Tying into Island Foot Vent

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Spencer Keenan

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I'm working on a commercial TI in California on the first floor of a 3 story mixed use building. The ground floor unit is commercial space and the second and third floors are condos. I asked the developer to send me plans for where to vent our plumbing to the roof. They sent me back a page showing me to tie to a 2" line that is also the kitchen island foot vent for the island drain in the 2nd floor apartment.
Fixture count- I'm fine, but I'm not sure if I can tie into this vent below the floor ( which is below the flood rim of the fixtures it serves? )

Code section 909.1 says " The return vent shall be connected to the horizontal drain through a wye-branch fitting and shall, in addition, be provided with a foot vent taken off the vertical fixture vent by means of a wye branch immediately below the floor and extending to the nearest partition and then through the roof to the open air, or shall be permitted to be connected to other vents at a point not less than 6 inches (152 mm) above the flood-level rim of the fixtures served. Drainage fittings shall be used on the vent below the floor level, and a slope of not less than 1/4 inch per foot (20.8 mm/m) back to the drain shall be maintained. "

Anyone see why I can't tie into this foot vent? Assuming the plumber for the island vent did their job correctly- that vent should slope back to the drain and never take on water.


Master Plumber
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Cave Creek, Arizona
You can tie into the foot vent's VERTICAL riser in the wall at a point 42" above the floor, but NOT into the underfloor horizontal line. if the foot vent's drain plugged up, YOUR vent would become a "secondary drain line" without giving any indication that the original drain is not working.

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Hey, wait a minute.

This is awkward, but...

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