Louisiana Administrative Code
Title 51 - PUBLIC HEALTH-SANITARY CODE
Part XIV - Plumbing
Chapter 9 - Vents
Section XIV-919 - Wet Venting

A. Single Bathroom Groups. A single bathroom group of fixtures may be installed with the drain from a back vented lavatory serving as a wet vent for a bathtub or shower stall and for the water closet, provided that the wet vent is one pipe size larger than the upper fixture drain but in no case smaller than the lower fixture drain, whichever is the larger, and that both fixture drains conform to Table 913.A of this code. No urinal exceeding 2.0 dfu or washing machine drain shall discharge into any wet vent. A minor fixture, such as a bathtub or shower, shall enter the wet vent/drain pipe upstream of a major fixture, such as a water closet [i.e., a minor (having less fixture units) over/upstream of a major (having more fixture units) rule]. The dry vent servicing the wet vent shall be sized based upon the developed length and the total fixture units connected thereto in accord with §937. B and Table 937.B of this code. (Note: Per the definition of "wet vent", the wet vent terminates at the connection with the water closet's fixture drain. If the water closet is being vented by a method other than the wet vent, the wet vent terminates where it connects to the stack, the lowest or most downstream fixture drain, or where it connects to a separate horizontal branch line or the building drain, as appropriate.)

B. Double Bath. Bathroom groups back-to-back on the top floor consisting of two bathtubs or shower stalls may be installed on the same horizontal branch with a common vent for the lavatories with no back vent for the water closets, bathtubs or shower stalls, provided that the wet vent is one pipe size larger than the upper fixture drain but in no case smaller than the lower fixture drain, whichever is the larger, and that both fixture drains conform to Table 913.A of this code. No urinal exceeding 2.0 dfu or washing machine drain shall discharge into any wet vent. A minor fixture, such as a bathtub or shower, shall enter the wet vent/drain pipe upstream of a major fixture, such as a water closet [i.e., a minor (having less fixture units) over/upstream of a major (having more fixture units) rule]. The dry vent servicing the wet vent shall be sized based upon the developed length and the total fixture units connected thereto in accord with §937. B and Table 937.B of this code.

NOTE: Per the definition of wet vent, the wet vent terminates at the connection with the water closet's fixture drain. If the water closet is being vented by a method other than the wet vent, the wet vent terminates where it connects to the stack, the lowest or most downstream fixture drain, or where it connects to a separate horizontal branch line or the building drain, as appropriate.

C. Multistory Bathroom Groups. On the lower floors of a multistory building, the waste pipe from one or two lavatories may be used as a wet vent for one or two bathtubs or showers provided that: