Need some direction, 2nd floor laundry

[brianstrange]

I would like to add a washer on the 2nd floor.
I have an existing 2" stack that has a 2nd floor wet vented tub drain feeding it at the top, and a santee at a 1st floor with a lav feeding into it. It then continues into the basement where it joins a 3" horizontal drain inside the basement finished ceiling.
I have the ability to replace the top of the 2" stack with a santee to the wet vented tub drain, and then straight up into a santee/washer trap, and up to a vent. I'm seeing many mixed opinions and would like to hear if this is okay. I'm trying to avoid cutting into finished walls, but I want it done right. The home is in MA.
Thank you

 

[wwhitney]

I have an existing 2" stack that has a 2nd floor wet vented tub drain feeding it at the top

So you are saying that a separately dry vented lav or shower joins the tub drain to wet vent it, before they jointly enter the top of the stack with a quarter bend?

, and a santee at a 1st floor with a lav feeding into it.

How is that lav vented? It may not rely on the stack for venting, as it is a drainage stack.

I have the ability to replace the top of the 2" stack with a santee to the wet vented tub drain, and then straight up into a santee/washer trap, and up to a vent. I'm seeing many mixed opinions and would like to hear if this is okay.

That's an acceptable way to vent the laundry trap and wouldn't affect the tub which is wet vented elsewhere. And as nothing below the 2nd floor can rely on the stack for venting, that's fine too. But if something on a floor below is currently relying on the stack for venting when it shouldn't, you should fix that first.

Cheers, Wayne

 

[Sponsor]

 

[brianstrange]

So you are saying that a separately dry vented lav or shower joins the tub drain to wet vent it, before they jointly enter the top of the stack with a quarter bend?


How is that lav vented? It may not rely on the stack for venting, as it is a drainage stack.


That's an acceptable way to vent the laundry trap and wouldn't affect the tub which is wet vented elsewhere. And as nothing below the 2nd floor can rely on the stack for venting, that's fine too. But if something on a floor below is currently relying on the stack for venting when it shouldn't, you should fix that first.

Cheers, Wayne

Thanks for the reply, Wayne. I'll try to clarify in order.

The tub (2nd floor) has a dedicated dry vent on the horizontal drain that goes to the existing stack.

The other lav tying into that stack is on the 1st floor. I can't confirm that there's an existing vent at the top of the stack, all measures are saying there's not. That said, I know I can add one easily when new construction starts. The washer drain would enter the 2" stack above both the 1st floor lav and 2nd floor tub tie in, on the same stack. Also, I have access to the wall behind the 1st floor lav, and can get creative there if needed. I'm hoping to avoid touching the finished basement ceilings etc..

The remaining fixtures on the same 2nd floor bathroom as the tub (WC, and lav) share a 3" stack on the other end of the bathroom
The 1st floor has a unique open concept making things unconventional. New work is circled in red

 

[brianstrange]

As I read more, I'm guessing that the attached diagram is what I should be aiming for (using the proper bends etc......)

 

[wwhitney]

As I read more, I'm guessing that the attached diagram is what I should be aiming for (using the proper bends etc......)

Yes, much clearer, although the rendering of the laundry trap arm, from the standpipe trap outlet to the stack, is not so clear. That trap arm may fall at most one trap diameter, or 2".

With that proviso, everything you show is fine (well, terminologically, a stack is vertical and at least one story high, so the horizontal bottommost drain is the building drain, not a stack). Each of the lav, tub, and laundry standpipe are individually dry vented.

Cheers, Wayne

 

[brianstrange]

the rendering of the laundry trap arm, from the standpipe trap outlet to the stack, is not so clear. That trap arm may fall at most one trap diameter, or 2". ................
Cheers, Wayne

Hi Wayne. The branch for the laundry can be a 2" Santee or a 2" wye, whichever is correct, and it would be situated above the tub flood line, 2" trap and proper length stand pipe.

Thanks! Brian

 

[wwhitney]

Hi Wayne. The branch for the laundry can be a 2" Santee or a 2" wye

It needs to be a 2" san-tee as you are using the top connection for venting. That 2" fall limit applies from the trap weir to the top of the pipe at the connection to the vertical barrel of the fitting--the wye would burn quite a bit of height unnecessarily and make it likely to fail to comply.

it would be situated above the tub flood line, 2" trap and proper length stand pipe.

No need for the laundry trap arm to be above the tub flood rim.

Cheers, Wayne

 

[brianstrange]

It needs to be a 2" san-tee as you are using the top connection for venting. That 2" fall limit applies from the trap weir to the top of the pipe at the connection to the vertical barrel of the fitting--the wye would burn quite a bit of height unnecessarily and make it likely to fail to comply.


No need for the laundry trap arm to be above the tub flood rim.

Cheers, Wayne

Thanks for the clarification. I can see the reason for the santee.