Industry professionals came together to discuss cladding and curtain walling at March’s AJ Specification live seminar
AJ Specification Live March was, as sports commentators are fond of saying, a game of two halves, with four speakers focussed on cladding and, generally, on sculptural approaches, to envelope design followed by three who concentrated more on projects with curtain walls flat facades, with a healthy degree of osmosis between the two.
Brian Cosgrave, specification manager at Equitone, the event’s sponsor, opened with a an outline of fibre cement’s properties and a potted history of its developments and antecedents reaching back to pozzolana, used by the ancient Romans in the formation of cementitious compounds and highlighting exemplary applications of this material, including Willy Guhl’s Loop rocking chair.
Sarah Renshaw, project architect for GA Studio’s Ashton Sixth Form College, discussed this project and the use of a fibre cement rainscreen to clad the frame and shard-like forms of its sculptural reception. As the project developed, GA Studio switched to bonded connections for this rainscreen to avoid visible connections. The shards and principle frame members appear to be jutting out of the ground, although they also rely on tie members to produce the stability required by the curtain wall members spanning between them. When Felix Mara, who chaired the event, asked about the compliance of the bonded connections, Brian Cosgrave reminded him that Renzo Piano Building Workshop’s Shard also relies on chemically fixed cladding panels.
Investcorp Building, St Antony’s College, Oxford University by Zaha Hadid Architects
Source: Luke Hayes
Zaha Hadid Architects senior associate Johannes Hoffmann discussed the stainless steel cladding to this year’s RIBA Gold Medalist’s Investcorp Building for the Centre for Middle Eastern Studies at St Antony’s College, Oxford. Felix Mara highlighted the crucial role of integrated structures in cladding design, especially in sculptural projects such as the Investcorp Building and Ashton Sixth Form College. The Investcorp Building relies on a concealed glulam frame, a cost-effective structure which facilitated the setting out of its double curvature cladding. Damian Rogan, Eckersley O’Callaghan, the client’s facade consultant, contributed to the panel discussion by elaborating the electro-polishing immersion process used to achieve the finish of the Investcorp Building’s stainless steel cladding, affirming Felix Mara’s supposition that it bears little resemblance to shoe-shining. Hoffmann concluded with an explanation of the Investcorp Building’s flat, frontalist glazed south facade, which uses fritting to the edges of its inner layer of glass to conceal the framing of its radiused edges.
Introducing his practice’s work on ‘bio-based’ approaches to cladding on its projects for Dutch transmission systems operator Enexis, Atelier PRO architect director Alexander Letterboer reminded the audience that, with continued reductions in the price of oil, it now costs less to make plastic than to recycle it. Letterboer discussed biodgradable cladding materials and the benefits of hemp, unwoven flax, expanded cork and furan resin. He also elaborated on the idea of facades which have ‘plug-and-play’ prefabricated units and are self-shading, using panel geometry, rather than devices such as view-obstructing brise-soleils, to reduce solar gain in the highly insulated Enexis suite of projects.
Launching the second group of talks, Jonathan Tuckey discussed The Yard House a live-work development in South London whose client encouraged exploration of materials such as translucent polycarbonate and profiled fibre cement. The photographs, hand sketches and CAD elevations demonstrated the artistic qualities of Jonathan Tuckey Design’s project, and the way elevations and scenes had been composed, with carefully chosen materials and diffused natural light. Tuckey, the practice’s director also explained approaches to designing and specifying the various types of Rodeca extruded polycarbonate sheet, whose length is not restricted by the manufacturing process.
Jonathan Tuckey Design’s The Yard House
Source: James Brittain
Next, Damian Rogan, leader of Eckersley O’Callaghan’s facade group demonstrated new ways in which his practice is expanding the boundaries of what is possible in structural glass design.
John Robertson Architects associate Josie Ogg discussed her practice’s work on the replacement facades of Great Arthur House, a residential tower designed by Chamberlin Powell and Bonn in 1956, ahead of its Barbican Centre nearby. The tower is Grade II* listed and John Robertson Architects’ challenge was to upgrade its facade’s performance without losing its architectural qualities, achieved through fine but thermally underperforming aluminium profiles. Ogg also demonstrated the resourcefulness with which related structural problems such as stress in the existing concrete slabs induced by their self-weight had been tackled, and other critical steps in the project which took place behind the scenes.
As a retrofit upgrade requiring a number of special extrusions, Greater Arthur House complemented the other projects discussed at the event, with cladding materials for all budgets, ranging from fibre cement panels to large format structural glass, as well as various takes on environmental performance and strategy.