Design Manual 421 Single Stack DWV System

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Single Stack

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Design Manual 421

Single Stack DWV System

PRINT DATE: 04/01/2021

Single Stack


INTRODUCTION TO SINGLE STACK

The Single Stack system is an engineered single-stack drainage concept for multi-story buildings typically three

stories and taller. Two primary fittings, the Aerator and De-aerator, in conjunction with standard DWV pipe and

fittings make the Single Stack concept unique by accomplishing the function of drainage, waste and venting within

one vertical pipe instead of two. This along with the elimination of individual fixture vents results in reduced costs,

reduced labor, and reduced space requirements.

HISTORY

The Single Stack system was developed in Switzerland in the 1950’s and represented the first time a scientific

approach was taken to the protection of trap seals in sanitary systems. The hydraulic and pneumatics characteristics

of intermittent flows were studied using a 10-story testing tower complete with measuring instruments. It was found

that controlled flow velocities reduced the excessive pressure excursions that can occur in traditional systems. The

unique interior geometry of the Single Stack fitting provides this control and maintains these pressures within

acceptable limits. Once fully perfected, the Single Stack system was marketed to other industrialized counties

around the world. Developed initially in cast iron, Single Stack was introduced to the United States marketplace in

the mid-1960s in the form of a copper DWV system. In 1977, Single Stack became available in hubless cast iron,

which offered superior noise suppression characteristics and ease of assembly.

APPROVALS

Single Stack Aerator and De-Aerator fittings are manufactured to conform to ASTM A1109.

Code approval procedures for Single Stack systems continue to change as model codes are revised and updated to

reflect new and different approaches to plumbing. Most model codes, including various city and state versions, do

not specifically address Single Stack systems and the approval process will differ slightly in each jurisdiction. Single

Stack approvals are often granted under Alternate Material & Methods or Alternate Engineered Design sections of

the prevailing code. In some cases, the approval must be sought for each individual project in a particular

jurisdiction.

Many areas require the manufacturers review and approval of the design and usually must bear the seal of a

Registered Professional Engineer having a license in that jurisdiction.

DESIGN

Wade Specification Drainage Products can assist with the approval process with respect to technical data and plan

review services. While traditional DWV plumbing systems certainly work well, the inventor and subsequent

developers of Single Stack have provided the industry with design criteria and techniques to engineer DWV systems.

This results in performance and savings that are attractive to the professionals of the plumbing industry is evidenced

by the fact that they continue to specify, install, and promote the use of Single Stack. The savings realized with the

use of this proven technological advancement in plumbing helps to maintain a healthy construction industry. Single

Stack is safe, economical, and functional. The performance record is excellent. Contact our office for ways Cast Iron

Single Stack can help you with your next multi-story project.

Single Stack Aerators and De-aerators may be used with stacks, branches, and run-outs made from any acceptable

DWV material providing proper transition couplings are used. Penetrations of floor/ceiling assemblies, shafts, and

fire rated assemblies must be incorporated in accordance with the Building Code requirements. The definition of

sweeps and bends shall be based on cast iron hubless fittings. The written rules shall prevail. Illustration drawings

are included for interpretation and clarity only. Designs and conditions not outlined in this manual shall be submitted

for approval. In accordance with our policy of continual product improvement, we reserve the right to amend

specifications without prior notification. Although every effort is made to ensure accuracy, Wade Specification

Drainage Products cannot be held responsible for errors and omissions in the printing of this manual. All Single

Stack technical data provided by Wade, including but not limited to drawings, catalogs, and consultations remain the

exclusive property of Wade. Use of this information for purposes other than Single Stack products made by Laperle

is strictly prohibited.

1

Single Stack


The Single Stack system controls the flow within the pipe to keep pressure excursions from exceeding +/- one-inch of water

column which is the standard for sanitary drainage systems. The system consists of a vertical stack open to the atmosphere,

horizontal branches to each fixture, Aerator fittings, and De-aerator fittings.

The Single Stack conveys waste from the upper levels of the building to the base of each stack. Flow through a vertical stack will

cling to the interior wall surface and proceed downward in a swirling motion leaving the center portion as an open airway. As long

as this airway exists, pressures are balanced within the stack. Left uncontrolled, the flow will increase in speed to a point known

as terminal velocity and can form a complete cross-sectional blockage of the tube. This will result in positive and negative

pressures ahead and behind the flow that may cause trap seal failures through induced siphonage and/or blowback. The Single

Stack system eliminates the formation of the "hydraulic plug" and maintains a core of air throughout the vertical stack.

The horizontal branches connect to the plumbing fixture and direct wastes to the Single Stack. Single Stack branch sizing criteria

allocates approximately 75% of the cross-sectional area for venting purposes. Single Stack branch design remains the key to

flexibility and the developed length limitations that exclude additional re-vent piping far exceed those of "traditional" systems. The

branch size may telescope allowing a possible run-out of fifty-seven feet without a return vent pipe. Developed length is

determined by measuring along the centerline of all horizontal piping located in the ceiling and/or wall space. The vertical drop

distance is not included in the calculation. A Single Stack system does not use the traditional "S-trap" configuration rather it

employs a sizing criteria designed to eliminate self-siphonage and provide proper venting. A typical Single Stack branch

connection to a lavatory would consist of a 1-1/4" tailpiece, a 1-1/2" trap-arm, and a 2" vertical drop making it impossible to

completely fill the 1-1/2" trap-arm with a 1-1/4" tailpiece – much less the 2" vertical drop.

The third component of a Single Stack system is the Aerator fitting. Aerators are placed in the vertical stack usually at each

typical floor level and must remain in a full upright position. They contain no moving parts and require no special tools for

maintenance. Their ability to balance the pressure excursions stem from the geometry of the full size waterways through the body

of the fitting. Two distinct chambers are found in the body of the Aerator fitting. One is called an offset chamber where flows from

the upper floors enter the fitting and actually "offset" around the horizontal branch inlets. This offset is designed to reduce the flow

velocity and also break up any "hydraulic plug" formation associated with terminal velocity. Once leaving the offset chamber it will

again cling to the interior surface of the pipe leaving the center area open for air. This occurs as the flow reaches Aerator fittings

at each floor and also eliminates the need for the "yoke-vents" required in "conventional" systems. Vertical distance between

Aerators must not exceed twenty feet. Interior baffles are situated to control the effects of flow through the Aerator. To guard

against blocking the cross-sectional area of the stack with a horizontal discharge, a second chamber is provided adjacent to the

offset chamber. This mixing chamber is completely separated from the vertical stack flow through the use of a separation baffle.

As horizontal flow enters the Aerator fitting, it must transition to a vertical flow before smoothly uniting with any stack flow. These

actions take place on an intermittent basis as both stack and branch flows may not be present simultaneously. At the top of the

separation baffle, a vent aperture or opening can be found. This provides the venting action between the branches and stack,

which balances any pressure fluctuations. A second baffle is located perpendicular to the separation baffle in the mixing chamber

to prevent cross-flow from opposing branch inlets.

The final component of the Single Stack system is the De-aerator fitting. It is located at the base of each stack and at any

horizontal stack offset. It is designed to effectively deal with the pressure fluctuations that occur when vertical flow transitions to

horizontal flow. This phenomenon is referred to as hydraulic jump and in some cases, can cause a complete cross-sectional

blockage of the horizontal pipe. The De-aerator fitting has two features designed to overcome these adverse effects. The first

feature is an internal nosepiece, which reduces the flow velocity prior to the horizontal transition. It also allows the air and waste

to separate thus balancing the internal pressures. The second feature of the De-aerator fitting is the Pressure Relief Line (P.R.L.).

The P.R.L. outlet is located on top of the De-aerator and is routed from the De-aerator to the horizontal drain. It connects to the

horizontal drain above the centerline at a minimum of distance of ten pipe diameters downstream from the stack. The ten pipe

diameters are based on the stack size (i.e. 4" stack = 40" minimum) and this places the P.R.L. connection beyond the hydraulic

jump zone. Note that all connections into the horizontal drain must meet this minimum distance requirement. The Single Stack

system terminates at the P.R.L. connection point to the horizontal drain

How Single Stack Works

2

Single Stack


3

Table A

Fixture Type Trap Size Fixture Unit

Bar Sink 1-1/2 2.0

Bath Group (Full) * 6.0

Bathtub 1-1/2 2.0

Bidet 1-1/2 2.0

Clothes Washer 2 4.0

Dishwasher 1-1/2 2.0

Disposer 1-1/2 3.0

Drinking Fountain 1-1/4 1.0

Floor Drain (2") 2 2.0

Floor Drain (3") 3 5.0

Kitchen Group *** 5.0

Lavatory 1-1/4 1.0

Table A-1 (Fixture Units for Water Saving Fixtures)

Fixture Type Trap Size Apartments &

Condominiums

Office Buildings &

Commercial Spaces Hotels & Motels

Bar Sink 1-1/4 0.5 0.5 0.5

Bath Group (Full) * 3.0 4.0

Bath Group (Half) ** 2.0 3.0

Bathtub 1-1/2 3.0 3.0

Bidet 1-1/2 1.0 1.0

Clothes Washer 2 4.0

Dishwasher 1-1/2 2.0 2.0

Disposer 1-1/2 0.5

Drinking Fountain 1-1/4 0.5

Floor Drain (Emergency) 2 thru 4 0.0 0.0 0.0

Kitchen Group *** 3.0

Lavatory 1-1/4 1.0 1.0 0.5

Service Sink 3 3.0 3.0 3.0

Shower 2 2.0 2.5

Sink 1-1/2 2.0 2.0 2.0

Urinal 2 3.0

Water Closet 3 3.0 3.0

Water Closet (Public) 3 4.0

Table A (continued)

Fixture Type Trap Size Fixture Unit

Lavatory 1-1/4 1.0

Service Sink 3 5.0

Shower 2 2.0

Sink 1-1/2 2.0

Urinal 2 4.0

Water Closet 3 6.0

All Other Fixtures

1-1/4 1.0

1-1/2 2.0

2 3.0

2-1/2 4.0

3 5.0

4 6.0

* Bath Group (Full) consists of (1) Water Closet (1) Lavatory and (1) Tub/Shower.

** Bath Group (Half) consists of (1) Water Closet and (1) Lavatory.

*** Kitchen Group consists of (1) Sink Trap with Dishwasher and Disposer.

Drainage Fixture Unit Values

Single Stack


4

Table B (Single Stack Loading)

Stack Size

(Inches)

Maximum Drainage

Fixture Units

3" * 64

3" (Over 7

Floors) * 102

4" 504

5" 1,010

6" 2,200

8" 3,900

* No more than 12 water closets are

permitted on 3" stacks. The 3" stack

will use a 4" De-Aerator at the base of

the stack.

Single Stack fittings are manufactured in accordance with ASTM A1109-18

Standard Specification for Special Fittings for Single-Stack Hubless Cast Iron

Soil Pipe Fittings for Sanitary, Waste and Vent Piping Applications

Table D (Branch Loading)

Maximum Drainage Fixture Units

Branch Size

(Inches)

Horizontal Piping

1/4" Per. Ft.

Slope

1/8" Per. Ft.

Slope

2" 6 ** 5 **

3" 16 13

4" 90 72

** No water closets are permitted on 2"

branch lines. Clothes washing machine

branch lines (2") shall not exceed five feet

(5’-0") in developed length.

Drainage Fixture Unit Values

Fixture Load Tables

Table B (Single Stack Stack Loading)

Stack Size (Inches) Maximum Drainage

Fixture Units

3" * 64

3" (Over 7 Floors) * 102

4" 504

5" 1,010

6" 2,200

8" 3,900

* No more than 12 water closets are permitted

on 3" stacks. The 3" stack will use a

4" De-Aerator at the base of the stack.

Table C (Building Drain Loading)


Drain Size

(Inches)

Horizontal Piping

1/4" Per. Ft.

Slope

1/8" Per. Ft.

Slope

4" 216 175

5" 350 280

6" 850 680

8" 2,700 2,160

10" 3,900 3,120

12" 5,800 4,640

Note: This Table is also used for sizing

horizontal stack offsets.



Drain Size

(Inches)

Horizontal Piping

1/4” Per. Ft.

Slope

1/8” Per. Ft.

Slope

3” 42 36

4” 120 96

5” 350 280

6” 850 680

8” 2,700 2,160

10” 3,900 3,120

12” 5,800 4,640

Note: This Table is also used for sizing horizon-

tal stack offsets.

Single Stack


5

Drawing 1

Sizing Requirements

Aerator and Stack Rules

See Table ‘B’ for

vertical stack

Extend stack full size thru roof

See to Table ‘C’ for

horizontal drain sizing

Refer to Table ‘D’ for horizontal

branch sizing

(A) The stack size shall be in accordance with Table B based on the total fixture unit load determined by Table A or

A-1.

(B) The stack shall not telescope or decrease in size and must be continued full size through the roof. (Drawing 1)

Single Stack


6

Drawing 2

Required Aerator Connections


Aerator Fitting

De-Aerator Fitting

Extend stack full size thru roof

(C.) An Aerator fitting is required at each level where the following horizontal branches enter the stack:

(Drawing 2) (1) Any soil branch (2) A waste branch the same size as the stack size (3) A waste branch one

pipe size smaller than the stack size.

(D.) The Aerator fitting must be placed in a vertical plane. Tilting the Aerator to offset the Single Stack stack is not

permitted.

Single Stack


7

Drawing 3

In-Line Offset Requirements

In-Line offsets are made using (1) quarter bend

and (2) eighth bends.

Maximum of (2) In-Line Offsets are permitted.


(E.) At any level where an Aerator is not required, an "in-line" offset consisting of two one-eighth bends and one

quarter bend may be used. The vertical distance between Aerators or "in-line" offsets shall not exceed twenty

feet (20’-0").

NO MORE THAN TWO CONSECUTIVE "IN-LINE" OFFSETS ARE PREMITTED. (Drawing 3)

Single Stack


8

(F.) Waste branches two pipe sizes smaller than the stack size may connect directly to the stack through a sani-

tary fitting. (Drawing 4)

Clear Waste water branches only. No soil branches from water closets are permitted.

Table F (Single Stack Waste

Branch Sizing) *

Stack Size

(Inches)

‘A’

Maximum Waste

Size

‘B’

3" 2"

4" 2 1/2"

5" 3"

6" 4"

* Clear Waste water branches only. No

soil branches from water closets are

permitted


Drawing 4

Direct Stack Connections

Stack Size ‘A’

Stack from upper floors

Stack Size ‘A’

Single Stack


9

(G) Horizontal stack offsets exceeding sixty degrees (60°) from vertical require a De-aerator fitting and Pressure

Relief Line (PRL). The Pressure Relief Line connects to the vertical portion of the stack downstream of the

offset. Soil and waste branches may connect to the horizontal portion of the offset. These connections should be

made between the two vertical portions of the stack at a minimum distance of ten pipe diameters (based on

stack size) downstream of the higher vertical stack. Branch connections to a horizontal stack offset less than ten

pipe diameters in length should be made as far downstream on the horizontal as possible. Soil and waste

branches must not connect where the offset makes a horizontal change of direction. Waste branches may

connect to the horizontal portion of the Pressure Relief Line (PRL), except on buildings with battery type water

closet installations. Waste branches shall be at least one pipe size smaller than the PRL. Waste branch

connections must not be made into any vertical portion of the PRL. Clothes washers must not connect to the

PRL. Horizontal stack offsets should be sized per Table ‘C’ based on the total fixture unit load of all fixtures

connecting to the offset and fixtures upstream. The entire stack size must not be smaller than the largest

horizontal offset size. (Drawing 5)


Drawing 5

Stack Offset Requirements

Stack from

upper floors

Installer is responsible for

proper support of piping

per local code authority.

PRL is not required to be directly above soil line. It is required to be at a higher elevation than the soil line prior to connection

Single Stack


10


Drawing 6

Combining Stacks

The PRL connection to the

horizontal drain terminates

the Single Stack system






(H) Single Stack stacks may be combined before entry into the main sewer connection. The stacks should combine

downstream of each Pressure Relief Line (PRL) termination point. The total fixture unit load of the combined

stacks determines collection main line sizing. (Drawing 6)

PRL is not required to be directly above soil line.

It is required to be at a higher elevation than the

soil line prior to connection

Single Stack


11

Waste & Soil Branch Rules

Drawing 40

Multiple Single Stack Connections

(I) An additional Single Stack may be connected to another Single Stack if a De-Aerator fitting is incorporated

below the stack Aerator fitting and a pressure relief line connects below the branch. The connection must be

made with a wye type fitting. Sizing of the branch is established by the drainage fixture units upstream of the

connection. Sizing for the main Single Stack is the total drainage fixture units of the combined stacks.

(Drawing 40)

PRL is not required to be directly above soil

line. It is required to be at a higher eleva-

tion than the soil line prior to connection

Single Stack


12

Drawing 7

Vent Offset Requirements


4" Stack

4" Stack

(J) Stack vent headers above the highest fixture may offset prior to the vent thru roof penetration (VTR). The

horizontal vent header and VTR should be increased one pipe size when exceeding twenty feet (20’-0") in

horizontal length. (Drawing 7)

Single Stack


13

Drawing 8

Vent Offset Requirements


4" Stack

4" Stack 4" Stack

4" Stack

(K) Stack vent headers above the highest fixture may be combined prior to the vent thru roof penetration (VTR)

with one vertical stack extending through the roof. The one combined vertical stack must be one pipe size

larger than the largest of the combined stacks. If the distance between any stack and the VTR exceeds twenty

feet (20’-0"), the horizontal offset shall be increased one (1) pipe size larger than the downstream stack.

(Drawing 8)

Single Stack


14

De-Aerator and Building Drain Rules

(A) A De-aerator fitting is required at the base of each stack. The De-aerator fitting shall be installed in the vertical

portion of the stack. The distance between the De-aerator fitting and the Single Stack building drain shall not

exceed five feet (5’-0"). (Drawing 9)


Drawing 9

Base of Stack Requirements





PRL is not required to be directly

above soil line. It is required to be

at a higher elevation than the soil

line prior to connection

Single Stack


15

(B) The Single Stack building drain size shall be in accordance with Table ‘C’ based on the total fixture unit load

determined by Table A or A-1. The transition to a larger Single Stack building drain size shall be made in the

vertical stack below the Deaerator fitting, except as noted in paragraph "L". (Drawing No. 10)

Drawing 10

Base of Stack Requirements




Drain Size

(Inches)

Horizontal Piping

1/4” Per. Ft.

Slope

1/8” Per. Ft.

Slope

3” 42 36

4” 120 96

5” 350 280

6” 850 680

8” 2,700 2,160

10” 3,900 3,120

12” 5,800 4,640

Note: This Table is also used for sizing horizon-

tal stack offsets.

Piping downstream of the Pressure Relief Line (PRL) is considered conventional

plumbing and shall be sized by the prevailing Plumbing Code or Table C, whichever is

applicable. Fixture unit values shall be based on data from Table A or Table A-1.


The Pressure Relief Line connection

to the horizontal drain terminates the

Single Stack system




Single Stack


16

(C) The De-Aerator fitting requires a Pressure Relief Line (PRL). The Pressure Relief Line (PRL) connects to the

Single Stack building drain a MINIMUM distance of ten pipe diameters (based on stack size) downstream from

the centerline of the stack. The PRL connects to the Single Stack building drain above the centerline of the

drain. The PRL may be rolled to the side providing the bottom of the PRL is above the centerline of the Single

Stack building drain. (Drawing 11)

Drawing 11

Pressure Relief Line Requirements

Minimum Pressure Relief

Line Elevation Requirements


Stack Size




PRL is not required to be directly above soil line.

It is required to be at a higher elevation than the

soil line prior to connection

Single Stack


17

(D) The installed slope for the Single Stack building drain and PRL is recommended to be one-quarter inch per

foot (2%). Installed slopes of one-eighth inch per foot (1%) are permitted, however pipe capacity is reduced by

a factor of 0.8 as shown in Table C. Installed slopes less than one-eighth inch per foot (1%) are strictly

prohibited. (Drawing 12)

Drawing 12

Installed Slope Requirements



Building Drain Line



Drain Size

(Inches)

Horizontal Piping

1/4” Per. Ft.

Slope

1/8” Per. Ft.

Slope

3” 42 36

4” 120 96

5” 350 280

6” 850 680

8” 2,700 2,160

10” 3,900 3,120

12” 5,800 4,640

Note: This Table is also used for sizing horizontal

stack offsets.

Single Stack


18


(E) Soil and waste branches may connect to the Single Stack building drain BETWEEN the centerline of the stack

and the termination point of the Pressure Relief Line (PRL). All connections shall be made a MINIMUM distance

of ten pipe diameters (based on stack size) downstream from the centerline of the stack. (Drawing No. 13)

See Table ‘C’ for Horizontal

Single Stack Drain Sizing

Note: Minimum distance requirements apply to any connection into the horizontal drain.

Drawing 13

Base of Stack Connections

Note: Recommended Lavatory waste is 1-1/4’ tailpiece with 1-1/2" trap arm.

Min. 10 Pipe Diameters

(Based on Stack Size)

Stack Size



Drain Size

(Inches)

Horizontal Piping

1/4” Per. Ft.

Slope

1/8” Per. Ft.

Slope

3” 42 36

4” 120 96

5” 350 280

6” 850 680

8” 2,700 2,160

10” 3,900 3,120

12” 5,800 4,640

Note: This Table is also used for sizing hori-

zontal stack offsets.

Single Stack


19


Drawing 14

Base of Stack Connections

(F) Soil and waste branches cannot connect where the Single Stack building drain makes a horizontal change of

direction. (Drawing 14)

Single Stack


20


Drawing 15

Branch Connections to P.R.L.

(G) Waste branches may connect to the horizontal portion of the Pressure Relief Line (PRL), except on battery type

installations. Waste branches shall be at least one pipe size smaller than the PRL. Waste branch connections

shall not be made into any vertical portion of the PRL. Clothes washers must not connect to the PRL.

(Drawing No. 15)

Note: Recommended Lavatory waste is 1-1/4" tailpiece with 1-1/2" trap arm.

Soil branches are not allowed to connect to PRL.

Minimum 10 Pipe Diameters

(Based on Stack Size)





Table H (Maximum Branch Size)


PRL Size

(Inches)

Max. Branch

Size

PRL Max.

DFU’s

3” 2 1/2” 16

4” 3” 90

6” 3” 90

Note: Minimum distance requirements

apply to any connection into a horizontal

drain line. Connections to PRL are for

clear water waste only—No soil waste

allowed; No clothes washers; No

connections allowed on any vertical

portion of the PRL.

Single Stack


21


(H) Soil and waste branches may connect downstream of the Pressure Relief Line (PRL) termination point

providing conventional plumbing rules are applied. The vent header from these fixtures may connect to the

vertical portion of a Single Stack stack below an Aerator fitting through a sanitary tee installed with the flow

radius down. The vent load of these fixtures shall be added to the fixture unit load on the Single Stack stack.

(Drawing No. 16)

Drawing 16

Conventional Remote Venting

Remote "conventional" plumbing.

Size waste and vents per local code.



Note 1: the Pressure Relief Line

(PRL) connection to the horizontal

drain terminates the Single Stack

System.


Single Stack


22


(I) Soil and waste branches may connect to the vertical stack below the De-aerator fitting. These connections shall

be made through a wye-type fitting or through an Aerator fitting. (Drawing No. 17)

Drawing 17 De-Aerator Transition Details

PRL = Pressure Relief Line

W.C. = Water Closet

PRL = Pressure Relief Line

F.M.B.O. = Floor Mount Back Outlet

W.C. = Water Closet

Single Stack


23


(J) Entry to the Single Stack building drain from the stack shall be made using a short sweep (where allowed by

code), long sweep, two one-eighth bends, or a combination wye & one-eighth bend with blind plug upstream.

Drawing 18 De-Aerator Transition Details

Short Sweep (where allowed by local code)

Single Stack


24


(K) Fixtures considered too remote from the Single Stack may be plumbed by conventional methods. This waste

and vent area shall be sized in accordance with local prevailing ordinances. (Drawings 16 & 19)

Drawing 19

Remote Plumbing Connections




Stack continues to lower floors

Single Stack


25


(L) Commercial building battery type installations and Single Stack stacks serving clothes washers shall use a De-

Aerator fitting equal in size to the Single Stack building drain serving that stack. A four-inch (4") De-aerator fitting

will be required on three-inch (3") Single Stack. (Drawing 20)

Drawing 20

Battery Installations

Single Stack


26

Branch Line Rules

(A) The maximum developed length of a three-inch (3") soil branch shall not exceed twelve feet (12’-0"). (Drawing

21)

Soil Branch Rules

Drawing 21

3" Soil Branch Developed Lengths

(B) The maximum developed length of a four-inch (4") soil branch shall not exceed twenty-seven feet (27’-0").

(Drawing 22)

Drawing 22

4" Soil Branch Developed Lengths

Maximum 12'-0"

Maximum 27'-0"

Single Stack


27

Soil Branch Rules

(C) Developed lengths are measured along the centerline of all horizontal branch piping located in ceiling and wall

areas. Vertical drops from trap arms or fixtures are not included in the developed length calculations. Developed

length distances include 45⁰ elevation changes. (Drawing 22)

Drawing 22

3" & 4" Combined Soil Branch Developed Lengths

Maximum 12'-0"

Maximum 27'-0"

Single Stack


28

(D) The maximum developed length of a two-inch (2") waste branch shall not exceed fifteen feet (15’-0"). The

maximum developed length of a three-inch (3") waste branch shall not exceed fifteen feet (15’-0"). Developed

lengths are measured along the centerline of all horizontal branch piping located in ceiling and wall areas.

Vertical drops from trap arms or fixtures are not included in the developed length calculations. Waste branches

two pipe sizes smaller than the stack size may connect directly to the stack through a sanitary fitting.

(Drawing 23)

Clear Waste Branch Rules

Drawing 23

Waste Branch Developed Lengths

Maximum 15'-0"

Maximum 15'-0"

Maximum 15'-0"

3" 3" 3"

3"

Developed length distances shall

include 45° elevation changes

Note: Recommended Lavatory waste is 1-1/4" tailpiece

with 1-1/2" trap arm

Single Stack


29

(E) Telescoping branches are allowed; each size can accommodate the maximum developed length for that size:

A two-inch (2") waste branch shall not exceed fifteen feet (15'-0"); a three-inch (3") waste branch shall not

exceed fifteen feet (15'-0"); a four-inch (4") waste branch shall not exceed twenty seven feet (27'-0").

Developed lengths are measured along the centerline of all horizontal branch piping located in ceiling and wall

areas. Vertical drops from trap arms or fixtures are not included in the developed length calculations. Waste

branches two pipe sizes smaller than the stack size may connect directly to the stack through a sanitary fitting.

(Drawing 24)

Waste Branch Rules

Drawing 24


Maximum 15'-0"

Maximum 15'-0"

Maximum 15' 0"

Maximum 27'-0"

Maximum 15'-0"

Single Stack


30

(F) Branch sizing shall be in accordance with Table D based on the total fixture unit load determined by Table A or

A-1. The installed slope for horizontal branches is recommended to be one-quarter inch per foot (2%). Installed

slopes of one-eighth inch per foot (1%) are permitted however pipe capacity is reduced by a factor of 0.8 as

shown in Table D. Installed slopes less than one-eighth inch per foot (1%) are strictly prohibited.

(G) Branches having three ninety degree (90°) horizontal changes of direction shall be increased one pipe size at

the third ninety degree ( 90°) change of direction nearest the stack. (Drawing 25)

Waste Branch Rules

Drawing 25

Change of Direction Branch Detail

(H) This increase is not required if one of the directional changes can be made with two one-eighth bends or a short

sweep radius bend. (Drawing 26)

Drawing 26


Single Stack


31

Waste Branch Rules

(I) The transition from a horizontal or vertical branch to another horizontal branch must be made with a wye-type

fitting. (Drawing 27)

(J) Horizontal branch piping at the base of a vertical drop exceeding forty inches (40") in height shall be increased

one pipe size. This increase is not required when the lower portion of the drop is made at forty-five degrees

(45°) and the upper vertical portion is less than forty inches (40"). (Drawing No. 28)

Drawing 28

Branch Sizing—Vertical Drops

40" or Less

Over 40"

40" or

Less

Over 40"

Drawing 27


Note: Recommended Lavatory waste is

1-1/4" tailpiece with 1-1/2" trap arm.

Single Stack


32

Waste Branch Rules

(K) Branch piping with vertical drops exceeding ten feet (10’-0") shall be increased one pipe size. (Drawing 29)

Drawing 29


Single Stack


33

Waste Branch Rules

Drawing 30

Soil Branch Connection Detail

(L) A three-inch (3") soil branch shall be increased one pipe size at the connection

point of other fixtures. This increase is not required when computing fixture unit

loads from Table A-1. (Drawing 30)

(M) Two fixtures using 1-1/4" tailpiece/trap sizes may combine into a single two-inch (2") vertical drop. (Drawing 31)

Drawing 31

Combining Branches into a Vertical Drop

Note: Recommended Lavatory

waste is 1-1/4" tailpiece with 1-1/2"

trap arm.

Single Stack


34

Waste Branch Rules

(N) Fixtures using 1-1/2" tailpiece/trap sizes and larger require separate vertical drops from each trap arm or may

combine into a single vertical drop that is increased one pipe size. This increase is not required if the change in

elevation is made at forty-five degrees (45°). The fixture trap arm shall be one pipe size larger than the fixture

tailpiece and this increase may be made at the wall. (Drawing 32)

Drawing 32



Single Stack


35

Waste Branch Rules

Drawing 33

Clothes Washer Branch

Maximum 5'-0"

Maximum 15'-0"

Clothes washer branches shall be three-inch (3") in size. Clothes washer branches with

no vertical drops and developed lengths five feet (5'-0") or less may be two-inch (2") in

size. (Drawing 33)

Single Stack


36


(O) Soil branch connections to the Single Stack shall be made through the "C" and/or "D" inlet of the Aerator fitting.

Soil branch developed lengths shall not exceed 12'-0" for a three inch branch size or 27'-0" for a four inch

branch size. (Drawing 34)

Maximum 12’-0"

Maximum 27’-0"

Drawing 34

Soil Branch Developed Lengths

Single Stack


37

(P) Pressure Equalizing Lines may be used as an alternate to the rules concerning increased branch sizes.

Pressure Equalizing Lines shall rise vertically above the branch and connect to the Single Stack stack above the

flood rim of the fixtures they serve. Pressure Equalizing Lines may be routed directly through the roof.

(Q) Soil branch lengths beyond the limits stated in paragraph (P) will require a conventional vent or a 2" Pressure

Equalizing Line (PEL). The vent header or PEL may connect to the Single Stack stack a minimum of 3'-0"

above the Aerator fitting. (Drawing 35)

Waste Branch Rules

Drawing 35

Clothes Washer Branch

Over 27’-0"

Over 15’-0"

Table I

(Minimum Pressure Equalizing Line)

Branch Size (Inches) Pressure Equalizing

Line Size (Inches)

4" 2"

3" 1-1/2"

2" 1-1/4"

Single Stack


38


Drawing 36


Maximum 15'-0"

Maximum 15'-0"

Maximum 27'-0"

Maximum 15'-0"

(R) Waste branch developed lengths shall not exceed 15'-0" for two or three inch pipe sizes; Waste branch

developed lengths shall not exceed 27'-0" for four inch pipe sizes. Developed lengths beyond these limits

require a convention vent or a Pressure Equalizing Line (PEL). The vent header or PEL may connect to the

Single Stack a minimum of 3'0" above the Aerator fitting. (Drawing 36)


Single Stack


39


Drawing 37

Waste & Soil Branch Connections

(S) Waste branches one pipe smaller than the pressure relief line (PRL) may connect to the PRL. Soil branches

and washing machine connections are not allowed. No connections are permitted into any vertical portion of

the PRL. Note 1: Soil and waste branches may connect to the horizontal drain between the Single Stack stack

and the PRL termination provided the connection is a minimum of 10 pipe diameters downstream of the stack

centerline.

The De-Aerator fitting may be installed above the finished floor providing it is within 5'-0" of the horizontal drain.

(Drawing 37)


Single Stack


40


(T) Horizontal stack offsets shall be sized per Table ‘C’ based on

the drainage fixture unit loading of all upstream fixtures.

Increasing the horizontal drain size at this point will require an

increase of the entire stack size from just above the lowest

level de-aerator fitting and continued to the vent terminal. The

pressure relief line (P.R.L.) shall connect to the vertical portion

of the stack downstream of the offset. The horizontal drain at

the base of the Single Stack shall be sized per Table ‘C’ and

shall not be smaller than the required stack size. (Drawing 38)

Drawing 38

Multiple Offset Stack Requirements



Drain Size

(Inches)

Horizontal Piping

1/4” Per. Ft.

Slope

1/8” Per. Ft.

Slope

3” 42 36

4” 120 96

5” 350 280

6” 850 680

8” 2,700 2,160

10” 3,900 3,120

12” 5,800 4,640

Note: This Table is also used for sizing horizontal

stack offsets.

Single Stack


41


Drawing 39

Multiple Vent Header Sizing Requirements

(U) Multiple Vent Header Sizing Requirements. (Drawing 39)

Note 1: The horizontal portion of each individual vent header that exceeds 20'-0" in length shall be increased

one pipe size larger than the downstream stack size.

Note 2: The vent header from two combined vent headers shall be increased one pipe size larger than the

largest individual vent. This increased sizing does not apply if previously made as noted above.

Note 3: Sizing for three or more combined vent headers is based on the cumulative drainage fixture unit total

from each stack and capacities shown in Table J.

Table J

Vent Header Size

(Inches) Maximum D.F.U. Load

5" 600

6" 1380

8" 3600

Single Stack


42

Aerator Rough-In and Block-out

Single Stack is adaptable to most multi-story projects with minimal structural impact and in many instances reduces space

requirements for DWV systems. The available space for dropped ceilings will alter the Aerator fitting location and the resulting

slab penetration. The following illustrations are minimal cored opening or block-out conditions for 4" pipe size Aerator fittings.

Note: Dimensions of Aerator rough-in can be

altered if a slab relief is provided on the bottom

of the cored opening or a larger diameter core

is utilized.

Slab Block-out

Cored Slab

Single Stack


43

De-Aerator Rough-In

The De-Aerator fitting is often located above the finish floor to reduce ceiling space requirements. The following

illustrations show dimensional data for connection methods to the De-Aerator fitting.

4" De-Aerator w/ PRL Fitting 4" De-Aerator w/ Upright Wye & Cap

4" De-Aerator w/ Quarter Bends 4" De-Aerator w/ Quarter Bends & Eighth Bends

Single Stack


44

Supplemental Illustrations

The following pages are to be used for interpretation and clarity of the written rules listed on the preceding pages. The

written rules shall take precedence over all illustrations. All possible scenarios are not covered by these illustrations.

Designs and conditions not shown may require approval by the manufacturer.

System Page

Water Closet Connections (Floor Mount Floor Outlet)……………………………………………... 47

Water Closet Connections (Wall Hung Foot Support)……………………………………………….48

Water Closet Connections (Floor Mount Back Outlet)……………………………………………... 49

Bathroom Connections (Water Closet / Lavatory / Tub)…………………………………………… 50



Bathroom Connections (Water Closet / Lavatory / Tub) Back to Back…………………………… 53

Bathroom Connections (Water Closet / Lavatory / Shower / Bidet)………………………………. 54

Bathroom Connections (Water Closet / Lavatory / Tub / Shower / Sink)………………………… 55

Miscellaneous Connections (Floor Drain / Water Cooler / Shower / Mop Sink / Sink)…………. 56

Commercial Building Connections (Water Closets / Urinals / Floor Drains)…………………….. 57

Single Stack


45

Typical Layouts

Water Closet Connections

Typical Floor Mount Floor Outlet

Single Stack


46

Typical Layouts


Wall Hung Foot Supported

Single Stack


47

Typical Layouts


Typical Floor Mount Back Outlet

Single Stack


48

Typical Layouts

Bathroom Connections

Water Closet / Tub / Lavatory (Back to Back)


Single Stack


49

Typical Layouts




Single Stack


50

Typical Layouts



Single Stack


51

Typical Layouts



Single Stack


52

Typical Layouts


Water Closet / Shower / Lavatory / Bidet


Single Stack


53

Typical Layouts


Water Closet / Tub / Shower / Lavatories / Sink


Single Stack


54

Typical Layouts

Miscellaneous Fixture Connections

Wash Machine / Shower / Sink / Water Cooler / Mop Sink

Single Stack


55

Typical Layouts

Commercial Building Connections

Water Closets / Floor Drains / Urinal

Single Stack


56

Terms and Conditions of Sale

Single Stack


57

Terms and Conditions of Sale

Single Stack


58

Specification and Manufacturer Services

We suggest the following specification.

The Cast Iron Single Stack DWV system shall be installed in accordance with approved construction plans and specifications,

and in compliance with criteria set forth by Design Manual #119 as published by Wade Specification Drainage Products.

The cast iron single stack Aerator and De-aerator fittings shall be manufactured and distributed by Wade. The Aerator and De-

aerator fittings shall be in compliance with ASME Standard A1109 as published by the American Society of Mechanical

Engineers.

Contact Wade Specification Drainage Products by phone at 800-638-9537 or fax at 888-879-9233 for additional information.

MANUFACTURER SERVICES

In addition to normal business services, Wade Specification Drainage Products will:

• Furnish complete technical assistance and information on the latest techniques of design, installation and inspection of the

Cast Iron Single Stack system.

• Provide design/drawing assistance, plans check, and drawing review.

• Provide Value Engineering assistance.

• Provide field inspection service with written reports furnished to all designated parties. Inspections and reports will be

subject to a negotiated, equitable fee.

• Provide assistance in training of designers, installers and inspectors on an as needed, invitational basis. Seminars will be

subject to a negotiated, equitable fee.

These services assume the obvious. Wade Specification Drainage Products shall furnish all Cast Iron Single Stack products and

the design shall comply with all appropriate criteria set forth by Design Manual #119.

DESIGN NOTES

All Cast Iron Single Stack technical data provided by Wade including but not limited to drawings, catalogs, and consultations

remain the exclusive property of Wade Specification Drainage Products. Use of this information for purposes other than Single

Stack products made by Wade is strictly prohibited and may result in the assessment of fees or charges.

The Wade Single Stack system represents a logical advancement in the technology of sanitary drainage systems. This

manual is intended to address basic plumbing rules that apply when designing, installing, or inspecting a Cast Iron

Single Stack system.

The use of Single Stack Design Manual #119 along with good plumbing practices and techniques will assure a safe and modern

plumbing system. Installation requirements such as clean-outs, hydraulic integrity, support systems, slab penetrations and

fireproofing do not differ from traditional DWV practices and continue to be the responsibility of the designers, installers and

inspectional authorities.

Single Stack Aerators and De-aerators may be used with stacks, branches, and run-outs made from any acceptable DWV

material providing proper transition couplings are used. Penetrations of floor/ceiling assemblies, shafts, and fire rated assemblies

must be protected in accordance with the Building Code requirements.

The definition of sweeps and bends shall be based on cast iron hubless fittings manufactured in accordance with ASTM Standard

A888.

In reference to Design Manual #119, the written rules shall prevail. Illustration drawings are included for interpretation and clarity

only.

Designs and conditions not outlined in this manual shall be submitted for approval to Wade Specification Drainage Products.

In accordance with our policy of continual product improvement, we reserve the right to amend specifications without prior

notification. Although every effort is made to ensure accuracy, Wade Specification Drainage Products cannot be held responsible

for errors and omissions in the printing of this manual.

Single Stack


59

Single Stack Aerator Rules

(A) The stack size shall be in accordance with Table B based on the total fixture unit load determined by Table A or

A-1.

(B) The stack shall not telescope or decrease in size and must be continued full size through the roof.

(C) An Aerator fitting is required at each level where the following horizontal branches enter the stack:

• Any soil branch

• A waste branch the same size as the stack size.

• A waste branch one pipe size smaller than the stack size

• The Aerator fitting shall be placed in a vertical plane. Tilting the Aerator to offset the Sovent® stack is not

permitted.

• At any level where an Aerator is not required, an "in-line" offset consisting of two one-eighth bends and one

quarter bend may be used. The vertical distance between Aerators or "in-line" offsets shall not exceed twenty

feet (20’-0"). No more than two consecutive "in-line" offsets are permitted.

(F) Waste branches two pipe sizes smaller than the stack size may connect directly to the stack through a sanitary

fitting.

(G) Horizontal stack offsets exceeding sixty degrees (60) from vertical require a De-aerator fitting and Pressure

Relief Line (PRL). The Pressure Relief Line (PRL) shall connect to the vertical portion of the stack downstream of

the offset. Soil and waste branches may connect to the horizontal portion of the offset. These connections shall be

made BETWEEN the two vertical portions of the stack at a minimum distance of ten pipe diameters (based on stack

size) downstream of the higher vertical stack. Branch connections to a horizontal stack offset less than ten pipe

diameters in length shall be made as far downstream on the horizontal as possible. Soil and waste branches shall

not connect where the offset makes a horizontal change of direction. Waste branches may connect to the horizontal

portion of the Pressure Relief Line (PRL), except on office building battery type installations. Waste branches shall

be at least one pipe size smaller than the PRL. Waste branch connections shall not be made into any vertical portion

of the PRL. Clothes washers shall not connect to the PRL. Horizontal stack offsets shall be sized per Table C based

on the total fixture unit load of all fixtures connecting to the offset and fixtures upstream. The entire stack size shall

be no smaller than the largest horizontal offset size.

(H) Wade Single Stack may be combined before entry into the main sewer drain. The stacks shall combine

downstream of each Pressure Relief Line (PRL) termination point. The total fixture unit load of the combined stacks

determines collection drain line sizing.

(I) Stack vent headers above the highest fixture may offset prior to the vent thru roof penetration (VTR). The

horizontal vent header and VTR shall be increased one pipe size when exceeding twenty feet (20’-0") in horizontal

length.

(J) Stack vent headers above the highest fixture may be combined prior to the vent thru roof penetration (VTR) with

one vertical stack extending through the roof. The one combined vertical stack shall be one pipe size larger than the

largest of the combined stacks. If the distance between any stack and the VTR exceeds twenty feet (20’-0"), the

horizontal offset shall be increased one (1) pipe size larger than the downstream stack.

Single Stack


60

Single Stack De-Aerator Rules

(A) A De-aerator fitting is required at the base of each stack. The De-aerator fitting shall be installed in the vertical portion of the

stack. The distance between the De-aerator fitting and the building drain shall not exceed five feet (5’-0").

The building drain size shall be in accordance with Table C based on the total fixture unit load determined by Table A or A-1. The

transition to a larger building drain size shall be made in the vertical stack below the Deaerator fitting, except as noted in

paragraph "I".

(B) The De-aerator fitting uses a Pressure Relief Line (PRL). The Pressure Relief Line (PRL) connects to the Single Stack system

building drain a MINIMUM distance of ten pipe diameters (based on stack size) downstream from the centerline of the stack. The

PRL connects to the Single Stack building drain above the centerline of the drain. The PRL may be rolled to the side providing the

bottom of the PRL is above the centerline of the Single Stack system building drain.

(C) The installed slope for the Single Stack system building drain and PRL is recommended to be one-quarter inch per foot (2%).

Installed slopes of one-eighth inch per foot (1%) are permitted however pipe capacity is reduced by a factor of 0.8 as shown in

Table C. Installed slopes less than one-eighth inch per foot (1%) are strictly prohibited.

(D) Soil and waste branches may connect to the building drain BETWEEN the centerline of the stack and the termination point of

the Pressure Relief Line (PRL). All connections shall be made a MINIMUM distance of ten pipe diameters (based on stack size)

downstream from the centerline of the stack. Soil and waste branches shall not connect where the building drain makes a

horizontal change of direction.

(E) Waste branches may connect to the horizontal portion of the Pressure Relief Line (PRL), except on battery type installations.

Waste branches shall be at least one pipe size smaller than the PRL. Waste branch connections shall not be made into any

vertical portion of the PRL. Clothes washers shall not connect to the PRL.

(F) Soil and waste branches may connect downstream of the PRL termination point providing conventional plumbing rules are

applied. The vent header from these fixtures may connect to the vertical portion of a stack below an Aerator fitting through a

sanitary tee installed with the flow radius down. The vent load of these fixtures shall be added to the fixture unit load on the Single

Stack system.

(G) Soil and waste branches may connect to the vertical stack below the De-aerator fitting. These connections shall be made

through a wye-type fitting or through an Aerator fitting. Entry to the building drain from the stack shall be made using a short

sweep, long sweep, two one-eighth bends, or a combination wye & one-eighth bend fitting.

(H) Fixtures considered too remote from the Single Stack system may be plumbed by conventional methods. This waste and vent

area shall be sized in accordance with local prevailing ordinances.

(I) Office building battery type installations and Single Stack systems serving clothes washers shall use a De-aerator fitting equal

in size to the building drain serving that stack. A four-inch (4") De-aerator fitting will be required on three-inch (3") Single Stack

system.

Documents

Design Manual 421 Single Stack DWV System