Tub vent advice needed

Discussion in 'Shower & Bathtub Forum & Blog' started by unplumbed, Jul 13, 2009.

  1. unplumbed

    unplumbed New Member

    Jul 13, 2009
    I'm having some difficulty with the vents in my bathroom. Lots of windows. I have found out (via inspector) that island vents for sinks are only allowed in kitchen islands and that a loop vent for my tub will not work. I live in Seattle.
    It is my intent (now) to tie my tub vent into my shower vent (1 1/2"). I need a few things clarified before I proceed.
    If my trap leg is 2" I can have a maximum trap/vent distance of 5 feet, correct?
    If the trap leg is 1 1/2" my maximum distance will be 3 and a half feet, correct?
    Or maybe not, I heard that it was reduced to three feet in the 2009 UPC.
    Regarding the shower vent that I inted to tie into. It is 1 1/2" ABS. My code check book (Taunton Press) says that a 1 1/2" vent can handle 8 DFU's (no WC's). A shower and tub are worth 2 DFU's each for a total of 4 DFU's on a 8 DFU rated vent.
    Can I go from a 2" trap leg to a 1 1/2" vent?
    My plan for the tub vent: Install a 2" trap leg; tie in a 1 1/2" vent line run through some floor joists up through a sill plate ; then through a few studs (beneath one of my many windows) and tie into the shower vent.
    In other words: the tub trap leg will run North the vent piping will tie in downstream from the trap and head West, 90 up through the sill plate, head vertical about a foot and a half then 90 to ~ horizontal and head North (at a slope of 1/4" per foot) through several studs (4 will be load bearing and nailed together) then I will throw in anther 90 and head vertical with the tub vent, and about 40 inches above the floor (something about 6 inches above highest fixture flood level) I will 45 my way into the shower vent.
    Thanks in advance.

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