Section SPS 382.31 - Vents and venting systems(1) SCOPE. The provisions of this section set forth the requirements for the design and the installation of vents and venting systems.(2) MATERIALS. All vents and venting systems shall be constructed of approved materials in accordance with ch. SPS 384.(3) GENERAL. (a)Vents. Every trap and trapped plumbing fixture shall be provided with an individual vent, except as otherwise permitted in this chapter. Vents and venting systems shall be designed and installed so that the water seal of a trap shall be subject to a maximum pneumatic pressure differential equal to one inch of water column.(b)Main stack. Each gravity-flow sanitary building sewer shall be served by at least one stack which extends from a building drain to a vent terminal or vent header. The stack shall be not less than 36 in diameter from the building drain to the vent terminal or vent header.(4) VENT STACKS AND STACK VENTS. (a)Where required. A vent stack and a stack vent shall be installed to serve any drain stacks of 5 or more branch intervals.(b)Installation.1. The connection of the vent stack to a drain stack shall be at or below the lowest branch drain connection to the drain stack. The connection to the drain stack shall be by means of a wye pattern fitting installed in a vertical portion of the stack.2. A vent stack and a stack vent shall:a. Extend to a vent terminal in accordance with sub. (16);b. Connect to a vent stack which extends to a vent terminal; orc. Connect to a stack vent at least 6" above the flood level rim of the highest fixture discharging into a drain stack.3. Vent stacks and stack vents may connect into a common vent header and then shall extend to a vent terminal.4. The connection of a vent stack with another vent may not be less than 386 above the next higher floor level where the plumbing fixtures are vented, but in no case lower than 2" above the elevation of the highest flood level rim of any fixture served by the vent. Note: See ch. SPS 382 Appendix for further explanatory material.
(5) RELIEF AND YOKE VENTS FOR STACK OFFSETS. (a)Vents serving offsets of 30 to 45° in drain stacks.1. Except as permitted in subd. 2., where a horizontal branch connects to a drain stack within 2 feet above or below an offset with a change of direction of 30 to 45° from the vertical and the offset is located below 5 or more branch intervals, the offset shall be vented in accordance with par. (b) 1. to 3.2. Where the drain stack and offset are sized as building drain as per Table 382.30-3, the vents serving the offset of 30 to 45° in a drain stack are not required.(b)Vents serving offsets of more than 45° in drain stacks. Offsets of more than 45 o in drain stacks shall be vented where 5 or more branch intervals are located above the offset. The offset shall be vented by venting the upper and lower section of the stack.1. 'Upper section.' The upper section of the stack shall be vented as a separate stack with a vent stack connection installed in accordance with sub. (4). The offset shall be considered the base of the stack.2. 'Vent connection above offset.' The vent stack shall connect with a wye pattern fitting above the stack offset and at or below the lowest drain branch above the offset.3. 'Lower section.' The lower section of the stack shall be vented by a yoke vent connecting below the offset above or at the next lower horizontal branch.a. Except as provided in subd. 3. b., the connection of the yoke vent to the drain stack shall be by means of a wye pattern fitting.b. The yoke vent connection may be a vertical extension of the stack.c. The connection of the yoke vent to another vent shall not be less than 38 inches above the next higher floor level where plumbing fixtures are installed that discharge into the drain stack.(6) RELIEF VENTS FOR STACKS OF MORE THAN 10 BRANCH INTERVALS. (a) Drain stacks of more than 10 branch intervals shall be provided with a relief vent at each tenth interval installed.(b) The lower end of the relief vent required in par. (a) shall connect to the stack by use of a wye pattern fitting below the horizontal branch serving that floor. (c) The upper end of the relief vent required in par. (a) shall connect to the vent stack not less than 38 inches above the next higher floor level where plumbing fixtures are installed that discharge into the drain stack.(7) RELIEF VENTS FOR BUILDING DRAINS. A building drain with a change in elevation of 12 feet or more and at an angle of 45° or more from the horizontal shall be provided with a relief vent. (a) The connection of the relief vent to the building drain shall be by means of a wye pattern fitting installed within 2 feet upstream of the top of the change in elevation.(b) The connection of the relief vent to another vent shall be not less than 38" above the next higher floor level where plumbing fixtures are installed that discharge through the building drain. Note: See ch. SPS 382 Appendix for further explanatory material.
(8) VENTS FOR SANITARY SUMPS. (a)Interior sanitary sumps. Sanitary sumps shall be provided with a vent connecting either to the sump above the drain inlet or to the drain inlet within 12" of the sump.(b)Exterior sanitary sumps. Sanitary sumps shall be provided with a vent that terminates in accordance with sub. (16) (h).(9) FIXTURE VENTS.(a)Developed length between vent and trap. Each fixture trap shall be protected with a vent located in accordance with the provisions of subds. 1. and 2. 1. Each fixture trap which is not an integral part of the fixture shall be protected with a vent so located that the developed length of the fixture drain piping from the trap weir to the vent connection is within the limits set forth in Table 382.31-1.2. Each fixture trap which is an integral part of the fixture shall be protected with a vent so located that the developed length of the fixture drain piping from fixture outlet to the vent connection is within the limits set forth in Table 382.31-1. For a floor outlet water closet or similar fixture, the point where the fixture drain piping turns horizontal shall be considered as the fixture outlet.(b)Minimum distance. A vent shall not connect to a fixture drain within the distance equal to 2 diameters of the drain piping from the weir of a trap. Note: See ch. SPS 382 Appendix for further explanatory material.
Table 382.31-1
Maximum Developed Length Between Vent and Trap (in feet)
Diameter of Fixture Draina (inches) | Vent Connecting to Horizontal Drain Piping | Vent Connecting to Vertical Drain Piping |
by means of a Sanitary Tee Fitting | by means of a Wye Pattern Fittingb |
Pitch of Fixture Drain (inch per foot) | Pitch of Fixture Drain (inch per foot) | Pitch of Fixture Drain (inch per foot) |
1/8 | ¼ | ½ | 1/8 | ¼ | ½ | 1/8 | ¼ | ½ |
1¼ | NPc | 5.0 | 2.5 | NP | 3.5 | 2.0 | NP | 1.5 | 1.0 |
1½ | NP | 6.0 | 3.0 | NP | 5.0 | 3.0 | NP | 4.0 | 2.0 |
2 | NP | 8.0 | 4.0 | NP | 6.0 | 4.0 | NP | 4.5 | 4.0 |
3 | 24 | 12.0 | 6.0 | 10.0 | 8.0 | 6.0 | 8.0 | 6.0 | 6.0 |
4d | 32 | 16.0 | 8.0 | 12.0 | 10.0 | 8.0 | 10.0 | 8.0 | 8.0 |
a Diameters to be selected on the basis of the smallest drain pipe installed downstream from the trap serving a particular fixture.
b The wye pattern fitting refers to a tee-wye fitting, a combination wye and eighth bend fitting or a wye and eighth bend combination of fittings with no more than one inch between the wye fitting and eighth bend fitting.
c NP means Not Permitted.
d The maximum developed length for fixture drains larger than 4 inches in diameter shall be approved by the department.
(10) CIRCUIT VENTING. In lieu of providing individual vents, a horizontal drain to which at least 2 but not more than 8 wall outlet fixtures or at least 2 but not more than 8 floor outlet fixtures, other than blowout type fixtures and wall-outlet carrier type water closets, are connected to the same horizontal branch drain, may be vented by a circuit vent in accordance with pars. (a) to (e). (a) The circuit vent shall connect to the horizontal drain at a point between the 2 most upstream fixtures.(b)1. A circuit vented horizontal drain into which 4 or more fixtures discharge shall be provided with a relief vent. The relief vent shall connect to the circuit vented horizontal drain downstream of the most downstream fixture drain which is vented by the circuit vent and upstream of any other drain connections.2. Two circuit vented horizontal drains serving a total of 8 fixtures, 4 on each branch, shall be provided with at least one relief vent, unless the horizontal drains connect to a drain stack with no other drain connections located above the circuit vented horizontal drains. One relief vent may serve both horizontal drains, if installed downstream of the point where the 2 horizontal drains are joined. Note: See ch. SPS 382 Appendix for further explanatory material.
(c) A horizontal drain served by a circuit vent may not diminish in size from the most downstream fixture drain connection vented by the circuit vented drain to the circuit vent connection. Where a relief vent is installed, the horizontal drain served by the circuit vent shall not diminish in size from the relief vent connection to the circuit vent connection.(d) Fixture drains served by a circuit vent shall conform to the provisions of sub. (9). The connection of the fixture drain to the branch drain served by the circuit vent shall be considered as the vent connection.(e) Additional wall outlet fixtures with a drainage fixture unit value of one or less which are served by individual vents or common vents may discharge into a horizontal drain served by a circuit vent.(11) COMMON VENTS. In lieu of providing individual vents, fixtures may be common vented in accordance with pars. (a) and (b). (a)Vertical drains. A common vent may serve a maximum of 2 fixtures where both fixture drains connect to a vertical drain at the same elevation. 1. Where this connection is by means of a sanitary tee fitting with a side inlet, the centerline of the side inlet opening may not be below the centerline of the larger opening.2. The drain connection of a blowout type fixture, kitchen sink where an appliance with pump discharge or a food waste grinder are installed, or a clothes washer served by a common vent may not be by means of a double sanitary tee fitting.(b)Horizontal branches. The fixture drains from 2 wall-outlet fixtures, each with a drainage fixture unit value of one or less, or the fixture drains from 2 traps serving a kitchen sink with or without a dishwasher may connect to a horizontal branch without individual vents provided a common vent connects to the branch drain downstream of both fixture drains. Both fixture drains shall be of the same diameter. The developed length of the drain from the vent to the farthest trap shall conform to sub. (9). Note: See ch. SPS 382 Appendix for further explanatory material.
(12) RETURN VENTS. Plumbing fixtures may be vented in accordance with pars. (a) to (d). (a) Wall outlet fixtures may be vented by extending an individual vent, vertical wet vent or a common vent as high as possible under the fixture enclosure and returning the vent vertically downward and connecting the vent to the fixture drain or branch drain by means of a wye pattern fitting.(b) Horizontal vent piping shall connect to the vertical section of the fixture vent and extend to a point where it can extend vertically to a vent terminal in accordance with sub. (16) or connect to another vent in accordance with sub. (15).(c) Drainage fittings shall be used on all sections of the vent pipe below the floor level and a minimum slope of 1D 4" per foot to the drainage point shall be provided.(d) Cleanouts shall be provided on the vent piping in accordance with s. SPS 382.35. Note: See ch. SPS 382 Appendix for further explanatory material.
(13) WET VENTING. In lieu of providing individual vents, fixtures may be wet vented in accordance with pars. (a) to (c). (a)Vertical wet vents.1. Where 2 wall outlet fixtures are located on the same floor level with their fixture drains connecting to the same vertical drain pipe at different elevations, the lower fixture drain may be wet vented in accordance with subd. 1. a. to e. a. No other fixtures may discharge into the vertical drain pipe above or between the 2 wall outlet fixtures. Additional fixtures may discharge into the vertical drain pipe below the 2 wall outlet fixtures.b. A branch vent shall connect to the vertical drain pipe immediately above the higher fixture drain connection.c. The drain between the 2 fixtures shall be at least one pipe size larger than the upper fixture drain, but not smaller than 2" in diameter.d. Both fixture drains shall conform to sub. (9). The connection of the lower fixture drain to the vertical drain shall be considered as the vent connection.e. The higher fixture drain may not serve a water closet. Note: See ch. SPS 382 Appendix for further explanatory material.
(b)Horizontal wet vents. A drain from a lavatory or lavatories which are either provided with individual vents or a common vent may serve as the wet vent for not more than 2 bathtubs or showers and not more than 2 water closets in accordance with subds. 1. to 7. No other fixtures may discharge into or be served by the wet vent. 1. All of the fixtures shall be located in nonpublic bathroom groups.2. The lavatories and bathtubs or showers shall have a common horizontal drain with the drain for the lavatories serving as a wet vent for the bathtubs or showers.3. Where 2 bathtubs or showers are served by the same wet vent, their fixture drains shall connect independently to the common horizontal drain downstream of the vertical drain serving the lavatory or lavatories.4. Where 2 bathtubs or showers and 2 water closets are served by the same wet vent a relief vent shall be provided, unless the wet vented horizontal drain connects to a drain stack with no other drain connections located above the wet-vented horizontal drain. The relief vent shall connect to the horizontal drain at a point downstream of the fixture drains for the water closets and upstream of any other fixture drain connections.5. One or 2 water closets may connect to the common horizontal drain with the drain from the lavatories and bathtubs or showers also serving as a wet vent for the water closets. Where 2 water closets are served by the same wet vent, their fixture drains shall connect independently to the common horizontal drain at the same point.6. The wet vent shall be at least 2" in diameter. No more than 4 drainage fixture units may discharge into a 2" diameter wet vent.7. A branch vent shall connect immediately above the highest fixture drain connection and shall be sized in accordance with sub. (14).(c)Other types of wet vents. An individual vent serving a floor outlet fixture, a common vent serving floor outlet fixtures, a circuit vent, a relief vent serving a circuit vented drain or a relief vent serving a wet vented horizontal drain may serve as a wet vent in accordance with subds. 1. to 4. 1. No more than 2 wall outlet fixtures, each fixture with a drainage fixture unit value of one or less, may have their fixture drains connected into the individual vent, common vent, circuit vent or relief vent.2. The wet vent shall be at least 2" in diameter.3. The branch vent to which the wet vent connects shall be sized in accordance with sub. (14). The branch vent may serve the wall outlet fixtures in lieu of individual vents or a common vent.4. The fixtures discharging into the wet vent shall be located on the same floor level as the fixtures served by the wet vent. Note: For explanatory material refer to ch. SPS 382 Appendix A-382.31 (13).
(14) VENT SIZE. (a)Stack vents and vent stacks. Stack vent and vent stack pipe sizes shall be determined in accordance with Table 382.31-2 on the basis of developed length and the diameter of the drain stack at its base.1. The developed length of the stack vent shall be measured along the vent pipe, from the highest drain branch connection to the vent terminal or to the connection to a vent header.2. The developed length of the vent stack shall be measured along the vent pipe from the vent stack base connection to the vent terminal or to the connection to a vent header. Note: See ch. SPS 382 Appendix for further explanatory material.
(b)Vent headers.1. Vent header pipe sizes shall be determined in accordance with Table 382.31-3 with the number of drainage fixture units being the sum of the fixture unit loads of the stacks vented through that portion of the header. The diameter of a vent header shall not be less than any vent connecting to it.2. The developed length of the vent header shall be measured along the pipe from the most distant vent stack or stack vent base connection to the vent terminal. Note: See ch. SPS 382 Appendix for further explanatory material.
(c)Branch vents. Branch vent pipe sizes shall be determined in accordance with Table 382.31-3. The developed length of the branch vent shall be measured along the pipe from the furthest fixture drain served by the branch vent to the point where it connects to a vent pipe of a larger diameter or to a vent terminal. Note: See ch. SPS 382 Appendix for further explanatory material.
(d)Individual vents. Individual vent pipe sizes shall be determined in accordance with Table 382.31-3. The developed length of an individual vent shall be measured along the vent pipe from the fixture drain served by the vent to the point where it connects to a vent pipe of a larger diameter or to a vent terminal. Note: See ch. SPS 382 Appendix for further explanatory material.
(e)Common vents. Common vent pipe sizes shall be determined in accordance with Table 382.31-3. The developed length of a common vent shall be measured along the vent pipe from the drain served by the vent to the point where it connects to a vent pipe of a larger diameter or to the vent terminal. Table 382.31-2
Size and Length of Vent Stacks and Stack Vents
Diameter of Drain Stack at Base (inches) | Maximum Developed Length of Vent (feet) |
Diameter of Vent (inches) |
1¼ | 1½a | 2 | 3 | 4 | 5 | 6 | 8 | 10 | 12 |
1½ | 50 | 150 | NLb | | | | | | | |
2 | NPc | 50 | 150 | NL | | | | | | |
3 | NP | 50 | 400 | NL | | | | | | |
4 | NP | 20 | 180 | 700 | NL | | | | | |
5 | NP | 50 | 200 | 700 | NL | | | | | |
6 | NP | 20 | 70 | 200 | 700 | NL | | | | |
8 | NP | 25 | 60 | 250 | 800 | NL | | | | |
10 | NP | 25 | 60 | 250 | 800 | NL | | | | |
12 | NP | 25 | 100 | 300 | 900 | | | | | |
a Not more than 2 water closets or similar flush action type fixtures of 4 or more drainage fixture units.
b NL means No Limit.
c NP means Not Permitted
Table 382.31-3
Minimum Diameters And Maximum Length Of Individual, Common, Branch And Cir cuit Vents And Vent Headers
Drainage Fixture Units (dfu) | Maximum Developed Length of Vent (feet) |
Diameter of Vent (inches) |
1¼a | 1½b | 2 | 3 | 4 | 5 | 6 | 8 | 10 |
2 | 50 | NLc | | | | | | | |
4 | 40 | 200 | NL | | | | | | |
8 | NPd | 150 | 250 | NL | | | | | |
10 | NP | 100 | 200 | NL | | | | | |
24 | NP | 50 | 150 | NL | | | | | |
42 | NP | 30 | 100 | 500 | NL | | | | |
72 | NP | 50 | 400 | NL | | | | | |
240 | NP | 40 | 250 | NL | | | | | |
500 | NP | 20 | 180 | 700 | NL | | | | |
1100 | NP | 50 | 200 | 700 | NL | | | | |
1900 | NP | 20 | 70 | 200 | 700 | NL | | | |
3600 | NP | 25 | 60 | 250 | 800 | NL | | | |
5600 | NP | 25 | 60 | 250 | 800 | | | | |
a No water closets permitted.
b Not more than 2 water closets or similar flush action type fixtures of 4 or more drainage fixture units.
c NL means No Limit.
d NP means Not Permitted
(f)Circuit vents. Circuit vent pipe sizes shall be determined in accordance with Table 382.31-3. The developed length of the circuit vent shall be measured along the vent from the connection with the branch drain served by the vent to the point where it connects to a vent pipe of a larger diameter or to a vent terminal.(g)Relief vents. Relief vents shall be sized in accordance with the provisions of subds. 1. to 3. The developed length of a relief vent shall be measured along the vent from the connection with the branch drain served by the vent to the point where it connects to a vent pipe of a larger diameter or to a vent terminal. 1. 'Circuit vented branch drain.' The diameter of a relief vent for a branch drain served by a circuit vent shall be at least one half the diameter of the branch drain. The maximum developed length shall be determined from Table 382.31-3 based on the number of drainage fixture units served by the vent.2. 'Building drain.' The diameter of a relief vent serving a building drain, as required in sub. (7), shall be at least one half the diameter of the building drain. The maximum developed length shall be determined from Table 382.31-3 based on the number of drainage fixture units served by the vent.3. 'Horizontal wet vent.' The diameter of a relief vent serving a horizontal wet vent shall be at least 1 1D 2". The maximum developed length shall be determined from Table 382.31-3 based on the number of drainage fixture units served by the vent.(h)Yoke vents. A yoke vent serving a drain stack shall be sized as a vent stack in accordance with par. (a).(i)Vents for sumps.1.a. Except as provided in subd. 1. b., the size of a vent for a sanitary pump with other than a pneumatic ejector, shall be determined in accordance with Table 382.31-4. b. The size of a vent for a sanitary sump located outside with other than a pneumatic ejector shall be determined in accordance with Table 382.31-4, but shall not be less than 26 in diameter.2. The air pressure relief pipe from a pneumatic ejector shall not be connected to vent or vent system serving a sanitary drain system, storm drain system or chemical waste system. a. The relief pipe shall be of a size to relieve the air pressure inside the ejector to atmospheric pressure, but shall not be less than 2" in diameter where the ejector is located outside and 1 1/ 4" in diameter for all other ejector locations.b. The vent shall terminate in accordance with the provisions of sub. (16). Table 382.31-4
Size and Length of Vents for Sanitary Sumps
Discharge Capacity of Ejector (gpm) | Maximum Developed Length of Venta(feet) |
Diameter of Vent (inches) |
1¼d | 1½d | 2 | 3 | 4 |
10 | NLb | | | | |
20 | 270 | NL | | | |
40 | 72 | 160 | NL | | |
60 | 31 | 75 | 270 | NL | |
80 | 16 | 41 | 150 | NL | |
100 | 10 | 25 | 97 | NL | |
150 | NPc | 10 | 44 | 370 | NL |
200 | | NP | 20 | 210 | NL |
250 | | NP | 10 | 132 | NL |
300 | | NP | 10 | 88 | 380 |
400 | | | NP | 44 | 210 |
500 | | | NP | 24 | 130 |
a The developed length of the vent is measured along the pipe from the connection to the sump, to the point where it connects to a vent pipe of a lar ger diameter.
b NL means No Limit.
c NP means Not Permitted.
d Diameter not permitted for exterior sumps.
(j)Vents for chemical basins. The size of vents serving chemical dilution or neutralizing basins shall be determined in accordance with Table 382.31-3 and based upon the number of drainage fixture units discharging into the basins.(15) VENT GRADES AND CONNECTIONS. (a)Vent grade.All vent and branch vent pipes shall be graded and connected so as to drain back to a drain pipe by means of gravity.(b)Installation. Vents shall be installed in accordance with subds. 1. to 3. 1. Except for wet vent piping, the connection of a vent to horizontal drain piping shall be at a point above the horizontal center line of the drain piping.2. Except as provided in subs. (12) and (17), vent piping serving a wall-outlet fixture may not offset horizontally less than 36" above the floor, but in no case lower than the elevation of the highest flood level rim of any fixture served by the vent.3. Vent piping may not connect to a branch vent less than 38" above the floor, but in no case lower than 2" above the elevation of the highest flood level rim of any fixture served by the vent. Note: See ch. SPS 382 Appendix for further explanatory material.
(16) VENT TERMINALS. All vents and vent systems shall terminate in the open air in accordance with this subsection. (a)Extension above roofs. Extensions of vents through a roof shall terminate at least 8" above the roof. Where the roof is to be used for any purpose other than weather protection, the vents shall extend at least 7 feet above the roof.(b)Waterproof flashings. The penetration of a roof system by a vent shall be made watertight with an approved flashing.(c)Prohibited uses. Vent terminals shall not be used as flag poles, support for antennas or other similar purposes.(d)Location of vent terminals.1. Location of vent terminals shall be all of the following:a. At least 10 feet from an air intake.b. At least 5 feet from a power exhaust vent.c. At least 10 feet horizontally from or 2 feet above roof scuttles, doors, and openable windows.d. At least 5 feet from or 2 inches above parapet walls.e. At least 5 feet below any overhang.2. Where a structure has an earth covered roof extending from surrounding grade, the vent extension shall run at least 7 feet above grade and terminate with an approved vent cap. The portion of vent pipe outside the structure shall be without joints, except one fitting may be installed where the pipe leaves the top or side of the structure.(e)Extension through wall. A vent shall terminate at least 10 feet horizontally from any lot line. Extension of vents through wall shall terminate beyond the soffit. The vent shall terminate downward and be screened. The vent shall comply with par. (d).(f)Extensions outside buildings. Drain or vent pipe extensions shall not be located or placed on the outside of an exterior wall of any new building, but shall be located inside the building.(g)Frost closure. For protection against frost closure, each vent terminal shall be at least 2" in diameter. Where it is necessary to increase the diameter of the vent, the change in diameter shall be made at least 6" inside the building. Note: See ch. SPS 382 Appendix for further explanatory material.
(h)Penetrations through grade.Except when installation is in accordance with par. (d) 2., penetrations through grade shall terminate at least 12" above finished grade and terminate with a vent cap or return bend.(17) COMBINATION DRAIN AND VENT SYSTEMS. In lieu of providing individual vents, fixtures may be vented in accordance with pars. (a) to (d). (a)Stacks.1. A drain stack may serve as a combination drain and vent system for fixtures in accordance with subd. 1. a. to e. a. The drain stack shall not serve more than 3 fixtures. Each fixture shall be located on a separate floor level.b. The drain stack shall be limited to serving fixtures with a drainage fixture unit value of no greater than 2.0. A urinal may not discharge into the combination drain and vent portion of the stack. The largest drainage fixture unit value served by the stack shall determine the stack size as specified in Table 382.31-5.c. The drain stack shall not be offset horizontally above the lowest fixture drain connection.d. The developed length of any fixture drain from the trap weir to the drain stack shall not exceed the limits specified in Table 382.31-1.e. The drain stack and its attendant vent shall be sized in accordance with Table 382.31-5. Note: See ch. SPS 382 Appendix for further explanatory material.
Table 382.31-5
Stack Sizing by DFU Value
Drainage Fixture Unit (dfu) Value | Size of Stack (inches) |
0.5 | 1½ |
1.0 | 2 |
2.0 | 3 |
2. A drain stack may serve as a combination drain and vent system for a kitchen sink and a wall outlet fixture with a drainage fixture unit value of 2 or less in accordance with subd. 2. a. to d. a. One kitchen sink within a dwelling unit, with or without a food waste grinder or dishwasher connection, shall connect to the drain stack above the wall outlet fixture with a drainage fixture unit value of 2 or less. No other fixtures may connect to the drain stack.b. The drain stack shall be at least 2 inches in diameter below the kitchen sink connection and it shall be at least 4 inches in diameter below the connection to the lower fixture.c. In lieu of the minimum sizes as required in subd. 2. b., the entire stack below the kitchen sink connection may be 3 inches in diameter.d. The drain stack shall not offset horizontally above the fixture drain connection for the lower fixture.(b)Building drains. A building drain or a building subdrain may serve as a combination drain and vent system for floor drains and floor outlet fixtures in accordance with subds. 1. to 6. 1. A vent or drain at least 2 inches in diameter shall be connected upstream of any building drain branch or building subdrain branch.2. No more than 2 water closets may connect to the building drain or building subdrain by means of building drain branches or building subdrain branches.3.a. That portion of the building drain or building subdrain between the connection of the building drain branch or building subdrain branch and the vent or drain required in subd. 1. shall be at least one pipe size larger than the minimum size permitted in Table 382.30-3 based on the total drainage fixture unit load, but not less than 3 inches.b. The vent or drain required in subd.1. shall be at least one-half the diameter of that portion of the building drain or building subdrain which is vented by the vent or drain, but may not be less than 2 inches in diameter. c. A vent serving a drain required in subd. 1., shall be at least one half the diameter of that portion of the building drain or building subdrain which is vented by the system, but may not be less than 2 inches in diameter.4. The trap of a floor drain or a floor outlet fixture, except a water closet, connected to a building drain branch or building subdrain branch shall be at least 3" in diameter.5. A building drain branch or building subdrain branch may not connect to a building drain or building subdrain downstream from the base fitting of a drain stack 2" or larger in diameter within the distance equal to 20 pipe diameters of the building drain or building subdrain.6. The pitch and the developed length of the building drain branch or building subdrain branch may not exceed the limits specified in Table 382.31-1. Note: See ch. SPS 382 Appendix for further explanatory material.
(c)Laboratory sink venting. A horizontal drain may serve as a combination drain and vent system for island laboratory sinks in accordance with subds. 1. to 7. 1. A vent stack or a drain stack at least 2" in diameter shall be connected upstream of any fixture drain vented by the combination drain and vent system.2.a. That portion of the horizontal drain between the connection of fixture drain and the vent stack or drain stack required in subd. 1. shall be at least one pipe size larger than the minimum size permitted in Table 382.30-2 based on total drainage fixture unit load. b. The vent stack or drain stack required in subd. 1. shall be at least one-half the diameter of that portion of the horizontal drain which is vented by the stack, but may not be less than 26 in diameter. c. A stack vent serving a drain stack required in subd. 1. shall be at least one half the diameter of that portion of the horizontal drain which is vented by the stack, but may not be less than 2" in diameter. 3. All fixture drains vented by the horizontal drain shall be at least 3" in diameter.4. Fixture drains to be vented by the horizontal drain shall connect individually to the horizontal drain.5. An individual vent or common vent shall be extended as high as possible under the sink enclosure and then returned vertically downward and connected to the horizontal drain. A cleanout shall be provided on the vent piping.6. In lieu of connecting the vent to the horizontal drain which forms the combination drain and vent system, the vent may connect to a horizontal fixture drain vented by the combination drain and vent system. The pitch and developed length of the horizontal fixture drain shall not exceed the limits specified in Table 382.31-1.7. Fixture drains to be vented by the horizontal drain shall not connect to a horizontal drain downstream from the base fitting of a drain stack 2" or larger in diameter within the distance equal to 20 pipe diameters of the horizontal drain serving the stack. Note: See ch. SPS 382 Appendix for further explanatory material.
(d)Elevator threshold drain vent stacks.1. The minimum size of an elevator threshold stack shall be 6 inches.2. The minimum size of an elevator drain trap shall be 4 inches.3. The drain stack may not offset horizontally above the lowest threshold drain connection.4. Elevator threshold drains, provided with individual traps that utilize other means of venting, are permitted to discharge into the stack.5. The drain stack shall be limited to serving elevators threshold drains serving elevator door areas.6. The developed length of any trap weir vented by the stack to the drain stack may not exceed the limits specified in Table 382.31-1.7. A vent, at least 3 inches in diameter and not less than ½ the diameter of the largest portion of the drain stack, shall extend from immediately above the highest branch connection to a vent terminal in accordance with sub. (16). Note: See ch. SPS 382 appendix for further explanatory material.
(17m) AIR ADMITTANCE VALVES. The use of air admittance valves in lieu of traditional venting shall comply with all of the following:(a) The AAV may only serve as a termination point for a branch vent, circuit vent, common vent, individual vent, wet vent or combination drain and vent system. The AAV may serve a pumped-discharge type clothes washer standpipe when the fixture drain downstream of the point of vent is at least 3 inches in diameter.(b) Branches that have fixtures served by the AAV, and when connected to a stack that has 4 or more branch intervals above the branch connection, must be provided with a relief vent located between the most downstream fixture and the stack.(c) The AAV may not serve as a vent termination point for any of the following:1. Areas of negative pressure such as parking garages, laboratories, and research facilities.2. A commercial parking structure.3. Vents installed to relieve positive pressures.4. A fixture serving a chemical waste system.5. POWTS components such as a holding tank or treatment tank.6. A stack vent serving two or more branch intervals.7. A vent stack that is required in accordance with s. SPS 382.31 (4) (a).8. A vent serving a sump.9. An enclosed stairwell.10. An area utilized as supply or return air plenum.11. A pit, vault, or depression which is below the adjacent grade or floor level.12. Plumbing wastewater and treatment devices used to treat fats, oils & grease (FOG).13. An area that subjects the valve to grease or other materials which could cause fouling of the valve's seal.14. Clean rooms such as FDA or DATCP regulated food and beverage production areas, bio safety labs, pharmaceutical production, and pharmaceutical processing facilities. Note: For specific applications not listed, please contact DSPS Division of Industry Services at P.O. Box 7162, Madison, WI 53707-7162; or at telephone (608) 266-2112 or (877) 617-1565 or 711 (Telecommunications Relay); or at the Division's Website at http://dsps.wi.gov/programs/industry-services.
15. A health care facility as defined is s. SPS 381.01 (116).16. A restaurant kitchen licensed by the state or local department of health.17. A residential bedroom. Note: Does not include closets or bathrooms with solid doors in accordance with Standard International Building Code s. 508.2.3.
(d) The size and developed length for a vent using an AAV shall conform with Table 382.31-6. Table 382.31-6
| Maximum Developed Distance of Vent to Connection of AAV in Feet |
Maximum DFUs | Diameter in Inches |
| 1-¼a | 1-½ | 2 |
1 | 35 | NLb | NLb |
3 | 28 | 140 | NLb |
6 | NPc | 100 | 200 |
20 | NPc | 60d | 110 |
160 | NPc | NPc | 25 |
a Drainage Fixture Units based on ch. SPS 382.
b NL means no limit.
c NP means not permitted.
d Not more than two water closets or similar type fixtures of four or more drainage fixture units.
(e) The installation of the AAV shall conform with all of the following: 1. The AAV must be installed in the vertical position, plus or minus 15 degrees from plumb.2. The vent system being served by the AAV may have horizontal offsets located less than 36 inches above the floor on which the fixtures are installed provided the vent does not connect to another vent.3. The installation location of the AAV shall conform with all of the following: a. A minimum of 4 inches above the top of the horizontal pipe being served (See Note).b. No more than 20 inches below the flood rim of any fixture served by this product (See Note).c. At least 6 inches above insulation materials (See Note).d. In an accessible area.e. Within a space that allows air to enter the product and has an opening equivalent to requirements in sub. (14).f. With at least one 3-inch or larger diameter vent, serving the same building drain on which the AAV is installed, which extends to the atmosphere outside of the building. Note: The distance is measured from termination of the vent pipe to the point specified in the rule.
(f) AAVs shall be tested. The AAV shall be tested prior to or after installation. The AAV shall be subjected to a pressure equal to 1 inch of water column. After observing for 1 minute, if the pressure falls .5 of an inch or less, it will be considered a passing AAV.(g) When an AAV is installed in a building, the contractor shall provide the owner with a copy of the manufacturer's written AAV description.(18) PROHIBITED USES. A vent or vent system shall not be used for purposes other than the venting of the plumbing system. (a)Boiler blowoff basin vents. Vent piping from boiler blowoff basins shall not be connected to a vent or vent system serving a sanitary drain system, storm drain system or chemical waste system.(b)Chemical waste vents. Vent piping for chemical waste systems shall not be connected to a vent system serving a sanitary drain system or storm drain system.(c)Steam vents. Vents serving steam operated sterilizers, cleansing or degreasing equipment, pressing machines or any other apparatus which normally discharges steam into the vent shall not be connected to a vent or a vent system serving a sanitary drain system, storm drain system or chemical waste system.Wis. Admin. Code Department of Safety and Professional Services § SPS 382.31
Cr. Register, February, 1985, No. 350, eff. 3-1-85; am. (11) (a), (17) (b) 3. b. and (c) 2. b., r. and recr. (11) (b), r. (13) (a) 2., cr. (17) (b) 3. c. and (c) 2. c., Register, May, 1988, No. 389, eff. 6-1-88; reprinted to correct (17) (c) 4., Register, February, 1991, No. 422; cr. (4) (b) 4. and (17) (a) l. f., r. and recr. (5) (c) l. c. and (17) (c) 4., am. (5) (c) 2. c., (10) (intro.), (b) 1., (11) (b), (17) (a) l. e. and (17) (b), Register, August, 1991, No. 428, eff. 9-1-91; am. (6) (c), (7) (b), (10) (intro.), (a), (b) 1., (e), (13) (a) 1. c., (c) (intro.), 1. and 4., r. (16) (h), Register, February, 1994, No. 458, eff. 3-1-94; CR 02-002: renum. (8) to be (8) (a) and am., cr. (8) (b), (14) (j) and (16) (h), am. (11) (a), (12) (intro.), (a), (13) (c) 1. (17) (a) 1. (intro.) to b., and Table 82.31-4, r. and recr. Table 82.31-5, Register April 2003 No. 568, eff. 5-1-03; CR 08-055: am. (4) (a), (10) (c), (13) (a) 1. e., (14) (g) 2., (17) (a) 1. e., (b) 1. and 3., r. and recr. (5) and (6), r. (17) (a) 1. f. Register February 2009 No. 638, eff. 3-1-09; correction in (17) (a) 1. (intro.) made under s. 13.92(4) (b) 7, Stats., Register February 2009 No. 638; CR 10-064: am. (5) (a) 2., (6) (c), (17) (a) 2., r. (14) (g) 2., renum. (14) (g) 3. and 4. to be (14) (g) 2. and 3. Register December 2010 No. 660, eff. 1-1-11; correction in (14) (g) (intro.) made under s. 13.92(4) (b) 7, Stats., Register December 2010 No. 660; correction in (2), (5) (a) 2., (9) (a) 1., 2., (12) (d), (14) (a) (intro.), (b) 1., (c), (d), (e), (f), (g) 1., 2., 3., (i) 1. a., b., (j), (17) (a) 1. b., d., e., (b) 3. a., 6., (c) 2. a., 6. made under s. 13.92(4) (b) 7, Stats., Register December 2011 No. 672.Amended by, CR 23-006: r. and recr. (11) (a), (16) (d), (e), am. (17) (intro.), cr. (17) (d), (17m) Register September 2023 No. 813, eff. 10-1-23; correction in (16) (h), made under 13.92 (4) (b) 7., Stats., and correction in (16) (e), (17m) (e) 3. e., f., (f) made under s. 35.17, Stats., Register September 2023 No. 813, eff. 10/1/2023