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Laminated
Glass Sloped And
Overhead Glazing
CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Using Laminated Glass for Sloped and Overhead Glazing
S e c t i o n 1 OVERVIEW
INTRODUCTION
Using glass in sloped and overhead applications presents numerous design and safety challenges. If the glass breaks, the glazing system must provide protection from falling glass. Additionally, an understanding of the unique thermal, solar and ultraviolet characteristics of sloped and overhead glazing is required to avoid occupant discomfort and poor energy efficiency, and reduce potential damage to household furnishings. This Product Application Note is intended to provide an overview of the range of options that exist to incorporate laminated glass in overhead and sloped applications.
SLOPED OR OVERHEAD GLAZING
Glass that slopes at an angle of 15° or more from the vertical plane, whether in sloped walls, overhead glazing, or skylights, is referred to as sloped or overhead glazing. The possibility of breakage of sloped or overhead glazing is a potential hazard and, with limited exceptions, building codes require laminated glass or screens to be used for occupant protection. When properly designed and installed, the adhesion of the glass to the interlayer means that laminated glass, even when broken, tends to remain in place, protecting occupants and property from injury and damage caused by rain, wind, snow, etc.
As is the case with safety glazing, sloped and overhead glazing is regulated. Sloped and overhead glazing is subjected to potential wind loads, snow loads, live and dead loads.
Laminated glass packages that incorporate spectrally selective low-E coatings are the preferred choice for sloped and overhead applications because they not only provide protection against falling glass, they offer energy efficiency gains as well.
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
S e c t i o n 2 USING LAMINATED GLASS IN SLOPED AND OVERHEAD APPLICATIONS
CODE COMPLIANCE
Laminated glass with PVB interlayer is recognized by the International Residential Code (IRC) and specific state and local laws and codes as an acceptable glazing product for sloped and overhead applications including skylights. The locations, allowable glazing materials, and standards with which safety glazing must comply are specified in the IRC, as well as in Consumer Product Safety Commission (CPSC) 16 CFR Part 1201, and American National Standards Institute (ANSI) Z97.1.
In addition to code requirements, the Glazing Industry Code Committee has established consensus requirements for sloped and overhead glazing. These standards recognize the safety performance of laminated glass. Unlike monolithic tempered or heat strengthened (HS) glass, laminated glass does not require the installation of screens when used in sloped and overhead glazings.
INCORPORATING GUARDIAN RESIDENTIAL LOW-E INTO LAMINATED GLAZING CONFIGURATIONS
There are two ways to use low-E coatings with laminated glass –either embedded, or exposed. In this context, embedded refers to a configuration in which the coating(s) are in direct contact with the PVB interlayer; exposed refers to coatings that are positioned facing the airspace of an IG unit. Positioning of low-E coated lites within a laminated glass configuration does not affect safety properties; however there are thermal and aesthetic implications that should be considered when designing any laminated glazing package. The thermal performance (U-factor) improvement that is associated with the use of low-E coatings only applies to laminated configurations in which the low-E coating is exposed to a sealed airspace. When a low-E coating is embedded in a laminated configuration, the thermal performance of the configuration is approximately the same as it would be without a low-E coated lite.
Embedded and exposed coatings both provide the solar control (SHGC) benefit associated with the low-E coating; however, the resulting SHGC can vary significantly depending on the glazing configuration. An additional consideration when determining the preferred positioning of low-E coatings within a glazing system is the potential for thermal stress. Although typical combinations of glass, PVB, and Guardian’s Residential Low-E coatings do not result in glass temperatures that are associated with thermal breakage, thermal and solar simulations should be performed by a qualified party prior to finalizing configuration design in order to fully
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
understand the SHGC values and the potential for heat build-up within the glazing system.
Guidelines for use and positioning of Guardian’s Residential Low-E coated glass in laminated configurations are provided for reference in Table 1. Note that mock-ups are advised for aesthetic reasons with some products when they are positioned on specific surfaces, as these configurations are likely to have more pronounced color properties.
Table 1— Guidelines for use and positioning of Guardian’s Residential Low-E coated glass in laminated configurations.
Illustration LegendGlassCoatingInterlayerSpacer
Surface #2
Surface #3
Surface #2
Surface #3
Surface #4
Surface #5
Performance Plus II Yes No YesMock-up Advised
YesMock-up Advised
YesMock-up Advised
ClimaGuard 75/68 Yes No No No Yes Yes No No
ClimaGuard 71/38 Yes No YesMock-up Advised
Yes Yes YesMock-up Advised
ClimaGuard 70/36 Yes No YesMock-up Advised
Yes Yes YesMock-up Advised
ClimaGuard 55/27 Yes No Yes No Yes Yes Yes No
Performance Plus II HT No Yes YesMock-up Advised
YesMock-up Advised
YesMock-up Advised
ClimaGuard DHT No Yes Yes No YesMock-up Advised
Yes No
ClimaGuard HT No Yes YesMock-up Advised
Yes Yes YesMock-up Advised
ClimaGuard 55 HT No Yes Yes No Yes Yes Yes No
Table 1. Laminated Coated Surface Guide
Laminated (Monolithic) IGU Lami (Inboard lami lite)
Coating
Annealed or Temper-Coated
Low-E
Heat-treatable
Low-E
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
U-factor vs. Installed Slope AngleClimaGuard 55/27 #2 Surface
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 15 30 45 60 75 90Slope (degrees)
U-F
acto
r
U-Factor: 0.235
90°
30°
U-Factor: 0.331
U-Factor: 0.235
90°
30°
U-Factor: 0.331
U-Factor: 0.235
90°
30°
U-Factor: 0.331
THERMAL PERFORMANCE NOTE FOR SLOPED APPLICATIONS
Center of glass values based on vertical installation are commonly used for simple comparison; however, U-factors for sloped glazing vary from vertical. Figure 1 and Figure 2 illustrate how U-Factor degrades as the installation slope is varied from vertical (90°) to horizontal (0°). This data indicates that a slower rate of heat transfer occurs in vertical glazing than in sloped glazing. In skylights, as the slope of the skylight becomes more horizontal, the rate of heat transfer through the glazing increases. If the same glass is used in a vertically-glazed application and in a sloped application, in the winter, the sloped-glazed application will lose heat more quickly than the vertically-glazed application.
Figure 1—Depiction of U-factor as a function of installed slope angle for 7/8” OA laminated glass solar-control IGU (lami inboard with ClimaGuard 55/27 low-E #2).
Figure 2. Illustration of center of glass U-factor for identically configured glazing packages in sloped and vertically glazed applications.
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
S e c t i o n 3 ADDITIONAL RESOURCES
SELECT LAMINATED GLAZING STANDARDS
CPSC 16 CFR 1201 Safety Standard for Architectural Glazing Materials
ANSI Z97.1 American National Standard for Safety Glazing Materials Used in Buildings – Safety Performance Specifications and Methods of Test
CAN/CGSB-12.1 Tempered or Laminated Safety Glass
ASTM C1172 Standard Specification for Laminated Architectural Flat Glass
ADDITIONAL GUARDIAN LAMINATED GLASS PRODUCT APPLICATION NOTES
Using Laminated Glass for Solar Control and Energy Management in Residential Applications – CFP PAN Lami Solar control and Energy Management.
Using Laminated Glass for Sound Control in Residential Applications – CFP PAN Lami Sound Control.
Using Laminated Glass for Hurricane-Impact and Windborne Debris-Resistant Applications – CFP PAN Lami Hurricane and Windborne Debris
Using Laminated Glass for Safety and Burglary-Resistance in Residential Applications – CFP PAN Lami Safety and Burglary-Resistance.
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
LAMINATED AND COATED GLAZING INSPECTION AND QUALITY STANDARDS
Table 2. ASTM C1172-03 – Maximum Allowable Laminating Process Blemishes
Central Outer Central Outer Central OuterBoil (bubble)
1/16 (1.6) 3/32 (2.4) 1/8 (3.2) 3/16 (4.8) 1/4 (6.4) 1/4 (6.4)
Blow-in; edge boil
n/aCE: 1/4 (6.4)
EE: 1/32 (0.8)n/a
CE: 1/4 (6.4) EE: 1/16 (1.6)
n/aCE: 5/16 (8.0) EE: 3/32 (2.4)
Fuse 1/32 (0.8) 1/16 (1.6) 1/16 (1.6) 3/32 (2.4) 3/32 (2.4) 5/32 (4.0)
Hair, lint (single strand)
light intensity
medium intensity
light intensity
medium intensity
medium intensity
medium intensity
Inside dirt (dirt spot)
1/16 (1.6) 3/32 (2.4) 3/32 (2.4) 5/32 (4.0) 1/8 (3.2) 3/16 (4.8)
Lint - areas of concentrated lint
light intensity
light intensity
light intensity
light intensity
light intensity
light intensity
Separation, discoloration
none none none none none none
Short Interlayer; unlaminated area chip
n/aCE: 1/4 (6.4)
EE: 1/16 (1.6)n/a
CE: 1/4 (6.4) EE: 3/32 (2.4)
n/aCE: 1/4 (6.4) EE: 1/4 (6.4)
Interlayer scuff; streaklight
intensitylight
intensitylight
intensitylight
intensitylight
intensitylight
intensity
6. Light Intensity: barely noticeable at 36 inches (914.4 mm).7. Medium Intensity: noticeable at 36 inches (914.4 mm) but not at 11 feet (3,352.8mm).8. All imperfections noted should be separated by a minium of 12 inches (305mm).
2. Central Area is defined by an oval / circle, whose axis, when centered, is <80% of the overall dimension.3. Outer Area is defined as the area outside of the central area.4. CE: covered edge of glass edge bite.5. EE: exposed edge (if CE or EE is unknown, use CE tolerance).
ASTM C1172-03 - Maximum Allowable Laminating Process Blemishes: Inches (mm)
Notes:1. Inspection must be performed with the glazing system in a vertical orientation.
Up to 25 ft.2 (2.5m2) 25 - 75 ft.2 (2.5 - 7.0m2) Over 75 ft.2 (7.0 m2)Blemish
Table 3. ASTM C1376-03 – Quality Specifications for Coated Overhead Glass
Blemish Central Area Outer Area
Pinhole 3/32" (2.4mm) Max. 1/8" (3.2mm) Max.
Spot 3/32" (2.4mm) Max. 1/8" (3.2mm) Max.
Coating Scratch 3" (75mm) max length 4" (100mm) max length
Mark / Contaminant 3" (75mm) max length 4" (100mm) max length
Coating Rublength + width not to exceed
3/4" (19mm)length + width not to exceed
3/4" (19mm)Crazing None allowed None allowed
Corrosion None Allowed None allowed
Notes:
ASTM C1376-03 - Quality Specifications For Coated Overhead Glass
1. These specifications apply to cut size glass only. For specifications of stock size glass contact the manufacturer.2. The glass shall be inspected, in transmission, at a distance of 15 ft.(3m) at a viewing angle of 90 degrees to the specimen against a bright uniform background. If a blemish is readily apparent under these viewing conditions, the above criteria applies.3. Central Area is defined by a square / rectangle, defined by the center 80% of the length and 80% of the width dimensions centered on a lite of glass.4. Outer Area is defined as the area outside of the central area5. No more than two readily apparent blemishes are allowed in a 3-in. (75mm) diameter circle, and no more than five readily apparent blemishes are allowed in a 12-in. (300mm) diameter circle.
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
PERFORMANCE AND COMPLIANCE OF LOW-E ENHANCED LAMINATED GLASS CONFIGURATIONS (REFERENCE TABLE NOTES ON THE FOLLOWING PAGE)
Table 4. Performance and Compliance of Low-E Enhanced Laminated Glass Configurations
Air ArgonSmall
MissileLarge
Missile
Uncoated 1/8" annealed glass - - - - 27 24 90% 74% 0.87 1.00 n/a - -Uncoated 1/8" tempered glass + + - - 27 24 90% 74% 0.87 1.00 n/a - -
UncoatedLami glass - 2.7mm
[0.030" PVB] Lami glass - 2.7mm
+ + - - 34 30 89% 0% 0.81 1.00 n/a - -
Uncoated + + - - 34 30 89% 0% 0.80 1.00 n/a - -ClimaGuard 75/68 #3 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/aClimaGuard 71/38 #2 + + - - 34 30 70% 0% 0.41 1.00 n/a - -ClimaGuard 70/36 #2 + + - - 34 30 69% 0% 0.38 1.00 n/a - -ClimaGuard 55/27 #2 + + - - 34 30 59% 0% 0.33 1.00 n/a - -
Uncoated + + + + 35 31 88% 0% 0.79 0.98 n/a + -ClimaGuard 75/68 #3 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/aClimaGuard 71/38 #2 + + + + 35 31 70% 0% 0.40 0.98 n/a + -ClimaGuard 70/36 #2 + + + + 35 31 69% 0% 0.38 0.98 n/a + -ClimaGuard 55/27 #2 + + + + 35 31 58% 0% 0.33 0.98 n/a + -
Uncoated + + + + 35 32 88% 0% 0.78 0.96 n/a + +
ClimaGuard 75/68 #3 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/aClimaGuard 71/38 #2 + + + + 35 32 70% 0% 0.40 0.96 n/a + +ClimaGuard 70/36 #2 + + + + 35 32 68% 0% 0.37 0.96 n/a + +
ClimaGuard 55/27 #2 + + + + 35 32 58% 0% 0.33 0.96 n/a + +
Uncoated - - - - 31 26 82% 59% 0.78 0.48 n/a - -ClimaGuard 75/68 #3 - - - - 31 26 75% 46% 0.69 0.32 0.27 - -ClimaGuard 71/38 #2 - - - - 31 26 71% 24% 0.39 0.29 0.24 - -ClimaGuard 70/36 #2 - - - - 31 26 70% 30% 0.36 0.29 0.24 - -ClimaGuard 55/27 #2 - - - - 31 26 55% 18% 0.27 0.29 0.24 - -
Uncoated + + - - 31 26 82% 59% 0.78 0.48 n/a - -ClimaGuard 75/68 #3 + + - - 31 26 75% 46% 0.69 0.318 0.27 - -ClimaGuard 71/38 #2 + + - - 31 26 71% 24% 0.39 0.29 0.24 - -ClimaGuard 70/36 #2 + + - - 31 26 70% 30% 0.36 0.293 0.24 - -ClimaGuard 55/27 #2 + + - - 31 26 55% 18% 0.27 0.289 0.24 - -
Uncoated + + - - 37 31 81% 0% 0.75 0.47 n/a - -ClimaGuard 75/68 #3 + + - - 37 31 75% 0% 0.67 0.314 0.27 - -ClimaGuard 71/38 #2 + + - - 37 31 70% 0% 0.39 0.287 0.24 - -ClimaGuard 70/36 #2 + + - - 37 31 68% 0% 0.36 0.29 0.24 - -ClimaGuard 55/27 #2 + + - - 37 31 54% 0% 0.27 0.285 0.24 - -
Uncoated + + + + 37 31 80% 0% 0.75 0.466 n/a + +
ClimaGuard 75/68 #3 + + + + 37 31 74% 0% 0.67 0.311 0.27 + +ClimaGuard 71/38 #2 + + + + 37 31 69% 0% 0.38 0.285 0.24 + +ClimaGuard 70/36 #2 + + + + 37 31 68% 0% 0.36 0.288 0.24 + +
ClimaGuard 55/27 #2 + + + + 37 31 53% 0% 0.27 0.281 0.23 + +Uncoated + + + + 37* 31* 80% 0% 0.74 0.462 n/a + +
ClimaGuard 75/68 #3 + + + + 37* 31* 74% 0% 0.67 0.309 0.26 + +ClimaGuard 71/38 #2 + + + + 37* 31* 69% 0% 0.38 0.283 0.23 + +ClimaGuard 70/36 #2 + + + + 37* 31* 68% 0% 0.36 0.285 0.24 + +
ClimaGuard 55/27 #2 + + + + 37* 31* 53% 0% 0.27 0.281 0.23 + +
CPSC Cat. II
ASTM F1233 Class 1
UL 972 STC OITC
T vis %
1/8 glass [1/2" AS ]
1/4" Lami (0.090")
Monolithic Laminated Glass [5/16"]
Standard Insulating Glass Unit [3/4"]
Laminated Insulating Glass Units (3/4" OA, Laminated Glass Inboard)
1/8" annealed glass [1/2" AS]
1/8" annealed glass
1/8" glass [0.090" PVB] 1/8" glass
1/8" tempered glass [1/2" AS]
1/8" tempered glass
1/8" glass [0.030" PVB] 1/8" glass
1/8" glass [0.060" PVB] 1/8" glass
Table 4. Performance and Compliance of Low-E Enhanced Laminated Glass Configurations
Configuration
1/8 glass [1/2" AS ]
1/4" Lami (0.030")
1/8 glass [1/2" AS ]
1/4" Lami (0.060")
Monolithic Clear Glass [1/8"]Tuv% SHGC
U+Factor HurricaneCPSC Cat. I
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CFP PAN – Lami Sloped
Overhead Glazing
and Skylights Edition 2.1
October 2008
Laminated
Glass Sloped And
Overhead Glazing
LAMINATED GLASS CONFIGURATION TABLE NOTES
The information contained in this table is based on center-of-glass performance based on vertical installation. Total window system simulation and testing is necessary to determine window system performance and compliance.
Accurate thermal performance modeling must include the anticipated installation angle.
– Indicates that the composition may not meet requirements of the test standard when annealed glass is used.
+ Indicates that the composition may provide the level of protection shown with correct installation and framing.
Information regarding CPSC Cat. I and II, ASTM F-1233 Cat.1, and UL 972 is included in Section 3.
Sound Transmission Class (STC): Expressed in laboratory-measured dB, indicating the level of sound insulation of interior construction material.
Outdoor-Indoor Transmission Class (OITC): Expressed in laboratory-measured dB, indicating the acoustic performances of exterior doors and windows.
GUARDIAN MANUFACTURES LAMINATED GLASS IN THE FOLLOWING LOCATIONS
Guardian Galax
110 Jack Guynn Drive, Galax, VA 24333
Phone: (276) 236-5196
Guardian Reedley
1485 East Curtis Ave., Reedley, CA 93654
Phone: (559) 638-3588
Guardian Rexdale
355 Attwell Drive, Rexdale, Ontario, Canada M9W 5C2
Phone: (416) 674-6945
For additional information regarding storage, handling, fabrication, Limited Warranty coverage or use of any Guardian glass product, please contact the Guardian Customer Engineering Group at 888-521-9734
