Other than I think there should be a ‘wye’ where the “t” is after the trap, this just isn’t pretty! :shock:
Mike
A little convoluted but probably ok. There should be a “T” (sanitary T) after the trap. Is that an air admitance valve just at the top of the picture? If not then the whole thing would most likely be improper.
It is an AAV above the ‘contraption’ and I guess that’s a ‘sanitary T’.
It was likely a lot of work to get it all to mate up though! 
I am not a code person but from a practical point of view it is correct
If it is wrong a BI could grant an exception and everything is ok
This is sort of a common way of doing a center island sink
rlb
And what about this, self venting?
David,
I am aware of AAV’s but that is not the case in the photo posted its just a 3’’ pipe with a cap.
Ohhh, it’s a cap?
I can’t quite see through the horizontal waste pipe.
Anyways, if there’s no venting for this fixture, it definitely needs one installed.
Does that waste pipe join another pipe (on the underside) which could be venting outside?
It’s on an island, closest wall is 6’. I see this often in new construction down here.
Well… it could have been plumbed better. I would have stacked three directional street tee’s and come of each one separate (the third being for the dishwasher). Also the AAV is too low. It should be above the flood rim of the sink. I put them as high as I can.
I noticed some other things.
I also would have gone straight into the end outlet waste tee from the disposal instead of dropping down first. I also would not use a 90 on the stack going into the trap but a 45 or 22.5. Of course if it were done right you may be able to go straight into the stack eliminating any bends.
Well, maybe it needs a vent. Jurisdictions differ, as this expands to a 3" waist you are allowed from 6 to 12 feet from the trap to the waist vent (so says my plumbing manual.) So, if that is a cap it may be fine. Again, horizontal to vertical connect always require a 45-degree transition. If that is a 2 inch pipe rather than 3inch, you may be allowed 5 to 8 feet to the vent.
Sorry Tony, not so - the minimum distance allowed to the AAV from the Trap Arm (carring waist away from the trap) is six inches. Jurisdictions could vary. This distance has nothing to do with the flood rim of the sink. (so says my manual.)
That may depend on where you are located and which plumbing code you are under. If I had done this in Iowa the plumbing inspector would have told me to do it correctly. Above the flood rim. This is done in case of backup.
While you may be right, I am certainly no expert, I have to wonder. If we think about the way the valve is constructed (if the manufacturer does not specifically state that the VVA must be above the flood rim) it is inherently a one way valve - either air or water is prevented from back flow. Then, even if we have a backup of the waist water, wouldn’t it’s placement above the flood rim make no difference? I don’t doubt that some code would say that but it is pretty hard to believe that it would be necessary. Am I off base?
It depends on what the purpose of the AAV is. For fixture venting it needs to be a certain distance above the weir of the trap. For stack venting it needs to be above the flood level of the highest fixture.
And it’s very doubtful that little sealing membrane would stop any kind of **waste **backup.
Though it’s technically a one way valve it’s still a mechanical valve and it may fail to hold water back as I’ve experienced. When they do leak and it is not above the flood rim it can be quit a mess and often times ends up in the basement if there is one.
Thanks guys. Good info.