BT5: Wall Construction Systems - Curtain Wall
Unit and Mullion System
also called the semi-unitized system; hybrid of the stick and unit system; mullions are the first to be installed then the spandrel and glazing are inserted into the stick system as a complete unit
stick system
can be delivered to the site more quickly but take longer to erect
Window Wall
careful detailing of _______________, bearing on the floor slab, can make it appear as a continuous curtain wall
Walls
constructed in different forms and of various materials to serve several functions
Walls
designed to be strong enough to safely resist the horizontal and vertical forces imposed upon them
Walls
designed to provide resistance to passage of fire; often contain doors and windows, which provide for controlled passage of environmental factors and people through it
Glass Curtain Walls
designed to span multiple floors and take into consideration design requirements such as: thermal expansion and contraction, water diversion, ventilation, and thermal efficiency
shadow box
example of coated glass; creates the illusion of opacity with a dark metal pan or insulation board that is held back from the glass
self-cleaning glass
example of coated glass; glass with photocatalytic coating that reacts with sunlight to break down and dislodge organic dirt
solar-reflective or low-emissivity glass
example of coated glass; most common coatings used for reflection, absorption and radiation of solar energy; reflects long-wave, infrared energy
Ceramic Frit
example of coated glass; used to create an opaque or spandrel glass; ceramic coating fused to the base glass during the heat treating process; can be applied thicker and also multiple layers to increase opacity; requires opaque back-up construction
solar-reflective glass and low emissivity glass; ceramic frit; polyester and silicone films and paints; self-cleaning glass; shadow box
examples of coated glass
Curtain Wall
external, lightweight, non-loadbearing wall (either glazing or cladding) that is hung from a metal frame rather than built from the ground like a brick wall; the framework is usually of concrete or steel
Advantages of Unit Panel Systems
fabrication in controlled environment; easier to isolate the glass unit from structural movement esp. seismic; with proper scheduling and lead time, it allows the building to be closed-in more quickly
Disadvantages of Stick System
field installation of glazing is often done by unskilled workers, certain amount of control is lost when installed on site, more suitable in small projects
Extruded Aluminum Frames
frames for the ethereal walls that was introduced in the 1950s
Window Wall
generally used to reduce cost; critical that it should be capable of withstanding the wind and seismic loads
Facades
were changed forever with the introduction of the frame building, which permitted a light exterior wall of glass instead of the meagre punched opening of masonry load-bearing walls
Alastair Pilkington
one of the contributors to the development of contemporary glass curtain walls
Hallidie Building
one of the first buildings with pure glass curtain wall in San Francisco, California by James Polk (1918)
polyester and silicone films and paints
other methods of creating opaque glass
similar
overall fabrication and installation time is often ___________ for stick and unitized systems
annealing
process of slowly cooling glass to relieve internal stresses after it was formed
Exterior Walls
protects the building interior from external environmental effects such as heat and cold, sunlight, ultraviolet radiation, rain and snow, and sound, while containing desirable interior environmental conditions
joint
rails and mullions of stick systems each have a _______ on each side that seals the glass to the frame
unitized system
require more lead time but are erected more quickly
fritted glass
requires opaque back-up construction
laminated glass
sealed, double-plane glass unit with a vacuum or gas in the space between the panes
Structural Glass or Bolt-Fixed Glass
series of glass units held together with patches or bolted connections that support the glass by direct bearing and friction
Unit Panel System
series of prefabricated units that interlock with the adjacent frame and is often pre-glazed; may be as high as 3 stories but generally span just one floor and range 4-12 ft. in width
column cover and spandrel system
similar to unit and mullion systems; building frame is emphasized in column covers, which act like sticks
annealed glass
standard float glass; not a safety glass; breaks into large sharp pieces
24 to 40, 7 to 12
sticky systems are purchased in ______________ ft. or ______________ m lengths and cut on-site or in the shop
tempered glass
strong, break-resistant type of safety glass that, if broken, shatters into small granular pieces
Stainless Steel
structural glass/bolt-fixed glass fittings material
Pilkington Planar
the first structural bolt-fixed glass system to be widely marketed developed by Alastair Pilkington
Industrial Revolution to early 1900s
time when architects expressed the need for an innovative and efficient wall construction system
Window Wall, Structural Glass
two types of glass curtain wall installation
Window Wall
type of glass curtain wall installation; all barriers and retarders can be continuous for the full height of the building
Window Wall
type of glass curtain wall installation; continuous laid installation
Structural Wall
type of glass curtain wall installation; makes use of bolts and other kinds of fittings which strengthens the glass and holds it together
joint
unitized systems have an additional _________ that seals the frame of one unit to the adjoining unit
point loaded structural glazing system
vertical framing member can be comprised of stick, cable, or another custom structure behind the glass; glass is supported by a system of four-point brackets and joints are sealed with silicone
Float Glass
was in full production in 1959
Drawbacks of Shiny Coated Glass Buildings
- heat - glare - confusion by the lights of office towers for migratory birds that uses stars to navigate at night
coated glass
glass with a chemical film applied to one surface
Bolting Glass
had small metal patches; structural glass (1960s)
tinted or heat-absorbing glass
has color and light- or heat-reducing capabilities; transmittance is 14-85% depending on the thickness and degree of tinting
Molten Tin
in 1952, Pilkington began his experiment using ______________ to support or float the molten glass
Disadvantages of Unit Panel Systems
increased cost and problems with transportation, protection of the units and on-site storage; installation must be sequential; "leave out" units are necessary to load construction materials into the interior of the building, these units installed out of sequence require special installation and joint design; replacements of components are more difficult; have more joints than stick systems
Stick system
installed piece by piece on-site, including the glazing
vertical glass fins (mullions) or steel, cable tension structures
lateral supports can be in the form of _________________ and ___________________
Advantages of Stick System
lower costs, flexibility, potential to adjust the curtain wall frame to structural frame, quick ease of storing and ability to work on different areas of the building at the same tim
float glass
made by floating molten on a bed of molten tin; clearest of the glazing options; transmittance is 75-92% of visible light; slight-greenish tint at a thickness of 10mm or greater
bearing walls or curtain walls
modern building walls may be designed to serve as either __________________________________________ or as a combination of both, depending on its use
aluminum frames
most common __________________ are based on either stick or unit system
extruded aluminum
most common curtain wall frames
