A puzzle in timber

The new Beech Court Pavilion at Abingdon School in Oxfordshire has been constructed to connect the students with nature, but its construction proved to be a puzzle in timber.

Beech Court Pavilion seamlessly blends slender glulam beams and a supporting steel structure – crowned by green roof planting above glazed elevations – to form an elegant and multi-functional space with green views in all directions. Its beauty however, belies its complexity.

The project team brought together David Morley Architects and Engineers HRW, with Beard Construction as the main contractor and B&K Structures (BKS) specialist timber and timber-steel subcontractor for connection design, fabrication and erection of the complex octagon roof. Around 35m3 of visual grade glulam beams were manufactured by BKS’ timber supply chain partner Rubner.

The sheer complexity of the pavilion’s roof structure posed unique challenges in terms of design, planning, prefabrication and the subsequent installation. Andy Holland, BKS Operations Manager, says: “We had to build the roof as four separate quadrants supported by temporary falsework columns. However, as they met at different angles of pitch, the geometry of the connections was very complex and required strong technical skill. As a result, a constantly changing variety of stub plates coming off the main steelwork was required.

“The buildability and temporary works review was also unusually challenging, and the tolerances on both fabrication and installation were far tighter than is normal – a maximum of 5mm rather than 10mm – meaning even a very small error on the steelwork would have made it impossible to align and fix the glulam beams.”

A collaborative process

These construction challenges were addressed through a collaborative process that combined developing HRW’s 3D model into fabrication information, a meticulous logistics plan and regular engineer inspections. Skilled alterations on-site included cutting, realigning, tack-welding, re-checking and completing a full arc-weld in situ.

BKS Drawing Office Manager Glyn Hubbard says: “Every project brings a number of challenges to be overcome – including co-ordination of information from other sub-contractors and trades and tight site programmes – but this was exacerbated on Abingdon, given the complexity of the roof structure and the individuality of the connections to be made.”

A building of glass and 34.896m3 of glulam timber (sequestering 24.543 tonnes of CO2), designed to seamlessly blend the inside with the outdoors and connect the students with nature, has ended up connecting specialist teams and giving them a platform to showcase their skill.

For more, visit bkstructures.co.uk

Image credit | Bowmer Kirkland