Double Vanity with AAV

[heckmab]

Hello, I really appreciate this amazing forum. I’m an HVAC guy trying to learn plumbing. I am currently remodeling my master bathroom and live in Rochester, NY. House was built in 1988. Please forgive me if I use the wrong terminology to describe my issue.

My issue is this: we want to install a double vanity sink, but my wife picked out a recessed medicine cabinet that extends pretty much the length of the wall.

The original floor plan had a single sink and jacuzzi. I removed the jacuzzi and planned to add a double vanity in leu of the single. The location of the double sink will be on the opposite wall 10ft away from the original single sink. For the double sink, I was planning to run a common vent straight up and connect to the existing venting in the attic, but with the enormous medicine cabinet, it’s not feasible.

To properly plumb the double vanity, am I allowed to use two AAV, one at each p-trapped sink? See attached drawing.

Both branch arms will connect to the existing jacuzzi 1.5” drain that then goes to a 2” drain that everything else in the bathroom connects to. All the vents in the master bath tie together in the attic and exhaust through the roof. I have confirmed with my town that AAVs are allowed.

From my research, I believe Rochester, NY follows IPC code and I believe IRC falls under this. I could be way off…please correct me if I’m wrong. My code book says for IRC code, the number of DFUs for two lavs is 2. The max DFUs for a 1.5” horizontal branch is 3. The book also says “A back-to-back fitting should be use for fixtures or trap arms entering at the same level. The IRC also allows a double sanitary tee to be used for this purpose, while the UPC allows it only for branch drains entering at the same level & into a barrel that is a minimum if 2 pipes sizes larger than the inlets.”

If I’m reading correctly, I can use an 1.5” branch arm and 1.5” drain for both sinks…right? However, what fitting should I use for connecting the two branch arms to the drain? All double fixture fittings have 4 openings. Is it okay to cap off the top? Maybe use 1.5” branch arm and a 2” drain?

I may be fundamentally misunderstanding venting, so please be easy on me, haha. Are there any issues with this design? I’d like to adhere to the code and avoid any major headaches down the road. Are AAVs frowned upon?

Thanks for all the help,
Brandon

 

[James Henry]

Use a double fixture fitting. install a piece of pipe around 8" in length in the top outlet and cap it. 1-1/2" is OK for 2 DFU 's.

 

[Sponsor]

 

[hj]

BAD advice. Are you really a "plumber"? You were doing great until you got the end and said "CAP IT", which WILL create "S" traps at both sinks. TEchnically 1 1/2" is not the size for two sinks.

 

[Sylvan]

I was supposed to go to Rochester this weekend (pennsfield) as I was there 3 weeks ago and have to go back and would have stopped by bbut I have to stay in NYC this week and the weather in Rochester is known for heavy snow conditions

Personally I never used an AAV or plan to

I think you might be better off contacting a local LMP and barter plumbing for AC work

 

[James Henry]

TEchnically 1 1/2" is not the size for two sinks.

WHAT?

 

[Reach4]

Rochester, NY follows IPC code and I believe IRC falls under this.

I don't think so. I think something like https://county.mckenziecounty.net/usrfiles/2009_International_Plumbing_Code.pdf would be a better thing to look at. I am not a plumber.

 

[James Henry]

I was planning to run a common vent straight up and connect to the existing venting in the attic, but with the enormous medicine cabinet, it’s not feasible.

One thing I missed while skimming your post, you can run your vent horizontal to avoid the medicine cabinet as long as the vent extends vertically a minimum of 6" above the top of the sink before turning horizontal. then you don't have to worry about changing out an AAV periodically.

 

[Terry]

I would not want that in my home. I'm with hj on this. I've always run 2" for two lavs and then branch off with 1.5" for each individual.
You also need to consider how any of that will be snaked later so that the snake actually follows the drain downward.

 

[James Henry]

I didn't say I liked it, I said it would pass. And I don't mind polite criticism from hj, but the man is way to rude!

 

[Reach4]

BAD advice. Are you really a "plumber"? You were doing great until you got the end and said "CAP IT", which WILL create "S" traps at both sinks.

Each trap arm has its own AAV well before the drainages combine

The top middle of the double fixture fitting could be a good place for a cleanout.

 

[hj]

When advice is ABSOLUTELY wrong, why would l want to pussyfoot around it. They would NEVER find a "double fixture fitting" with ALL openings 1 1/2"

 

[Reach4]

1-1/2" PVC DWV Double Wye and 45° Elbow Combo

1-1/2" PVC DWV Fitting Cleanout Adapter w/ Plug

1-1/2 in. PVC DWV 90-Degree Spigot x Hub Street Elbow

 

[heckmab]

Thanks for all the feedback, very helpful. We're now discussing options of having two recessed medicine cabinets so that I can run a vent up to the attic.

It was mentioned that I should plan how it will be snaked . See attached. Am I right in assuming this will work, or will the circled area not snake properly?

Thanks again

 

[Reach4]

We're now discussing options of having two recessed medicine cabinets so that I can run a vent up to the attic.

What is the total length along the path between the trap and the proposed double fixture fitting?

 

[Jadnashua]

If the fitting circled is a Y, oriented properly, it should work.

 

[heckmab]

What is the total length along the path between the trap and the proposed double fixture fitting?

Reach4, sorry for the long delay. For each fixture, the total length from the trap to the fitting itself is appropriately 40".

 

[heckmab]

My wife and I decided to go with 2 separate recessed medicine cabinets instead of one super large one. This gives me an area where I can run a vent into the attic to connect to the existing. Before I do this, I wanted to confirm I don't have too many elbows within a certain distance that may cause problems.

Two issues.

1. I have a 16x4" beam (not a joist) that I can't bore through. The only way that I can see to get the drain line from the floor cavity into the stud wall cavity is to 90 up, then use two 45s to go over and in. This will expose some of the pipe above the finished floor, but my plan is to notch out the vanity. See image for example of what I am talking about.

2. To avoid the recessed medicine cabinets with the vent, I have to offset to the right about 16". Is the image below good? Are there any minimum distances I need to worry about before or after the 90s? I'm basically combing both attached images into one.

Here are the new plans. Please let me know if there are any issues with having too many elbows within such a short distance. Appreciate all the help.

 

[Reach4]

Reach4, sorry for the long delay. For each fixture, the total length from the trap to the fitting itself is appropriately 40".

Good. That is much shorter than the IPC max for 1-1/2.

You may want to put a mirror over the area between medicine cabinets.

If your medicine cabinets both have the doors with hinges on the vent side, you can adjust the mirrors to let you see the back of your head.