dhk Architects has completed The Rubik, an elegant 27-storey tower located in the heart of the Cape Town CBD, for Abland Property Developers. The building comprises retail, commercial and residential accommodation on an 821m2 site which straddles the city’s financial and heritage districts. The design features distinctive angled cubes that break up the volumetric mass. The parking base features varied vertical and horizontal elements and planes to directly reference the lower-rise heritage buildings on the southern boundary. The Rubik is a true mixed-use development that densifies the city and offers walkable access to local amenities, adding a significant contemporary architectural insertion to the city centre.
Site background and challenges
The Rubik is situated in the heart of the Cape Town CBD, on the corners of Loop, Riebeek and Sea Streets. The site straddles the financial district, where city planners encourage taller buildings; and the heritage district, characterised by smaller two- and three-storey heritage buildings. This juxtaposition presented a notable design and developmental challenge. The site is located in a Heritage Overlay Zone, and so the design required approval from Heritage Western Cape and the City of Cape Town’s Land Use Management authority. The site also had an existing height restriction of 60m above base level, with a zero-metre street setback up to 38m and a diagonal setback for higher than 38m. Common boundaries carried a zero-metre setback.
Client brief
The initial design brief was for a 12-storey building on the southern portion of the site. Abland subsequently acquired the northern part, consolidating four erven into a single square site. Two existing buildings of no significant architectural or heritage merit were proposed for demolition.
The second design brief called for a much higher mixed-use scheme. dhk developed several proposals of various masses, heights and façade articulations, eventually finalising the design for a 91-metre tower. The resulting form is an elegant, aesthetically striking design that enhances the city skyline, rather than imposing a conventional monolithic tower. The design required a major departure from the zoning height and setback restriction.
Design concept
Retail uses are accommodated at ground and first floor level. The parking podium rises 10 floors above, bucking the common development typology of landing an inactive parking mass at ground level. Above the parking plinth, from floors 11 to 26, the office and residential portion is broken into three stacked orthogonal twisting cubes rotated around a central axis. This fragments the building into smaller volumetric masses, creating a dynamic sculptural form. The glazing on these levels forms smooth, differently angled planes that capture different reflections of the sky and surrounding buildings, further fragmenting the mass and creating visual interest across the skyline.
With typical mullion and generous 1.6m centres, the flush glazing offers a consistent visual appearance for the office and residential components, and conceals the slab edges, fire break spandrel panels and walls behind. The façade on the second and third cubes – the residential floors – feature discreet incisions, forming recessed balconies small enough not to detract from the cuboid form.
Façade description
The façade that wraps around the parking podium has been designed to reference the scale, vertical rhythm and massing of the surrounding lower-scale heritage buildings, reflecting their more detailed urban grain. This façade combines primary elements of pre-cast concrete in vertical and horizontal bands, secondary vertical elements of extruded aluminium in between, and a combination of glazed panels, aluminium louvres and plastered masonry walls as the infill façade. The intentionally irregular pattern, geometry and varying scales add visual interest. Cladding is articulated into various panel sizes to break down the scale of the parking levels base relative to the scale of the lower buildings in Loop Street. Glazing effectively ‘stitches in’ elements of the tower above into the parking podium.
This approach responds to Heritage Western Cape concerns that the early design iterations of flatter translucent screens at the parking levels might negatively impact the surrounding context.
The lowest floor of office accommodation above the parking podium is recessed inwards, forming a shadow gap where the office terrace exists, to emphasise activity on this level. This intentional exaggeration and expression creates a clearer distinction between the retail, parking and office uses. It also creates a scale relative to the surrounding buildings and unifies the parking plinth with the office and residential components above.
Building access
Access to the residential entrance is off Loop Street. Access to the commercial accommodation is off the busier Riebeek Street. Both are flanked by retail units, accessed from the corner of Riebeek and Loop. This strategy maximises street activation on the small site. Vehicle entry points are on the southern edge of the Loop Street boundary, adjacent to the heritage buildings, set as far from the Loop/Riebeek intersection as possible. The Sea Street entrance is also positioned away from the street corners on the southern boundary. To maximise street-level activity, the only services at ground floor are the municipality’s non-negotiable requirements of an electric sub-station, firefighting equipment and a small metering room.
Floors and usage
Internal planning
At only 28m x 29m, the constricted site area presented challenges to resolve the internal layout. The building was configured to accommodate five lifts, two escape stairs, active street level entrances, municipal services, internal vehicle circulation and parking, office floor layouts and residential units above. Locating lifts at the centre of the building accommodates vehicle circulation and maximises efficiency of multi-tenanted offices and residential layouts. Deeper spaces away from the façade are used for structural stability and space efficiency.
The centralised lift core and scissor stair positioned on the common southern boundary accommodates the parking and spiral vehicle ramp circulation below. The WC core and lift lobby is positioned between the lift and stair core. Full height glazing flanking the scissor stair core on the common boundary maximises views of Table Mountain and the CBD. These views would be lost in the unlikely event of neighbouring buildings being built up above the parking levels. This layout also adds to the efficiency, expansiveness and tenant flexibility on each floor plate.
An additional challenge in the tight site area was how to provide efficient parking spaces and compliant vehicle which required careful positioning of large columns to secure City planning approval.
Residential layouts
The challenge of using the full extent of a square site is having sufficient frontage for bedrooms and living spaces, while also accommodating usable space in the deeper zones inside the perimeter.
On the typical floors, larger two-bedroom apartments are positioned on the two northern corners, and one-bedroom units on the southern corners. Longer bedrooms in the narrower one-bedroom flats are positioned at the rear to maximise use of the deeper spaces for the areas between corner units.
Larger units are on the top three floors, with five duplex and four triplex configurations. Bedrooms not adjacent to the outer façade are lit and ventilated from small courtyards open to the roof. The triplexes have roof terraces with partial pergola covering and glazed balustrades to maximise views. Terraces are inboard, behind strategic openings in the glazed façade to provide weather protection, and to enable residents to open their sliding doors onto the terraces.
A common roof terrace is situated on the western edge, with rim flow pool, braai counter and seating and indigenous fynbos planting.
Mixed uses
The Rubik introduces retail uses at ground- and first-floor levels, creating a more dynamic and active street frontage with natural surveillance. The retail space on the first floor on the northern portion of the building connects to the ground floor retail area. This activates the first-floor façade, as required by the Tall Building policy of Cape Town.
Colour palette and materials
Natural-looking materials and a muted colour palette throughout the building create a more natural, warm feel.
Sustainable elements
The Rubik incorporates several sustainable design features. It is a true mixed-use development that maximises the site area and helps densify and animate the city within walking distance to workplaces, local amenities and public transport.
Environmentally friendly and sustainable construction materials and techniques were used, including sustainably sourced timber and durable composite materials to ensure longevity, paints with low volatile organic compound (VOC), limiting plastering on masonry walls in the service and escape areas or on exposed reinforced concrete walls, soffits and columns.
High-performance double glazing throughout, with desk-height opaque spandrels in offices to reduce solar gain and improve space efficiency. Recessed, semi-enclosed balconies promote natural ventilation and reduce wind loads. Above-ground parking facilitates natural ventilation and smoke extraction. Energy-saving electrical devices and efficient mechanical, electrical, and wet services are installed throughout. The building optimises lift usage with just five elevators, using careful destination control and dual-purpose fire-fighting lifts to maintain efficiency without compromising on waiting times or safety.
Photo credits: Sean Gibson
About dhk Architects
dhk Architects is an award-winning full-service, design-led studio of architects, urban designers and interior designers. Our multidisciplinary design expertise is supported by meticulous technical implementation and precise on-site administration capabilities. With a steadfast commitment to design and dedication to quality, our team of more than 130 people, spread across two offices, has built dhk into one of the largest and leading architectural firms in Africa.
The practice was established in 1998. Over the years we have built a portfolio of award-winning elegant, considered architectural, urban and interior design projects in South Africa and abroad. We have expertise in multiple sectors, including commercial, residential, hospitality and leisure, retail, healthcare and education. Our projects are benchmarks for design excellence. We believe in a holistic, integrated design approach that places people at the centre of whatever we create. With a broad worldview, we draw inspiration from international influences and incorporate advanced technical sophistication into our designs, while balancing economic realities to ensure fully grounded solutions for our clients.
