WINDOWS IN RATED APPLICATIONS

A SUMMARY OF RATED WINDOWS, ATRIA, & WINDOW SPRINKLERS

February 14, 2018 | Published by Joseph Meyer, P.E. at MeyerFire.com

Protection of windows within a rated assembly is a surprising

complex topic within fire protection due to a combination of
passive and active fire protection elements. Three principal
options are available to architects and engineers looking to
address windows within rated applications; a rated window
assembly, closely-spaced sprinklers for atrium enclosures,
and use of special application window sprinklers.

The following summary is a starting point for comparison,

which considers requirements from the International Building
Code (2000-2018 Editions), NFPA 13 (only 2016 and 2019
have requirements), NFPA 101 (2003-2018 Editions), ICC-ES
ESR-2397 Report (2018-2020 Issuance), and Tyco’s WS
Sprinkler Product Data and Listing. Refer to the cited codes
and standards for full details and requirements.

Find many more articles and resources like this at

www.MeyerFire.com.

CODE REFERENCES
APPLICATION RATED WINDOWS CLOSELY-SPACED FOR ATRA TYCO WS SPRINKLERS
Fire Partitions (IBC 708), Fire
In lieu of Atrium 1-hour Enclosure Barrier (IBC 707), or Exterior
Where Applied? Fire Partitions & Fire Barriers [IBC 2000-06 404.5, 2009-18 404.6, Wall (IBC 705) for up to 2-hour
or NFPA 101 2003-18 8.6.7(c)] fire-resistance rating
[ICC-ES ESR-2397 3.1, 5.3]
No. Yes; alternate method.
Alternative to Code? No; rated glazing can meet
[IBC 2000-06 404.5, [IBC 2003-18 104.11]
Requires AHJ prescriptive code
2009-18 404.6, [ICC-ES ESR-2397 3.3]
Approval? requirements.
or NFPA 101 2003-18 8.6.7(c)] [NFPA 101 2003-18 1.4.3]
Supporting ICC-ES ESR-2397 Report
- -
Documentation [ICC-ES Link]

Building Code
Yes. Yes. N/A
Criteria Apply?
No. Yes.
NFPA 13 Criteria
N/A [NFPA 13 2016 A.8.15.26(3), 2019 [NFPA 13 2016 A.8.15.26(3),
Apply?
A.9.3.15(3)] 2019 A.9.3.15(3)]
IBC 2006: 5-ft (1524 mm) min
Fire Separation
IBC 2009-15: 10-ft (3048 mm)
Distance for Exterior N/A N/A
min.
Wall Use
[ICC-ES ESR-2397 5.7]
No.
No.
In Lieu of Firewall? - [IBC 2000-06 404.5, 2009-18 404.6,
[ICC-ES ESR-2397 5.9]
or NFPA 101 2003-18 8.6.7(c)]

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 GLASS & WALL CONSTRAINTS
RATED WINDOWS CLOSELY-SPACED FOR ATRA TYCO WS SPRINKLERS
IBC: Yes, self- or automatic-closing
doors are permitted.
[IBC 2012 404.6.1.1.2,
2015-18 404.6.1.1.3] No, glazing must be fixed.
Yes; use of rated door
Doors Permitted? NFPA 101: Yes, but doors must resist [NFPA 13 2016 8.15.26(3), 2019
assembly permitted.
smoke and be self-or automatic- 9.3.15(3)]
closing upon smoke detection.
[NFPA 101 2003-18
8.6.7(c)(v, vi)]
ICC: ¼-in thick heat-
strengthened or tempered glass
[ICC-ES ESR-2397 3.3]
NFPA 13: Glass ceramic, heat-
strengthened, or tempered.
NFPA 101:
[NFPA 13 2016 8.15.26(3),
Glazing Type N/A Laminated, tempered, or wired.
2019 9.3.15(3)]
[NFPA 101 2003-18 8.6.7(c)(iii)]
Tyco: heat-strengthened and
tempered (1/4-in, 6mm min.),
FireLite Plus WS ceramic glass
(5/16-in, 8 mm min), or stronger
[WS Product Data p3]
Must deflect in gasketed frame w/o
breaking before sprinklers operate. Metallic frame with elastomeric
Gasketing System [IBC 2000-06 404.5(1), seal.
2009-18 404.6(1)] [ICC-ES ESR-2397 3.3]
[NFPA 101 2003-18 8.6.7(c)(iii)]
Not Permitted.
[NFPA 13 2016 8.15.26(5),
Load Bearing? Yes, where permitted by IBC. -
2019 9.3.15(5)]
[ICC-ES ESR-2397 3.1, 5.6]
ICC: No.
[ICC-ES ESR-2397 3.3, 5.10]
NFPA 101: No horizontal mullions NFPA 13: horizontal members
Horizontal Mullions
Yes permitted. cannot interfere with uniform
Permitted?
[NFPA 101 2009-18 8.6.7(c)(vii)] distribution of water.
[NFPA 13 2016 8.15.26(6), 2019
9.3.15(6)]
NFPA 101:
No; obstructions cannot
No window treatments or
Any Obstruction obstruct water distribution.
N/A obstructions that would interfere
Permitted? [NFPA 13 2016 8.15.26(6), 2019
with wetting of glass surface.
9.3.15(6)]
[NFPA 101 2009-18 8.6.7(c)(vii)]
13-ft (4 m)
Maximum Height of
- - [ICC-ES ESR-2397 3.3]
Glass
[WS Product Data p3]
All combustibles must be 2-in
(51 mm) from glass. Can be 36-
Nearby Combustible in rated “pony wall”. No deflagr.
N/A N/A
Materials? or detonation hazards.
[ICC-ES ESR-2397 4.1, 5.4]
[WS Product Data p3]

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 SPRINKLER CONSTRAINTS
RATED WINDOWS CLOSELY-SPACED FOR ATRA TYCO WS SPRINKLERS
Any permitted (commonly standard- Tyco WS Sprinkler,
Sprinkler Type? N/A
spray pendent recessed or concealed) TY3388 or TY3488
Wet-pipe only.
[NFPA 13 2016 8.15.26(2), 2019
System Type? N/A -
9.3.15(2)]
[ICC-ES ESR-2397 3.1, 5.6]
IBC: Yes, or on room-side-only if there
is no walkway on the atrium side.
[IBC 2000-06 404.5(1), Yes, where assembly is required
2009-18 404.6(1)] to be protected by both sides.
Sprinklers Required
No. NFPA 101: Yes, or only on non-atrium [NFPA 13 2016 8.15.26(4), 2019
on Both Sides?
side where there is no walkway or 9.3.15(4)]
other floor area on atrium side above [ICC-ES ESR-2397 3.1]
main level.
[NFPA 101 2003-18 8.6.7(c)(iv)]
Horizontal Sidewall: Deflector
½-in (12.7) to 4-in (102) from
glass and 1-in (25) to 3-in (76.2
IBC: 4-in (102) to 12-in (305 mm) mm) down from top of frame.
[IBC 2000-06 404.5, ‘09-18 404.6] Vertical Sidewall: 4-in (102) to
Distance from Glass N/A
NFPA 101: 12-in (305 mm) or less 12-in (305 mm) from face of
[NFPA 101 2003-18 8.6.7(c)(ii)] glass and 2-in (51) to 4-in (102
mm) down from top of frame.
[ICC-ES ESR-2397 4.1]
[WS Product Data p3]
Yes; entire surface must be wet upon
Yes, as governed by listing and
activation
ICC-ES Report.
Entire Surface Wet? N/A [IBC 2000-06 404.5(1),
[ICC-ES ESR-2397 4.1]
2009-18 404.6(1)]
[WS Product Data p3]
[NFPA 101 2003-18 8.6.7(c)(ii)]
6-ft (1830 mm) on center 6-ft (1830 mm) minimum
Sprinkler Spacing [IBC 2000-06 404.5(1), 8-ft (2440 mm) maximum
N/A
(along glass) 2009-18 404.6(1)] [ICC-ES ESR-2397 4.1]
[NFPA 101 2003-18 8.6.7(c)(i)] [WS Product Data p3]
Sprinkler Distance 4-in (101.6 mm) minimum
from Vertical N/A - 4-ft (1.22 mm) maximum
Mullion [WS Product Data p3]

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 HYDRAULICS
RATED WINDOWS CLOSELY-SPACED FOR ATRA TYCO WS SPRINKLERS
Tyco WS Sprinkler,
Any permitted (commonly standard-
Sprinkler Type? N/A TY3388 or TY3488
spray pendent recessed or concealed)
[ICC-ES ESR-2397 3.2]
Not Less than Required Rating
(Typically 1 or 2-hour)
Water Supply
N/A - [NFPA 13 2016 8.15.26(7),
Duration
2019 9.3.15(7)]
[ICC-ES ESR-2397 4.1]
Horizontal Sidewall: 175 psi
(1207 kPa) when separated by
vertical mullion, or 70 psi (483
kPa) when not separated
Maximum Pressure N/A (Per listing of sprinkler)
Vertical Sidewall: 175 psi
(1207 kPa)
[ICC-ES ESR-2397 4.2]
[WS Product Data p3]
Not specifically addressed;
Most demanding 46.5 linear
NFPA 13 provides similar criteria for
feet (14.2 m), or 36 linear feet
Water Curtains to meet minimum
Remote Area N/A where quick-response reduction
remote area length of NFPA 13
is used. Added to remote area.
[NFPA 13 2002 11.2.3.8.2, 2007-16
[ICC-ES ESR-2397 4.2]
11.3.3.2, 2019 19.4.3.2]
Not specifically addressed;
NFPA 13 requires both closely-spaced
and adjacent sprinklers be calculated Yes, where a single fire can
Window Sprinklers
for Water Curtains where a cause operation of window and
Added to Remote N/A
single fire can cause operation of ordinary sprinklers.
Area?
window and ordinary sprinklers. [ICC-ES ESR-2397 4.2]
[NFPA 13 2002 11.2.3.8.3, 2007-16
11.3.3.3, 2019 19.4.3.5]
Not specifically addressed;
NFPA 13 provides similar criteria for 20 GPM (75.7 LPM) for spacing
Water Curtains of 3 GPM per lineal of 6-ft to 8-ft, or
Minimum Flow per
N/A foot (37 L/min per lineal m), and not 15 GPM (56.8 LPM) for sprinkler
Sprinkler
less than 15 GPM (57 L/min) each spacing less than 6-ft (1.83 m)
[NFPA 13 2002 11.2.3.8.1, 2007-16 [WS Product Data p4]
11.3.3.1, 2019 19.4.3.1]

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