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Automatic Sprinkler Plan Review

OBSTRUCTIONS

March 8, 2016 Jimbo Schifiliti

[email protected]

136

mailto:[email protected]

CHAPTER 6

SPRINKLER SPACING AND OBSTRUCTIONS

A. Basic Sprinkler System Principles (Chapter 8)

1. The basic principles of providing adequate sprinkler protection is as follows:

a. SPRINKLER ALL AREAS - including electrical equipment rooms, computer rooms, bathrooms, shower areas, telephone equipment rooms, hospital operating rooms, combustible attic spaces, and closets. (1-6.1, 8.1.1, and 5.12)

b. Provide adequate sprinkler coverage per sprinkler.

c. Do not obstruct the sprinkler discharge spray pattern. (8.5.5)

d. Provide adequate clearance between the sprinklers and the top of the ceiling or beams. (8.5.5.2)

e. Obstructions to Sprinkler Discharge Pattern Development for Standard Upright or Pendent Spray Sprinklers.

SPRINKLER4'

8'

18"

4'

DISTRIBUTION PATTERN FROM ASTANDARD SPRAY SPRINKLER

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2. Protection Areas and Maximum Spacing (Standard Spray Upright / Standard Spray Pendent) for Light Hazard. (Table 8.6.2.2.1(a))

Construction Type System Type Protection Areasq. ft.

Maximum Spacingfeet

Noncombustible obstructed and unobstructed and combustible unobstructed with members 3' or more on center

Pipe Schedule 200 15

Noncombustible obstructed and unobstructed and combustible unobstructed with members 3' or more on center

Hydraulically Calculated 225 15

Combustible obstructed with members 3' or more on center

All 168 15

Combustible obstructed or unobstructed with members less than 3' on center

All 130 15

Unoccupied attics having combustible wood joist or wood truss construction with members less than 3' on center with slopes having a pitch of 4 in 12 or greater

All 120

8* x 15(minimum 7 psi)

10* x 12(minimum 20 psi)

*The smaller dimension shall be measured perpendicular to the slope.

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B. Upright & Pendent Standard Sprinkler Spacing Requirements (8.4.1)

1. The following chart provides the maximum distance between sprinklers and the maximum protection area per sprinkler: (8.6.2; Table 8.6.2.2.1(a) (b) (c) and (d))

OCCUPANCY MAXIMUM DISTANCEPROTECTION

AREABETWEEN

SPRINKLERS FROM WALL SQ. FT.

Light Hazard 15 ft. 7 ft. 6 in. * 225 **

Ordinary Hazard 15 ft. 7 ft. 6 in. 130Extra Hazard (Except with 25 ft. bays) 12 ft. † 6 ft. 100+

High Piled Storage (Except with 25 ft. bays) 12 ft. † 6 ft. 100+

Extra Hazard or High Piled Storage in Bays 25 ft. Wide 12 ft. 6 in. † 6 ft. 3 in. 100+

* Except for small room rule to be discussed later. (3.3.15; 8.6.2.1.2)

† For hydraulically calculated systems with design densities below 0.25 gpm per sq. ft., a maximum 15 ft. distance is allowed between sprinklers and a maximum 130 sq. ft. of protection area per sprinkler is allowed.

** For pipe schedule systems the maximum protection area per sprinkler is:

a. Light Hazard - 200 sq. ft.b. Extra Hazard - 90 sq. ft.

For light combustible framing members spaced less than 3' on centers for light hazard occupancies, the maximum protection area is 130 sq. ft.

For combustible, obstructed construction in light hazard occupancies, the maximum protection area is 168 sq. ft.

2. Exception: Sprinklers can be more than 15' apart when listed for a greater spacing.

3. Example: An ordinary hazard occupancy with sprinklers spaced at 130 sq. ft. maximum.L X W = 130 sq. ft. maximum.13' x 10' = 130 sq. ft.The maximum distance of the sprinkler from the walls is 1/2 L = 6'-6" on one wall and 1/2 W = 5' off the other wall.

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4. Example: Sprinkler System Spacing for a Light Hazard Occupancy (8.6.3)

15' MAX

L2 L1 L1 L3

W2

W1

W3

TYPICAL PENDENT SPRINKLER

15' MAX

7 1 2'MAX

7 1 2'MAX

Note:1.2.

a. L1 x W1 < 225 sq. ft./sprinkler

b. (2 x L2) x (2 x W2) < 225 sq. ft./sprinkler

c. (2 x L2) x (2 x W3) < 225 sq. ft./sprinkler

d. (2 x L3) x (2 x W2) < 225 sq. ft./sprinkler

e. (2 x L3) x (2 x W3) < 225 sq. ft./sprinkler

f. L1 x (2 x W2) < 225 sq. ft./sprinkler

g. L1 x (2 x W3) < 225 sq. ft./sprinkler

h. (2 x L2) x W1 < 225 sq. ft./sprinkler

i. (2 x L3) x W1 < 225 sq. ft./sprinkler

j. .75 L < 11.25'

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5. Example: Sprinkler system spacing for an Ordinary Hazard Occupancy

.75L

L2 L1 L1 L3

W2

W1

W3


12 L

MAX

12 W

MAX

Note:1.2.

a. L1 x W1 < 130 sq. ft./sprinkler

b. (2 x L2) x (2 x W2) < 130 sq. ft./sprinkler

c. (2 x L2) x (2 x W3) < 130 sq. ft./sprinkler

d. (2 x L3) x (2 x W2) < 130 sq. ft./sprinkler

e. (2 x L3) x (2 x W3) < 130 sq. ft./sprinkler

f. L1 x (2 x W2) < 130 sq. ft./sprinkler

g. L1 x (2 x W3) < 130 sq. ft./sprinkler

h. (2 x L2) x W1 < 130 sq. ft./sprinkler

i. (2 x L3) x W1 < 130 sq. ft./sprinkler

j. .75 L < 11.25'

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6. Examples: Sprinkler Spacing

a. Light Hazard

1. Standard sprinklers are spaced a maximum of 225 sq. ft. per sprinkler.

2. L1 (15') x W1 (15') = 225 sq. ft.

3. ½ L1 = 7.5' , ½ W1 = 7.5' maximum.

b. Light Hazard


2. L1 (14') x W1 (14') = 196 sq. ft. per sprinkler.

3. ½ L1 = 7' , ½ W1 = 7'.

c. Ordinary Hazard


2. L1 (10') x W1 (13') = 130 sq. ft. per sprinkler.

3. ½ L1 = 5', ½ W1 = 6.5'.

d. Ordinary Hazard


2. L1 (12') x W1 (10') = 120 sq. ft.

3. ½ L1 = 6', ½ W1 = 5'.

4. .75 L = .75 (12′) = 9′.

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7. Small Room Rule (3.3.17, 8.6.3.2.1, 8.6.3.2.4)

a. Can be used for small rooms of light hazard occupancy classification that do not exceed 800 sq. ft. in total area. (3.3.17)

b. Automatic sprinkler may be placed a maximum of 9' off any one wall.

c. Do not exceed the maximum spacing between sprinklers of 15' .

d. Do not exceed the maximum area coverage per sprinkler of 200 sq. ft. for non-calculated systems or 225 sq. ft. for calculated systems. (Table 8.6.2.2.1(a))

e. The small room rule is used in areas where there are ceiling obstructions such as lighting fixtures and HVAC diffusers.

f. Example: Small Room Rule


7'-6" 7'-6"15'-0"

6'-0"

9'-0"


7'-6"

7'-6"

15'-0"6'-0" 9'-0"

SMALL ROOM RULE1: LIGHT HAZARD OCCUPANCY2: 800 Sq.Ft. MAX. ROOM SIZE3: 9' MAX. OFF ANY ONE WALL4: 225 Sq.Ft. MAX. SPRINKLER SPACING

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8. UNOBSTRUCTED construction (3.7.2; 8.6.4.1.1)

a. Construction where the beams, trusses, and/or other structural members do not obstruct the fire heat flow or the sprinkler water distribution.

b. Unobstructed construction has:

1. structural members that are not solid.

2. openings must be at least 70% open of the members cross section. (3.7.2; A.3.7.1 (7))

3. the thickness of the member does not exceed the least dimension of the openings, or

4. or, in all construction types the structural beam members exceed 7½' spacing on centers. (A.3.7.2(3))

5. Example: Unobstructed Construction

a

a = THICKNESS OF THE MEMBER b = LEAST OPENING DIMENSION

a MUST BE LESS THEN b

b

BAR JOIST

70% OPEN

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9. Sprinkler location for UNOBSTRUCTED construction. (3.7.2; 8.6.4.1.1.1)

a. Locate the sprinkler deflector 1" to 12" below the roof or ceiling. If a concealed, recessed, or flush sprinkler is used, install it per it’s listing. See NFPA 13, A.3.7.2 for examples.

b. Example: Smooth Ceiling and Bar Joist

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10. Types of unobstructed construction are: (A.3.7.2)

a. smooth ceilings.

SPRINKLER BRANCH LINE BELOW THE CEILING

SMOOTH CEILING SPRINKLER BRANCH LINE ABOVE THE CEILING

SPRINKLERS

b. flat slabs - smooth ceiling.

CONCRETE

SPRINKLER

SPRINKLER BRANCH LINE

c. pan-type, waffle, reinforced concrete - smooth ceiling for upright and pendent sprinklers. (A.3.7.2(3)(a)), Exhibit 3.37.8.4.2)

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d. smooth roofs or floor decks that are supported by beams, girders, or trusses that are spaced more than 7½' on center.

7 1/2' OR GREATERON CENTER


SPRINKLER

BEAM

ROOF OR FLOOR

e. smooth ¾" plaster, or combination of other materials, ceilings attached to wood joists, wood trusses, and/or bar joists.

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f. open web steel beams and bar joists.

g. suspended ceilings of non-combustible and combustible construction.

148

h. heavy timber or standard mill construction.

i. open wood truss construction.

20"OR GREATER

SPRINKLER

4" ORLESS

FLOOR OR ROOF

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11. OBSTRUCTED construction.

a. Sprinkler location for OBSTRUCTED construction (8.6.4.1.2; 8.6.4.1.2(1))

1. Example 1: Locate the sprinklers 1" to 6" below the structural members AND a maximum of 22" below the ceiling.

NOT TO EXCEED 22"

CEILING / ROOF

1" to 6" BELOWTHE MEMBER

DISTANCE BETWEEN SPRINKLERS NOT TOEXCEED SPRINKLER LISTING

b. Example 2: Sprinklers can be located at or above the bottom of the structural member, to a maximum of 22" below the ceiling, when the sprinklers conform to the beam rule for obstruction. (8.6.4.1.2(2))

CEILING / ROOF

22" MAXIMUM

DISTANCE FROM SPRINKLER TO NEARSIDE OF OBSTRUCTION MUST COMPLY WITH

NFPA-13: 8.6.5.1.2

7'-6" MAXIMUM

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c. Example 3: Sprinklers shall be located 1" to 12" below the ceiling when sprinklers are installed in each bay of obstructed construction.

CEILING / ROOF

1" to 12" MAXIMUM

7'-6" MAXIMUM

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d. Example 4: Composite wood joists.

1. Sprinklers shall only be permitted below composite wood joists (A.3.7.1(b)) when the joist channels are fire stopped, to the depth of the joist, with material equivalent to the web construction so that the individual channel areas do not exceed 300 sq. ft.. When the joist depth exceeds 22" up to 48", follow the other rules for obstructed construction. (3.7.1(3))

2. Composite wood joists are wood I beams that vary in depth up to 48". They can be spaced up to 48" apart on center. The spans can be up to 60' between supports. Joist channels should be fire stopped to the full depth of the joists with the same material the joists are made of so that the individual channel areas do not exceed 300 sq. ft.

3. Example: Composite Wood Joist

4. Example: Fire Stopping

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e. Example 5: Concrete tees – obstructed construction.

1. For concrete tee construction with tees spaced between 3' and 7½' on center. No maximum distance below the ceiling applies as long as sprinklers are in the plane 1" below or 1" above the bottom of the concrete stems. (3.7.1(2); 8.6.4.1.2(5))

2. Location of the sprinkler to the tee obstructions shall be spaced per the BEAM RULE Table 8.6.5.1.2 for obstructions.

3. Exception: If concrete tees are spaced less than 3' on center, use the rules for obstructed construction.

4. Example: Concrete Tee

CEILING / ROOF

1" MAX BELOW

1" MAX ABOVE

LOCATE THE SPRINKLER ON THE PLANEOR A MAXIMUM 1" ABOVE OR BELOW THE STEMS

3'

WEBLEGS

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f. Example 6: Wood joist construction

1. Wood joist construction is rectangular solid wood members than can vary from 2" to 4" wide and up to 14" deep. They can be spaced up to 3' on center and can span up to 40' between supports. (8.6.4.1.2(1))

2. Solid wood members less than 4" wide and up to 14" deep that are spaced more than 3' on center are also considered wood joist construction.

3. Example: Wood Joist

4. Example: Wood Joist Dry Wall Ceiling

154

12. Vertical ceiling changes. (8.6.4.1.1.3)

a. This obstruction rule is for ceiling changes of 36" or less.

b. Ceiling changes that are greater than 36" are considered a wall for sprinkler spacing.

c. For ceilings of 36" or less follow the beam rule.

d. Example: x < 36"

1. x < 36"

2. Follow the beam rules for sprinkler locations and spacing.

CEILING

S

BRANCHLINESPRINKLER

BRANCHLINESPRINKLER

S = Maximum allowable distance between sprinklers

x < 36"

e. Example: x > 36"

CEILING

1/2 S

x > 36"

BRANCHLINESPRINKLER

BRANCHLINESPRINKLER

1/2 S

MAX

S = Maximum allowable distance between sprinklers

MAX Imaginary Wall

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13. Pitched roof sprinkler protection (8.6.4.1.3)

a. Sprinklers shall be located not more than 3' vertically down from the roof peak.

b. Maintain a minimum of 2' horizontal clearance from the sprinkler at the peak to the side of the roof.

c. Sprinkler spacing shall be measured along the roof slope. (8.6.3)

d. Example 1: Sprinkler at the Pitched Roof Peak; Central Attic Sprinkler

BACK TO BACKSPRINKLER

6"

CEILING

PITCHED ROOF

e. Example 2: For a Standard Sprinkler Pitched Roof Vertical Clearance

SPRINKLER

3' max

CEILING

PITCHED ROOF

f. Example 3: Steeply Pitched Roofs – Horizontal and Vertical Clearances For a Standard Sprinkler (8.6.4.1.3.3

SPRINKLER

3' MAX

2'MIN

4'

CEILING

PITCHED ROOF

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14. Obstructions to the sprinkler discharge. (8.6.5)

a. The obstruction prevents the sprinkler pattern from fully developing.

b. Obstructions such as beams, columns, and pipes.

c. Exception: Place sprinklers on each side of the obstruction a maximum of half the allowable distance (½S) between sprinklers for the occupancy.


OBSTRUCTION4' WIDE MAX

SPRINKLER SPRINKLER

OR 12 THE SPRINKLERS LISTING7'-6" MAXIMUM

OR 12 THE SPRINKLERS LISTING7'-6" MAXIMUM

LESS THAN 18"

Beam Rule

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15. Horizontal ceiling obstructions. The spacing and location requirements for horizontal obstructions not along a wall is as follows. This was previously known as “beam rule”:

a. NFPA 13, Table 8.6.5.1.2

POSITION OF DEFLECTOR WHEN LOCATED ABOVEBOTTOM OF OBSTRUCTION

Distance for sprinkler to side of obstructionMaximum allowable distance of deflector above bottom of obstruction

Standard Sprinklers

When A dimension is B dimension shall not be more than

Less than 1' 0"

1' to less than 1' 6" 2½"

1' 6" to less than 2' 3½"


2' 6" to less than 3' 7½"


3' 6" to less than 4' 12"

4' to less than 4' 6" 14"

4' 6" to less than 5' 16½"





7' to less than 7'-6" 35"

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b. Example: NFPA 13, Figure 8.6.5.1.2(a)

OBSTRUCTION

CEILING

= NOT TO EXCEED THE MAX

A

B

BRANCHLINESPRINKLER

DISTANCE BELOW THE CEILINGPER THE SPRINKLERS LISTING

C

c. Workshop Example

1. “A” dimension is 3'.

2. “B” dimension shall not exceed 9½" for a standard sprinkler.

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16. Horizontal Obstructions against walls. (8.6.5.1.2(3)) If the horizontal obstruction is against a wall (i.e. soffit, cabinets, etc.) and the obstruction is a maximum 30" wide, then the sprinkler shall be located as shown below OR add sprinkler protection in the soffit.

a. Example: NFPA 13, Figure 8.6.5.1.2(b)


SPRINKLER

OBSTRUCTION

WALL

CEILING

7'-6" MAXOR PER SPRINKLER LISTING

a

b

d

1. a > (d - 8") + b when:

2. d < 30"

b. Plan View of Example

d

S1/

2 S

a

1/2 S

SPRINKLER

SPRINKLER

OB

STR

UC

TIO

NS

OFF

IT

160

c. Workshop Example

1. d is 24", b is 8".

2. What is minimum “a” allowed.

3. a > (d - 8") + b

a > (24 - 8) + 8

a > 16 + 8

a > 24"

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17. Column obstructions.

a. Example: NFPA 13, Figure 8.6.5.2.1.3 - Plan view of Column Obstruction.

3X RULE

SPRINKLER

A

C

D

OBSTRUCTION

PLAN VIEW OF COLUMN

b. This rule applies to light and ordinary hazard occupancies only (8.6.5.2.1.4)

c. A > 3C or 3DA < 24"

d. For this rule to apply, A has to be a minimum of 12" from the obstruction and a maximum of 24" from the obstruction.

e. When A is greater than 24" the 3 times rule is not applicable and there is no obstruction. When A is less than 12" another sprinkler is required.

f. Use dimension C or D, whichever is greater.

g. Workshop Example:

1. A is 20".

2. C and D are each 6".

3. A > 3C or 3D.

4. A > 3 (6") or 3 (6").

5. A > 18" and A is 20".

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18. Truss obstruction.

a. Example: NFPA 13, Figure 8.6.5.2.1.3 - Elevation view of Truss Obstruction

CEILING

OPEN WEB STEELOR WOOD TRUSS

SPRINKLER

DC

AMIN. 12"MAX. 24"

b. A > 3C or 3DA < 24"

c. A has to be a minimum of 12" and a maximum of 24" from the obstruction when measured on an angle.

d. When A is greater than 24" the 3 times rule is not applicable and there is no obstruction.

e. When A is less than 12" the truss is considered an obstruction and additional sprinklers are required on the other side of the truss. The truss is now acting like a wall.

f. Use dimension C or D, whichever is greater.

g. Workshop Example:

1. A is 24"

2. C + D are each 6"

3. A > 3C or 3D

4. A > 3(6") or 3(6")

5. A > 18"

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6. A is 24" in this example so the truss is not an obstruction.

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19. Open truss obstruction.

a. If the construction is open truss 20" or greater apart (24” on center) with all truss members 4" or smaller in width, provide sprinklers half way in between obstructed truss. (8.6.5.2.1.6)

4" OR LESS

SPRINKLER CENTERED BETWEEN TRUSS

20" OR GREATER

1/2 1/2

20. Open beam and bar joist construction.

a. If the construction is bar joists beams or trusses, locate the sprinklers in the centerline of the bar joist beams or truss. (8.6.5.2.1.7)

1. The beam or truss chord shall not exceed 8".

2. The sprinkler deflector shall be located a minimum of 6" above the structure members’ bottom chord.

3. The sprinkler shall be a minimum of 3 times greater than the maximum web dimensions.

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21. Suspended or floor mounted vertical obstructions (8.6.5.2.2). If an obstruction is entirely below the sprinklers (i.e. privacy curtain, room dividers, free-standing partitions, etc.) but, less than 18" below the sprinklers, the spacing and location requirements are as follows:

a. NFPA 13, Table 8.6.5.2.2

HORIZONTAL AND MINIMUM VERTICAL DISTANCE FOR SPRINKLERSLIGHT HAZARD OCCUPANCIES ONLY

HORIZONTAL DISTANCE AMINIMUM VERTICAL DISTANCE BELOW DEFLECTOR B

6" or less 3"

More than 6" to 9" 4"



More than 15" to 18" 9½"



More than 30" 18"

b. Example: NFPA 13, Figure 8.6.5.2.2

166

c. Workshop Example:

1. “A” is 24".

2. “B” must be a minimum of 12½"

d. Workshop Problem #1

1. “A” is 36"

2. “B” is 24"

3. Will this example work?

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22. Ceiling Pockets (8.6.7.1)

a. Sprinklers shall be required in all ceiling pockets.

b. The requirements of 8.6.7.1 shall not apply where ALL of the following are met:

1. The total volume of the unprotected ceiling pocket does not exceed 1,000 cu. ft.

2. The depth of the unprotected pocket does not exceed 36″.

3. The entire floor under the unprotected ceiling pocket is protected by the sprinklers at the lower ceiling elevation.

4. Each unprotected ceiling pocket is separated from any adjacent unprotected ceiling pocket by a minimum 10′ horizontal distance.

5. The unprotected ceiling pocket is constructed of noncombustible or limited combustible construction.

6. Skylights not exceeding 32 sq. ft. shall be permitted to have a plastic cover.

7. Quick response sprinklers are utilized throughout the compartment.

c. Example: Ceiling Pocket – No Sprinklers Required

MAX. VOLUME 1000 CUBIC FEET

QUICK RESPONSE SPRINKLER

10' MIN.36" MAX.

36" MAX.

UNPROTECTED CEILING POCKET OR SKYLIGHT

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23. Shelving obstruction rule. (8.6.6, A.8.6.6)

a. There shall be a minimum 18" clearance between the top of storage and the sprinkler deflector.

b. Exception: when other code sections or other NFPA standards specify greater clearances.

c. Tire storage is 36".

d. Exception: shelving against a wall.

e. When shelving is installed on a wall and is not directly below sprinklers, the shelves and the storage on them can go up to the ceiling.

1. The 18" clearance rule doesn’t apply unless the sprinkler is directly above the shelves.

f. Example of the Shelving Rule

FLOOR

TOYS

SHELVING

SHELVING

ROOF

CORRECT CORRECT

PENDENTSPRINKLER LESS THEN 18"

IS ALLOWED18"

MINIMUM

PENDENTSPRINKLER

FLOOR

ROOF

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24. Obstructions located below sprinklers. (8.6.5.3.3) If a fixed obstruction is over 4' wide (i.e. ducts, decks, cat walks, overhead doors, cutting tables, etc.) sprinklers shall be installed below the obstruction.

a. Example: Sprinkler Under Duct

ROOF

BAR JOIST

DUCT BRANCH LINE

CEILING SPRINKLER

SPRINKLER UNDER DUCT

b. Example: Sprinkler Under Overhead Door

1. Most overhead doors are located in Ordinary Hazard occupancies. Sidewall sprinkler spacing for Light Hazard at 196 sq. ft. maximum and 14' maximum between sprinklers is allowed for noncombustible construction. (8.7.3.1.7). Ordinary hazard is 100 sq. ft. / sidewall sprinkler.

OR

OVER14'

14'

14'

14' ORLESS

OUTLINE OFOVERHEAD DOOR

OVER 14'

14'

OVER 14'

14'

STANDARD SIDEWALLSPRINKLER

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25. Open grating sprinkler protection (8.5.5.3.1; 8.6.5.3.5; 8.6.5.3.3)

a. Sprinkler protection shall be installed under open grate flooring over 4' wide.

b. Slatting of shelves, decks, walkways, or the use of open grating is not a substitute to eliminate the sprinkler protection below them. (A.12.3.2.5.1.1)

c. Sprinkler under open grating shall be provided with water shields. (8.5.5.3.3)

d. Gratings are frequently covered with storage and/or other obstructions that prevent the sprinklers at the roof from getting water below the grating.

e. Example: Open Grating Sprinkler Protection

TYPICAL SPRINKLER PIPING

METAL MESH GRATING

TYPICAL SPRINKLER WITH WATER SHIELD

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F. ESFR (Early Suppression Fast Response) Sprinkler Requirements (8.12)

1. The maximum area of coverage shall not exceed 100 sq. ft. per sprinkler. The minimum area of protection shall not be less than 80 sq. ft. per sprinkler. (8.12.2.2.2)

a. Exception: It shall be permitted to deviate from the maximum sprinkler spacing to eliminate obstructions created by trusses and bar joists by moving a sprinkler along the branch line a maximum of 1' from its allowable spacing provided coverage for that sprinkler does not exceed 110 sq. ft. and the average spacing for the moved sprinkler and the adjacent sprinkler do not exceed 100'. Adjacent branch lines shall maintain the same pattern. The maximum distance between sprinklers shall not exceed 12'. (8.12.2.2.3)

2. Example: ESFR Sprinkler Spacing with Obstructions

10'-0"

10'-0"11'-0" 5'-0"

10'-0"

10'-0"

10'-0"

5'-0"

5'-0"

5'-0"

BAR JOIST OBSTRUCTION

1'-0"MIN

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3. The distance between ESFR sprinklers shall be as follows:

a. NFPA 13, Table 8.12.2.2.1, Protection Areas and Maximum Spacing of ESFR Sprinklers

CEILING/ROOF HEIGHTS UP TO 30'

CEILING/ROOF HEIGHTS OVER 30'

PROTECTION AREA SPACING

PROTECTION AREA SPACING

CONSTRUCTION TYPE SQ. FT. FT. SQ. FT. FT.Noncombustible unobstructed 100 12 100 10Noncombustible obstructed 100 12 100 10Combustible unobstructed 100 12 100 10Combustible obstructed N/A N/A N/A N/A

Table 8.12.2.2.1 indicates that ESFR sprinklers cannot be used under obstructed combustible construction. However paragraph 8.4.6.3 identifies construction that can be considered in this category.

4. A minimum of 36" of clear space is required below the ESFR sprinkler deflector. (8.12.6)

FLOOR

BAR JOISTROOF

ESFR SPRINKLERS

36"MINIMUM

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5. ESFR’s are only permitted with the following construction types (8.4.6.3):

a. ESFR sprinklers shall be permitted for use in buildings with unobstructed construction. Where depths of the solid structural members (beams, stems, etc.) exceed 12" ESFR sprinklers shall be installed in each channel formed by the solid structural members. Minimum sprinkler spacing and area of coverage shall comply with 8.12.2.3 and 8.12.3.4.

b. ESFR sprinklers are not suitable for all types of building construction. Various ceiling construction features such as those with deep narrow ceiling channels can cause unacceptable delays with sprinkler activation and obstruct the sprinkler’s discharge pattern. Where sprinklers are installed in each channel of obstructed construction, there needs to be adequate separation between sprinklers as identified in Section 8.11. The limitations of 8.12.2.3 and 8.12.3.4 will preclude the use of ESFR sprinklers under narrow deep channels.

6. ESFR’s cannot be used in buildings with roof slopes greater than 2" per ft. (8.4.6.2)

a. This is a roof slope of 16.7%.

7. ESFR’s are only permitted for wet systems unless specifically listed for dry system application. (8.4.6.1)

8. The allowable ESFR sprinkler deflector distances below the ceiling are as follows for pendent ESFR sprinklers: (8.12.4.1)

PENDENT ESFR SPRINKERS

K-Factor Deflector Distance Below the Roof/Ceiling

14 6" to 14"16.8 6" to 14"22.4 6" to 18"25.2 6" to 18"

9. For obstructions located at the ceiling, the same rules apply as for standard upright and pendent sprinklers. However, ESFR’s must be installed a minimum of 1' horizontally from the nearest edge of any bottom chords at open trusses or open bar joists. (8.12.5.3.1)

10. For obstructions over 2' wide and located entirely below the sprinklers, the sprinkler location must meet the requirements of NFPA 13, Figure 8.12.5.2 – beam rule.

a. Otherwise sprinklers must be installed below the obstruction.

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