Prefabrication is, and always has been, a key issue in construction on account of the advantages associated with it: components can be manufactured under ideal conditions independent of weather and then mounted or assembled efficiently so as to save time and money. In this way, it is now possible to mount prefabricated houses within a single day.
Prefabricated elements also play a key role in the safety-relevant area of façades. Apart from time and cost savings, there is another key advantage in densely- populated cities: in many cases, there simply is not enough space to store semi-finished products on construction sites.
A perfect example of where these benefits were realised took place in London in 2018 and involved collaboration by two German companies: Lindner Fassaden GmbH and Agrob Buchtal GmbH.
Imperial College is a university and technical college of applied sciences in London. Founded in 1907, it is among the leading international institutions of its kind. In 2013, the facility acquired a site spanning 46,500 sq. metres in the London suburb of White City, with plans to erect a building housing research, teaching, companies, and apartments. This saw the entire campus area double to 93,000 sq. metres, on new site referred to as White City Campus. The Translation & Innovation Hub opened in 2016; while 2017 saw the Invention Rooms go into operation and ground was broken for the Michael Uren Biomedical Engineering Research Hub. The Molecular Sciences Research Hub opened in 2018, and the so-called Block F was also built during this period. Completed in 2018, it accommodates around 200 apartments for key college personnel.
Block F: high-end facade elements
In this context ‘high end’ clearly has a double meaning: it relates to the high technical demands and the fact that the residential tower is approximately 140 metres high. With its 35 floors and its distinctive sculptural architecture, it is now a West London landmark. The building shell comprises about 2,400 prefabricated façade elements, clad with glass, ceramics, or a combination of the two.
The elements were realised through close collaboration between Lindner Fassaden (in co-operation with its local partner Lindner Facades of London) and Agrob Buchtal (in co-operation with its local partner, E H Smith).
The warm façade largely comprises elements that are 1.5 metres wide and 3.25 metres high. The Lindner CW85 system permitted a certain level of standardisation, improving the project’s feasibility. At the same time, the building’s distinctive silhouette also demanded bespoke solutions. One example is the staggered eastern elevation where every second floor forms a step offering patios for its residents; with steel balconies incorporated elsewhere in the project. This required the use of thermally separated wing elements, 2.25 metres wide, which not only clad the cold area but also serve as wind and visual protection.
The southwest elevation is marked by another typical feature in the form of an elevator shaft that is visible from afar and where all-glass elements measuring 3.05 by 3.25 metres ensure optimum transparency.
All elements were manufactured by Lindner Fassaden in Germany. Before that, the elements and composite system were inspected in detail in terms of the requisite properties such as sealing against air and water or noise protection. The standardised versions were then manufactured within the framework of sophisticated line production; while special versions – such as wing or corner elements – were manufactured in a so-called island production process. In optimising the material flow, the company’s in lean production and the Kanban system paid off.
The architects, PLP Architecture, London, desired a salmon-coloured terracotta shade in three differentiated nuances and two surface finishes (smooth and grooved) for the ceramic-clad elements. Agrob Buchtal complied with these explicit specifications using specially-manufactured façade tiles in three lengths of up to almost 1,500mm and a height of 2,970mm (a perfect fit for the element grid) as well as other special formats. This provides further evidence of Agrob Buchtal’s strength in providing tailored project-specific solutions. In line with the specification, the tiles feature a mesh glued to the back which serves as fall protection in the event of intentional mechanical damage.
To secure the façade ceramics to the elements manufactured by Lindner, a special variant of the Omega profile for the modern KeraTwin K20 fastening system was developed and used. One relevant issue concerned the weight of the façade cladding. Here Agrob Buchtal scored well, at around 32 kg per square metre without compromising performance.
To ensure a smooth site workflow, the prefabricated components were loaded in accordance with a special system onto steel pallets at the Lindner Fassaden plant. Each truck load comprised 18 standard elements. Over 100 trucks were needed to deliver the 2,400 elements, all following a carefully timed material flow, since the site was too restricted to allow storage of these components on site.
On arrival, the pallets were forklifted from the truck and transported to a buffer area where the elements were inspected and cleaned before being transferred to the building’s designated safety zone. From there, they were lifted by crane into a vertical position, hoisted to their respective spots on one of the 35 floors, and fastened by qualified fitters from R F Fixing Ltd.
Block F on the new White City Campus of Imperial College is a perfect example of the advantages offered by prefabricated façade elements. Smooth co-operation by everyone involved resulted in an outstanding and visually-striking façade redolent with architectural brilliance and power.