Horizontal Washer Drain AFTER Standpipe 3 inch??????

Originally Posted by Alan

Sounds like you answered your own question with this one anyway, no need for a drawing. Just for fun, look up the definition of TRAP ARM and see what they say, even though I already know the answer.

Then based off of these definitions you should be able to size your piping accordingly.

Since there are no other drains tied in between the 3" stack and your clothes washer, the piping downstream of the vent is your fixture drain. Judging by the original excerpt from the code that you posted, that section should be allowed to be 2" To clarify, starting at the clotheswasher you have : Standpipe -> P-trap - > Trap arm -> vent -> Fixture drain -> Branch drain or stack.

Make sense?


I'd print all these sections out, and show him that you understand what you're looking at, and get his input on why he wants it to be 3". If he says it must be, then that's his call, but the way the code reads, a 2" is well within reason.

Originally Posted by TheEplumber

I totally agree, but what about the sink that drains into the WC vent?

Originally Posted by Alan

But he said no other fixtures drain into that stack except the floor drains in the garage.

Originally Posted by Ishmael

He's talking about the laundry tray/utility sink that's wet venting the washing machine connection (labelled in the 2nd picture above).

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On a side note (not that it matters in Ohio), here in MA, we're not allowed to wet vent a washing machine connection.

Originally Posted by hammerlane

Spoke with city plumbing inspector again today. From when I spoke with him last there may have been a little confusion about what size stack the laundry tub/washer standpipe branch drain would be dumping into.

After he verified that my existing stack was 4", he said :

1)a 2" horizontal branch drain to pick up both both the laundry tub and washer standpipe would suffice since my existing stack was 4"

2)would be OK to use an AAV on the laundry tub

3)would be OK to tie into the stack with a San-Tee....no need to use the Tee-Wye.

Originally Posted by TheEplumber

That is an inspector I can work with