From: Fundamentals of Building Construction, Allen/Iano
From: Fundamentals of Building Construction, Allen/Iano
Sheridan College
Architectural Technology
ARCH29969 - STUDIO 3
MODULE 14: WALL ASSEMBLIES: CURTAIN WALLS
A Curtain Wall is an exterior wall assembly supported entirely by the steel or concrete structural frame of a building. It alone has no capacity to bear any part of a building’s load; it maintains its own structural capacity to bear its own weight plus wind loads.
Think of a curtain wall assembly as a structure in and of itself, hung from the structure of the building. The building’s structure (in addition to resisting lateral loads, carrying live and dead loads, etc.) will also carry the weight of the curtain wall assembly. The curtain wall does not transfer any load of the building to which it is attached into the earth.
A Curtain Wall may be made from metal framing containing glass (clear vision or opaque spandrel units), or thin veneer stone, metal, masonry or concrete.
2.0 External Forces and Elements
A curtain wall, like other wall systems, must withstand:
+ Loads – Movement must be allowed to occur between the structural system of the building and the structure of the curtain wall assembly. Deformation or deflection of the building’s structural system cause by seismic, wind, or differential settlement, for example, must be separated from the curtain wall assembly. Deflection in the curtain wall assembly itself could lead to the failure of glazing and stone veneers.
+ Wind – The curtain wall has to transfer wind loads through itself to the structural frame of the building without excessive deflection.
- Wind can create positive or negative pressure on the wall, either pushing the assembly into the structural frame of the building or acting as a force pulling it off. The curtain wall’s connections to the building must adequately resist these lateral forces as well as its own gravity loads.
+ Fire – While a glazed curtain wall provides no fire resistance rating, the building code enforces the use of fire stopping between floor assemblies to prevent the vertical passage of smoke and fire between floors. Opaque spandrel panels employed throughout a clear glass curtain wall at floor assemblies may provide a fire resistance rating.
From: Fundamentals of Building Construction, Allen/Iano
From: Fundamentals of Building Construction, Allen/Iano
3.0 Assembly Modes of Glazed Metal Systems:
+ Stick System
+ Unit System
+ Unit and Mullion System
+ Panel System
+ Column Cover and Spandrel System
From Francis D. K. Ching, Building Construction Illustrated
Vertical Mullions of a two-storey Stick System at World Trade Center in New York
BELOW: A glazed metal Unit System curtain wall assembly. Note the construction worker in the top right of the photo and the size of the steel anchor plates bolted to the edge of the slab. This Unit spans two storeys and was manufactured off-site, then hoisted into place on-site. Note the difference in size and colour between the structural steel members of the unit (closest to the slab) and the extruded aluminum mullions (farther away from the slab). Note also the spray-on fire-proofing on the building’s structural steel columns.
Below: An all-aluminum unit with an insulated portion. The unit is hung from plates connected to the slab by substantial anchors (that act liked hooks) on either end of the top of unit. The threaded rod emanating from either anchor is adjusted on-site to level the unit. The insulated portion meets and hides the floor assembly and plenum.
(See Connections image below.)
4.0 Connections
Both images above feature robust anchor points at the top corners of each unit (parallel to the unit on the left, and perpendicular to the unit on the right) that are suspended to anchor plates bolted to embedded steel components cast within the slab.
5.0 Glazed Curtain Walls
HMC: Curtain wall at parapet, pg. A601 (Insulated unit with metal panel at left, Double-glazed at right.)
Kawneer
6.0 Pre-Cast Concrete Curtain Walls
Steel Building Structure (left), Concrete Building Structure (right)
Curved Surfaces are actually panels facetted together. How would the edge of a floor slab be designed and constructed to receive such a configuration?
7.0 Brick Veneer Curtain Wall Assembly
