Snowdon Aviary Refurbishment

London, UK

The Snowdon Aviary is one of London Zoo’s most high-profile landmarks. Its refurbishment and repurposing as a playground for monkeys demanded sensitivity to the original design intent and a detailed understanding of this innovative structural system.

Originally inspired by the Skylon at the 1951 Festival of Britain, the Grade II* listed Snowdon Aviary was designed in the early 1960s by Cedric Price and Frank Newby.  It was the first aviary in Britain to offer a ‘walk-through’ experience in which visitors could observe birds in their natural habitat.   

By the time restoration began, this pioneering futuristic structure with its suspended aluminium-framed tetrahedrons and wire mesh fabric had already exceeded its design life by almost two decades. 

Initial designs for an ambitious renovation and expansion of the facility had to be scaled back when post-Covid budgets were squeezed.  Expedition was retained to oversee the structural engineering elements of the subsequent design-build contract on behalf of the client.   

We benefitted from the early work we had done on the project, analysing and critiquing the original scheme to build a thorough knowledge of the structure and an understanding of the design intention. This enabled us to steer critical detailing decisions towards a solution that respected the aesthetics while still meeting the budgetary constraints of the project.  

The project required all the mesh and structural cables to be replaced, alongside cleaning and repairs to the aluminium tubes and the concrete structures. The connection detailing of the cables was kept as close as possible to the original, in order to retain the distinctive character of the nodal joints.  Specialist cable company Pfeifer developed an ingenious erection methodology whereby eight temporary cables were used to hold the structure up while the permanent cables were de-tensioned and replaced, avoiding the need for temporary props. 

The modern clamped cable mesh gives the impression of a seamless ‘soap film’ stretched between the cables.  By eliminating the need for the bulky clamping details alongside the cables and internal joints, this lightens and simplifies the mesh compared to the original, helping emphasise the fineness of the cables and reducing distractions from the rich detailing of the original structural connections. 

Image gallery


Expedition Engineering were a fantastic design partner to ZSL on the Grade 2 listed Snowdon Aviary project, guiding us through the complex re-engineering of the UK’s only tensegrity structure.  From modelling the forces to developing sympathetic connections for the modern enclosure netting, Expedition led the way with quality and attention to detail.

Robin Fitzgerald

Head of Capital Projects at ZSL

Key People