Venting/Plumbing for Island Sink in MA

oldbat2beDecember 9, 2011

We're in Massachusetts and have been busy with a major remodel over the past six months. New kitchen has a perimeter sink and will have a prep sink in the island.

Perimeter countertops just went in and cleanup sink has been connected (working water in the kitchen -- major milestone!)

Our builder anticipates that the plumbing/gas inspector will give us a hard time, due to the island sink venting/plumbing and has suggested that we hold off putting the countertop on the island (which has the sink cut-out), schedule the final plumbing/gas inspection now, and then proceed with countertop and the plumbing/venting for the island sink.

I do not want to vent up through the countertop.

I'd appreciate comments on the above. Also, can anyone provide what the requirements are, in MA, for venting/plumbing an island sink? TIA - Oldbat2be

. we get plumbing final signoff before we in

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An island loop vent is legal under both plumbing codes. It just requires space in your cabinet.

Here is a link that might be useful: How to Plumb an Island Sink

    Bookmark   December 9, 2011 at 11:58AM
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Thanks live_wire_oak, that looks doable.

DH's preference is to install an AAV. From what I've been able to find, these are not legal in MA, without prior permission from the inspector.

Can anyone confirm whether this is correct?

    Bookmark   December 9, 2011 at 1:05PM
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The island loop that live-wire-oak shows is the standard configuration for an island loop vent under the UPC(Uniform Plumbing Code).

Under the IRC an island loop vent is a bit simpler...however the question is what is correct in Massachusetts?

Massachusetts is primarily based upon the UPC but they have made a slight revision...Under the Mass Plumbing Code the vertical auxiliary vent must tie to the horizontal vent by means of a sanitary TEE and the vertical vent must continue down and tie into the drain line as I have shown in the photo.

Your DH is correct that you may have a maximum of one AAV per structure with the expressed consent of your inspector, but there is nothing saying that the inspector must grant that consent. (Personally, I would make every effort to avoid using an AAV.)

I would also be leary of your plumbers idea of leaving the countertop off and hoping to avoid the issue with the plumbing inspector. When they applied for your permit they had to submit a list of all fixtures in your house, and when the inspector comes to inspect he/she will have that list. If the list shows a sink on your island and it is not there at the time of the inspection the inspector has the right to withold approval until the final inspection of the structure. You simply don't want to get into a pissing contest with your inspector.

    Bookmark   December 9, 2011 at 1:46PM
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would the same apply to CT, i.e. a single AAV per structure?

    Bookmark   December 9, 2011 at 4:25PM
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No..the code is based on the IRC and they may have an unlimited number of AAV's.

    Bookmark   December 9, 2011 at 4:34PM
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"they may have an unlimited number of AAV's."

Just keep in mod anything tat moves to operate has a higher failure rate than just pipes.

    Bookmark   December 10, 2011 at 1:54PM
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