The traditional definition of balustrade is being a row of repeating balusters - small posts that support the upper rail of a railing. However, balustrade is also taken to mean 'void-edge protection' - obviously a phrase that describes the function or role of the structure, rather than relating to its appearance or specific construction methodology.
In casual usage, the term balustrade is no longer taken to mean an array of traditional spindle-moulded balusters. In a modern architectural context, arrays of vertical balusters are rarely employed, with an array of alternative structural (e.g. cantilevered panels or stanchions), and infill materials (glass panels, solid wall framing, folded metal, etc) being preferred. Where vertical infill members do exist (e.g. timber or stainless steel battens), they rarely serve the traditional role of providing structural support to the top rail of the structure. This is partly because advances in materials and construction methods have removed the design constraints that determined the use of rows of vertical balusters. The evolution and dominance of the modernist aesthetic since the 1920's has led to a variety of forms being preferred over the relatively ornate and detailed appearance of traditional balustrade The diversity of possible designs and structural approaches means it is no longer possible to equate the
function of balustrade with the traditional construction methodology of using an array of vertical balusters. Though the term balustrade is now routinely informally used to describe the function of providing a barrier to protecting individuals from falls, this usage is technically incorrect. Therefore, most professionals such as architects and builders prefer the usage of the term 'void-edge protection' on technical documents and plans to refer to the barrier structure. However, term 'balustrade' continues in common use, but now is taken to refer the general concept of void-edge protection, rather than the traditional and 'correct' definition.
Traditional definitions and history
Balustrades are historically defined moulded poles that support the handrail of a staircase or create the individual shafts in parapets, fencing, gates, and railings. The earliest representations of balustrade have been noted in ancient Assyrian bas-reliefs as window balustrades. A single vertical member is called a ‘baluster’, and the plural form is ‘balustrade’. The term ‘balustrade’ developed from the Italian word ‘balaustra’ meaning pomegranate flower because of the similarity to the curved form of the half-open flower. Ancient balustrades were moulded and hand-carved from material such as bronze, marble, or timber. In the 20th century, traditional designs have been recreated in materials such as polystyrene, various hardwoods as well as softwoods, wrought iron, glass, polymer stone, cast stone and plaster. Wooden and stone balustrades are classically shaped on a turner’s lathe, which spins an unshaped block to cut and sand it with symmetry. Ornamental lathes can create balustrades of amazing complexity, using two centres or axis of rotation. Concrete, iron, plaster and polymer balustrades are created from cast moulds The degree of complexity or ornamentation varies does depend on the historical style in consideration. The Baroque style, for instance, was particularly ornate and decorative. A traditional 'Queenslander' homestead balustrade incorporates balusters of a relatively simple profile, but may include varies forms of ornamentation in the posts or between balusters.
In contrast to traditional designs, contemporary balustrade design tends to aim for simplicity through clean lines and the definition of geometric shapes. Ornamentation is virtually eliminated. In common with other trends in modern architecture, it makes an impact generally through the use of contrasting materials. A common design priority in the design of modern balustrade is to create the impression of space and openness. The strength inherent in stainless steel or mild steel stanchions or posts means that, when they are employed, they can be situated at relatively long intervals. The use of glass infill panels also contributes to the sense of light and space. Another feature of modern balustrading is the 'frameless cantilevered' approach, where the glass itself is a structural element that supports the handrail from a structural connection to the floor or void edge through a vertical cantilever. This allows the architect to eliminate not only the balusters, but also the stanchions / posts, in the balustrade design. Clearly, these newer approaches to balustrade display a trend towards minimalism and functionalism, consistent with the broader architectural movement in modernism that has been occurring for more than a century.
New directions in balustrade
With the current trend towards more organic and playful approaches to architecture, it will be interesting to observe how this affects balustrade design. Certainly the increased use of new materials such as solid surface acrylic products seems certain. Since transparency will probably always be a priority, 'high tech' materials that permit light to penetrate, but are yet strong enough to fulfill the role of void edge protection, will probably play a role. Whatever comes next for balustrade, it is probably safe to say that the traditional turned baluster will never again make an appearance.
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Published on: 03-Dec-2010. Topic/s: