Concrete evidence


KLH UK's cross-laminated timber can do anything concrete can - and often do it better. Keren Fallwell reports

Sitting on the floor of KLH UK's offices in Clerkenwell is a celluar shape of cross-laminated timber that looks like a piece from a giant, Alice in wonderland jigsaw puzzle.

This curvy cutout, from a window aperture at Kingsdale School in Dulwich - KLH's largest project in the UK to date - demonstrates the construction of the timber panels, and the surprising flexibility of something so solid and so heavy.

The structural panels, which comprise layers of timber set at right angles to each other, are made in widths from 70-256mm thick, depending on the application. Because of the nature of the panels, it is with concrete and steel that comparisons are drawn, rather than timber frame.

"It's always dangerous to compare this with traditional timber frame because it's a solid panel," said Karl Heinz Weiss, director of KLH UK. "It's not a frame which is stablised with two cover plates; it has all the structural properties within the panel. It's actually acting in two directions structurally, like precast concrete. That's why you can work with it as you can precast concrete, creating large spans, cantilevers or overhangs."

All the panels, produced from PEFC-certified Austrian spruce and fir, are manufactured in KLH's Austrian factory, which is itself built from cross-laminated lumber. Europe's largest manufacturer and supplier of cross-laminated lumber, KLH's process differs from its competitors in that it uses a steel press, rather than a vacuum press, which allows thicker lamination layers and the use of formaldehyde-free adhesive. The KLH product is also the only one that has full European technical approval.


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