wet vent the WC just by running a 1-1/2" lav drain into the 3" W/C drain. If the tub trap is at the same elevation as that 3" W/C drain, and the run to the 3" W/C drain is short enough (8' for a 2" tub trap, 6' for a 1-1/2" tub trap, assuming you get a perfect 1/4" per foot slope), then the lav can wet vent the tub as well. The clothes washer drain would then have to join the 3" W/C drain downstream of the wet venting connections, so downstream of the lav connection, and downstream of the tub connection if the lav is also wet venting the tub.

Cheers, Wayne

 

[Sponsor]

 

[Billboe]

Thanks very much Wayne!

It is a bummer to hear that the washer needs to join the 3" downstream of the tub. I hate to ask this question, but, if washer entered the 3" earlier would it work reliably (see drawing below)? The vanity/washer area is over a garage so I'm trying to minimize plumbing in that area. I would plan to vent the vanity & washer separately. And, our town doesn't have inspections (for good or bad)...

 

[wwhitney]

If you dry vent (or AAV) each of the 4 fixtures separately, the connectivity you show in the last drawing is fine. A clothes washer can't be part of a horizontal wet vent. That would just be two extra vents, since the vanity and clothes washers, having their traps above the floor, need their own vents regardless.

Actually, it would be sufficient to add a single dry vent to the 3" line between the WC and where the bath joins. That would make the 3" line a circuit vent, so the bath would be vented. For a circuit vent, the 3" line between the bath interconnection and the WC could not be sloped more than 1" per foot, so no vertical offsets.

Note that the 2" bath trap arm can fall at most 2" before it is vented. So if the 3" line is going to vent the bath trap, the trap elevation is determined by the elevation of the 3" line.

Cheers, Wayne

 

[Billboe]

Actually, it would be sufficient to add a single dry vent to the 3" line between the WC and where the bath joins. That would make the 3" line a circuit vent, so the bath would be vented. For a circuit vent, the 3" line between the bath interconnection and the WC could not be sloped more than 1" per foot, so no vertical offsets.

Wayne! Thank you again! I like the idea of the circuit vent. I think I'm going to go with that!

Note that the 2" bath trap arm can fall at most 2" before it is vented. So if the 3" line is going to vent the bath trap, the trap elevation is determined by the elevation of the 3" line.

Yes, that makes sense. Thanks!

And, in my latest diagram, I had run the 3" to pick up the vanity & washer (with the 3" sweep 90 & wye) because I thought it would be better for the wet vent. Since I'm no longer wet venting I imagine 2" will suffice. Correct?

Thanks again!!!

Bill

 

[wwhitney]

And, in my latest diagram, I had run the 3" to pick up the vanity & washer (with the 3" sweep 90 & wye) because I thought it would be better for the wet vent. Since I'm no longer wet venting I imagine 2" will suffice. Correct?

Well, if you are subject to the IPC, there's this weird section 406.2 that says when the clothes washer drain joins another drain, the combined drain should be at least 3". The plumbing portion of the IRC doesn't have that requirement, but Vermont doesn't use the IRC.

But if you don't want to bring 3" through the rim joist, you could instead bring a 2" for the washer and a 1-1/2" for the vanity, and keep the 3" on the WC side of the rim joist.

For the details on circuit venting, see IPC 914. I don't believe this link requires an account, but if it does, the account is free:

Chapter 9 Vents: Vermont Plumbing Code 2024 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

Cheers, Wayne

 

[zomiee333]

If you already have 3 inches up to the toilet, I don’t think you need to keep that size all the way to the vanity and washer. 2 inches should be enough for that branch, especially if the vent is separate. Just make sure the slope is correct.

 

[Billboe]

Well, if you are subject to the IPC, there's this weird section 406.2 that says when the clothes washer drain joins another drain, the combined drain should be at least 3". The plumbing portion of the IRC doesn't have that requirement, but Vermont doesn't use the IRC.

But if you don't want to bring 3" through the rim joist, you could instead bring a 2" for the washer and a 1-1/2" for the vanity, and keep the 3" on the WC side of the rim joist.

For the details on circuit venting, see IPC 914. I don't believe this link requires an account, but if it does, the account is free:

Chapter 9 Vents: Vermont Plumbing Code 2024 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

Cheers, Wayne

Thanks Wayne!

And hmmmm... I was thinking of plumbing it like a laundry sink.