Building Design and Construction Handbook - Merritt - Ventech!

BUILDING MATERIALS 4.39
Polished Wired Glass. More expensive than obscure wired glass, polished wired
glass is used where clear vision is desired, such as in school or institutional doors.
There are also many special glasses for specific purposes:
Heat-Absorbing Glass. This reduces heat, glare, and a large percentage of ultraviolet
rays, which bleach colored fabrics. It often is used for comfort and reduction
of air-conditioning loads where large areas of glass have a severe sun exposure.
Because of differential temperature stresses and expansion induced by heat absorption
under severe sun exposure, special attention should be given to edge conditions.
Glass having clean-cut edges is particularly desirable, because these affect the edge
strength, which, in turn must resist the central-area expansion. A resilient glazing
material should be used.
Corrugated Glass, Wired Glass, and Plastic Panels. These are used for decorative
treatments, diffusing light, or as translucent structural panels with color.
Laminated Glass. This consists of two or more layers of glass laminated together
by one or more coatings or a transparent plastic. This construction adds strength.
Some types of laminated glass also provide a degree of security, sound isolation,
heat absorption, and glare reduction. Where color and privacy are desired, fadeproof
opaque colors can be included. When fractured, a laminated glass tends to
adhere to the inner layer of plastic and, therefore, shatters into small splinters, thus
minimizing the hazard of flying glass.
Bullet-Resisting Glass. This is made of three or more layers of plate glass laminated
under heat and pressure. Thicknesses of this glass vary from 3 ⁄4 to 3 in. The
more common thicknesses are 1 3 ⁄16 in, to resist medium-powered small arms: 1 1 ⁄2
in, to resist high-powered small arms; and 2 in, to resist rifles and submachine guns.
(Underwriters Laboratories lists materials having the required properties for various
degrees of protection.) Greater thicknesses are used for protection against armorpiercing
projectiles. Uses of bullet-resisting glass include cashier windows, bank
teller cages, toll-bridge booths, peepholes, and many industrial and military applications.
Transparent plastics also are used as bullet-resistant materials, and some
of these materials have been tested by the Underwriters Laboratories. Thicknesses
of 1 1 ⁄4 in or more have met UL standards for resisting medium-powered small arms.
Tempered Glass. This is produced by a process of reheating and sudden cooling
that greatly increases strength. All cutting and fabricating must be done before
tempering. Doors of 1 ⁄2- and 3 ⁄4-in-thick tempered glass are commonly used for
commercial building. Other uses, with thicknesses from 1 ⁄8 to 7 ⁄8 in, include backboards
for basketball, showcases, balustrades, sterilizing ovens, and windows,
doors, and mirrors in institutions. Although tempered glass is 4 1 ⁄2 to 5 times as
strong as annealed glass of the same thickness, it is breakable, and when broken,
disrupts into innumerable small fragments of more or less cubical shape.
Tinted and Coated Glasses. These are available in several types and for varied
uses. As well as decor, these uses can provide for light and heat reflection, lower
light transmission, greater safety, sound reduction, reduced glare, and increased
privacy.