Venting - What's code?

rick in Alaska

As far as I know, there is no difference on the residential side anyway. I have always plumbed two story houses using the aggregate area, and generally wind up with one three inch vent through the roof, but not necessarily all the way to the main.
Rick

Mad Dog_2

In Ireland, many of the houses' Sanitary waste & vent plumbing is on the outside of the house, especially since they can be a few hundred years old with thick Stone walls. Mad Dog 🐕 

pecmsg

What does it matter, it’s pre existing!

ChicagoCooperator

Mad Dog_2 said:

In Ireland, many of the houses' Sanitary waste & vent plumbing is on the outside of the house, especially since they can be a few hundred years old with thick Stone walls. Mad Dog 🐕 

I've seen that in Britain and Portugal as well as San Francisco...

ChrisJ

So,

Regarding New Jersey Code I'm 99% sure I understand what's written but I'm not positive.


Best I can tell, if there's a vertical drop from a 2nd story to the 1st story, that's considered a drain stack and drain stacks must be vented full size. But, it seems like a 2 story "drain stack" is treated the same as a 10 story drain stack? Am I understanding this correctly? Where's a ranch house doesn't fall into this category and thus can be vented via multiple smaller vents that equal the required total venting.

But a 2nd floor bathroom automatically has to go full size?


Here's the scenario at hand. I apologize as this drawing isn't to scale and was rushed.
Anything I labeled wet means a sink or tub drains into it but isn't shown. To be specific, 1 1/2" on left side is 2nd story bathroom sink vent. 1 1/2" on right side is 2nd story tub vent. 2" vent is 1st story bathroom sink AND toilet vent. Not shown is the kitchen which ties in further downstream and has a 1 1/2" or 2" vent.


The question at hand is, as per NJ NSPC code, does that 8 foot tall "stack" to the 2nd story bathroom require a full size 3" vent (circled in red), or would a 2" be completely compliant? Due to framing etc, a 2" would be so much easier. The total amount of venting exceeds the requirement, but the fact that vertical connection goes to a 2nd floor is what's got me thinking it has to be 3".

This isn't about frost closure etc, in fact I can easily go to a 3" in the main attic. It's getting the pipe from the bathroom into the attic that is the rub.

ChrisJ

Here's the code that's got me....

Bathroom groups that are not more than 1 story height. Does this mean 1st story, or 1 story height as in my 2nd floor bathroom? That 2nd floor is only 1 story height, no?







Here's the vent rule regarding drain stacks.



@Jamie Hall How do you interpret that code?

ChrisJ

Assuming 1 story means literal height........

I have two 1.5" wet vents venting that "bathroom group" which according to code all it needs is a single 1.5" due to 3" pipe.

That means it's actually compliant without any additional venting and that's not technically a "drain stack".
If I remove that stack vent completely I'll still have a total of 1 two inch and three 1.5" vents which is a total cross sectional area of 8.5" or, more than a 3". It's actually totally compliant without any stack vent.

According to code.

I've got a headache.

CLamb

@ChrisJ You can get an informal opinion from the New Jersey Code Assistance Unit. I've contacted them before. Once you get through the preliminary bureaucratic steps the fellow I talked to was quite friendly and helpful.

ChrisJ

CLamb said:

@ChrisJ You can get an informal opinion from the New Jersey Code Assistance Unit. I've contacted them before. Once you get through the preliminary bureaucratic steps the fellow I talked to was quite friendly and helpful.

I'm going to contact them.
Even if it wasn't a big pain in the butt to try and route a full size vent due to old framing, I actually want to know the real answer just for curiosity sake.

ChrisJ

Add this for good measure.

ChrisJ

I had someone local explain it to me and got it thru my thick head.

2 or more story heights means how many floors drain into it.  In my case only one story.

I have a bad habit of overcomplicating things.

The good news is the only studor vent I have is going bye bye soon.