Glass And Glazing

The Material Glass
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 John Wiley & Sons. All rights reserved.
17 Glass & Glazing

The Material Glass
Advanced Glazing
Systems
• Glass is the most-used cladding
material for tall buildings due to its
strength, light weight, durability, and
wide range of available optical and
thermal properties

The Material Glass
Advanced Glazing
Systems
• Glass has seemingly unlimited
optical and aesthetic possibilities

Glass Ingredients and
Thicknesses
• Glass is made from
– Sand (silicone dioxide)
– Soda ash (sodium hydroxide or
sodium carbonate)
– Lime (calcium)
– Alumina
– Potassium oxide
• Glass is supercooled liquid and in
sheet form strength is impacted by
imperfections in glass
• Thicknesses range from
approximately 3/32 inch (single
strength) to 1/8 inch (double
strength) to 1 inch.
• Heat treatments such as tempering
impact glass strength and uses
The Material Glass
Tempered Glass is Used in Store Front
For Strength and Breakage Safety

Glass Types by Heat
Treatment and Strength
• Annealed glass
ˉ Regular float glass which is cooled slowly
to reduce in built stress
• Tempered glass
ˉ Produced by cutting annealed glass to
required size, reheating and then cooling
rapidly. Higher strength and breaks into
small shards
• Heat-strengthened glass
ˉ Between annealed and tempered with
breakage behavior like annealed
• Laminated glass
ˉ Sandwich of multiple layers of glass with
PVB interlayer. Suitable for security
applications as glass stays in place
• Fire-rated glass
The Material Glass
Laminated Glass Used in Sloped
Glazing Provides Safety Against Falling
Shards

Glass Types by
Architectural Treatments
• Patterned glass
ˉ Hot glass can be rolled into sheets with
many different surface textures and
patterns to obscure vision for privacy
• Fritted glass
ˉ Pigmented glass particles called frits are
used to imprint glass. Glass is dried and
fired in tempering furnace to make it
permanent
• Spandrel glass
ˉ Used to cover bands of floor/wall
around the floor edges. Usually
tempered or heat strengthened with
insulation behind them
The Material Glass
Fritted Glass Used
to Create Patterns
Darker Colored
Spandrel Glass

Glass For Controlling
Solar Radiation
• Tinted Glass
– Made by adding small amounts of
selected chemical elements to the
molten glass mixture
• Reflective Glass or Solar Control Glass
– Thin Durable films of metal or metal
oxide are deposited on the surface of
either tinted glass or clear glass to make
the glass reflective. The film turns away
significant portion of solar radiation
The Material Glass
Building With Reflective Coated Glass

Impact of Glass Type on
Control of Visible Light
and Solar Radiation
• Transmitted Radiation
• Reflected Radiation
• Absorbed Radiation
• Re-radiation
The Material Glass
Effect of Three Different Glazing Assemblies on
Incoming Sunlight – Outside is on Left

Glass and Thermal
Considerations
• IGU – Insulating Glass Unit
– Made of multiple glass with sealed air space
reducing conductance, single glazing is single
glass, double glazing is two sheets and triple
glazing is three sheets of glass
– Space filled by air or inert gas in a
hermetically sealed cavity
– Different spacers used including warm-edge
spacer
– Performance given in terms of U values
• Low Emissivity coated glass (Low-e)
– Formed with transparent metallic coating to
improve thermal performance
– Located on surface 2 and sometimes on
surface 3.
– Improves thermal performance
The Material Glass
Two Methods of Sealing
Edge of Double Glazing

Glass and Thermal
Considerations
• Visible Light Transmittance - VT
– Ratio of visible light passing to the
amount striking the glass
• Solar Heat Gain Coefficient - SHGC
– Ratio of heat admitted to the amount
striking the glass
• Light Solar Gain Ratio – LSG
– Ratio of VT to SHGC
The Material Glass
Glazing Type VT SHGC LSG U
1
R
2
Single glazing
, clear 0.90 0.85 1.3 1.1
6.3
0.91
0.16
Double glazing, clear 0.79 0.70 1.1 0.47
2.7
2.1
0.37
Double glazing,
medium gray tinted
0.40 0.45 0.9 0.47
2.7
2.1
0.37
Triple glazing, clear 0.53 0.52 1.0 0.34
1.9
2.9
0.52
Double glazing,clear,
low-e (low SHGC)
0.64 0.27 2.4 0.28
1.6
3.6
0.63
Double glazing, clear,
low-e (high SHGC), argon filled
0.78 0.63 1.2 0.27
1.5
3.7
0.65
1
U-Factor: Btu/ft
2
-hr-
o
F followed byW/m
2
-
o
K
2
R-Value: ft
2
-hr-
o
F/Btu followed bym
2
-
o
KW
Glass Properties Impacting Thermal
Visual Performance

The Material Glass
Glass and Thermal
Considerations
• The label on this fabricator's
glass sample indicates that this
IGU consists of
– a ¼"-thick low-e, annealed lite
(with the trade name
Solarban 60)
– a ½" spacer and
– a ¼" clear annealed light.
– VLT of 0.70
– SC of 0.44
– SHGC of 0.38
– U-Value of 0.29

Glazing
17 Glass & Glazing

Glazing Small Lights
• Not subject to excessive wind force or
stresses due to thermal expansion
• Glass first held in place by Glazier’s
points and then sealed on outside with
putty followed by painting
• Factory glazed units employ improved
putties or glazing compounds which stay
elastic for longer period of time
Glazing
Alternative Methods of Single Glazing
Small Lights – Outdoor Side on Left

Glazing Large Lights
• Large lights, those over 6 ft2 (0.6 m2)
require more care in glazing due to
stresses
• Design objectives are
– Support weight of glass without
abnormal stress patterns
– Support glass against wind pressure and
suction
– Allow for expansion and contraction of
glass and frame without damage
– Avoid contact of glass with any hard
material such as frame
Glazing
Glaziers Install Lights of Glass that
Weigh as Much as 125 pounds (57 kg)

• Setting blocks are of synthetic
rubber and support weight of glass
• Bite or depth of grip on the edge
of glass of certain amount is
required to resist wind load
• Glazing components used
between frame and glass are either
wet or dry such as
– Preformed solid tape sealant
made of polybutene
– Wedge or roll in gasket
– Lock strip gasket
• In good design reliance for
waterproofing relies on wet and
dry seals in conjunction with
pressure equalization and drainage
Glazing
Alternative Methods of Single Glazing
Large Lights – Outdoor Side on Left

• Lockstrip gasket is a dry glazing method
• It is faster, easier and less dependent on
workmanship then wet glazing method
• Wet glazing with good workmanship is
more effective
Glazing
Lockstrip Gasket Installation in
Progress and Completed

Advanced Glazing
Systems
• Butt-joint glazing system
– Head and sill of the
glass sheets are
supported
conventionally in metal
frames, but vertical
mullions are eliminated
– The vertical joints
between sheets of glass
are made by injection of
colorless silicone sealant
– There is a strong effect
of unbroken horizontal
band of glass around the
building
Glazing
Mullionless Butt-Joint Glazing With
Single Glazing

Advanced Glazing
Systems
Glazing
Mullionless
Butt-Joint
System Seen
from the
Outside

Glazing
• Horizontal strip windows that need to
appear mullionless only from the outside
can use a mullion on the inside
• Sill and head are conventionally glazed
Advanced Glazing
Systems

Advanced Glazing
Systems
• Structural silicone flush
glazing
– The metal mullions lie
entirely inside the glass
with glass adhered to the
mullion by silicone
sealant
– Outside skin is
completely flush
– Systems with critical
silicone work done in
factory are also possible
Glazing
Glass Mounted With Four-Side
Structural Silicone Glazing

Glazing
Steps in assembly of a mullion for a four-side
structural silicone exterior flush glazing system
Advanced Glazing
Systems

Glazing
• Structural Spacer Glazing is a proprietary
system
• The glass is fastened to the mullion with an
aluminum pressure plate.
• The face is then sealed
• Desiccant is integrated into the system
Advanced Glazing
Systems

Advanced Glazing
Systems
• Suspended Glazing Systems and
Glass Mullion System
– Used primarily for high walls of
glass around building lobbies
– Tempered glass sheets are
suspended from above and
stabilized by tempered glass
perpendicular stiffeners
– Metal fittings are used to join
multiple sheets of glass
– Stainless steel cables and fittings
are used in roof applications
Glazing
Glass Suspended from Above With
Vertical Glass Stiffeners

Glazing
• Four point spider fitting
• Adjustable vertical stainless steel rod carries
the load to the structure above
Advanced Glazing
Systems

Glazing
A suspended glazing
system with "saddle"
(anticlastic) curvature
keeps the entire wall
system in tension.
Advanced Glazing
Systems

Glazing
The spider fittings and cable
system must resist wind,
seismic, and dead loads
without inducing bending
forces in the glass or creating
stress concentrations around
the points of attachment
Advanced Glazing
Systems

Glazing
The glass wall obtains additional
stiffness where the cable system is
tied to adjacent columns.
Advanced Glazing
Systems

Building Construction
Glazing
• Insulating laminated glass
units serve as roof
• Laminated glass fins
serve as beams
• Vertical rods take the
load from the fins
• Vertical rods transfer
load to cables which in
turn transfers it to steel
trusses
Advanced Glazing
Systems

Glazing
• Vertical rods take the
load from the fins
• Vertical rods transfer
load to cables which in
turn transfers it to the
steel trusses
• Upward arching cables
provide wind uplift
resistance
Advanced Glazing
Systems

MasterFormat Sections For
Glass
17 Glass and Glazing
CSI/CSC MASTERFORMAT SECTIONS FOR GLASS
08 80 00 GLAZING
08 81 00 Glass Glazing
08 83 00 Mirrors
08 84 00 Plastic Glazing
08 85 00 Glazing Accessories
08 88 00 Special Function Glazing
Hurricane-Resistant Glazing
Cable-Suspended Glazing
Pressure-Resistant Glazing
Radiation-Resistant Glazing
Security Glazing
Ballistics-Resistant Glazing

Glass And Glazing

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