Vent pipes shall be cast iron (hub or hubless), galvanized malleable iron split
couplings (victaulic), type DWV copper tubing or heavier, brass, stainless steel (409 type "G" copper-coated), ABS
plastic pipe or PVC plastic pipe. The pipe and fittings for each type of pipe including malleable fittings, shall comply
with the applicable specifications listed in Section P-305.
Fittings on ferrous pipe shall be of cast iron or malleable iron. Drainage type fittings shall be
required only where vent lines connect to drainage lines.
Underground vent pipe shall be of cast iron or copper tube of a weight not less than
type "L" hard temper. All underground vent piping installed parallel to a foundation wall shall be at least 3 feet from
the building foundation wall when the depth does not exceed 4 feet. One foot of additional distance from the
foundation wall shall be required for each additional one-foot depth below 4 feet.
Vent pipes of ABS plastic and PVC plastic shall be limited to installations of buildings
containing dwelling units only. Such buildings shall consist of from one to four families and shall not exceed three
stories in height. For the purpose of this section, basements are not considered a story height.
A vent stack or main vent shall be installed with a soil or waste stack when relief vents or other
branch vents are required in more than five branch intervals. The vent stack shall terminate independently in the open
air above the roof or shall be connected with the stack vent at least 6 inches above the flood level rim of the highest
fixture and shall connect with the soil or waste stack through, at, or below the lowest horizontal soil or waste branch,
or with the house drain, in such manner as to prevent the accumulation of rust scale. When water closets are installed
on this lowest horizontal branch, they shall be connected to the side of the horizontal branch
Every building in which plumbing is installed shall have at least one stack vent or vent
stack which shall run undiminished in size and as directly as possible from the building drainage system through to
the open air above the roof and in accordance with Section P-1103.4. The minimum size of the stack vent or vent
stack shall be 3 inches.
No vent terminal from a sanitary drainage system shall be directly beneath any
door, window or other ventilating opening of the same or adjacent building, nor shall any such vent terminal be within
12 feet horizontally of such an opening unless it is at least 3 feet above the top of such opening.
Extensions of vent pipes through a roof shall be terminated at least 2 feet above the roof
surface and shall be properly flashed. Where the roof is used for any purpose other than weather protection, the
vent pipe shall extend at least 7 feet above the roof surface and shall be properly supported.
Velocity breaks shall be required in soil stacks in buildings more than 30 stories above grade to
impede the velocity of the waste. At each velocity break, the stack shall be offset by two 45-degree breaks. A relief
vent one-half the size of the soil stack shall be installed at the top of the second 45-degree break and shall be connected
to the nearest vent stack.
A relief vent pipe shall be installed on the maindrain before the mainhouse trap inside the
building and be connected to the nearest vent line for any building 75 feet or higher. On maindrains of 8 inches or less, the vent shall be a minimum of 4 inches. On maindrains 10 inches and over, the relief vent shall be a minimum
of 5 inches.
Where the center of a water closet outlet is not more than 48 inches in developed length
from the center of 4-inch vented soil pipe on a vertical line, or through a wye or wye and 1/8 bend on a vented
horizontal line, connection of small fixture wastes - not exceeding two that are 1-1/2 inches or less in diameter - to
the side of an ideal bend (closet bend) above the center line without an additional vent, or by using no-hub, copper,
ABS or PVC pipe and fittings in accordance with Section P-902.0, shall be approved by the Department. Where
the center of a water closet outlet is not more than 18 inches from the center of a 3-inch vented soil pipe and the 4-
inch ideal bend (closet bend) is connected directly to a sanitary tee on a vertical line, connection of small fixture
wastes - not exceeding two that are 1-1/2 inches or less in diameter — to the sides of the bend above the center line
without an additional vent and in accordance with Section P-904.5 shall be approved. As an alternative to increasing
the size of a stack from 3 inches to 4 inches, a merion fitting shall be used to receive the discharge of a water closet
and small fixture wastes.
The water closet soil line connected to a merion fitting shall be a maximum of 8
feet developed length. The ideal bend (closet bend) shall not be less than 4 inches nominal diameter when
receiving the discharge of small fixture wastes. When using 3-inch ideal bends (closet bend) to receive discharges
of water closets, this fitting shall be a blind bend containing no drainage connections for other fixtures.
On existing stacks in buildings where the center of a water closet outlet is more than
4 feet but not more than 8 feet from the center of a vented soil pipe, an additional 1-1/2 inch vent will be permitted
if the vent is not longer than 30 feet, provided the conditions are the same as in Section P-1105.1.1.
Any single water closet or pedestal urinal branch more than 8 feet in length or any
single waste branch for fixtures other than water closets or pedestal urinals more than 12 feet in length shall have a
vent sized at least one-half the diameter of the branch pipe. Depending on its length, the number of fixture units
connected shall be in accordance with Table P-1110.4.
Figure P-1105.2
SINGLE WASTE BRANCHES IN EXCESS OF 8' - 0" and 12'-0" VENTING REQUIREMENTS
All ejectors, except pneumatic ejectors or receiving tanks used for receiving
sewage or other sanitary waste, shall be provided with a fresh air inlet. The size of the fresh air inlet shall be 4 inches
for 4-inch, 5-inch, and 6-inch drain pipe and 6 inches for 8-inch drains discharging into the ejector.
All sumps receiving the discharge from fixtures other than water closets shall be provided with a
fresh air inlet pipe. The size of the fresh air inlet shall not be less than two inches, and the locations of the fresh air
inlet piping shall be in accordance with Section P-503. The drainage piping discharging into the sump shall be vented
as provided in Chapter 11.
Offsets in soil or waste stacks at an angle greater than 45 degrees from the vertical serving
fixtures above the offset shall be vented as provided in Sections P-1107.1.1 or P-1107.1.2.
Such offsets shall be provided with a yoke vent equal to one-half the diameter of
the vent stack or soil stack but not less than 1-1/2 inches. The lower end of the yoke vent shall connect to the soil
or waste stack through a wye below the offset and above the next lower horizontal branch, and the upper end shall
connect to the stack vent or the vent stack not less than 6 inches above the highest fixture.
All buildings of not more than three stories having a soil or waste stack with one
offset at an angle greater than 45 degrees from the vertical and which does not exceed 10 feet in length shall not require additional venting. No fixtures shall be permitted above the offset, except that one small fixture may be
installed for a heel wash.
Figure P-1107.2
OFFSET OF SOIL STACK IN BUILDINGS 3-STORIES and LESS
Stack vents and vent stacks shall be permitted to connect into a common vent
header at the top of the stacks and extend to the open air above the roof at one point. Such header shall be sized in
accordance with the requirements of Table P-1110.4. As per Section P-1105, the size of the horizontal branch entering
a stack shall have a vent of the same size; therefore, one of the stacks entering into a common vent header shall be of
the same size as the branch entering the stack and shall maintain that size through the roof. Other sizes of the header
can then be sized as per Table P-1110.4.
The number of fixture units considered in sizing the vent header shall be the sum of all fixture units
on all stacks connected thereto. The developed length shall be the longest vent length from the intersection at the base of the most distant stack to the vent header terminal in the open air above the roof. The latter shall be extended to the
open air above the roof as a direct extension of one stack.
All vent and branch-vent pipes shall be free from drops or sags and shall be graded and connected
so as to drip back to the soil or waste pipe or vent stack by gravity.
A connection between a vent pipe and a vent stack shall be at least 6 inches
above the flood level rim of the highest fixture served by the vent pipe. Horizontal vent pipes forming branch vents,
relief vents, circuit vents or loop vents, shall be at least 6 inches above the flood level rim of the highest fixture served.
The length of a vent shall be its developed length from the lowest connection of the vent
with the soil stack, waste stack, or house drain to the vent terminal above the roof.
A vent stack or main vent connecting relief vents, circuit vents, or loop vents shall have
a diameter of at least one-half the diameter of the soil or waste stack to which the vent stack or main vent is connected,
but in no case less than 1-1/2 inches. The maximum number of fixture units connected to the vent stack shall be in
accordance with Table P-1110.4. The vent stack or main vent shall not be less in size than the branch, circuit, or loop
vent it is servicing. Where fixtures are installed on the house drain behind the line of vent, a minimum vent stack of 1-1/2 inches shall be required for small fixtures having a fixture unit value not greater than 10 and a minimum of 2
inches for one or more water closets and other fixtures, except if a larger size is required according to Table P-1110.4.
The diameter of a relief vent shall not be less than one-half the diameter of the horizontal
branch to which it is connected, with a minimum size of 1-1/2 inches. The maximum number of fixture units connected
to the relief vent shall be in accordance with Table P-1110.4.
