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 glassAnnealed glass is cooled slowly to relieve internal stresses.

• Heat-strengthened glassHeat-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 glassTempered 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.

• LaminatedLaminated or safety glasssafety 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 glassWired 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 glassPatterned glass has a linear or geometric surface pattern formed in the rolling process to obscure vision or to diffuse light.

• Obscure glassObscure 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 glassSpandrel 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 glassInsulating 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

• TintedTinted or heat-absorbing glassheat-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 …other types

• Reflective glassReflective 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) glassLow-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 …other types

1. GLASS

3.304.806.358.00

(1830 x 3050)(1830 x 3050)(1830 x 3050)(1830 x 3050)

72 x 12072 x 12072 x 12072 x 120

(6.4)(9.5)(12.7)(15.9)

¼3/8

½5/8

(2) 1/8” floatHeavy float

Laminated Glass

3.503.502.823.504.45

(1525 x 3660)(1525 x 3660)(1370 x 3050)(1525 x 3660)(1525 x 3660)

60 x 14460 x 14454 x 12060 x 14460 x 144

(6.4)(6.4)(5.6)(6.4)(9.5)

¼¼

7/32¼

3/8

Polished-meshPatterned-meshParallel wires

Wired Glass

1.602.40

(1525 x 3355)(1525 x 3355)

60 x 13260 x 132

(3.2)(5.6)

1/87/32

Various patterns

Patterned Glass

4.104.926.548.179.1811.45

(3150 x 5080)(3150 x 5080)(3050 x 5080)(3050 x 5080)(2920 x 5080)(2920 x 5080)

124 x 200124 x 200120 x 200120 x 200115 x 200115 x 200

(7.9)(9.5)(12.7)(15.9)(19.1)(22.2)

5/16

3/8½

5/8¾

7/8

GlazingHeavy Float or Plate

3.281.643.28

(7 m2)(1880 x 3050)(3250 x 5180)

75 sf74 x 120128 x 204

(6.4)(3.2)(6.4)

¼1/8

¼

MirrorGlazing

Float or Plate

1.221.63

(1525 x 1525)(1525 x 2030)

60 x 6060 x 80

(2.4)(3.2)

SS 3/32DS 1/8

AA, A, BSheet Glass

psf*(mm)inches(mm)inch

* 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

WeightMaximum AreaNominal ThicknessTypeGlass Product

*1 psf = 47.88 Pa

2.403.20

3.273.274.904.906.546.54

(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 sf24 sf

22 sf22 sf34 sf42 sf50 sf70 sf

(9.5)(11.1)

(12.7)(19.1)(15.9)(22.2)(19.1)(25.4)

3/87/16

½¾

5/87/8

¾1

Glass edge units3/16” air space3/16” air spaceMetal edge units¼” air space½” air space¼” air space½” air space¼” air space½” 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) ¼”Plate or float

1.642.453.274.906.541.642.453.274.906.54

(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 sf120 x 144128 x 204124 x 200120 x 20035 sf120 x 144128 x 204124 x 200120 x 200

(3.2)(4.8)(6.4)(9.5)(12.7)(3.2)(4.8)(6.4)(9.5)(12.7)

1/83/16

¼3/8

½1/8

3/16¼

3/81/2

BronzeGray

Tinted Glassd

psf*(mm)inches(mm)inch

WeightMaximum AreaNominal ThicknessTypeGlass 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/ ½” air space and low-e coating:e = 0.20, R = 3.13e = 0.40, R = 2.63e = 0.60, R = 2.33

1. GLASS

*1 psf = 47.88 Pa

2. HARDWARE2.01 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).• Nails range in length from 2d, about 1” (25) long, to 60d

about 6” (150) long• 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 NAILS2. HARDWARE

2. HARDWARE2.02 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

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. 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. HARDWARE2.02 SCREWS

2. HARDWARE2.03 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. HARDWARE2.03 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. HARDWARE2.03 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. HARDWARE2.03 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. HARDWARE2.04 ADHESIVESAdhesives 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. HARDWARE2.04 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.

Common types of adhesives:

END OFDIVISION 08DOORS AND WINDOWS