BUILDING TECHNOLOGY I
1.
GLASS
Glass is a hard, brittle, chemically inert substance produced by
fusing silica together with a flux and a stabilizer into a mass that
cools to a rigid condition without crystallization. It is used in
building construction in various forms.
Foamed or cellular glass is used as rigid, vapor proof
thermal insulation.
Glass fibers are used in textiles and for material
reinforcement. In spun form, glass fibers form
glass wool, which is used for acoustical and
thermal insulation.
Glass block is used to control light transmission,
glare, and solar radiation.
Glass, however, is used most commonly to glaze
the window, sash and skylight openings of
buildings.
1.
GLASS
The three major types of flat glass are the following:
Sheet glass is fabricated by drawing the molten glass from a
furnace (drawn glass), or by forming a cylinder, dividing it
lengthwise, and flattening it (cylinder glass). The firepolished surfaces are not perfectly parallel, resulting in some
distortion of vision. To minimize this distortion, glass should
be glazed with the wave distortion running horizontally.
Plate glass is formed by rolling molten glass into a plate that
is subsequently ground and polished after cooling. Plate
glass provides virtually clear, undistorted vision.
Float glass is manufactured by pouring molten glass onto a
surface of molten tin and allowing it to cool slowly. The
resulting flat, parallel surfaces minimize distortion and
eliminate the need for grinding and polishing. Float glass is
the successor to plate glass and accounts for the majority of
flat-glass production.
1.
GLASS
Other types of glass include the following:
• Annealed glass is cooled slowly to relieve internal
stresses.
• Heat-strengthened glass is annealed glass that is
partially tempered by a process of reheating and sudden
cooling. Heat-strengthened glass has about twice the
strength of annealed glass of the same thickness.
• Tempered glass is annealed glass that is reheated to just
below the softening point and then rapidly cooled to induce
compressive stresses in the surfaces and edges of the
glass and tensile stresses in the interior. Tempered glass
has three to five times the resistance of annealed glass to
impact and thermal stresses but cannot be altered after
fabrication. When fractured, it breaks into relatively
harmless pebble-sized particles.
• Laminated or safety glass consists of two or more plies of
flat glass bonded under heat and pressure to interlayers of
polyvinyl butyral resin that retains the fragments if the
glass is broken. Security glass is laminated glass that has
exceptional tensile and impact strength.
1.
GLASS …other types
• Wired glass is flat or patterned glass having a square or
diamond wire mesh embedded within it to prevent shattering
in the event of breakage or excessive heat. Wired glass is
considered a safety glazing material and may be used to
glaze fire doors and windows.
• Patterned glass has a linear or geometric surface pattern
formed in the rolling process to obscure vision or to diffuse
light.
• Obscure glass has one or both sides acid-etched or
sandblasted to obscure vision. Either process weakens the
glass and makes it difficult to clean.
• Spandrel glass is an opaque glass for concealing the
structural elements in curtain wall construction, produced by
fusing a ceramic frit to the interior surface of tempered or
heat-strengthened glass.
• Insulating glass is a glass unit consisting of two or more
sheets of glass separated by a hermetically sealed air space
to provide thermal insulation and restrict condensation; glass
edge units have a 3/16” (5) air space; metal edge units have
a ¼” or ½” (6 or 13) air space.
1.
GLASS …other types
• Tinted or heat-absorbing glass has a chemical admixture
to absorb a portion of the radiant heat and visible light that
strike it. Iron oxide gives the glass a pale blue-green tint;
cobalt oxide and nickel impart a grayish tint; selenium
infuses a bronze tint.
• Reflective glass has a thin, translucent metallic
coating to reflect a portion of the light and radiant
heat that strike it. The coating may be applied to
one surface of single glazing, in between the
plies of laminated glass, or to the exterior or
interior surfaces of insulating glass.
1.
GLASS …other types
• Low-emissivity (low-e) glass
transmits visible light while
selectively reflecting the lo9nger
wavelengths of radiant heat,
produced by depositing a low-e
coating either on the glass itself or
over a transparent plastic film
suspended in the sealed air space
of insulating glass.
1.
GLASS
Glass Product
Type
Nominal Thickness
Maximum Area
Weight
inch
(mm)
inches
(mm)
psf*
(2.4)
(3.2)
60 x 60
60 x 80
(1525 x 1525)
(1525 x 2030)
1.22
1.63
Sheet Glass
AA, A, B
SS 3/32
DS 1/8
Float or Plate
Mirror
Glazing
¼
1/8
¼
5/
16
3/8
½
5/8
¾
7/8
1/8
7/32
¼
¼
7/32
¼
3/8
(6.4)
(3.2)
(6.4)
(7.9)
(9.5)
(12.7)
(15.9)
(19.1)
(22.2)
(3.2)
(5.6)
(6.4)
(6.4)
(5.6)
(6.4)
(9.5)
75 sf
74 x 120
128 x 204
124 x 200
124 x 200
120 x 200
120 x 200
115 x 200
115 x 200
60 x 132
60 x 132
60 x 144
60 x 144
54 x 120
60 x 144
60 x 144
(7 m2)
(1880 x 3050)
(3250 x 5180)
(3150 x 5080)
(3150 x 5080)
(3050 x 5080)
(3050 x 5080)
(2920 x 5080)
(2920 x 5080)
(1525 x 3355)
(1525 x 3355)
(1525 x 3660)
(1525 x 3660)
(1370 x 3050)
(1525 x 3660)
(1525 x 3660)
3.28
1.64
3.28
4.10
4.92
6.54
8.17
9.18
11.45
1.60
2.40
3.50
3.50
2.82
3.50
4.45
¼
3/8
½
5/8
(6.4)
(9.5)
(12.7)
(15.9)
72 x 120
72 x 120
72 x 120
72 x 120
(1830 x 3050)
(1830 x 3050)
(1830 x 3050)
(1830 x 3050)
3.30
4.80
6.35
8.00
Heavy
Plate
Float
Patterned Glass
Wired Glass
Laminated Glass
or
Glazing
Various
patterns
Polished-mesh
Patternedmesh
Parallel wires
(2) 1/8” float
Heavy float
*1 psf = 47.88 Pa
* Verify maximum sizes with
glass manufacturer
*Any glass 1/8” or thicker can
be tempered, except for
patterned or wired glass;
tempered glass can also be
incorporated into insulating or
laminated glass units
* Reflective coatings may be
applied to float, plate,
tempered, laminated or
insulating glass
1.
GLASS
Glass Product
Type
Nominal Thickness
inch
Tinted Glassd
Insulating Glass
(2) 3/32” sheets
(2) 1/8” sheets
(2) 1/8”
Sheet, plate or float
(2) 3/16”
Plate or float
(2) ¼”
Plate or float
Bronze
Gray
Glass edge units
3/16” air space
3/16” air space
Metal edge units
¼” air space
½” air space
¼” air space
½” air space
¼” air space
½” air space
Maximum Area
Weight
(mm)
inches
(mm)
psf*
1/8
3/16
¼
3/8
½
1/8
3/16
¼
3/8
1/2
(3.2)
(4.8)
(6.4)
(9.5)
(12.7)
(3.2)
(4.8)
(6.4)
(9.5)
(12.7)
35 sf
120 x 144
128 x 204
124 x 200
120 x 200
35 sf
120 x 144
128 x 204
124 x 200
120 x 200
(3 m2)
(3050 x 3660)
(3250 x 5180)
(3150 x 5080)
(3050 x 5080)
(3 m2)
(3050 x 3660)
(3250 x 5180)
(3150 x 5080)
(3050 x 5080)
1.64
2.45
3.27
4.90
6.54
1.64
2.45
3.27
4.90
6.54
3/8
7/16
(9.5)
(11.1)
10 sf
24 sf
(0.9 m2)
(2.2 m2)
2.40
3.20
½
¾
5/8
7/8
¾
1
(12.7)
(19.1)
(15.9)
(22.2)
(19.1)
(25.4)
22 sf
22 sf
34 sf
42 sf
50 sf
70 sf
(2.0 m2)
(2.0 m2)
(3.2 m2)
(3.8 m2)
(4.6 m2)
(6.5 m2)
3.27
3.27
4.90
4.90
6.54
6.54
*1 psf = 47.88 Pa
* Solar energy transmission
reduced 35% to 75%
•Visible light transmission
reduced 32% to 72%
* R-value = 1.61
* R-value = 1.61
* R-value = 1.72
* R-value = 2.04
* R-values for units w/
½” air space and low-e
coating:
e = 0.20, R = 3.13
e = 0.40, R = 2.63
e = 0.60, R = 2.33
2.
HARDWARE
2.01
NAILS
Nails are straight, slender pieces of metal having one end pointed
and the other enlarged and flattened for hammering into wood or
other building materials as a fastener.
Material • Nails are usually of mild steel, but may also be of aluminum,
copper, bras, zinc or stainless less.
• Tempered, high-carbon steel nails are used for greater
strength in masonry applications.
• The type of metal used should be compatible with the
materials being secured to avoid loss of holding power and
prevent staining of the materials.
Length and • Nail lengths are designated by the term penny (d).
Diameter of • Nails range in length from 2d, about 1” (25) long, to 60d
about 6” (150) long
the Shank
• Nail length should be about 3 x thickness of the material
being secured
• Large diameter nails are used for heavy work while lighter
nails are used for finish work; thinner nails are used for
hardwood rather than for softwood.
2.
HARDWARE
2.01
NAILS
Form of the
Shank
• For greater gripping strength, nail shafts may be serrated,
barbed, threaded, fluted or twisted.
• Nail shafts may be cement-coated fro greater resistance
to withdrawal, or be zinc-coated for corrosion resistance.
Nail Heads
• Flat heads provide the largest amount of contact area and
are used when exposure of the heads is acceptable.
• The heads of finish nails are only slightly larger than the
shaft and may be tapered or cupped.
• Double-headed nails are used for easy removal in
temporary construction and concrete formwork
Nail Points • Most nails have diamond-shaped points.
• Sharp-pointed nails have greater holding strength but
may tend split some woods; blunt points should be
used for easily split woods.
2.
HARDWARE
2.01
NAILS
Power-Driven • Pneumatic nailers and
Fasteners
staplers, driven by a
compressor, are capable of
fastening materials to wood,
steel or concrete.
• Powder-driven fasteners
use gunpowder charges to
drive a variety of studs into
concrete or steel.
2.
HARDWARE
2.02
SCREWS
Screws are metal fasteners having tapered, helically threaded
shanks and slotted heads, designed to be driven into wood or the
like by turning, as with a screwdriver. Because of their threaded
shafts, screws have greater holding power than nails, and are
more easily removable. The more threads they have per inch,
the greater their gripping strength. Screws are classified by use,
type of head, material, length and diameter.
• Material: steel, brass, aluminum, bronze,
stainless steel
• Lengths: ½” to 6” (13 to 150)
• Diameters: up to 24 gauge
2.
HARDWARE
2.02
SCREWS
The length of a wood screw should be about 1/8” (3) less than
the combined thickness of the boards being joined, with ½ to 2/3
of the screw’s length penetrating the base material. Finethreaded screws are generally used for hardwoods while
coarse-threaded ones are used for softwoods.
Holes for screws should be predrilled and be equal to the base
diameter of the threads. Some screws, such as self-tapping
and drywall screws, are designed to tap corresponding female
threads as they are driven.
2.
HARDWARE
2.03
BOLTS
Bolts are threaded metal pins or rods, usually having a head at
one end, designed to be inserted through holes in assembled
parts and secured by a mating nut. Carriage bolts are used
where the head may be inaccessible to the placement of a nut or
where an exceptionally long bolt would be needed to penetrate a
joint fully.
• Lengths: ¾” to 30”
(75 to 760)
• Diameters: ¼” to
1-¼” (6 to 32)
2.
HARDWARE
2.03
BOLTS
• Washers are perforated disks of metal, rubber or plastic
used under the head of a nut or bolt or at a joint to distribute
pressure, prevent leakage, relieve friction or insulate
incompatible materials.
• Lock washers are specially constructed to prevent a nut
from shaking loose
• Load-indicating washers have small projections that are
progressively flattened as a bolt is tightened, the gap
between the head or nut and the washer indicating the
tension in the bolt.
2.
HARDWARE
2.03
BOLTS
• Expansion bolts are anchor bolts having a
split casing that expands mechanically to
engage the sides of a hole drilled in
masonry or concrete.
• Molly is a trademark for a brand of
expansion bolt having a split, sleevelike
sheath threaded so that turning the bolt
draws the ends of the sheath together and
spreads the sides to engage a hole drilled
in masonry or the inner surface of a hollow
wall.
• Expansions shields are lead or plastic
sleeves inserted into a predrilled hole and
expanded by driving a bolt or screw into it.
• Toggle bolts are used to fasten materials to
plaster, gypsum board and other thin wall
materials. They have two hinged wings that
close against a spring when passing through
a predrilled hole and open as they emerge
to engage the inner surface of a hollow wall.
2.
HARDWARE
2.03
BOLTS
• Rivets are metal pins that are used for permanently joining
two or more structural steel members by passing a headed
shank through a hole in each piece and hammering down
the plain end to form a second head. Their use has been
largely superseded by the less labor-intensive techniques
of bolting or welding.
• Explosive rivets, used when a joint is accessible from
one side only, have an explosive-filled shank that is
detonated by striking the head with a hammer to
expand the shank on the far side of the hole.
2.
HARDWARE
2.04 ADHESIVES
Adhesives are sued to secure the surfaces of two materials
together. Numerous types of adhesives are available, many of
them being tailor-made for use with specific materials and under
specified conditions. They may be supplied in the form of a solid,
liquid, powder or film; some require a catalyst to activate their
adhesive properties. Always follow the manufacturer’s
recommendations in the use of an adhesive. Important
considerations in the selection of an adhesive include:
• Strength: Adhesives are usually strongest in resisting tensile
and shear stresses and weakest in resisting cleavage or
splitting stresses.
• Curing or setting time: This ranges from immediate bonding to
curing times of up to several days.
• Setting temperature range: Some adhesives will set at room
temperature while others require baking at elevated
temperatures.
• Method of bonding: Some adhesives bond on contact while
others require clamping or higher pressures.
• Characteristics: Adhesives vary in their resistance to water,
heat, sunlight and chemicals as well as their aging properties.
2.
HARDWARE
2.04
ADHESIVES
Common types of adhesives:
• Animal or fish glues are primarily for indoor use where
temperature and humidity do not vary greatly; they may be
weakened by exposure to heat or moisture.
• White or polyvinyl glue sets quickly, does not stain and is
slightly resilient.
• Epoxy resins are extremely strong, waterproof and may be
used to secure both porous and nonporous materials; they
may dissolve some plastics. Unlike other adhesives, epoxy
glues will set at low temperatures and under wet conditions.
• Resorcin resins are strong, waterproof and durable for
outdoor use, but they are flammable and their dark color may
show through paint.
• Contact cement forms a bond on contact and therefore does
not require clamping. It is generally used to secure large sheet
materials such as plastic laminate.
END OF
DIVISION 08
DOORS AND WINDOWS