iamzoner

I was on a job site in British Columbia. It is a 4 story retirement home. The kitchens of all 4 floors are being drained into a 2" stack. So 4 times 1 and a half fixtures which to me equals 6 fixture units.

My code book states that a 2" stack can handle up to 24 fixture units vertical and 6 fixtures horizontal. It also states that a 2" line can wet vent up to 4 fixture units as long as it doesn't serve water closets.

My question is, if this 2" stack is serving as a wet vent for the entire kitchen line, it is actually serving a total of 4.5 fixture units as a wet vent, not 4. Is this just one of those things that an inspector will pass anyway?

Just trying to learn the codes on my own as I go here.

futz

Totally depends on your inspector. Where I work (Delta/Richmond/Surrey/etc.) they won't let us slide at all. If we're 1/2 a fixture unit over then that's it - upsize it or do it different. In Kamloops (and many other smaller towns) I bet you get a pass. They'd let it slide in Kelowna for sure (don't get me started about their inspectors ).

Will it work at 4.5 FU? Of course it will. It'll be fine. But any municipality that's been successfully sued lately will be gun-shy and will enforce very strictly.

markb

According to the Ontario Building code, which is very close to the NPC or BC plumbing code, states that wet-vents (Single or multi-story) must be sized according to your wet-vent charts. It may only serve one WC at first (bottom) connection (two WCs can be wet vented, but must use a double Y fitting).

The 4 FU rule applies to the maximum FU allowed to be drained PER FLOOR.

Less than 4 stories means that you can connect to the rest of the in-house venting system.

More than 4 stories requires the vent to be taken through the roof (sized as a vent terminal, 3" min).

Hope that helps!

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Pipe Rat

Are you saying each floor just has a branch to the kitchens and they are not individually vented? Don't think that would fly in my neck of the woods.

Tommy plumber

So there is one vertical line serving as both drain and vent for 4 floors? That won't pass here. Wet venting is permitted only for fixtures on same floor level.

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iamzoner

Yes. It is 1 2" stack which serves as both drain AND vent for all 4 floors. I spoke with someone locally here in my town and they said to check my code book for what a STACK can handle. Sure enough, a 2" stack can handle 24 fixture units vertical and 6 horizontal.

So I guess that even though this looks like a wet vent to me, I may simply have it confused as a stack that goes up all 4 floors. The only fixture that goes into this stack on each floor is the kitchen.

I may be confused by the definition of wet venting vs a stack. But if this stack is also its own vent, isn't that a wet vent? Isn't any stack that serves as its own vent a wet vent?

markb

It is sized as a wet vent, not as a stack. The definition part of your code book should explain the differences.

Also, keep in mind the limited distances for offsets.

Your code book should have a few examples of this in the appendix.

One thing to keep in mind as well is to use a TY or (better) a Y and FITTING (not regular) 45 at each branch connection; to stay withing the trap arm requirements.

__________________
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Never give in. Never give in. Never, never, never, never--in nothing, great or small, large or petty--never give in, except to convictions of honor and good sense. Never yield to force. Never yield to the apparently overwhelming might of the enemy.
- Winston Churchill

Redwood

Yep, there are a lot of things different in the codes north of the border. I do however pay attention to what they do because it is interesting to compare the differences...

Things like yellow ABS Cement, kitchen sink traps under the floor, venting between floors are just a few of the differences...

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markb

Why wouldn't you be able to vent between floor joists? Or back vent kitchen sink traps?

__________________
--
Never give in. Never give in. Never, never, never, never--in nothing, great or small, large or petty--never give in, except to convictions of honor and good sense. Never yield to force. Never yield to the apparently overwhelming might of the enemy.
- Winston Churchill

Redwood

We can't wet vent between floors and we also have a maximum fall on a drain before the trap.
And we have black ABS cement...

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