Charterhouse School’s new science and mathematics centre by Design Engine Architects is an outstanding example of hybrid construction combining cross laminated timber (CLT) and glued laminated timber (glulam) with steel and concrete to overcome complex structural and design requirements.
The innovative building forms phase one of three to co-locate science and mathematics teaching at the school, eventually resulting in a full STEM centre.
Originally the subject of an invited design competition won by Design Engine in 2009, the 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’.
The result is a modern building that sits comfortably within the historic 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; it was this historic context, along with the functional requirements of the chemistry labs from which Design Engine drew inspiration.
The building is a two-storey structure with concrete at ground floor and a CLT and steel structure above. It abuts an existing Grade II-listed museum interfaced by a complex cantilevered steel frame.
An overall area of 1,700m2 is predominantly dedicated to teaching areas and laboratories which measure a generous 113m2 each.
Three distinctive, steeply pitched roof structures, or ‘chimneys’, provide a striking architectural feature and an important architectural link to the original campus where these forms feature widely.
The chimney structures provide a means for exhausting the fume cupboard ductwork safely away from the chemistry labs below, facilitating natural ventilation through stack effect and allowing diffuse north light to penetrate deep into the plan.
The vaulted ceiling design created in the laboratories by the complex roof geometry makes for a very cool space
Structurally, CLT has provided an efficient way of achieving the uninterrupted 6m tall partitions for the first floor labs. These floor-to-ceiling-height CLT panels are tied back into the chimneys and the overall CLT structure is supported by a central vertical steel ridge beam. On one side of this beam, the CLT spans continuously between the walls, and on the other side an unusual geometry is formed by an inclined CLT wall.
“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,” comments Gareth Mason, sales director of Western Europe at Stora Enso, which manufactured the CLT used for the project. “It also demonstrates the way in which an ultra-modern building can sit comfortably within a historic setting such as Charterhouse.”
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. Matthew Vowels, senior architect at Design Engine, said: “We were keen to retain natural finishes as much as possible, recognising that the quality of the environment has a profound impact on learning and teaching. CLT has warmth and honesty which we felt was appropriate to a building of scientific learning.”
He continues: “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.”
Andy Goodwin, managing director at B&K Structures, which installed the CLT at the school, says: “If only all schemes were designed to be unique in this way, construction would be a lot more interesting.
“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.”