Laura Mark talks to Jon Leach, the engineer behind the Serpentine’s summer houses
Jon Leach, Aecom
What was your involvement in the project?
For the fourth year running, AECOM, in collaboration with David Glover, delivered technical advisory services for the project, including structural engineering of the substructure, fire engineering, electrical engineering and lighting design. For the first time, the Serpentine Gallery expanded the programme to include four summer houses and we also delivered full technical and engineering design services for these structures. AKT II joined the technical team this year and provided structural engineering services for the main pavilion superstructure.
How was it working with the different architects?
The architects for the summer houses were given a common brief, which was to take inspiration from Queen Caroline’s Temple; a classical style summer house built in 1734 and located close to the Serpentine Gallery. However, their designs were vastly different and submitted in a variety of ways, ranging from sketches and simple physical models to free-form digital models. The engineering challenge is to work with each architect and artist to create a structurally stable space while maintaining their original vision, irrespective of how different these might be.
Given the rapid pace of the project, we must quickly build close relationships with the architects. As engineers, part of our role is to work with them to identify what is achievable in the time available. In line with the Serpentine Gallery’s criteria, each architect is yet to build a permanent building in England so using our knowledge of the planning and Building Control processes to help them is also key.
How does the collaboration work with the architects?
With four architecture practices, a highly collaborative approach was essential. For the summer houses each architect had a different approach to the design process, and we quickly needed to adapt our own approach between each team.
Almost no drawings were created, so we shared 3D models to aid design development. We also used pioneering augmented reality technology for engineering design reviews, which encouraged greater communication. The mixed reality headsets certainly helped speed up the engineering design process.
Did the designers have a particular vision for how the engineering of each of their buildings would work?
Some of the architects had a very clear vision in terms of detailing and geometry and were more prescriptive in the process, whereas others presented only an initial concept which allowed for more creative freedom by the engineer.
The outward materiality is important for all of the designs. Early agreement of samples and mock-ups helped everybody involved to understand the importance of this. However, the detailing of connections and interfaces between those materials, and the engineering behind them, was very much an evolving process throughout the build, dependant on time and availability within the short programme.
Was there a different approach to each of the five installations?
Each installation was completely different in terms of materials, engineering design and construction methodology. Each required specific skillsets, from stone masonry, carpentry and furniture design to conventional steel frame erection. All were done by a very small team in terms of both engineering design and construction to ensure a common understanding and lean communications. Everybody involved had to be highly versatile and flexible, with the lines between traditional engineering disciplines blurred to aid the project’s success.
What were the challenges you faced with the designs?
The biggest challenge is the project’s tight programme constraints, which require careful planning in terms of construction sequencing. A particular technical challenge for the summer houses was to construct them without foundations to minimise their impact on the park grounds upon removal, and the fact that no cranes or large lifting equipment were allowed in the park. With each structure manufactured off site and installed manually, every section needed to be both lightweight and easily transportable. Even the sandstone used to create Kunle Adeyemi’s summer house was engineered to a minimal thickness so that it could be installed without cranes.
Did anything change due to the fact that you were building five structures rather than just one as in previous years?
Similar to previous years, we worked closely with the contractor, Stage One, to develop digital prototypes that were used for manufacture. But with five structures across multiple sites, maximising the benefits of offsite construction this year was key. The logistical challenge on site was immense and we attended site daily throughout the process in order to assist with any issues and make sure progress was maintained.
What were the timescales for the project?
The pavilion was built and delivered in six weeks and all four summer houses were built in just three weeks.
What are the different pavilions made from?
The summer houses have used a range of materials, including steel, sandstone, timber and aluminium. The main pavilion is made from glass fibre reinforced polymer (GFRP) bricks. It is usually the interfaces between these different materials that are the most challenging aspects of the design.
Which was the most difficult to design and which was the simplest?
Our view on that changed continuously throughout the process! Yona Friedman’s summer house adopts the simplest materials and is essentially a modular build, but it is also an experimental one, which needed much trial and error in positioning the cubes to suit the artistic intent.
Kunle Adeyemi’s summer house involved the most different materials, bespoke details and skillsets, including interfacing the steel frame and timber carcassing with stone specialist Grants.
Where were they all manufactured?
The structures were manufactured at Stage One’s workshops in York and transported by road to Kensington Gardens. The limited space on site meant that a ‘just in time’ approach was necessary with meticulous logistical planning.
Are there any special considerations given the structures are temporary?
As with the pavilion, each summer house has been designed with deconstruction and repurposing in mind. Developing simple and reversible build sequences was therefore an important part of the designs, using discrete bolted connections where possible and considering the extended design life of the materials beyond their tenure in the park.
How does working on the pavilion differ from your day-to-day work?
The Serpentine pavilion and summer houses programme is unique, which makes it a really exciting project to work on. It is very unusual to deliver a project from start to finish in just a matter of months, so as engineers we must play an important role in the creative process and think about every aspect of the design and detailing. It is a much more hands-on and experimental process, relying less on analysis and calculation and more on testing, experience and intuition.
What has been your favourite Serpentine Pavilion?
That is always a difficult question to answer, as one of the most exciting parts of the project is the sheer variation from year to year, as well as the anticipation each year of finding out which architect has been selected by the Serpentine Gallery.
Sou Fujimoto’s 2013 pavilion was the first one that AECOM worked on and is still perhaps the most memorable in terms of the satisfaction of seeing something seemingly so complex delivered in such a short and intense period of time.
Jon Leach, director and technical practice group leader, AECOM