Venting Bathroom Addition

[Goodimike]

I am currently adding new DWV plumbing for new fixtures to extend a master bathroom space located on the second story. The new addition consists of a soaker tub located under and exterior window between two lavs. All fixtures are located on an exterior wall. I am trying to figure the easiest way to properly vent these 3 fixtures with as little demo needed. This first picture I have uploaded shows my initial idea on how to vent the lavs. Per my drawing I have the first lav tied into an existing 1 1/2” vent that was already tied in to the 3” vent stack. I am thinking an AAV for the lav to the right with an access grill. I am running into issues on how to vent the soaker tub without running horizontal below the flood level rim and what the vent and drain assembly would exactly look like after the tub P trap. Any ideas? Is wet venting the tub from one of the lavs an option here? Thanks.

I am new to plumbing and DIY in general so there may be a way easier way that I am not seeing.

Thank you for your help.

Here are some sketches and pictures that may help visualize the layout (sorry they are not too great).

Pic 1: drawing of my vent ideas for the lavs
Pic 2: detailed drawing without venting
Pic 3: actual pic
Pic 4: vent stack located in attic space (existing 11/2” vent is circled in red (this Is where I want to connect the most downstream lav vent to).
Pic 5: top down view of proposed plumbing

 

[Jeff H Young]

why not use the abandoned vent connection in attic for the shower vent tie in ?

 

[Sponsor]

 

[Goodimike]

Hi Jeff, thank you for your helpful response. That sound like a really good idea so I don't have to cut and retrofit the main stack. Does my my second drawing still represent the way you would bring the vents across or do you think there is a more efficient way? If I bring the vents through the wall then I will have to cut the plywood and use a hole saw to open up 2'' holes through >5 2x6 loadbearing studs. Do you think I need the relief vent or do you think a single vent after the most upstream P trap would be sufficient for venting purposes? Also the ceilings are vaulted and the only attic space is located above the toilet and shower (first illustration). Thank you.

 

[John Gayewski]

So your removing the tub and adding a shower?

 

[Goodimike]

So your removing the tub and adding a shower?

Hi John, I am adding 2 lavs and a soaker tub. The existing shower is staying a shower. The only thing that is not going to stay is where the old lav used to be to the left of the waste closet. I might need to draw a better sketch or take some pictures.

 

[Goodimike]

I would tie into the vent stack or the unused lav vent line.

 

[Goodimike]

I have updated my original post to ask more of a specific question. I tried looking for any forum rules on bumping a post so I am sorry if there is a better way to do this.

 

[Reach4]

Both lavs need venting, whether with AAV or VTR(vent thru roof).
I think the path downstream of the right-hand (upstream) lav needs to be 2 inch after the sanitary tee, since it is wet-venting the tub. You have one of places in that path labeled 1-1/2. Maybe I am wrong about needing 2 inch.

For the downstream lav only, you could also consider the Magic Vent. Since you are doing all of this new work, a VTR would be better, and a separate AAV in a vented box made for the purpose is practical. If you wanted to have an AAV, the Rectorseal Magic Trap on the downstream lav could make that easy.

https://www.supplyhouse.com/Rectorseal-97402-Magic-Trap-Tubular-Fitting-w-Tee

An AAV mounts onto that. The second of two reviews on that site says "This part is not designed to accept Oatey air admittance valves, which are male threaded."I suspect that you don't have to use the Rectorseal AAV, but I am not sure what else would be compatible.
https://www.supplyhouse.com/Rectorseal-97400-Micro-Size-Magic-Vent-AAV

 

[Goodimike]

Thank you for your helpful answer, Reach. Yes, good point. I should change the 1 1/2'' lav drain connection to a 2'' line from the most upstream lav. So is the soaker tub technically wet vented by the most upstream lav in the setup I have drawn? I may use an AAV for the most downstream lav like you mention, but there would be no issue tying into the 1 1/2' vent that is already tied into the 3" stack that goes through the roof, right? Thanks.

 

[Reach4]

See the bottom of page 12 of https://www.iccsafe.org/wp-content/uploads/20-18927_GR_2021_Plumbing_Venting_Brochure.pdf for a superset of what you are doing.

 

[Goodimike]

Hi Reach, I looked over page 12 and got the gist of things, but had a few questions. In the example on page 12 the lav drain runs vertically down into a 1/8th bend that changes directions directly into the main horizontal run. My drawing is a little different in that the lav drain/vent runs vertically down until it turns horizontal using a long sweep 90 perpendicular to the main 2'' line and then connects to the main 2'' line using a combo fitting. Does that setup work? I will draw a picture from the a bird's eye view and upload it tonight which should help with visualization of what I am saying. It is hard to tell w/ my current drawing. Also can an AAV that I planned to use for the most upstream lav be used to supply the wet vent with air? Thank you

 

[Jeff H Young]

I like the horrizontal wet vent that you plan

 

[Goodimike]

I like the horrizontal wet vent that you plan

Hi Jeff, I added a top down view (pic 5) to make sure that the layout will still work for wet venting the bathtub by the most upstream lav. I am also not sure what pvc fitting to use when connecting the new 1 1/2” vent perpendicular to the existing 1 1/2” vent that is located in the attic (circled in red). Should I use a combo or wye? I plan on maintaining 1/4” slope on the new vent. Thanks.

 

[Jeff H Young]

vent circled in red generally we use a san tee the cheapest fitting and only real reason to use a wye is if its easier or perhaps its a neater installation. slope can be less than 1/4 per ft on that vent but 1/4 is fine.
pic number 5 looks good!

 

[Goodimike]

Awesome, thank you for your help!