CODES

ADOPTS WITH AMENDMENTS:

International Plumbing Code 2015 (IPC 2015)

Chapter 1 Scope and Administration

Chapter 2 Definitions

Chapter 3 General Regulations

Chapter 4 Fixtures, Faucets and Fixture Fittings

Chapter 5 Water Heaters

Chapter 6 Water Supply and Distribution

Chapter 7 Sanitary Drainage

Chapter 8 Indirect/Special Waste

Chapter 9 Vents

Chapter 10 Traps, Interceptors and Separators

Chapter 11 Storm Drainage

Chapter 12 Special Piping and Storage Systems

Chapter 13 Nonpotable Water Systems

Chapter 14 Subsurface Landscape Irrigation Systems

Chapter 15 Referenced Standards

Appendix A Plumbing Permit Fee Schedule

Appendix B Rates of Rainfall for Various Cities

Appendix C Structural Safety

Appendix D Degree Day and Design Temperatures

Appendix E Sizing of Water Piping System

1101.1 Scope

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The provisions of this chapter shall govern the materials, design, construction and installation of storm drainage except one- and two-family dwellings.

1101.2 Disposal

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Rainwater from roofs and storm water from paved areas, yards, courts and courtyards shall drain to an approved place of disposal. For one- and two-family dwellings, and where approved, storm water is permitted to discharge onto flat areas, such as streets or lawns, provided that the storm water flows away from the building.
Storm water shall not be drained into sewers intended for sewage only.
The conductors and the building storm drain shall be tested in accordance with Section 312.
The size of a drainage pipe shall not be reduced in the direction of flow.
All connections and changes in direction of the storm drainage system shall be made with approved drainage-type fittings in accordance with Table 706.3. The fittings shall not obstruct or retard flow in the system.
Roofs shall be designed for the maximum possible depth of water that will pond thereon as determined by the relative levels of roof deck and overflow weirs, scuppers, edges or serviceable drains in combination with the deflected structural elements. In determining the maximum possible depth of water, all primary roof drainage means shall be assumed to be blocked. The maximum possible depth of water on the roof shall include the height of the water required above the inlet of the secondary roof drainage means to achieve the required flow rate of the secondary drainage means to accommodate the design rainfall rate as required by Section 1106.
Cleanouts shall be installed in the storm drainage system and shall comply with the provisions of this code for sanitary drainage pipe cleanouts.

Exception: Subsurface drainage system.
Storm drainage systems shall be provided with backwater valves as required for sanitary drainage systems in accordance with Section 715.
The materials and methods utilized for the construction and installation of storm drainage systems shall comply with this section and the applicable provisions of Chapter 7.

1102.2 Inside Storm Drainage Conductors

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Inside storm drainage conductors installed above ground shall conform to one of the standards listed in Table 702.1.

Exception: Plastic pipe with an inside diameter of 2 inches and larger shall not be used for storm drainage conductors in buildings in which the top occupied floor exceeds 75 feet (23 m) in height.
Underground building storm drain pipe shall conform to one of the standards listed in Table 702.2.
Building storm sewer pipe shall conform to one of the standards listed in Table 1102.4.

TABLE 1102.4 BUILDING STORM SEWER PIPE

MATERIAL STANDARD
Acrylonitrile butadiene
styrene (ABS) plastic pipe
ASTM D 2661; ASTM D 2751; ASTM F 628; CSA B181.1; CSA B182.1
Cast-iron pipe ASTM A 74; ASTM A 888; CISPI 301
Concrete pipe ASTM C 14; ASTM C 76;
CSA A257.1M; CSA A257.2M
Copper or copper-alloy
tubing (Type K, L, M or DWV)
ASTM B 75; ASTM B 88; ASTM B 251; ASTM B 306
Polyethylene (PE) plastic pipe ASTM F 2306/F 2306M
Polyvinyl chloride (PVC)
plastic pipe (Type DWV, SDR26, SDR35, SDR41,
PS50 or PS100)
ASTM D 2665; ASTM D 3034; ASTM F 891; CSA B182.4; CSA B181.2; CSA B182.2
Vitrified clay pipe ASTM C 4; ASTM C 700
Stainless steel drainage systems, Type 316L ASME A112.3.1
Subsoil drains shall be openjointed, horizontally split or perforated pipe conforming to one of the standards listed in Table 1102.5.

TABLE 1102.5 SUBSOIL DRAIN PIPE

MATERIAL STANDARD
Cast-iron pipe ASTM A 74; ASTM A 888;
CISPI 301
Polyethylene (PE) plastic pipe ASTM F 405; CSA B182.1;
CSA B182.6; CSA B182.8
Polyvinyl chloride (PVC)
Plastic pipe (type sewer pipe,
SDR35, PS25, PS50 or PS100)
ASTM D 2729; ASTM D 3034,
ASTM F 891; CSA B182.2; CSA
B182.4
Stainless steel drainage systems,
Type 316L
ASME A 112.3.1
Vitrified clay pipe ASTM C 4; ASTM C 700
Roof drains shall conform to ASME A112.6.4 or ASME A112.3.1.

1102.7 Fittings

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Pipe fittings shall be approved for installation with the piping material installed, and shall conform to the respective pipe standards or one of the standards listed in Table 1102.7. The fittings shall not have ledges, shoulders or reductions capable of retarding or obstructing flow in the piping. Threaded drainage pipe fittings shall be of the recessed drainage type.

Exception: Plastic pipe fittings and plastic plumbing appurtenances with an inside diameter of 2 inches and larger shall not be used for storm drainage conductors in buildings in which the top occupied floor exceeds 75 feet (23 m) in height.

TABLE 1102.7 PIPE FITTING

MATERIAL STANDARD
Acrylonitrile butadiene
styrene (ABS) plastic
ASTM D 2661; ASTM D 3311; CSA B181.1
Cast-iron ASME B16.4; ASME B16.12; ASTM A 888; CISPI 301;
ASTM A 74
Coextruded composite ABS
and drain DR-PS in
PS35, PS50, PS100, PS140, PS200
ASTM D 2751
Coextruded composite ABS DWV Schedule 40 IPS pipe (solid or cellular core) ASTM D 2661; ASTM D 3311; ASTM F 628
Coextruded composite PVC DWV Schedule 40 IPS-DR, PS140, PS200 (solid or cellular core) ASTM D 2665; ASTM D 3311; ASTM F 891
Coextruded composite PVC sewer and drain DR-PS in PS35, PS50, PS100, PS140, PS200 ASTM D 3034
Copper or copper alloy ASME B16.15; ASME B16.18; ASME B16.22; ASME B16.23; ASME B16.26; ASME B16.29
Gray iron and ductile iron AWWA C110/A21.10
Malleable iron ASME B16.3
Plastic, general ASTM F 409
Polyethylene (PE) plastic pipe ASTM F 2306/F 2306M
Polyvinyl chloride (PVC)
plastic
ASTM D 2665; ASTM D 3311; ASTM F 1866 (10 inches in diameter and larger)
Steel ASME B16.9; ASME B16.11; ASME B16.28
Stainless steel drainage systems, Type 316L ASME A112.3.1

Section 1103 Traps

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

1103.1 Main Trap

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Leaders and storm drains connected to a combined sewer shall be trapped. Individual storm water traps shall be installed on the storm water drain branch serving each conductor, or a single trap shall be installed in the main storm drain just before its connection with the combined building sewer or the public sewer. Leaders and storm drains connected to a building storm sewer shall not be required to be trapped.

1103.2 Material

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Storm water traps shall be of the same material as the piping system to which they are attached.

1103.3 Size

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Traps for individual conductors shall be the same size as the horizontal drain to which they are connected.

1103.4 Cleanout

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
An accessible cleanout shall be installed on the building side of the trap.
Conductor pipes shall not be used as soil, waste or vent pipes, and soil, waste or vent pipes shall not be used as conductors.
Floor drains shall not be connected to a storm drain.
Roof drains shall be installed in accordance with the manufacturer’s instructions. The inside opening for the roof drain shall not be obstructed by the roofing membrane material.

1105.1.1 Strainers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Roof drains shall have strainers extending not less than 3 inches (76 mm) above the surface of the roof immediately adjacent to the roof drain. Strainers shall have an available inlet area, above roof level, of not less than one and one-half times the area of the conductor or leader to which the drain is connected.

1105.1.2 Flat decks

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Roof drain strainers for use on sun decks, parking decks and similar areas that are normally serviced and maintained shall comply with Section 1105.1 or shall be of the flat-surface type, installed level with the deck, with an available inlet area not less than two times the area of the conductor or leader to which the drain is connected.

1105.1.3 Roof drain flashings

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The connection between roofs and roof drains that pass through the roof and into the interior of the building shall be made water-tight by the use of approved flashing material.
The published roof drain flow rate, based on the head of water above the roof drain, shall be used to size the storm drainage system in accordance with Section 1106. The flow rate used for sizing the storm drainage piping shall be based on the maximum anticipated ponding at the roof drain.

1106.1 General

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The size of the vertical conductors and leaders, building storm drains, building storm sewers and any horizontal branches of such drains or sewers shall be based on the 100-year hourly rainfall rate indicated in Figure 1106.1Figures 1106.1(a) and 1106.1(b) or on other rainfall rates determined from approved local weather data.

For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.


FIGURE 1106.1 100-YEAR, 1-HOUR RAINFALL (INCHES) EASTERN UNITED STATES


For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.


FIGURE 1106.1‒continued 100-YEAR, 1-HOUR RAINFALL (INCHES) CENTRAL UNITED STATES


For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.


FIGURE 1106.1‒continued 100-YEAR, 1-HOUR RAINFALL (INCHES) WESTERN UNITED STATES


For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.


FIGURE 1106.1‒continued 100-YEAR, 1-HOUR RAINFALL (INCHES) ALASKA


For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.


FIGURE 1106.1‒continued 100-YEAR, 1-HOUR RAINFALL (INCHES) HAWAI


FIGURE 1106.1(a)
100-YEAR, 1-HOUR RAINFALL (INCHES/HOUR) NORTH CAROLINA FOR PRIMARY ROOF DRAINS
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.


FIGURE 1106.1(b)
100-YEAR, 15-MINUTE RAINFALL (INCHES/HOUR) NORTH CAROLINA FOR SECONDARY ROOF DRAINS
For SI: 1 inch = 25.4 mm.
Source: National Weather Service, National Oceanic and Atmospheric Administration, Washington D.C.

1106.2 Size of Storm Drain Piping

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Vertical and horizontal storm drain piping shall be sized based on the flow rate through the roof drain. The flow rate in storm drain piping shall not exceed that specified in Table 1106.2.

TABLE 1106.2 STORM DRAIN PIPE SIZING

PIPE SIZE (inches) CAPACITY (gpm)
VERTICAL DRAIN SLOPE OF HORIZONTAL DRAIN
1/16inch per foot 1/8inch per foot 1/4 inch per foot 1/2 inch per foot
2 34 15 22 31 44
3 87 39 55 79 111
4 180 81 115 163 231
5 311 117 165 234 331
6 538 243 344 487 689
8 1,117 505 714 1,010 1,429
10 2,050 927 1,311 1,855 2,623
12 3,272 1,480 2,093 2,960 4,187
15 5,543 2,508 3,546 5,016 7,093

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute = 3.785 L/m.

1106.2 Vertical conductors and leaders

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Vertical conductors and leaders shall be sized for the maximum projected roof area, in accordance with Tables 1106.2(1) and 1106.2(2).

TABLE 1106.2(1)
SIZE OF CIRCULAR CONDUCTORS AND LEADERS
DIAMETER OF LEADER (inches)a HORIZONTALLY PROJECTED ROOF AREA (square feet)
Rainfall rate (inches per hour)
1 2 3 4 5 6 7 8 9 10 11 12
2 2,880 1,440 960 720 575 480 410 360 320 290 260 240
3 8,800 4,400 2,930 2,200 1,760 1,470 1,260 1,100 980 880 800 730
4 18,400 9,200 6,130 4,600 3,680 3,070 2,630 2,300 2,045 1,840 1,675 1,530
5 34,600 17,300 11,530 8,650 6,920 5,765 4,945 4,325 3,845 3,460 3,145 2,880
6 54,000 27,000 17,995 13,500 10,800 9,000 7,715 6,750 6,000 5,400 4,910 4,500
8 116,000 58,000 38,660 29,000 23,200 19,315 16,570 14,500 12,890 11,600 10,545 9,600
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.
  1. Sizes indicated are the diameter of circular piping. This table is applicable to piping of other shapes, provided the cross-sectional shape fully encloses a circle of the diameter indicated in this table. For rectangular leaders, see Table 1106.2(2). Interpolation is permitted for pipe sizes that fall between those listed in this table.
TABLE 1106.2(2)
SIZE OF RECTANGULAR VERTICAL CONDUCTORS AND LEADERS
DIMENSIONS OF COMMON LEADER SIZES WITH × LENGTH (inches)a HORIZONTALLY PROJECTED ROOF AREA (square feet)
Rainfall rate (inches per hour)
1 2 3 4 5 6 7 8 9 10 11 12
1¾ x 2½ 3,410 1,700 1,130 850 680 560 480 420 370 340 310 280
2 × 3 5,540 2,770 1,840 1,380 1,100 920 790 690 610 550 500 460
2¾ x 4¼ 12,830 6,410 4,270 3,200 2,560 2,130 1,830 1,600 1,420 1,280 1,160 1,060
3 × 4 13,210 6,600 4,400 3,300 2,640 2,200 1,880 1,650 1,460 1,320 1,200 1,100
3½ x 4 15,900 7,950 5,300 3,970 3,480 2,650 2,270 1,980 1,760 1,590 1,440 1,320
3½ x 5 21,310 10,650 7,100 5,320 4,260 3,550 3,040 2,660 2,360 2,130 1,930 1,770
3¾ x 4¾ 21,960 10,980 7,320 5,490 4,390 3,660 3,130 2,740 2,440 2,190 1,990 1,830
3¾ x 5¼ 25,520 12,760 8,500 6,380 5,100 4,250 3,640 3,190 2,830 2,550 2,320 2,120
3½ x 6 27,790 13,890 9,260 6,940 5,550 4,630 3,970 3,470 3,080 2,770 2,520 2,310
4 × 6 32,980 16,490 10,990 8,240 6,590 5,490 4,710 4,120 3,660 3,290 2,990 2,740
5½ x 5½ 44,300 22,150 14,760 11,070 8,860 7,380 6,320 5,530 4,920 4,430 4,020 3,690
7½ x 7½ 100,500 50,250 33,500 25,120 20,100 16,750 14,350 12,560 11,160 10,050 9,130 8,370
  1. Sizes indicated are nominal width × length of the opening for rectangular piping.
  2. .For shapes not included in this table, Equation 11-1 shall be used to determine the equivalent circular diameter, Do, of rectangular piping for use in interpolation using the data from Table 1106.2(1).
Do = [width x length]½ (Equation 11-1)

where:
Do = equivalent circular diameter and Do width and length are in inches.

1106.3 Vertical Leader Sizing

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Vertical leaders shall be sized based on the flow rate from horizontal gutters or the maximum flow rate through roof drains. The flow rate through vertical leaders shall not exceed that specified in Table 1106.3.

TABLE 1106.3 VERTICAL LEADER SIZING

SIZE OF LEADER (inches) CAPACITY
(gpm)
2 30
2 × 2 30
11/2 × 21/2 30
21/2 54
21/2 × 21/2 54
3 92
2 × 4 92
21/2×3 92
4 192
3 × 41/4 192
31/2 × 4 192
5 360
4 × 5 360
41/2 × 41/2 360
6 563
5 × 6 563
51/2 × 51/2 563
8 1208
6 × 8 1208

For SI: 1 inch = 25.4 mm, 1 gallon per minute = 3.785 L/m.

1106.3 Building storm drains and sewers

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The size of the building storm drain, building storm sewer and their horizontal branches having a slope of one-half unit or less vertical in 12 units horizontal (4-percent slope) shall be based on the maximum projected roof area in accordance with Table 1106.3. The minimum slope of horizontal branches shall be one-eighth unit vertical in 12 units horizontal (1-percent slope) unless otherwise approved.

TABLE 1106.3
SIZE OF HORIZONTAL STORM DRAINAGE PIPINGa
SIZE OF HORIZONTAL PIPING (inches) HORIZONTALLY PROJECTED ROOF AREA (square feet)
Rainfall rate (inches per hour)
1 2 3 4 5 6
⅛ unit vertical in 12 units horizontal (1-percent slope)
3 3,228 1,644 1,096 822 657 548
4 7,520 3,760 2,506 1,800 1,504 1,253
5 13,360 6,680 4,453 3,340 2,672 2,227
6 21,400 10,700 7,133 5,350 4,280 3,566
8 46,000 23,000 15,300 11,500 9,200 7,600
10 82,800 41,400 27,600 20,700 16,580 13,800
12 133,200 6,600 44,400 33,300 26,650 22,200
15 218,000 109,000 72,800 59,500 47,600 39,650
¼ unit vertical in 12 units horizontal (2-percent slope)
3 4,640 2,300 1,546 1,160 928 773
4 10,600 5,300 3,533 2,650 2,120 1,766
5 18,880 9,440 6,293 4,720 3,776 3,146
6 30,200 15,100 10,066 7,550 6,040 5,033
8 65,200 32,600 21,733 16,300 13,040 10,866
10 116,800 58,400 38,950 29,200 23,350 19,450
12 188,000 94,000 62,600 47.000 37,600 31,350
15 336,000 168,000 112,000 84,000 67,250 56.000
½ unit vertical in 12 units horizontal (4-percent slope)
3 6,576 3,288 2,295 1,644 1,310 1,096
4 15,040 7,520 5,010 3,760 3,010 2,500
5 26,720 13,360 8,900 6,680 5,320 4,450
6 42,800 21,400 13,700 10,700 8,580 7,140
8 92,000 46,000 30,650 23,000 18,400 15,320
10 171,600 85,800 55,200 41,400 33,150 27,600
12 266,400 133,200 88,800 66,600 53,200 44,400
15 476,000 238,000 158,800 119,000 95,300 79,250
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.
  1. For Tables 1106.3 and 1106.6 when rainfall rates exceed 6 inches per hour, then the figures for roof area shall be adjusted proportionally by multiplying the figure by six and dividing by the maximum rate of rainfall in inches per hour [see Figure 1106.1(b)].

1106.4 Vertical Walls

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
In sizing roof drains and storm drainage piping, one-half of the area of any vertical wall or parapet that diverts rainwater to the roof shall be added to the projected roof area for inclusion in calculating the required size of vertical conductors, leaders and horizontal storm drainage piping.

1106.5 Parapet Wall Scupper Location

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Parapet wall roof drainage scupper and overflow scupper location shall comply with the requirements of Section 1503.4 of the International Building Code.Figure 1106.5.

(Note: 1 gpm = 0.0104 × (rainfall rate) × area)



HEAD (H) (inches) CAPACITY OF SCUPPER (gallons per minute)
Length (L) of scupper (inches)
4 6 8 10 12 18 24 30 36 48
1 10.7 17.4 23.4 29.3 35.4 53.4 71.5 89.5 107.5 143.7
2 30.5 47.5 64.4 81.4 98.5 149.4 200.3 251.1 302.1 404.0
3 52.9 84.1 115.2 146.3 177.8 271.4 364.9 458.5 552.0 739.0
4 76.7 124.6 172.6 220.5 269.0 413.3 557.5 701.8 846.0 1135.0
6 123.3 211.4 299.5 387.5 476.5 741.1 1005.8 1270.4 1535.0 2067.5
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute = 3.785 L/m.

Based on the Francis formula:

Q = 3.33 (L - 0.2H) H1.5

where

Q = Flow rate (cubic feet per second).
L = Length of scupper opening (feet).
H = Head on scupper {feet (measured 6 feet back from opening)].
FIGURE 1106.5
SIZE OF SCUPPERS

1106.6 Size of Roof Gutters

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Horizontal gutters shall be sized based on the flow rate from the roof surface. The flow rate in horizontal gutters shall not exceed that specified in Table 1106.6.

TABLE 1106.6 HORIZONTAL GUTTER SIZING

GUTTER DIMENSIONSa
(inches)
SLOPE
(inch per foot)
CAPACITY
(gpm)
11/2 × 21/2 1/4 26
11/2 × 21/2 1/2 40
4 1/8 39
21/4 × 3 1/4 55
21/4 × 3 1/2 87
5 1/8 74
4 × 21/2 1/4 106
3 ×31/2 1/2 156
6 1/8 110
3 × 5 1/4 157
3 × 5 1/2 225
8 1/16 172
8 1/8 247
41/2 × 6 1/4 348
41/2 × 6 1/2 494
10 1/16 331
10 1/8 472
5 × 8 1/4 651
4 × 10 1/2 1055

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute = 3.785 L/m, 1 inch per foot = 83.3 mm/m.
a. Dimensions are width by depth for rectangular shapes. Single dimensions are diameters of a semicircle.
The size of semicircular gutters shall be based on the maximum projected roof area in accordance with Table 1106.6.

TABLE 1106.6
SIZE OF SEMICIRCULAR ROOF GUTTERSa
DIAMETER OF GUTTERS (inches) HORIZONTALLY PROJECTED ROOF AREA (square feet)
Rainfall rate (inches per hour)
1 2 3 4 5 6
116 unit vertical in 12 units horizontal (0.5-percent slope)
3 680 340 226 170 136 113
4 1,440 720 480 360 288 240
5 2,500 1,250 834 625 500 416
6 3,840 1,920 1,280 960 768 640
7 5,520 2,760 1,840 1,380 1,100 918
8 7,960 3,980 2,655 1,990 1,590 1,325
10 14,400 7,200 4,800 3,600 2,880 2,400
⅛ unit vertical 12 units horizontal (1-percent slope)
3 960 480 320 240 192 160
4 2,040 1,020 681 510 408 340
5 3,520 1,760 1,172 880 704 587
6 5,440 2,720 1,815 1,360 1,085 905
7 7,800 3,900 2,600 1,950 1,560 1,300
8 11,200 5,600 3,740 2,800 2,240 1,870
10 20,400 10,200 6,800 5,100 4,080 3,400
¼ unit vertical in 12 units horizontal (2-percent slope)
3 1,360 680 454 340 272 226
4 2,880 1,440 960 720 576 480
5 5,000 2,500 1,668 1,250 1,000 834
6 7,680 3,840 2,560 1,920 1,536 1,280
7 11,040 5,520 3,860 2,760 2,205 1,840
8 15,920 7,960 5,310 3,980 3,180 2,655
10 28,800 14,400 9,600 7,200 5,750 4,800
½ unit vertical in 12 units horizontal (4-percent slope)
3 1,920 960 640 480 384 320
4 4,080 2,040 1,360 1,020 816 680
5 7,080 3,540 2,360 1,770 1,415 1,180
6 11,080 5,540 3,695 2,770 2,220 1,850
7 15,600 7,800 5,200 3,900 3,120 2,600
8 22,400 11,200 7,460 5,600 4,480 3,730
10 40,000 20,000 13,330 10,000 8,000 6,660
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.
  1. For Tables 1106.3 and 1106.6 when rainfall rates exceed 6 inches per hour, then the figures for roof area shall be adjusted proportionally by multiplying the figure by six and dividing by the maximum rate of rainfall in inches per hour [see Figure 1106.1(b)].
Siphonic roof drains and drainage systems shall be designed in accordance with ASME A112.6.9 and ASPE 45.
Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason. Where primary and secondary roof drains are manufactured as a single assembly, the inlet and outlet for each drain shall be independent.
Secondary roof drain systems shall have the end point of discharge separate from the primary system. Discharge shall be above grade, in a location that would normally be observed by the building occupants or maintenance personnel.

1108.3 Sizing of Secondary Drains

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Secondary (emergency) roof drain systems shall be sized in accordance with Section 1106 based on the rainfall rate for which the primary system is sizedindicated in Figure 1106.1(b). Scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1101.7. Scuppers shall have an opening dimension of not less than 4 inches (102 mm). The flow through the primary system shall not be considered when sizing the secondary roof drain system.
Where the public sewer is a combined system for both sanitary and storm water, the storm sewer shall be connected independently to the public sewer.
The roof of a structure shall be designed for the storage of water where the storm drainage system is engineered for controlled flow. The controlled flow roof drain system shall be an engineered system in accordance with this section and the design, submittal, approval, inspection and testing requirements of Section 316.1. The controlled flow system shall be designed based on the required rainfall rate in accordance with Section 1106.1.
The control devices shall be installed so that the rate of discharge of water per minute shall not exceed the values for continuous flow as indicated in Section 1110.1.
Runoff control shall be by control devices. Control devices shall be protected by strainers.
Not less than two roof drains shall be installed in roof areas 10,000 square feet (929 m2) or less and not less than four roof drains shall be installed in roofs over 10,000 square feet (929 m2) in area.
Subsoil drains shall be open-jointed, horizontally split or perforated pipe conforming to one of the standards listed in Table 1102.5. Such drains shall not be less than 4 inches (102 mm) in diameter. Where the building is subject to backwater, the subsoil drain shall be protected by an accessibly located backwater valve. Subsoil drains shall discharge to a trapped area drain, sump, dry well or approved location above ground. The subsoil sump shall not be required to have either a gas-tight cover or a vent. The sump and pumping system shall comply with Section 1113.1.
Building subdrains located below the public sewer level shall discharge into a sump or receiving tank, the contents of which shall be automatically lifted and discharged into the drainage system as required for building sumps. The sump and pumping equipment shall comply with Section 1113.1.
The sump pump, pit and discharge piping shall conform to Sections 1113.1.1 through 1113.1.4.
The sump pump shall be of a capacity and head appropriate to anticipated use requirements.
The sump pit shall be not less than 18 inches (457 mm) in diameter and not less than 24 inches (610 mm) in depth, unless otherwise approved. The pit shall be accessible and located such that all drainage flows into the pit by gravity. The sump pit shall be constructed of tile, steel, plastic, cast iron, concrete or other approved material, with a removable cover adequate to support anticipated loads in the area of use. The pit floor shall be solid and provide permanent support for the pump.
Electrical service outlets, when required, shall meet the requirements of NFPA 70.
Discharge piping shall meet the requirements of Section 1102.2, 1102.3 or 1102.4 and shall include a gate valve and a full flow check valve. Pipe and fittings shall be the same size as, or larger than, the pump discharge tapping.

Exception: In one- and two-family dwellings, only a check valve shall be required, located on the discharge piping from the pump or ejector.

Section 1114 VALUES FOR CONTINUOUS FLOW

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

1114.1 Equivalent roof area

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Where there is a continuous or semi-continuous discharge into the building storm drain or building storm sewer, such as from a pump, ejector, air conditioning plant or similar device, each gallon per minute (L/m) of such discharge shall be computed as being equivalent to 96 square feet (9m2) of roof area, based on a rainfall rate of 1 inch (25.4 mm) per hour.
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