Learning The Hybrid Way

The new Science and Mathematics Centre at Charterhouse School is an exemplar of hybrid construction, demonstrating the way in which materials can work together to overcome complex design and engineering challenges. Eve Dennehy reports.

The scheme by Design Engine Architects combines the structural benefits of cross laminated timber (CLT), glulam, steel frame and reinforced concrete to create a modern and welcoming learning environment that complements the school’s historic Godalming campus.

The building is Design Engine’s third completed project for Charterhouse and the first of three phases to co-locate science and mathematics teaching, which will eventually result in a full STEM Centre. Originally the subject of an invited design competition won by Design Engine in 2009, the School’s brief asked for ‘a building that represents the essence of modern science teaching – respectful of the past, enquiring in its formulation, advanced in its thinking and concerned in the understanding application of its potential’.

“Our aim in response to this brief was to provide a modern, high-quality environment,” explains Matthew Vowels, Senior Architect at Design Engine.

“That would allow Charterhouse to continue innovating in their teaching methods, and ensure the School remains one of the leading academic institutions in the country.”

The result is a modern, innovative building that sits comfortably within the Charterhouse campus which was designed by Phillip Charles Hardwick in the 1870s. The campus has many listed and neo-gothic buildings with connections provided by traditional colonnades, quads and courtyards and it was this historic context, along with the functional requirements of the chemistry laboratories from which Design Engine drew inspiration.

The Centre provides space for seven chemistry labs, five teaching rooms, a project research room and a selection of staff areas. It is a two-storey structure formed of a podium slab of reinforced concrete and exposed soffits to the ground floor spaces, with a CLT and steel structure above. The building is laid out as a simple ‘L’ shape with a central, full height CLT staircase in the main entrance at the knuckle of the ‘L’. An overall area of 170sq m ispredominantly dedicated to teaching areas and laboratories which measure a generous 113sq m each.

The new building abuts the school’s existing Grade 2 listed museum, interfaced by a complex steel frame which cantilevers over a single-storey section of the adjacent museum. To the courtyard side of the building, a ground floor external colonnade provides circulation directly into the teaching spaces and at first floor this circulation is internalised by a glazed corridor. As the circulation wraps around the south west corner of the of the building, it joins a staircase to the ground floor which is ‘hung’ on one corner from roof level and cantilevers out at first floor with a series of external columns as it rises up. Three distinctive, steeply pitched roof structures, or ‘chimneys’, provide a striking architectural feature and a subtle yet important architectural link to the original campus where these forms feature widely.

Structurally CLT has provided an efficient way of achieving the uninterrupted 6m tall partitions for the first floor laboratories. These floor to ceiling height CLT panels are tied back into the chimneys, reinforcing the importance of those forms in terms of services, structure and architecture. The new centre for Charterhouse School really plays to the strengths of CLT as a versatile, precision engineered structural material that can meet complex engineering requirements without compromising on design,” says Gareth Mason, Business Development Manager at Stora Enso who manufactured the CLT used for the project. “It also demonstrates the way in which an ultra-modern building can sit comfortably within an historic setting such as Charterhouse.”

The CLT structure has walls supporting the roof at approximately 8.1m centres with the overall structure supported by a central vertical steel ridge beam. On one side of the ridge beam, the CLT spans continuously between the walls, and on the other side an unusual geometry is formed by an inclined CLT wall that sits on a glulam beam which also supports the CLT at either side. CLT forms part of a mix of contemporary and traditional materials along with oak, brick and glulam that reflect the materials already featured in the School estate. Internally, the exposed CLT has been treated with an overall 5% white tinted Class O surface spread of flame lacquer. “We were keen to retain natural finishes as much as possible, recognising that the quality of the environment has a profound impact on the ability of teachers to teach and students to study and learn,” says Matthew Vowels. “CLT has warmth and honesty which we felt was appropriate to a building of scientific learning. Also, as a practice, Design Engine seeks to design low embodied energy and energy use buildings that can perform well and CLT helped to achieve this due to its high levels of airtightness and strong environmental qualities.

“If only all schemes were designed to be unique in this way construction would be a lot more interesting.” Says Andy Goodwin, Managing Director at B&K Structures who installed the CLT at the school. “The vaulted ceiling design created in the laboratories by the complex roof geometry makes for a very cool space. The design combined with the use of visual grade CLT in the classrooms and communal areas has resulted in a stunning, high quality educational facility.”


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