Louisiana Administrative Code › Title 51 - PUBLIC HEALTH-SANITARY CODE › Part XIV - Plumbing › Chapter 9 - Vents › Section XIV-915 - Common Vent

Current through Register Vol. 50, No. 6, June 20, 2024
A. Individual
				Vent. An individual vent, installed vertically, may be used as a common vent
				for two fixture traps when both fixture drains connect with a vertical drain at
				the same level. Also, see §311. C of this code in regards to double sanitary
				tee pattern limitations on fixtures or appliances with a pumping action
				discharge.
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Figure 915.A - Common Vent
(Fixtures Connecting at Same Level)
B. Fixtures on Same Floor Connecting at
				Different Levels in the Stack. A common vent may be used for two fixtures set
				on the same floor level but connecting at different levels in the stack,
				provided the vertical drain 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 drains conform to Table 913.A of this code. A minor
				fixture, such as a lavatory, shall enter the common vent above 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]. See Figure 915.A, Figure 915.B,
				and Section 915. D of this code.
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Figure 915.B (1 of 2) - Common Vent
(Fixtures Connecting at Different
				  Levels)
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Figure 915.B (2 of 2) - Common Vent
(Fixtures Connecting at Different
				  Levels)
C. Distance. The
				maximum distance allowed between back-to-back or side-by-side fixture traps and
				their vent, when vented by a "common vent", shall be in accord with the
				requirements of §913. A of this code. In addition, the following shall apply.
1. Two fixtures set back-to-back, or
				side-by-side connected to a common horizontal branch within the distance
				allowed between a trap and its vent may be served with one continuous soil or
				waste vent-pipe, provided that each fixture wastes separately into an approved
				double fitting having inlet openings at the same level. The vent shall be
				installed in a vertical position at the interconnection of the fixture drains
				or downstream of the interconnection in accordance with the distance of trap
				from vent requirements in Table 913.A of this code. See left-hand depiction of
				Figure 915.C in this code.
2. When
				not more than two fixtures are set back-to-back or side-by-side, within the
				distance allowed between a trap and its vent, they may be connected to a common
				horizontal branch served by a common vertical vent located between the two
				fixtures, provided the branch is one pipe size larger than either of the
				fixture drains, except as permitted by §923. A of this code. This vent shall
				not serve as a waste for any other fixture. A minor fixture, such as a floor
				drain, shall enter the common horizontal branch served by a common vertical
				vent 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]. See right-hand depiction of Figure
				915.C in this code.
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