Vet my Venting please? IPC code

[RoseHawke]

I've struggled with this for several days now. When you wake up at 3 in the morning with vent patterns running through your head, Something Is Wrong. I think I've got it figured out, but if not, now is the time to find out, not after it's done.

That one long run is going to the washing machine. Due to its length, I'm considering just venting that through the roof although I'd rather not put another hole in the roof if at all possible, especially since this is also just off my deck.

If this is okay, not okay, totally wrong or What were you thinking?!? I would appreciate any help. Thanks guys!

[Terry]

You can't wet vent the kitchen sink over the shower drain. Too many fixture units on the sink for that to work as a vent. Only "1 and 2 fixture unit" items can wet vent.
The kitchen sink is a "3 fixture unit" fixture.
Doing so will siphon the p-trap on the shower.
Run the kitchen separate from the shower, and tie those vents together at 42" from the floor.

The shower needs 2" waste with 2" trap
The kitchen sink needs 2" waste with 1.5" trap

The "overhead" venting is fine with 1.5" for the washer, sink and shower.

[RoseHawke]

Thank you for the reply! I suspected as much with that shower vent/drain. Oh, well. Would the following be more acceptable? I got lazy, by the way and didn't make the pipe to scale in the models. All the green is 2", all the red is 1.5", and the blue 2.5". That gold represents a suspended concrete slab (old porch that's been enclosed) which means the tailpiece on the shower will have to be rather long, just guesstimating at least 12." Is a long tailpiece likely to create a problem with drainage?

ETA: The 2" is referring just to the size of the pipe, not the size of the traps by the way. 1.5" for the kitchen sink trap. Gotcha .

[Terry]

That looks good.
My son Taylor says the drawing was Google Sketch Up?

[RoseHawke]

Excellent !

Yes, Google Sketchup. I've piddled with it quite a bit so I'm moderately decent with it, although I don't mess with it often enough to learn all the little tricks and everything it can do. I've found it invaluable for designing things like simple cabinets so I can work out the little problems up front before I take a saw to a piece of wood.

First time I've done a plumbing layout with it though!

[hj]

And WHERE did/do you find 2.5" drain OR vent pipe and fittings? Usually that size is only in drawings by mechanical engineers who do not know any better.

[RoseHawke]

I don't actually. It wasn't until later that I said "hmmmm." It'll be 2" rather. This stack will be probably within 10' of the main 4" cast iron stack but in an effort not to have runs of PVC all over the attic it just seemed best to go ahead and do an auxiliary.

[johncollins]

I am looking at my code book and a kitchen sink in 2 fixture units and as long as you upsize the drain for the shower and the kitchen sink to 2 1/2 or 3" it would be legal

[Tom Sawyer]

There is where that word Nominal comes in to play

[geniescience]

trap arm max 2" : do not upsize to 2.5" or 3". Stay tuned for Master Plumbers who will comment more.

[cacher_chick]

Is it just me, or is digging up and adding to a 6 month old post kind of silly?

[geniescience]

old thread, out of date. Yes. I see the dates.