Curtain walling is a vertical building enclosure which supports no load other than its own weight and the environmental forces which act upon it
A curtain wall is defined as thin, usually aluminum-framed wall, containing in-fills of glass, metal panels, or thin stone.
Hallidie Building, San Francisco, California 1918
Structural Glazing
Structure Glazing refers to a method of retaining the glass in a window, storefront or curtainwall. Instead of the edges of the glazing being capture in a pocket of the framing and secured in place with gaskets, the structurally-glazed glass is retained on one or more sides by an adhesive, normally silicone.
structural glazing is one of the fastest-growing and most innovative forms of curtainwall construction the commercial facade mark: has seen in many years.
In 1983, Park Avenue Tower was New York City’s first experiment with structural silicone glazing. With over 220,000 square feet of reflective glass curtainwall adhered with an adhesive/sealant
Classification of Curtainwall Systems
- The conventional or the ‘stick’ system
- The unitized structurally glazed curtainwall system
- The semi-unitized structurally glazed curtainwall system
Functional Requirements of Curtainwalls
- Withstanding the action of elements
- Thermal Performance (Conduction, Solar Radiation, Thermal Break, Comfort)
- Acoustical Performance : Selectively impeding or controlling the flow sound
- Moisture Protection (Water Penetration, Condensation Resistance)
- FIRE SAFETY : Acting as a barrier not only to intruders but also to deteriorating influences affecting its own integrity including fire safety.
Elements of Curtainwall
Anchorage to the Building
In curtain wall critical part is its anchorage to the building
The mullion to mullion joint on each floor is achieved by special aluminum sliding sleeve. There is an expansion gap between two mullions to allow thermal movements.
Basic joint types in curtainwall
In curtain wall critical part is its anchorage to the building
The mullion to mullion joint on each floor is achieved by special aluminum sliding sleeve. There is an expansion gap between two mullions to allow thermal movements.
Rain Screen Principle
The ‘rain screen’ is the outer skin or surface of a curtainwall, the part exposed to the weather. Pressure-Equalized (P-E) Wall Design
‘Rain screen principle’ understanding for leakage to take place there must be present three essential ingredients:
- water
- Opening
- some kind of force to move water through the opening
CONVENTIONAL (STICK) CURTAINWALL SYSTEM
In this system the wall is installed piece by piece. Usually the mullion members are installed first, followed by transoms (horizontal members), the panels, and finally the glazing or window units.
HORIZONTAL SECTION (COURTESY: SP FABRICATORS PVT LTD.)
HORIZONTAL SECTION (COURTESY: SP FABRICATORS PVT LTD.)
UNITISED STRUCTURALLY GLAZED (USG) CURTAINWALL SYSTEM
In this system the wall is composed entirely of large framed units pre-assembled at the factory, complete with spandrel panels (if any) and also pre-glazed. Unitized structurally glazed (USG) panels consist of aluminum alloy split mullions and split transom on to which the glass panels are directly fixed with structural silicone glazing sealant without a sub-frame to form designed arrangement of vision and spandrel panels.
TYPICAL SPLIT MULLION DETAIL-FIX VISION/FIX VISION PANEL
(COURTESY: SP FABRICATORS PVT. LTD, MAHAPE, NAVI MUMBAI)
SEMI-UNITIZED STRUCTURALLY GLAZED CURTAINWALL SYSTEM
It is a compromise between conventional ‘stick’ and the unitized
curtainwall systems. The mullion and transom grid is fabricated at site and it is fixed to the structural frame by fixing brackets and angle cleats.
TYPICAL MULLION DETAILS-FIX SPANDREL/FIX SPANDREL PANEL
(COURTESY: S P FABRICATORS PYT LID. MAHAPE. NAVI MUMBAi)
Drawing are Taken from Handbook of BUILDING CONSTRUCTION (Vol. 2) – The Essential Source of MODERN CONSTRUCTION Practices, Materials & Equipment by M.M.Goyal
Structural Glazing System
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