External curtain Wall

Refurbishing Curtain Walling

Curtain walling is an outer layer on the exterior of a commercial building and is used for multi-storey constructions of any size including large shop fronts, car showrooms and office blocks. It is attached to the floors or columns of an elevation rather than it being a structural support, so it doesn’t carry any extra dead load weight. Since weight is the main issue, a curtain wall is composed of a lightweight framework. Historically, the frameworks were invariably steel, but lighter metals became more popular with aluminium now being the most common. The grid like frame often surrounds glass panes, but metal or stone panels, known as infills are also used. Glazed curtain walling enables light to soar in and there is nothing like the aesthetic impact of an uninterrupted glass façade, but the drama can be ruined by shoddy metalwork. Luckily, refurbishing curtain walling can be achieved by a professional onsite company who can work at height to clean and recoat any metal.

The main advantage of curtain wall systems is that they are able to cover large expanses because they are not too heavy, and so are ideal for multiple floors. Before steel and reinforced concrete were used in columns to structurally support buildings, the exterior walls would take the weight of the entire load. Outside walls that didn’t have to be load bearing didn’t need to be as large and cumbersome as solid masonry walls. This enabled a larger proportion of glass to be integrated into exterior elevations leading the way for the development of the curtain wall.

Modern day curtain walling stemmed from the use of wrought iron frames filled with glass in the late 18th Century such as Ditherington Flax Mill. Curtain Walling then evolved using steel mullions which comprises the vertical frame that divides up the infill panels. In glazing systems, mullions are attached to horizontal supports known as transoms. Plate glass was fastened to the mullions with a sealant which is now silicone or glazing tape and gradually, steel was substituted with the more lightweight aluminium. By the 1970’s fixed cross-sectional aluminium profiles (known as extrusions) became common. As well as being lightweight, aluminium can be moulded into any shape which is a distinct advantage for architects.

Advantages of Recoating and Refurbishing Curtain Walling

The aluminium extrusions are sometimes anodised and dirt can be a problem on this surface because some cleaning chemicals will ruin the finish. Unfortunately, curtain walling cannot be re-anodised in situ, so protecting them with a fresh coating will not only improve the way they look, but will also make the metalwork last many more years than if left untreated.

The aluminium frames in curtain walling are often powder coated during manufacturing, but if they are not cleaned regularly they can deteriorate. Architects have to account for expansion and contraction of the metal grids in response to temperature changes and building movement. Both extremes of temperatures and sway can affect the integrity of the paint on mullions and transoms.
Other factors such as acid rain, ultraviolet light and pollution can lead to powder coating failure which can then mean that water will permeate the substrate.

One of the main problems of curtain walling deteriorating is water penetration where moisture seeps through to the inside of the curtain walling system from the outside of the building. Part of the function of a curtain wall is to guard the structure inside against inclement weather, so if the coating on the architectural metalwork isn’t intact then the curtain walling can’t do its main job.

A new coat of paint will protect the surface as well as improving the appearance of curtain walling. Any metal and even glass can be sprayed in any RAL or British Standard colour, so façades can look completely different. Coatings can have anti-corrosive properties and may also be able to protect against UV light. Furthermore, any improvements including refurbishing curtain walling will increase the value of the commercial property as well as its street appeal. A good onsite spraying company will prepare the surfaces properly before applying a new coating. This process is essential for durable coatings. As curtain walling invariably spans multiple floors, working at height is unavoidable when recoating the metal framework, so all personnel must be qualified and experienced in carrying out this work.

Anthony

Anthony is a director of Vanda Coatings. He has been with the company since 2000. For further information relating to any aspect of the business please feel free to contact him.

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