Bathroom Vent Design Check

[Lightningwill]

Hey Folks,

I am plumbing an addition to my house and want to check in on a couple of venting items for the master bath. Please see the attached diagram. Questions below. Thank you very much in advance. Code wise, I am under the 2015 NSPC (NJ).

1. As drawn, is there sufficient venting for the shower trap via the dry vent off the main trunk?
2. Any concern with the dry vent (outlined in a dotted purple line) being a sanitary tee on its back? Or does it need to be a wye?
3. As for the branch from the sinks, does the wye (outlined in a dotted orange line) have any requirement to be rolled to 45 degrees? My understanding is that if the dry vent is sufficient in this configuration, no wet venting is needed via the sink branch.

 

[Terry]

The toilet needs to come in downstream of the shower, or the shower needs it's own vent.
Wyes not santees on the horizontal. I don't think they allow flat venting unless it's part of a wet vent. The lavs would do that, again assuming the toilet comes in downstream of the shower.

 

[Sponsor]

 

[Lightningwill]

The toilet needs to come in downstream of the shower, or the shower needs it's own vent.
Wyes not santees on the horizontal. I don't think they allow flat venting unless it's part of a wet vent. The lavs would do that, again assuming the toilet comes in downstream of the shower.

Thank you! I just want to make sure I understand the principles behind the requirement. Is the concern that the toilet will siphon the shower trap? If so, why doesn't the dry vent provide an easier path for air to follow the moving water from the toilet? Or, is it also a question of positive pressure build up in front of flow from the toilet after it passes the dry vent? Again--not challenging the requirement, just want to understand as it will help prevent me from doing other similar things.

I've modified the drawing. Does the rearrangement create a legit wet vent for the shower?

 

[Plumber69]

Thank you! I just want to make sure I understand the principles behind the requirement. Is the concern that the toilet will siphon the shower trap? If so, why doesn't the dry vent provide an easier path for air to follow the moving water from the toilet? Or, is it also a question of positive pressure build up in front of flow from the toilet after it passes the dry vent? Again--not challenging the requirement, just want to understand as it will help prevent me from doing other similar things.

I've modified the drawing. Does the rearrangement create a legit wet vent for the shower?

that will work, you wont need vent for toilet. Double vanity will vent whole bathroom if its 2 inch

 

[Lightningwill]

that will work, you wont need vent for toilet. Double vanity will vent whole bathroom if its 2 inch

Thanks! Yes, I thought that the wet vent can handle it all, strictly speaking. That being said, would anyone be inclined to add the dry vent as well for belt and suspenders?

 

[Lightningwill]

I was just rechecking the code requirements on this and I believe that the wye after the lavatory does not need to be rolled to 45 degrees given it's a wet vent. Is my understanding correct?

 

[Terry]

The wye does not need to be rolled.

 

[Lightningwill]

It was mentioned that the toilet did not need its own vent (highlighted in green below). I thought that might be the case, but I want to make sure I understand the aspect of the code that allows for it. Here's the relevant portion (12.8.4) of the 2015 NSPC: “For water closets and other fixtures that operate by siphonic action, the distance between the outlet of the fixture and its vent connection shall not exceed 3 feet vertically and 9 feet horizontally.”

Should I take the accumulated length indicated in purple as “the distance between the outlet of the fixture and its vent connection” and if so, is that what effectively allows the toilet to go without its own vent (assuming it meets the distance requirement)?

 

[Lightningwill]

Hey folks. Getting ready to actually plumb this and want to make sure I proceed in the correct fashion. Thanks for all the help thus far. If you have thoughts on this final question, I would very much appreciate it!

 

[Jeff H Young]

Kinda late but good questions you have.
Im way behind times on horizontal wet venting from when it was "prohibited" . If I had open walls and everything was assesable I (just for belts and suspendors as you say) Would vent it out in conventional way each fixture its own vent and tieing them together befor heading thru roof if practical. adittionaly there would be no AAV or Studor vents.
I think the length of the W/C from its vent would measure from finish floor down to centerline of horizontal and then back to the 3x3x2 y and not back all the way to the 2 inch verticle. normaly your alloyed 6 ft on a 3 inch watercloset arm (dont know if it apllys to horizontal wet venting) If so the seperate vent for watercloset might be a choice.
Further for future never is there a legit reason for santee on back.
I too learning on horizontal wet venting Im not against it just a bit skittish because I never did it and learning it on sites like this because no where else to really turn. Terry and others been big help for me too. keeping the old mind working Thanks All!