Africa’s tallest building

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The Leonardo at 75 Maude Street in Sandton is the tallest building in Africa. The R3bn project, developed in partnership by the Legacy Group and Nedbank CIB, has 55 floors and stands a record 233m high. The Carlton Centre, previously Africa’s tallest building and completed in 1973, reaches 223m. This new architectural landmark has redefined the Sandton skyline, and introduces a new concept of luxury living to the Sandton CBD. The first two levels from the ground floor include public access, with retail, hospitality and conferencing facilities. These two levels are sandwiched between four basement parking levels and six above ground, making a total of 1 251 parking spaces and forming the podium of the building. On the seventh floor, restaurants and bars, a spa and gym, and a Montessori creche as well as a swimming deck constitute the recreational and lifestyle zones. Above that is five floors of office space, and up to the 38th level, 234 residential apartments. The next 10 floors house a hotel, and above that are eight penthouse suites, including The Leonardo Suite, a three-storey, 3 000m 2 penthouse. The narrow street front and limited public space, a consequence of the building being a tower, is maximised and made inviting and hospitable to the public with a colonnade that encourages pedestrians to walk beneath it and engage with the building, particularly the retail space on the ground floor. These three-storey granite columns and glass canopy at the entrance not only provide shelter, but also help to unlock the potential of the public space in front of the building to become a pedestrian thoroughfare.

Co-Arc’s partner emeritus, Francois Pienaar, who is largely responsible for the concept and design of the Leonardo, also planned the urban framework between the Sandton Convention Centre and Nelson Mandela Square, and in working on the Leonardo was able to see his earlier urban design realised. The colonnade also translates and expresses the magnitude or high-rise aspect of the building at street level, which is difficult to comprehend at its base. But between the Johannesburg Roads Agency widening the road to create four lanes and a drop-off feeder road, a small piazza-type space extends the main entrance area to the street.

The main reception area opens directly on the street, encouraging direct interface with the public. The first floor lobby includes a lounge, coffee shop, business and conference centre, and reception area. There is also a range of sophisticated, large-scale artworks throughout the new Leonardo building, realised by contemporary art production team The Trinity Session, who also commissioned or collaborated with a number of local artists and crafters. The large-scale artworks in the lobby include a sculpted representation of a cross-section through the Johannesburg reef on the walls of the stairwell, led by sculptor Damien Grivas, showing the strata formed by tectonic plates shifting and colliding to form the intricate patterns of geological formations.

A two-story-high floor-to-ceiling mural by Mbongeni Buthelezi running the full length of the lobby, “painted” in melted recycled plastic, defines the opposite wall adjacent to the escalator – deliberately positioned towards the back of the lobby to draw people through the space and play out the narrative aspect of the artwork, enhancing the public experience of the building.

The original site included an existing basement four to five levels deep and foundations which, rather than being excavated, became the footing of the Leonardo.

The massive transfer columns necessary to shift the grid have become a feature of the architecture, exposed at the interlinking levels, expressing the structure of the building at key points, and celebrating its design and materials with honesty and integrity. The fins at the top of the building, forming its crown, are an expression of the structural force running through the building. The spines running up the centre of the north and south elevations also express the geometry of the columns and define the balconies. On the seventh level, the “heel columns” are expressed – another instance of the way in which the synergy between structure and architecture can be read in the design. The architectural aesthetic of the building complements developers Legacy and Nedbank CIB’s branding and the architectural styles associated with other buildings in their portfolios in the area, such as the Michelangelo and Nedbank’s Sandton headquarters. The architects describe the form of the building as “the consequence of a very functional set of requirements resolved in a contemporary classical manner”.

Interestingly, the Leonardo was not designed as an object, but rather as a system that could respond to market demands – a “complex growing organism”. Thus, the design became an expression of the structural logic that was taken though the building. This flexible architectural strategy worked in conjunction with a highly innovative commercial model, designed to be complete and viable at a variety of heights. Its height was boosted during the construction as it became financially viable to add each new section.

Each group of levels is supported vertically downward (hung from above) as well as upward from below, which means that they remain supported and intact in the event of a catastrophe.

Deliberately labour-intensive construction methods – largely created by building with concrete and masonry – were selected to maximise the employment opportunities created by the project and to include locally available skills. Thus, the Leonardo has become not just a symbolic beacon of hope during a difficult period in South Africa’s economic development, but actively maximised the social and economic upliftment of those involved in its construction. As a result, the very methods and materiality of the building became a celebration of the labour and skills of those who have contributed to its construction. The building created an estimated 2 000 direct employment opportunities and between 18 000 and 20 000 indirect employment opportunities through materials supply chain, manufacture and industry.

The external protective “skin” of the building involved the pioneering use of Dekton, a brand of engineered stone. The material was an easy choice because of its aesthetic, high strength, UV resistance, stain resistance and ability to withstand both high and low temperatures. The pleasing colour and texture mixes a satin finish with the roughness of quartzite giving the building its solid appearance. The high strength meant the thickness could be reduced compared to natural stone – making the façade panels much lighter. This was a great benefit to the façade engineers on the project – design, engineering and planning consultants Arup – who had to get creative with the installation of the façade at the upper levels because the footprint of the building, as well as its height and the lack of available on-site storage, made the use of additional cranes and scaffolding prohibitive.

Inspired by unitised glazing systems, Arup designed storeyheight support that made it possible to manufacture large Dekton panels off-site, and then hoist them up with a mini-crane from inside the building – eliminating the need for scaffolding. Like the glass-curtain sections, the Dekton was structurally bonded to the aluminium frames. This is the first project of this magnitude not only in South Africa but worldwide to use this type of construction system. Arup also designed the steel mast that tops the building and brings it to its full record-breaking height. Global expertise provided an elegant damper solution to deal with the dynamic loading causing by wind at that height.

Other noteworthy suppliers include Afrisam, Samsung, distributed by Fourways Air, Belgotex Floors, bathroom accessories by Geberit, Melibo and Kludi (imported by WiiN). Major Tech, a specialist importer of lighting, electrical products, switches and sockets, has supplied 10km of the strip lighting, over 10 000 panel lights, and 500 star lights to the Leonardo, and a unique lighting automation system. Major Tech has used AA-rated LEDs throughout the building, so the Leonardo’s lighting needs will be met by roughly 10% of the power required by regular incandescent lightbulbs. The Leonardo includes a Skydeck on the 55th floor, from which the public can take in the surroundings from the highest building in Africa. This landmark in architecture and engineering is not merely symbolic of a new era of African development, but stands as a reminder of how innovative and flexible approaches can realise unexpected heights of achievement.

The beautifully expressed “heel columns” on the new Restaurant, Aurum, on the seventh level are decorated with a copper-mesh installation inspired by the flight-paths of birds, as part of the art installation by The Trinity Session.