Bathroom rebuild - mini stack with vent?

[Michal Krombholz]

Hi,

I am new DIY in process of rebuilding a bathroom.

The question is about using a mini vertical drain stack with stack vent (essentially a 2x 3"x2": san tees on top of each other with a 2" vent on top - as pictured). The shower and sink will be connect to this mini stack branches. Is this vent and its location OK? There is existing WC downstream from it.

The old bath had a WC and LAV connected to main 3" drain, separately, no vents, only a relief vent downstream and further up the horizontal/vertical stack vent (for the rest of the house). I doubt it was in any code or sanity.

Please, do not make too much fun of my drawing and concept ;-)

Regards,
Michal

 

[MicEd69]

In all codes, a dry vent must be vertical, or no more than 45 degrees off vertical, until it reaches 6" above the flood line of the fixture(s) being served. So, the answer to your question "Is this vent and its location OK?" is no.

 

[Michal Krombholz]

Thanks! I see, there no space for 6" above flood; :-(. Bummer.

Could it all be considered a wet vent?

Would laying out horizontally the joint between shower and sink into a horizontal (ie removing the 'mini stack') and than going into a vent be more acceptable?

out <-- horizontal <-- shower <--- sink <-- horizontal <-- elbow up --> vertical vent

I think this still does not work as there is a horizontal vent area not above flood level. So same problem as before?

Alternatively I could vent from sink p-trap join and then have a wet vent for the shower downstream but this makes the vent location rather inconvenient.

out <-- horizontal <-- shower tee <-- horizontal <-- elbow up <-- vertical <-- sink tee --> vertical vent

 

[Michal Krombholz]

Ah!
"A vent pipe should rise vertically at least 6 inches above the flood level rim of the highest fixture it serves" - the key being "the *highest* fixture" so the vent must be connected to the sink connection.

 

[MicEd69]

Ah!
"A vent pipe should rise vertically at least 6 inches above the flood level rim of the highest fixture it serves" - the key being "the *highest* fixture" so the vent must be connected to the sink connection.

Yes. I'm sorry it wasn't clear to you. As I said, a "dry vent" must be vertical, or no more than 45 degrees off vertical, until it reaches 6" above the flood line of the fixture(s) being served. If the dry vent services more than one fixture at the same level, it needs to be vertical to at least 6" above the flood plain of both fixtures. If fixtures enter at different levels, then the "dry vent" is only serving the highest fixture and the "dry vent" needs to be vertical until it reaches 6" above the flood plain of that fixture. The lower fixture(s) are vented through the drain line of the higher fixture, which is then a "wet vent" for the lower fixture(s). And as that is a wet vent, it CAN run horizontally. But the connection of that "wet vent" should enter the drain line of the fixture it serves vertically or at least at some angle rather than directly horizontally. There are also distances that must be adhered to for all vents and wet vents.

 

[Michal Krombholz]

Thank you for the explanation. All new to me, learning!

When you say "more than one fixture at the same level" do mean like the floor level (same building story) or flood level of the fixtures? The IRC (the quote above) refers to 'flood level' of the fixtures.

I was wandering if a dry vent can technically have no dry-vented fixture at all but connect to a horizontal drain that, per your above explanation, would have to enter it vertically/on an angle (prob> 45deg).

So something like this (all on the same floor)

/\
:
:
:   Lv-e
:       |   Sh-e    WC
:       |      |     |
E------T------T-----T----main
     
E/e - elbows
Lv - lavatory
Sh - shower
T - tee/wye/comp

 

[MicEd69]

When you say "fixtures at the same level" do mean like the floor level (same story) or flood level of the fixtures?

No, it means the level the fixtures enter the vent stack. See below what fixtures are dry vented and those that are wet vented.

 

[Michal Krombholz]

Got it - reasonably so the level of the traps is important vs the vent vertical requirement.

So I think I can do this then instead. In my case the bathtub is replaced by shower and there is not individual vent for it but it's wet-vented via the sink's.