Page 704 - 2018_IRC

VENTS

TABLE P3107.3 P3108.4 Vertical wet vent permitted. A combination of fix-
COMMON VENT SIZES
tures located on the same floor level shall be permitted to be
PIPE SIZE MAXIMUM DISCHARGE FROM vented by a vertical wet vent. The vertical wet vent shall be
(inches) UPPER FIXTURE DRAIN (d.f.u.) considered to be the vent for the fixtures and shall extend
1
1 / 2 1 from the connection of the dry vent down to the lowest fixture
2 4 drain connection. Each wet-vented fixture shall connect inde-
1
2 / to 3 6 pendently to the vertical wet vent. All water closet drains
2
shall connect at the same elevation. Other fixture drains shall
For SI: 1 inch = 25.4 mm. connect above or at the same elevation as the water closet fix-
ture drains. The dry-vent connection to the vertical wet vent
shall be an individual or common vent serving one or two fix-
SECTION P3108 tures.
WET VENTING
P3108.1 Horizontal wet vent permitted. Any combination P3108.5 Trap weir to wet-vent distances. The maximum
developed length of wet-vented fixture drains shall comply
of fixtures within two bathroom groups located on the same with Table P3105.1.
floor level shall be permitted to be vented by a horizontal wet
vent. The wet vent shall be considered to be the vent for the
fixtures and shall extend from the connection of the dry vent SECTION P3109
along the direction of the flow in the drain pipe to the most WASTE STACK VENT
downstream fixture drain connection. Each fixture drain shall
connect horizontally to the horizontal branch being wet P3109.1 Waste stack vent permitted. A waste stack shall be
vented or shall have a dry vent. Each wet-vented fixture drain considered to be a vent for all of the fixtures discharging to
shall connect independently to the horizontal wet vent. Only the stack where installed in accordance with the requirements
the fixtures within the bathroom groups shall connect to the of this section.
wet-vented horizontal branch drain. Any additional fixtures P3109.2 Stack installation. The waste stack shall be vertical,
shall discharge downstream of the horizontal wet vent. and both horizontal and vertical offsets shall be prohibited
P3108.2 Dry vent connection. The required dry-vent con- between the lowest fixture drain connection and the highest
nection for wet-vented systems shall comply with Sections fixture drain connection to the stack. Every fixture drain shall
P3108.2.1 and P3108.2.2. connect separately to the waste stack. The stack shall not
receive the discharge of water closets or urinals.
P3108.2.1 Horizontal wet vent. The dry-vent connection
for a horizontal wet-vent system shall be an individual P3109.3 Stack vent. A stack vent shall be installed for the
vent or a common vent for any bathroom group fixture, waste stack. The size of the stack vent shall be not less than
except an emergency floor drain. Where the dry vent con- the size of the waste stack. Offsets shall be permitted in the
nects to a water closet fixture drain, the drain shall connect stack vent and shall be located not less than 6 inches (152
horizontally to the horizontal wet-vent system. Not more mm) above the flood level of the highest fixture, and shall be
than one wet-vented fixture drain shall discharge upstream in accordance with Section P3104.5. The stack vent shall be
of the dry-vented fixture drain connection. permitted to connect with other stack vents and vent stacks in
accordance with Section P3113.3.
P3108.2.2 Vertical wet vent. The dry-vent connection for
a vertical wet-vent system shall be an individual vent or P3109.4 Waste stack size. The waste stack shall be sized
common vent for the most upstream fixture drain. based on the total discharge to the stack and the discharge
within a branch interval in accordance with Table P3109.4.
P3108.3 Size. Horizontal and vertical wet vents shall be not The waste stack shall be the same size throughout the length
less than the size as specified in Table P3108.3, based on the of the waste stack.
fixture unit discharge to the wet vent. The dry vent serving
TABLE P3109.4
the wet vent shall be sized based on the largest required diam- WASTE STACK VENT SIZE
eter of pipe within the wet-vent system served by the dry
vent. STACK SIZE MAXIMUM NUMBER OF FIXTURE UNITS (d.f.u.)
(inches) Total discharge into Total discharge
TABLE P3108.3 one branch interval for stack
WET VENT SIZE 1 / 1 2
1
WET VENT PIPE SIZE FIXTURE UNIT LOAD 2
(inches) (d.f.u.) 2 2 4
1
1 / 1 2 / No limit 8
1
2 2
2 4 3 N o l i m i t 2 4
1
2 / 6 4 N o l i m i t 5 0
2
3 1 2 For SI: 1 inch = 25.4 mm.
4 3 2
For SI: 1 inch = 25.4 mm.

2018 INTERNATIONAL RESIDENTIAL CODE ® 679
Copyrighted © 2017 by, or licensed to, ICC (ALL RIGHTS RESERVED); licensed to UL, LLC pursuant to License Agreement with ICC. No further reproductions authorized or distribution authorized.
ANY UNAUTHROIZED REPRODUCTION OR DISTRIBUTION IS A VIOLATION OF THE FEDERAL COPYRIGHT ACT AND THE LICENSE AGREEMENT; AND SUBJECT TO CIVIL AND CRIMINAL PENALTIES THEREUNDER.