Where areas are not physically separated by a draft curtain, barrier, or partition capable of delaying heat from a fire in one area from fusing sprinklers in the adjacent area, the required sprinkler protection for the more demanding design basis shall extend 15 ft (4.6 m) beyond its perimeter.
The requirements of 11.1.2(1) shall not apply where the areas are separated by a draft curtain, or barrier located above an aisle, where the aisle has a minimum 2 ft (600 mm) horizontal separation from the adjacent hazard on each side, or a partition that is capable of delaying heat from a fire in one area from fusing sprinklers in the adjacent area.?
The requirements of 11.1.2(1) shall not apply to the extension of more demanding criteria from an upper ceiling level to beneath a lower ceiling level where the difference in height between the ceiling levels is at least 2 ft (600 mm), located above an aisle, where the aisle has a minimum 2 ft (600 mm) horizontal separation from the adjacent hazard on each side.

For hydraulically calculated systems, the total system water supply requirements for each design basis shall be determined in accordance with the procedures of Section 23.4 unless modified by a section of Chapter 11 or Chapter 12.

11.1.4 Water Demand

11.1.4.1*

The water demand requirements shall be determined from the following:

Occupancy hazard fire control approach and special design approaches of Chapter 11
Storage design approaches of Chapter 12 through Chapter 20
Special occupancy approaches of Chapter 22

11.1.4.2*

The minimum water demand requirements for a sprinkler system shall be determined by adding the hose stream allowance to the water demand for sprinklers.

11.1.5 Water Supplies

11.1.5.1

The minimum water supply shall be available for the minimum duration specified in Chapter 11.

11.1.5.2*

Tanks shall be sized to supply the equipment that they serve.

11.1.5.3*

Pumps shall be sized to supply the equipment that they serve.

11.1.6 Hose Allowance

11.1.6.1 Systems With Multiple Hazard Classifications

For systems with multiple hazard classifications, the hose stream allowance and water supply duration shall be in accordance with one of the following:

The water supply requirements for the highest hazard classification within the system shall be used.
The water supply requirements for each individual hazard classification shall be used in the calculations for the design area for that hazard.
*For systems with multiple hazard classifications where the higher classification only lies within single rooms less than or equal to 400 ft (37 m²) in area with no such rooms adjacent, the water supply requirements for the principal occupancy shall be used for the remainder of the system.

11.1.6.2*

Water allowance for outside hose shall be added to the sprinkler requirement at the connection to the city main or a private fire hydrant, whichever is closer to the system riser.

11.1.6.3

Where inside hose connections are planned or are required, the following shall apply:

A total water allowance of 50 gpm (190 L/min) for a single hose connection installation shall be added to the sprinkler requirements.
A total water allowance of 100 gpm (380 L/min) for a multiple hose connection installation shall be added to the sprinkler requirements.
The water allowance shall be added in 50 gpm (190 L/min) increments beginning at the most remote hose connection, with each increment added at the pressure required by the sprinkler system design at that point.

11.1.6.3.1

Where the system is a combined sprinkler/ standpipe system (Class I or Class III) and the building is fully sprinklered in accordance with NFPA 13, no inside hose demand shall be required at any of the standpipe outlets.

11.1.6.4*

When hose valves for fire department use are attached to wet pipe sprinkler system risers in accordance with 8.17.5.2, the following shall apply:

The sprinkler system demand shall not be required to be added to standpipe demand as determined from NFPA 14.
Where the combined sprinkler system demand and hose stream allowance of Table 11.2.3.1.2 exceeds the requirements of NFPA 14, this higher demand shall be used.
For partially sprinklered buildings, the sprinkler demand, not including hose stream allowance, as indicated in Figure 11.2.3.1.1 shall be added to the requirements given in NFPA 14.

11.1.7* High Volume Low Speed (HVLS) Fans

The installation of HVLS fans in buildings equipped with sprinklers, including ESFR sprinklers, shall comply with the following:

The maximum fan diameter shall be 24 ft (7.3 m).
The HVLS fan shall be centered approximately between four adjacent sprinklers.
The vertical clearance from the HVLS fan to sprinkler deflector shall be a minimum of 3 ft (0.9 m).
All HVLS fans shall be interlocked to shut down immediately upon receiving a waterflow signal from the alarm system in accordance with the requirements of NFPA 72.

11.2 Occupancy Hazard Fire Control Approach for Spray Sprinklers

11.2.1 General

11.2.1.1*

The water demand requirements shall be determined by either the pipe schedule method in accordance with 11.2.2 or the hydraulic calculation method in accordance with 11.2.3.

11.2.1.2 Occupancy Classifications

11.2.1.2.1

Occupancy classifications for this standard shall relate to sprinkler installations and their water supplies only.

11.2.1.2.2

Occupancy classifications shall not be used as a general classification of occupancy hazards.

11.2.1.2.3

Occupancies or portions of occupancies shall be classified according to the quantity and combustibility of contents, the expected rates of heat release, the total potential for energy release, the heights of stockpiles, and the presence of flammable and combustible liquids, using the definitions contained in Section 5.2 through Section 5.5.

11.2.1.2.4

Classifications shall be as follows:

Light hazard
Ordinary hazard (Groups 1 and 2)
Extra hazard (Groups 1 and 2)
Special occupancy hazard (see Chapter 22)

11.2.2 Water Demand Requirements — Pipe Schedule Method

11.2.2.1

Table 11.2.2.1 shall be used in determining the minimum water supply requirements for light and ordinary hazard occupancies protected by systems with pipe sized according to the pipe schedules of Section 23.7.

Table 11.2.2.1 Water Supply Requirements for Pipe Schedule Sprinkler Systems

Occupancy Classification	Minimum Residual Pressure Required		Acceptable Flow at Base of Riser (Including Hose Stream Allowance)		Duration (minutes)
Occupancy Classification	psi	bar	gpm	L/min	Duration (minutes)
Light hazard	15	1	500—750	1900—2850	30—60
Ordinary hazard	20	1.4	850—1500	3200—5700	60—90

11.2.2.2

Pressure and flow requirements for extra hazard occupancies shall be based on the hydraulic calculation methods of 11.2.3.

11.2.2.3

The pipe schedule method shall be permitted as follows:

Additions or modifications to existing pipe schedule systems sized according to the pipe schedules of Section 23.7
Additions or modifications to existing extra hazard pipe schedule systems
New systems of 5000 ft² (465 m²) or less
New systems exceeding 5000 ft² (465 m²) where the flows required in Table 11.2.2.1 are available at a minimum residual pressure of 50 psi (3.4 bar) at the highest elevation of sprinkler

11.2.2.4

Table 11.2.2.1 shall be used in determining the minimum water supply requirements.

11.2.2.5

The lower duration value of Table 11.2.2.1 shall be acceptable only where the sprinkler system waterflow alarm device(s) and supervisory device(s) are electrically supervised and such supervision is monitored at an approved, constantly attended location.

11.2.2.6* Residual Pressure

11.2.2.6.1

The residual pressure requirement of Table 11.2.2.1 shall be met at the elevation of the highest sprinkler.

11.2.2.6.2 Friction Loss Due to Backflow Prevention Valves

11.2.2.6.2.1

When backflow prevention valves are installed on pipe schedule systems, the friction losses of the device shall be accounted for when determining acceptable residual pressure at the top level of sprinklers.

11.2.2.6.2.2

The friction loss of this device [in psi (bar)] shall be added to the elevation loss and the residual pressure at the top row of sprinklers to determine the total pressure needed at the water supply.

11.2.2.7

The lower flow figure of Table 11.2.2.1 shall be permitted only where the building is of noncombustible construction or the potential areas of fire are limited by building size or compartmentation such that no open areas exceed 3000 ft² (280 m²) for light hazard or 4000 ft² (370 m²) for ordinary hazard.

11.2.3 Water Demand Requirements — Hydraulic Calculation Methods

11.2.3.1 General

11.2.3.1.1

The water demand for sprinklers shall be determined only from one of the following, at the discretion of the designer:

Density/area curves of Figure 11.2.3.1.1 in accordance with the density/area method of 11.2.3.2
The room that creates the greatest demand in accordance with the room design method of 11.2.3.3
Special design areas in accordance with 11.2.3.4

FIGURE 11.2.3.1.1 Density/Area Curves.

11.2.3.1.2

The minimum water supply shall be available for the minimum duration specified in Table 11.2.3.1.2.

Table 11.2.3.1.2 Hose Stream Allowance and Water Supply Duration Requirements for Hydraulically Calculated Systems

Occupancy	Inside Hose		Total Combined Inside and Outside Hose		Duration (minutes)
Occupancy	gpm	L/min	gpm	L/min	Duration (minutes)
Light hazard	0, 50, or 100	0, 190, or 380	100	380	30
Ordinary hazard	0, 50, or 100	0, 190, or 380	250	950	60—90
Extra hazard	0, 50, or 100	0, 190, or 380	500	1900	90—120

11.2.3.1.3

The lower duration values in Table 11.2.3.1.2 shall be permitted where the sprinkler system waterflow alarm device(s) and supervisory device(s) are electrically supervised and such supervision is monitored at an approved, constantly attended location.

11.2.3.1.4 Restrictions

When either the density/area method or room design method is used, the following shall apply:

*For areas of sprinkler operation less than 1500 ft² (139 m²) used for light and ordinary hazard occupancies, the density for 1500 ft² (139 m²) shall be used.
For areas of sprinkler operation less than 2500 ft² (232 m²) for extra hazard occupancies, the density for 2500 ft² (232 m²) shall be used.

11.2.3.1.5 Unsprinklered Combustible Concealed Spaces

11.2.3.1.5.1*

When using the density/area or room design method, unless the requirements of 11.2.3.1.5.2 are met for buildings having unsprinklered combustible concealed spaces, as described in 8.15.1.2 and 8.15.6, the minimum area of sprinkler operation for that portion of the building shall be 3000 ft² (280 m²).

(A)

The design area of 3000 ft² (280 m²) shall be applied only to the sprinkler system or portions of the sprinkler system that are adjacent to the qualifying combustible concealed space.

(B)

The term adjacent shall apply to any sprinkler system protecting a space above, below, or next to the qualifying concealed space except where a barrier with a fire resistance rating at least equivalent to the water supply duration completely separates the concealed space from the sprinklered area.

11.2.3.1.5.2

The following unsprinklered concealed spaces shall not require a minimum area of sprinkler operation of 3000 ft² (280 m²):

Noncombustible and limited-combustible concealed spaces with minimal combustible loading having no access. The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.
Noncombustible and limited-combustible concealed spaces with limited access and not permitting occupancy or storage of combustibles. The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.
Combustible concealed spaces filled entirely with noncombustible insulation.
*Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are directly attached to the bottom of solid wood joists or solid limited-combustible construction or noncombustible construction so as to create enclosed joist spaces 160 ft³ (4.5 m³) or less in volume, including space below insulation that is laid directly on top or within the ceiling joists in an otherwise sprinklered concealed space.
Concealed spaces where rigid materials are used and the exposed surfaces have a flame spread index of 25 or less and the materials have been demonstrated to not propagate fire more than 10.5 ft (3.2 m) when tested in accordance with ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, or ANSI/ UL 723, Standard for Test for Surf ace Burning Characteristics of Building Materials, extended for an additional 20 minutes in the form in which they are installed in the space.
Concealed spaces in which the exposed materials are constructed entirely of fire-retardant-treated wood as defined by NFPA 703.
Concealed spaces over isolated small rooms not exceeding 55 ft² (5.1 m²) in area.
Vertical pipe chases under 10 ft² (0.9 m²), provided that in multifloor buildings the chases are firestopped at each floor using materials equivalent to the floor construction, and where such pipe chases contain no sources of ignition, piping shall be noncombustible, and pipe penetrations at each floor shall be properly sealed.
Exterior columns under 10 ft² (0.9 m²) in area formed by studs or wood joists, supporting exterior canopies that are fully protected with a sprinkler system.
*Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are attached to the bottom of composite wood joists either directly or on to metal channels not exceeding 1 in. (25 mm) in depth, provided the adjacent joist channels are firestopped into volumes not exceeding 160 ft³ (4.5 m³) using materials equivalent to ¹/₂ in. (13 mm) gypsum board, and at least 3¹/₂ in. (90 mm) of batt insulation is installed at the bottom of the joist channels when the ceiling is attached utilizing metal channels.

11.2.3.2 Density/Area Method

11.2.3.2.1 Water Supply

11.2.3.2.1.1

The water supply requirement for sprinklers only shall be calculated from the density/area curves of Figure 11.2.3.1.1 or from Chapter 22 where density/area criteria are specified for special occupancy hazards.

11.2.3.2.1.2

When using Figure 11.2.3.1.1, the calculations shall satisfy any single point on the appropriate density/area curve.

11.2.3.2.1.3

When using Figure 11.2.3.1.1, it shall not be necessary to meet all points on the selected curves.

11.2.3.2.2 Sprinklers

11.2.3.2.2.1

The densities and areas provided in Figure 11.2.3.1.1 shall be for use only with spray sprinklers.

11.2.3.2.2.2

Quick-response sprinklers shall not be permitted for use in extra hazard occupancies or other occupancies where there are substantial amounts of flammable liquids or combustible dusts.

11.2.3.2.2.3

For extended coverage sprinklers, the minimum design area shall be that corresponding to the hazard in Figure 11.2.3.1.1 or the area protected by five sprinklers, whichever is greater.

11.2.3.2.2.4

Extended coverage sprinklers shall be listed with and designed for the minimum flow corresponding to the density for the hazard as specified in Figure 11.2.3.1.1.

11.2.3.2.3 Quick-Response Sprinklers

11.2.3.2.3.1

Where listed quick-response sprinklers, including extended coverage quick-response sprinklers, are used throughout a system or portion of a system having the same hydraulic design basis, the system area of operation shall be permitted to be reduced without revising the density as indicated in Figure 11.2.3.2.3.1 when all of the following conditions are satisfied:

Wet pipe system
Light hazard or ordinary hazard occupancy
20 ft (6.1 m) maximum ceiling height
No unprotected ceiling pockets as allowed by 8.6.7 and 8.8.7 exceeding 32 ft² (3.0 m²)
No unprotected areas above cloud ceilings as allowed by 8.15.24

FIGURE 11.2.3.2.3.1 Design Area Reduction for Quick-Response Sprinklers.

11.2.3.2.3.2

The number of sprinklers in the design area shall never be less than five.

11.2.3.2.3.3

Where quick-response sprinklers are used on a sloped ceiling or roof, the maximum ceiling or roof height shall be used for determining the percent reduction in design area.

11.2.3.2.4 Sloped Ceilings

The system area of operation shall be increased by 30 percent without revising the density when the following types of sprinklers are used on sloped ceilings with a pitch exceeding 1 in 6 (a rise of 2 units in a run of 12 units, a roof slope of 16.7 percent) in nonstorage applications:

Spray sprinklers, including extended coverage sprinklers listed in accordance with 8.4.3 (4), and quick-response sprinklers
CMSA sprinklers

11.2.3.2.5* Dry Pipe and Double Interlock Preaction Systems

For dry pipe systems and double interlock preaction systems, the area of sprinkler operation shall be increased by 30 percent without revising the density.

11.2.3.2.6 High-Temperature Sprinklers

Where high-temperature sprinklers are used for extra hazard occupancies, the area of sprinkler operation shall be permitted to be reduced by 25 percent without revising the density, but not to less than 2000 ft² (186 m²).

11.2.3.2.7* Multiple Adjustments

11.2.3.2.7.1

Where multiple adjustments to the area of operation are required to be made in accordance with 11.2.3.2.3, 11.2.3.2.4,11.2.3.2.5, or 11.2.3.2.6, these adjustments shall be compounded based on the area of operation originally selected from Figure 11.2.3.1.1.

11.2.3.2.7.2

If the building has unsprinklered combustible concealed spaces, the rules of 11.2.3.1.5 shall be applied after all other modifications have been made.

11.2.3.3 Room Design Method

11.2.3.3.1*

The water supply requirements for sprinklers only shall be based upon the room that creates the greatest demand.

11.2.3.3.2

The density selected shall be that from Figure 11.2.3.1.1 corresponding to the occupancy hazard classification and room size.

11.2.3.3.3

To utilize the room design method, all rooms shall be enclosed with walls having a fire-resistance rating equal to the water supply duration indicated in Table 11.2.3.1.2.

11.2.3.3.4

If the room is smaller than the area specified in Figure 11.2.3.1.1, the provisions of 11.2.3.1.4(1) and 11.2.3.1.4(2) shall apply.

11.2.3.3.5

Minimum protection of openings shall be as follows:

Light hazard — Nonrated automatic or self-closing doors.
Light hazard with no opening protection —Where openings are not protected, calculations shall include the sprinklers in the room plus two sprinklers in the communicating space nearest each such unprotected opening unless the communicating space has only one sprinkler, in which case calculations shall be extended to the operation of that sprinkler. The selection of the room and communicating space sprinklers to be calculated shall be that which produces the greatest hydraulic demand. For light hazard occupancies with unprotected openings in walls, a minimum lintel of depth of 8 in. (200 mm) is required for openings and the opening shall not exceed 8 ft (2.4 m) in width. It shall be permitted to have a single opening of 36 in. (900 mm) or less without a lintel, provided there are no other openings to adjoining spaces.
Ordinary and extra hazard — Automatic or self-closing doors with appropriate fire resistance ratings for the enclosure.

11.2.3.3.6

Where the room design method is used and the area under consideration is a corridor protected by a single row of sprinklers with protected openings in accordance with 11.2.3.3.5, the maximum number of sprinklers that needs to be calculated is five or, when extended coverage sprinklers are installed, all sprinklers contained within 75 linear feet (23 linear meters) of the corridor.

11.2.3.3.7

Where the area under consideration is a corridor protected by a single row of sprinklers with unprotected openings, in a light hazard occupancy, the design area shall include all sprinklers in the corridor to a maximum of five or, when extended coverage sprinklers are installed, all sprinklers within 75 linear feet (23 linear meters) of the corridor.

11.2.3.4 Special Design Areas

11.2.3.4.1

Where the design area consists of a building service chute supplied by a separate riser, the maximum number of sprinklers that needs to be calculated is three, each with a minimum discharge of 15 gpm (57 L/min).

11.2.3.4.2*

Where an area is to be protected by a single line of sprinklers, the design area shall include all sprinklers on the line up to a maximum of seven.

11.2.3.4.3

Sprinklers in ducts as described in Section 7.9 and 8.15.13 shall be hydraulically designed to provide a discharge pressure of not less than 7 psi (0.5 bar) at each sprinkler with all sprinklers within the duct flowing.

11.3 Special Design Approaches

11.3.1 Residential Sprinklers

11.3.1.1*

The design area shall be the area that includes the four adjacent sprinklers that produce the greatest hydraulic demand.

11.3.1.2*

Unless the requirements of 11.2.3.1.5.2 are met for buildings having unsprinklered combustible concealed spaces, as described in 8.15.1.2 and 8.15.6, the minimum design area of sprinkler operation for that portion of the building shall be eight sprinklers.

11.3.1.2.1*

The design area of eight sprinklers shall be applied only to the portion of the residential sprinklers that are adjacent to the qualifying combustible concealed space.

11.3.1.2.2

11.3.1.3

Unless the requirements of 11.3.1.4 are met, the minimum required discharge from each design area sprinkler shall be the greater of the following:

In accordance with minimum flow rates indicated in the sprinkler listings
In rooms or compartments greater than 800 ft² (74.3 m²), calculated based on delivering a minimum of 0.1 gpm/ft² (4.1 mm/min) over the design area in accordance with the provisions of 8.5.2.1
In rooms or compartments 800 ft² (74.3 m²) or less calculated based on delivering a minimum of 0.1 gpm/ft² (4.1 mm/min) over the room or the compartment using the area of the room divided by the number of sprinklers in the room

11.3.1.4

For modifications or additions to existing systems equipped with residential sprinklers, the listed discharge criteria less than 0.1 gpm/ft² (4.1 mm/min) shall be permitted to be used.

11.3.1.4.1

Where replacing residential sprinklers manufactured prior to 2003 that are no longer available from the manufacturer and that are installed using a design density less than 0.05 gpm/ft² (2.04 mm/min), a residential sprinkler with an equivalent K-factor (± 5 percent) shall be permitted to be used provided the currently listed coverage area for the replacement sprinkler is not exceeded.

11.3.1.5

Where areas such as attics, basements, or other types of occupancies are outside of dwelling units but within the same structure, these areas shall be protected as a separate design basis in accordance with Section 11.1.

11.3.1.6

Hose stream allowance and water supply duration requirements shall be in accordance with those for light hazard occupancies in Table 11.2.3.1.2.

11.3.2 Exposure Protection

11.3.2.1*

Piping shall be hydraulically calculated in accordance with Section 23.4 to furnish a minimum of 7 psi (0.5 bar) at any sprinkler with all sprinklers facing the exposure operating.

11.3.2.2

Where the water supply feeds other fire protection systems, it shall be capable of furnishing total demand for such systems as well as the exposure system demand.

11.3.3 Water Curtains

11.3.3.1

Sprinklers in a water curtain such as described in 8.15.4 or 8.15.17.2 shall be hydraulically designed to provide a discharge of 3 gpm per lineal foot (37 L/min per lineal meter) of water curtain, with no sprinklers discharging less than 15 gpm (57 L/min).

11.3.3.2

For water curtains employing automatic sprinklers, the number of sprinklers calculated in this water curtain shall be the number in the length corresponding to the length parallel to the branch lines in the area determined by 23.4.4.2.

11.3.3.3

If a single fire can be expected to operate sprinklers within the water curtain and within the design area of a hydraulically calculated system, the water supply to the water curtain shall be added to the water demand of the hydraulic calculations and shall be balanced to the calculated area demand.

11.3.3.4

Hydraulic design calculations shall include a design area selected to include ceiling sprinklers adjacent to the water curtain.

11.3.4 Sprinklers Under Roof or Ceiling in Combustible Concealed Spaces of Wood Joist or Wood Truss Construction With Members 3 ft (0.9 m) or Less on Center and Slope Having Pitch of 4 in 12 or Greater