MultiPly’s story began when David Venables, European director of the American Hardwood Export Council (AHEC) met Peter Wilson, director of Timber Design Initiatives, to discuss the possibility of a pavilion comprising large tulipwood CLT panels. When asked where in the UK might be able to produce these panels, Peter directed David to CSIC’s newly-opened Innovation Factory, where we have the UK’s only CLT vacuum press.

AHEC then appointed Waugh Thistleton Architects and Arup to design the pavilion, and Peter contacted Edinburgh Napier University’s Centre for Offsite Construction and Innovative Structures (COCIS) and the Glenalmond Timber Company to bring in their expertise. The project team was complete.

The tulipwood arrived from the US in June. Glenalmond sorted through it and performed visual grading, defect cutting, finger-jointing, cutting to length and planing, ready for delivery to CSIC.

First we produced some trial panels, followed by test specimens. To determine the CLT’s structural properties, COCIS submitted the sample panels to thorough testing; edgewise and flatwise bending, rolling shear, tension and glue line shear – all specimens performed well.

In July the four-week manufacturing programme began to produce all 111 panels – a mix of 60mm thick (3 ply) and 100mm thick (5 ply) structural and nonstructural panels. The first step was to apply primer to all lamellae and sort them into stacks for each panel. The first layer was then laid up in the vacuum press and adhesive applied. Subsequent layers were then laid up perpendicularly to the preceding layer and adhesive applied between each.

Hydraulic rams were applied to remove gaps from layers, the vacuum sheet brought over and clamped to encapsulate the panels in the press, and the vacuum applied. After the allotted time, they were removed using our overhead gantry crane and left to cure on the shop floor, before being sanded and lacquered, then wrapped ready for delivery to specialist makers Stage One, the company that would assemble MultiPly.

The finished panels look beautiful – the colour variation and contrast between the layers and lamellae is striking. Working through the entire manufacturing process of CLT, particularly using hardwood for a product that more commonly uses softwood has provided us with invaluable experience, which is directly transferable to similar projects. We have also formed a strong team of partners for future collaborations.

Given the ever-increasing demand of solid laminate timber systems in the UK, MultiPly has allowed us to demonstrate the manufacturing process, structural characteristics, flexibility, environmental credentials, visual impact and consistency of solid timber laminate systems such as CLT, and the benefits of modular construction. The pavilion has been designed to be dismantled and re-assembled, which also introduces concepts of circular economy usage. The panels are a manageable size, extremely thin, and compatible with current offsite modular housebuilding proportions, opening up new possibilities there.

The project also demonstrates CSIC’s capability and further cements our position, in collaboration with academic and industry partners, to facilitate innovation and R&D activity in construction.