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 fire-

polished 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.

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

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

1. GLASS

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.

1. GLASS

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.

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

1. GLASS

3.30

4.80

6.35

8.00

(1830 x 3050)

(1830 x 3050)

(1830 x 3050)

(1830 x 3050)

72 x 120

72 x 120

72 x 120

72 x 120

(6.4)

(9.5)

(12.7)

(15.9)

3/8

5/8

(2) 1/8 float

Heavy float

Laminated Glass

3.50

3.50

2.82

3.50

4.45

(1525 x 3660)

(1525 x 3660)

(1370 x 3050)

(1525 x 3660)

(1525 x 3660)

60 x 144

60 x 144

54 x 120

60 x 144

60 x 144

(6.4)

(6.4)

(5.6)

(6.4)

(9.5)

7/32

3/8

Polished-mesh

Patterned-

mesh

Parallel wires

Wired Glass

1.60

2.40

(1525 x 3355)

(1525 x 3355)

60 x 132

60 x 132

(3.2)

(5.6)

1/8

7/32

Various

patterns

Patterned Glass

4.10

4.92

6.54

8.17

9.18

11.45

(3150 x 5080)

(3150 x 5080)

(3050 x 5080)

(3050 x 5080)

(2920 x 5080)

(2920 x 5080)

124 x 200

124 x 200

120 x 200

120 x 200

115 x 200

115 x 200

(7.9)

(9.5)

(12.7)

(15.9)

(19.1)

(22.2)

5/16

3/8

5/8

7/8

Glazing Heavy Float or

Plate

3.28

1.64

3.28

(7 m2)

(1880 x 3050)

(3250 x 5180)

75 sf

74 x 120

128 x 204

(6.4)

(3.2)

(6.4)

1/8

Mirror

Glazing

Float or Plate

1.22

1.63

(1525 x 1525)

(1525 x 2030)

60 x 60

60 x 80

(2.4)

(3.2)

SS 3/32

DS 1/8

AA, A, B Sheet Glass

psf* (mm) inches (mm) inch

* Verify maximum sizes with

glass manufacturer

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

Weight Maximum Area Nominal Thickness Type Glass Product

*1 psf = 47.88 Pa

2.40

3.20

3.27

3.27

4.90

4.90

6.54

6.54

(0.9 m2)

(2.2 m2)

(2.0 m2)

(2.0 m2)

(3.2 m2)

(3.8 m2)

(4.6 m2)

(6.5 m2)

10 sf

24 sf

22 sf

22 sf

34 sf

42 sf

50 sf

70 sf

(9.5)

(11.1)

(12.7)

(19.1)

(15.9)

(22.2)

(19.1)

(25.4)

3/8

7/16

5/8

7/8

1

Glass edge units

3/16 air space

3/16 air space

Metal edge units

air space

air space

air space

air space

air space

air space

Insulating Glass

(2) 3/32 sheets

(2) 1/8 sheets

(2) 1/8

Sheet, plate or float

(2) 3/16

Plate or float

(2)

Plate or float

1.64

2.45

3.27

4.90

6.54

1.64

2.45

3.27

4.90

6.54

(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)

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

(3.2)

(4.8)

(6.4)

(9.5)

(12.7)

(3.2)

(4.8)

(6.4)

(9.5)

(12.7)

1/8

3/16

3/8

1/8

3/16

3/8

1/2

Bronze

Gray

Tinted Glassd

psf* (mm) inches (mm) inch

Weight Maximum Area Nominal Thickness Type Glass Product

* 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/

-e

coating:

e = 0.20, R = 3.13

e = 0.40, R = 2.63

e = 0.60, R = 2.33

1. GLASS

*1 psf = 47.88 Pa

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.

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.

Material

Nail lengths are designated by the term penny (d).

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.

Length and

Diameter of

the Shank

2. HARDWARE

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.

Form of the

Shank

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 Heads

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.

Nail Points

2.01 NAILS

Pneumatic nailers and

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.

Power-Driven

Fasteners

2.01 NAILS

2. HARDWARE

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

Diameters: up to 24 gauge

The length of a wood screw

the combined thickness of the boards being joined, with to 2/3

Fine-

threaded 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

2.02 SCREWS

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.

(75 to 760)

1-

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.