Wet vent stack

I have a 3" vertical wet vent stack. It has the toilet connection at the bottom then the tub, then lav, all these are using the stack as a drain and vent. The kitchen sink is also connected to the stack for drain only, it has its own vent. My question is can I run a 2" drain line from the washing machine into the stack above the others as a drain? I will vent the washer with its own vent. Will that create a problem in the wet stack?

If the tub and the lav are connected below the water closet, they must be separately vented. There are very few places where a vertical wet vent is permitted at all.

cacher_chick said:

If the tub and the lav are connected below the water closet, they must be separately vented. There are very few places where a vertical wet vent is permitted at all.

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I think he is saying that the water closet is the lowest, then the tub and lav above.

And he wants to know if it's a problem to drain a washing machine into the stack above all of that. And the answer to that is of course "yes".

JJG -- Dude, Code aside, the simple way to think of it is whether the water running into the stack above the other non-vented items will siphon the traps on those items. So -- does a huge burst of water out of a draining washing machine and into that stack have the potential to siphon the traps of your tub and lav?

See? Easy to answer without even referencing the Code.

If the answer is yes, it will create a problem to drain the washer into the wet stack how do you fix it? The toilet is on the bottom of the stack. Do you dry vent all the fixtures? Can the CW stay wet vented at the bottom of the stack?

Have a look at this:
http://www.klickitatcounty.org/documentcenter/view/103
And this: Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

The washer isn't a fixture that can be wet vented.
Only bathroom groups on the same floor.

A washer will siphon all the traps below it.

i'll start the squabbling - LOL - our code would allow it... up to 8 fixture units on a 3" wet vent....in theory with it being separately vented and draining to a 3" stack it should have enough "breathing capacity" as it drains that it wont create a siphon on other traps.

I was going to dry vent the washer and only drain it into the stack. If I dry vented all the fixtures, and the washer, can I drain them all into the stack? My main sewer pipe runs under ground from the street, and come up out of the ground under the bathroom in the crawl space where the 3" wet stack goes vertically to the roof and all the fixtures in the house are drained into that stack. Could the washer, dry vented, drain into the wet stack below the fixtures?

jjgmorgan said:

I was going to dry vent the washer and only drain it into the stack. If I dry vented all the fixtures, and the washer, can I drain them all into the stack? My main sewer pipe runs under ground from the street, and come up out of the ground under the bathroom in the crawl space where the 3" wet stack goes vertically to the roof and all the fixtures in the house are drained into that stack. Could the washer, dry vented, drain into the wet stack below the fixtures?

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It's always okay to bring in a line below the other fixtures.