Building Design and Construction Handbook - Merritt - Ventech!

4.38 SECTION FOUR
two thicknesses—a 2-in plank, which is 15 in wide and 10 ft long, and a 3-in plank
which is 12 in wide and 30 in long. (See ASTM C377.)
GLASS AND GLASS BLOCK
Glass is so widely used for decorative and utilitarian purposes in modern construction
that it would require an encyclopedia to list all the varieties available. Clear
glass for windows and doors is made in varying thicknesses or strengths, also in
double layers to obtain additional thermal insulation. Safety glass, laminated from
sheets of glass and plastic, or made with embedded wire reinforcement, is available
for locations where breakage might be hazardous. For ornamental work, glass is
available in a wide range of textures, colors, finishes, and shapes.
4.31 WINDOW GLASS
Various types and grades of glass are used for glazing:
Clear Window Glass. This is the most extensively used type for windows in all
classes of buildings. A range of grades, as established by Federal Government
Standard DD-G-451c, classifies quality according to defects. The more commonly
used grades are A and B. A is used for the better class of buildings where appearance
is important, and B is used for industrial buildings, some low-cost residences,
basements, etc.
With respect to thickness, clear window glass is classified as ‘‘single-strength’’
about 3 ⁄32 in thick; ‘‘double-strength,’’ about 1 ⁄8 in thick; and ‘‘heavy-sheet,’’ up to
7 ⁄32 in thick. Maximum sizes are as follows: single-strength, 40 � 50 in; doublestrength,
60 � 80 in; and heavy sheet, 76 � 120 in. Because of flexibility, single
strength and double strength should never be used in areas exceeding 12 ft 2 , and
for appearance’s sake areas should not exceed 7 ft 2 .
Plate and Float Glass. These have, in general, the same performance characteristics.
They are of superior quality, more expensive, and have better appearance,
with no distortion of vision at any angle. Showcase windows, picture windows, and
exposed windows in offices and commercial buildings are usually glazed with polished
plate or float glass. Thicknesses range from 1 ⁄8 to 7 ⁄8 in. There are two standard
qualities, silvering and glazing, the latter being employed for quality glazing.
Processed Glass and Rolled Figured Sheet. These are general classifications of
obscure glass. There are many patterns and varying characteristics. Some provide
true obscurity with a uniform diffusion and pleasing appearance, while others may
give a maximum transmission of light or a smoother surface for greater cleanliness.
The more popular types include a clear, polished surface on one side with a pattern
for obscurity on the other side.
Obscure Wired Glass. This usually is specified for its fire-retarding properties,
although it is also used in doors or windows where breakage is a problem. It should
not be used in pieces over 720 in 2 in area (check local building code).