This chapter shall govern the materials,
design, and installation of plumbing vent systems.
Each plumbing fixture trap, except
as otherwise provided in this code, shall be protected
against siphonage and backpressure, and air circulation
shall be ensured throughout all parts of the drainage system
by means of vent pipes installed in accordance with the
requirements of this chapter and as otherwise required by
this code.
The vent system shall be
designed to prevent a trap seal from being exposed to a
pressure differential that exceeds 1 inch water column (0.24
kPa) on the outlet side of the trap.
Vent piping shall be permitted to be
omitted on an interceptor where such interceptor acts as a
primary settling tank and discharges through a horizontal
indirect waste pipe into a secondary interceptor. The second
interceptor shall be properly trapped and vented.
Traps serving
sinks that are part of the equipment of bars, soda fountains,
and counters need not be vented where the location and
construction of such bars, soda fountains, and counters is
such as to make it impossible to do so. Where such conditions
exist, said sinks shall discharge by means of approved
indirect waste pipes into a floor sink or other approved type
of receptor.
Vent pipe and fittings shall
comply with the applicable standards referenced in Table
701.2, except that:
- No galvanized steel or 304 stainless steel pipe shall be installed underground and shall be not less than 6 inches (152 mm) aboveground.
- ABS and PVC DWV piping installations shall be in accordance with the applicable standards referenced in Table 1701.1, this code, and the California Building Code. Except for individual single-family dwelling units, materials exposed within ducts or plenums shall have a flame-spread index of not more than 25 and a smoke-developed index of not more than 50 where tested in accordance with ASTM E84 or UL 723.
[HCD 1 & HCD 2] ABS or PVC installations
are limited to not more than two stories of areas of
residential accommodation.
[HCD 1] All malleable iron vents shall be
galvanized.
[OSHPD 1, 2, 3 & 4] ABS and PVC installations
are not allowed.
Copper or copper alloy tube for underground drainage and vent piping shall have a weight of not less than that of
copper or copper alloy drainage tube type DWV.
Copper or copper alloy tube for aboveground drainage and vent piping shall have a weight of not less than that of copper or copper alloy drainage tube type DWV.
Copper or copper alloy tube shall not be used for chemical or industrial wastes as
defined in Section 811.0.
Copper or copper alloy tubing, in addition to the required incised marking, shall be
marked in accordance with either ASTM 8306 or
ASTM 888 as listed in Table 1701.1. The colors shall
be: Type K, green; Type L, blue; Type M, red; and
Type DWV, yellow.
Changes in direction of vent
piping shall be made by the appropriate use of approved
fittings, and no such pipe shall be strained or bent. Burred
ends shall be reamed to the full bore of the pipe.
The size of vent piping shall be determined
from its length and the total number of fixture units
connected thereto, in accordance with Table 703.2. The
diameter of an individual vent shall be not less than 11⁄4
inches (32 mm) nor less than one-half the diameter of the
drain to which it is connected. In addition, the drainage
piping of each building and each connection to a public
sewer or a private sewage disposal system shall be vented
by means of one or more vent pipes, the aggregate cross-sectional
area of which shall be not less than that of the
largest required building sewer, as determined from Table
703.2. Vent pipes from fixtures located upstream from
pumps, ejectors, backwater valves, or other devices that
obstruct the free flow of air and other gases between the
building sewer and the outside atmosphere shall not be used
for meeting the cross-sectional area venting requirements of
this section.
Exception: Where connected to a common building sewer, the drainage piping of two or more buildings located on the same lot and under one ownership shall be permitted to be vented by means of piping sized in accordance with Table 703.2, provided the aggregate cross-sectional area of vents is not less than that of the largest required common building sewer.
Exception: Where connected to a common building sewer, the drainage piping of two or more buildings located on the same lot and under one ownership shall be permitted to be vented by means of piping sized in accordance with Table 703.2, provided the aggregate cross-sectional area of vents is not less than that of the largest required common building sewer.
Not more than one-third of the total permitted length, in accordance with Table 703.2, of a minimum-sized vent shall be installed in a horizontal position.
Exception: Where a minimum-sized vent is increased one pipe size for its entire length, the maximum length limitation shall not apply.
Exception: Where a minimum-sized vent is increased one pipe size for its entire length, the maximum length limitation shall not apply.
Vent and branch vent pipes shall be free from
drops or sags, and each such vent shall be level or shall be
so graded and connected as to drip back by gravity to the
drainage pipe it serves.
Where vents connect to a
horizontal drainage pipe, each vent pipe shall have its invert
taken off above the drainage centerline of such pipe downstream
of the trap being served.
Unless prohibited by structural
conditions, each vent shall rise vertically to a point not less than 6 inches (152 mm) above the flood-level rim of the
fixture served before offsetting horizontally, and where two
or more vent pipes converge, each such vent pipe shall rise
to a point not less than 6 inches (152 mm) in height above
the flood- level rim of the plumbing fixture it serves before
being connected to any other vent. Vents less than 6 inches
(152 mm) above the flood-level rim of the fixture shall be
installed with approved drainage fittings, material, and
grade to the drain.
Vent pipes shall extend undiminished in size above the roof, or shall be reconnected with a soil or waste vent of proper size.
The vent pipe opening from a
soil or waste pipe, except for water closets and similar
fixtures, shall not be below the weir of the trap.
Two fixtures shall be
permitted to be served by a common vertical pipe where
each such fixture wastes separately into an approved double
fitting having inlet openings at the same level.
Each vent pipe or stack shall
extend through its flashing and shall terminate vertically not
less than 6 inches (152 mm) above the roof nor less than 1
foot (305 mm) from a vertical surface.
Each vent shall terminate not less than 10
feet (3048 mm) from, or not less than 3 feet (914 mm)
above, an openable window, door, opening, air intake, or
vent shaft, or not less than 3 feet (914 mm) in every direction
from a lot line, alley and street excepted.
[OSHPD 1, 2, 3 & 4] Each vent pipe shall
terminate not less than twenty-five (25) feet (7620 mm)
from any air intake or vent shaft.
Vent pipes shall be extended separately
or combined, of full required size, not less than 6 inches
(152 mm) above the roof or fire wall. Flagpoling of vents
shall be prohibited except where the roof is used for assembly purposes or parking. Vents within 10 feet (3048
mm) of a part of the roof that is used for assembly purposes
or parking shall extend not less than 7 feet (2134 mm)
above such roof and shall be securely stayed.
Vent pipes for outdoor
installations shall extend not less than 10 feet (3048 mm)
above the surrounding ground and shall be securely
supported.
Joints at the roof around vent pipes shall be
made watertight by the use of approved flashings or
flashing material.
(See Table 1701.1) Sheet lead shall comply
with the following:
- For safe pans - not less than 4 pounds per square foot (lb/ft2) (19 kg/m2) or 1⁄16 of an inch (1.6 mm) thick.
- For flashings or vent terminals - not less than 3 lb/ft2 (15 kg/m2).
- Lead bends and lead traps shall be not less than 1⁄8 of an inch (3.2 mm) in wall thickness.
Where frost or snow closure
is likely to occur in locations having minimum design
temperature below 0°F (-17.8°C), vent terminals shall be
not less than 2 inches (50 mm) in diameter, but in no event
smaller than the required vent pipe. The change in diameter
shall be made inside the building not less than 1 foot (305
mm) below the roof in an insulated space and terminate not
less than 10 inches (254 mm) above the roof, or in accordance
with the Authority Having Jurisdiction.
Each drainage stack that extends 10
or more stories shall be served by a parallel vent stack, which shall extend undiminished in size from its upper
terminal and connect to the drainage stack at or immediately
below the lowest fixture drain. Each such vent stack
shall also be connected to the drainage stack at each fifth
floor, counting down from the uppermost fixture drain, by
means of a yoke vent, the size of which shall be not less in
diameter than either the drainage or the vent stack,
whichever is smaller.
The yoke vent connection to the vent
stack shall be placed not less than 42 inches (1067 mm)
above the floor level, and the yoke vent connection to the
drainage stack shall be by means of a wye-branch fitting
placed below the lowest drainage branch connection
serving that floor.
Wet venting is limited to
vertical drainage piping receiving the discharge from the
trap arm of one and two fixture unit fixtures that also serves
as a vent not exceeding four fixtures. Wet-vented fixtures
shall be within the same story; provided, further, that
fixtures with a continuous vent discharging into a wet vent
shall be within the same story as the wet-vented fixtures.
No wet vent shall exceed 6 feet (1829 mm) in developed
length.
The vertical piping between two consecutive
inlet levels shall be considered a wet-vented
section. Each wet-vented section shall be not less than one pipe size exceeding the required minimum waste
pipe size of the upper fixture or shall be one pipe size
exceeding the required minimum pipe size for the sum
of the fixture units served by such wet-vented section,
whichever is larger, but in no case less than 2 inches
(50 mm).
Common vent sizing shall
be the sum of the fixture units served but, in no case,
smaller than the minimum vent pipe size required for a
fixture served, or by Section 904.0.
A
bathroom group located on the same floor level shall be
permitted to be vented by a horizontal wet vent where all of
the conditions of Section 908.2.1 through Section 908.2.5
are met.
The dry vent connection to
the wet vent shall be an individual vent for the bidet,
shower, or bathtub. One or two vented lavatory(s) shall
be permitted to serve as a wet vent for a bathroom
group. Only one wet-vented fixture drain or trap arm
shall discharge upstream of the dry-vented fixture drain
connection. Dry vent connections to the horizontal wet
vent shall be in accordance with Section 905.2 and
Section 905.3.
The wet vent shall be sized based on the
fixture unit discharge into the wet vent. The wet vent
shall be not less than 2 inches (50 mm) in diameter for
4 drainage fixture units (dfu) or less, and not less than
3 inches (80 mm) in diameter for 5 dfu or more. The
dry vent shall be sized in accordance with Table 702.1
and Table 703.2 based on the total fixture units
discharging into the wet vent.
The length of the trap arm shall not
exceed the limits in Table 1002.2. The trap size shall
be in accordance with Section 1003.3. The vent pipe
opening from the horizontal wet vent, except for water
closets and similar fixtures, shall not be below the weir
of the trap.
The water closet fixture drain or
trap arm connection to the wet vent shall be downstream
of fixture drain or trap arm connections to the
horizontal wet vent.
Additional fixtures shall
discharge downstream of the wet vent system and be
conventionally vented. Only the fixtures within the
bathroom group shall connect to the wet-vented horizontal
branch.
Traps for island sinks and similar equipment
shall be roughed in above the floor and shall be
permitted to be vented by extending the vent as high as
possible, but not less than the drainboard height and then
returning it downward and connecting it to the horizontal
sink drain immediately downstream from the vertical
fixture drain. 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. The return
bend used under the drainboard shall be a one piece fitting
or an assembly of a 45 degree (0.79 rad), a 90 degree (1.57
rad), and a 45 degree (0.79 rad) elbow in the order named.
Pipe sizing shall be as elsewhere required in this code. The
island sink drain, upstream of the returned vent, shall serve
no other fixtures. An accessible cleanout shall be installed
in the vertical portion of the foot vent.
Combination waste and vent
systems shall be permitted where structural conditions
preclude the installation of conventional systems as otherwise
prescribed by this code.
Construction documents for each combination waste and vent system shall first be approved by the
Authority Having Jurisdiction before a portion of such
system is installed.
Each combination waste and vent system, as
defined in Chapter 2, shall be provided with a vent or vents
adequate to ensure free circulation of air. A branch
exceeding 15 feet (4572 mm) in length shall be separately
vented in an approved manner. The area of a vent installed
in a combination waste and vent system shall be not less
than one-half the inside cross-sectional area of the drain
pipe served. The vent connection shall be downstream of
the uppermost fixture.
Each waste pipe and each trap in such a system
shall be not less than two pipe sizes exceeding the sizes
required by Chapter 7 of this code, and not less than two
pipe sizes exceeding a fixture tailpiece or connection.
No vertical waste pipe shall be
used in such a system, except the tailpiece or connection
between the outlet of a plumbing fixture and the trap. Such
tailpieces or connections shall be as short as possible, and
in no case shall exceed 2 feet (610 mm).
Exception: Branch lines shall be permitted to have 45 degree (0.79 rad) vertical offsets.
Exception: Branch lines shall be permitted to have 45 degree (0.79 rad) vertical offsets.
An accessible cleanout shall be installed
in each vent for the combination waste and vent system.
Cleanouts shall not be required on a wet-vented branch
serving a single trap where the fixture tailpiece or connection
is not less than 2 inches (50 mm) in diameter and
provides ready access for cleaning through the trap.
No water closet or urinal shall be installed
on such a system. Other one, two, or three unit fixtures
remotely located from the sanitary system and adjacent to a
combination waste and vent system shall be permitted to be
connected to such system in the conventional manner by
means of waste and vent pipes of regular sizes, providing that the two pipe size increase required in Section 910.4 is
based on the total fixture unit load connected to the system.
See Appendix B of this code for explanatory notes on the design of combination waste and vent systems.
See Appendix B of this code for explanatory notes on the design of combination waste and vent systems.
A maximum of eight fixtures connected to a horizontal branch drain shall be permitted to be circuit vented. Each fixture drain shall connect horizontally to the horizontal branch being circuit vented. The horizontal branch drain shall be classified as a vent from the most downstream fixture drain connection to the most upstream fixture drain connection to the horizontal branch.
Circuit-vented
horizontal branch drains are permitted to be
connected together. Each group of a maximum of eight
fixtures shall be considered a separate circuit vent and
shall be in accordance with the requirements of this
section.
The circuit vent shall be
not less than 2 inches (50 mm) in diameter and the connection
shall be located between the two most upstream fixture
drains. The vent shall connect to the horizontal branch on
the vertical. The circuit vent pipe shall not receive the
discharge of a soil or waste.
The slope of the vent section of the horizontal branch drain shall be not
more than 1 inch per foot (83.3 mm/m). The entire length of
the vented section of the horizontal branch drain shall be
sized for the total drainage discharge to the branch.
Multiple circuit vented branches shall be permitted to connect on the same floor level. Each separate circuit-vented horizontal branch that is interconnected shall be sized independently in accordance with Section 911.3. The downstream circuit-vented horizontal branch shall be sized for the total discharge into the branch, including the upstream branches and the fixtures within the branch.
A 2 inch (50 mm) relief vent shall be
provided for circuit-vented horizontal branches receiving
the discharge of four or more water closets and connecting
to a drainage stack that receives the discharge of soil or
waste from upper horizontal branches.
The relief vent
shall connect to the horizontal branch drain between the
stack and the most downstream fixture drain of the
circuit vent. The relief vent shall be installed on the
vertical to the horizontal branch.
The relief vent is
permitted to be a fixture drain or fixture branch for a
fixture located within the same branch interval as the
circuit-vented horizontal branch. The discharge to a
relief vent shall not exceed 4 fixture units.
Fixtures, other than the circuit-vented fixtures, are permitted to discharge to the horizontal
branch drain. Such fixtures shall be located on the same
floor as the circuit-vented fixtures and shall be either individually
or common vented.
The design and sizing of a vent system shall be permitted to be determined by accepted engineering
practices. The system shall be designed by a registered
design professional and approved in accordance with
Section 301.5.
An engineered vent system shall provide protection of the trap seal in accordance with Section 901.3.