Property

Behind PwC’s twisting skyscraper

Kirsten Minnaar • 12 February 2025

Located in Waterfall City, Midrand, PwC’s R1.5 billion high-rise head office stands 106 meters tall, and its twisting design makes it one of the most recognisable buildings in South Africa.

Designed by LYT Architecture for Attacq Waterfall Investment Company and their developer Atterbury, the project was expected to take 36 months and was scheduled for completion early in 2018.

The 26-storey tower features 40,000 m² of modern office space and is designed to accommodate 3,500 employees from PwC in an efficient and well-structured workplace.

The building’s height, combined with its construction on top of a high point in Waterfall City, makes it the tallest structure on the corridor between the Sandton and Pretoria/Tshwane CBDs.

In fact, the tower is visible from almost anywhere within a 30 km radius.

“The brief for the PwC Tower at Waterfall City called for an iconic building form that would be unique to the development and which would mark the property as a new top-tier destination for business,” Guy Steenekamp, a director at LYT Architecture, explained.

What makes the building so distinctive is not only its height but also its unique twisting design.

To achieve the building’s twist, each floor of the 28-storey office tower rotates 1.2 degrees relative to the floor below.

This posed a variety of design challenges for both the structure and façade, many of which Arup – an important collaborator on the project – was able to solve using parametric modelling.

Arup is one of South Africa’s leading design engineering consultancies and helped achieve this complicated design.

“We needed to ensure our design solutions met the architect’s intent and that a creative concept could be successfully applied,” Richard Lawson, buildings associate at Arup, said.

“At Arup, we are fortunate to be able to share cutting-edge research and technology within our global network.”

“It enables us to tap into the latest scientific knowledge and creative thought, which, when combined with the utilisation of software, allows us to push the boundaries of design.”

Essentially, parametric modelling is a design process that uses rules and relationships to create flexible and dynamic models.

Instead of manually adjusting each part of a design, you set parameters like height, width, or angles, and the model automatically updates when you change them.

This is often used in architecture, engineering, and 3D modelling to quickly explore different design options and make complex shapes easier to modify.

“Our advanced parametric modelling software and systems enable us to explore many options in our search to establish the optimal solution for complex building designs such as the PwC Tower project,” Lawson said.

“A further beneficial aspect to parametric modelling is the way it feeds into other software, particularly our Building Information Modelling (BIM). Arup uses BIM as our default method for producing and managing design work.”

According to Lawson, the biggest structural challenge in designing the PwC building was managing the twisting shape, which naturally created a twisting force or torsion on the structure.

Normally, a thick central wall would be needed to counter this, but by testing different designs, the team found a better solution.

They added structural columns on the outer facade that sloped in the opposite direction of the twist.

This helped balance the forces, reducing stress on the core, which allowed them to use a thinner 450 mm core wall – similar to what a straight tower would need.

They also used parametric modelling to design the facade. Since the glass and aluminium panels had to fit a twisted, concave shape, the software helped find the best way to achieve this.

The tool also allowed architects and engineers to instantly see changes in 3D, making collaboration much faster and easier.

Parametric modelling was also used to prevent dangerous solar reflections, a problem seen in other curved buildings, such as London’s “Walkie-Talkie”, which once melted car parts.

Since no software existed to predict these reflections, the team used their parametric design to calculate and analyse them. They tested different solutions, such as adjusting glass reflectance, to ensure the building wouldn’t create hazardous glare.

“Many factors went into the parametric modelling equation for the PwC Tower to come to the final optimised solution,” Lawson said.

“Our use of parametric modelling software on a project of this scale is unique within South Africa, and our clients, as well as ourselves, are reaping benefits from the optimised holistic design on projects where we are collaborating.”

“The beauty of taking a parametric design approach is both in time and cost efficiencies and a better integrated and well-considered design, with all architectural and construction factors in sync.”