Curtain wall systems are
typically designed with extruded aluminum members, although the first
curtain walls were made of steel. The aluminum frame is typically
infill with glass, which provides an architecturally pleasing
building, as well as benefits such as daylighting. However,
parameters related to solar gain control such as thermal comfort and
visual comfort are more difficult to control when using highly glazed
curtain walls.
Other common infills
include: -
Stone Veneer, Metal
panels, Louvres, and Operable windows or Vents.
A Curtain wall is which
encloses the space within a building but does not support the roof.
Curtain walls differ
store-front systems in that they are designed to span multiple
floors, and take into consideration design requirements such as:-
Thermal Expansion and
Contraction; building way and movement; water diversion; and thermal
efficiency for cost-effective heating, cooling and lighting.
The Curtain wall systems
are a non-structural claddding systems for the external walls of
buildings. They are generally associated with large, multi-storey
buildings.
The classification of
types of curtain walling varies but the following terms are commonly
used:-
Stick, Unitised,
Panellised, Spandrel panel ribbon glazing, Structural sealant
glazing, Structural glazing.
The general arrangement of
a stick system curtain wall is:-
Horizontal and Vertical
framing members(‘sticks’) are normally extruded aluminum
protected by anodizing or power coating, but may be cold-rolled steel
(for greater fire resistance) or aluminum Clad with PVC-U. Members
are cut to length and machined in the factory prior to assembly on
site as a kit of parts: Vertical mullions, which are fixed to the
floor slab, are erecteds first followed by horizontal transoms, which
are fixed in-between mullions. Mullions are typically spaced between
1.0 and 1.8m centres.
The framework are fixed
infill units, which may comprise a mixture of fixed and opening
glazing and insulated panels (which may have metal glass or stone
facings). These units are typically sealed with gaskets and retained.
Building were constructed
with the exterior walls of the building (bearing walls, typically
masonry) supporting the load of the entire structure. The development
and widespread use of structural steel and later reinforced concrete
allowed relatively small column to support large loads and the
exterior walls of building were no longer required for structural
support.
The exterior walls could
be non-load-bearing and thus much lighter and more open than the
masonry load-bearing walls of the past. This gave way to increased
use of glass as an exterior facade, and the modern-day curtain wall
was born.
Early prototype versions
of curtain walls may have existed in buildings of timber construction
before the nineteenth century, should columns have been used to
support the building rather than the walls themselves, particularly
when large panels of glass infill were involved.
When iron began to be used
extensively in buildings in late 18th-Century Britain such as at
Ditherington Flax Mill, and later when buildings of wrought iron and
glass such as The Crystal Palace were built, the building blocks of
structural understanding were laid for the development of curtain
walls.
