Many forms of engineered timber are commonplace in Britain: plywood, hardboard and chipboard have been standard materials for many decades, while glulam beams, OSB and I-beams are also now well established. But the most recent engineered timber products from the Continent are as yet little known.
In Britain there is much less timber construction of any kind than elsewhere in Europe or in North America. And what there is mainly takes the form of standard timber frame houses.
On the Continent there has been a much more extensive use of engineered wood, particularly as a structural material. Oslo’s spectacular new Gardemoen airport, for example, is a temple to engineered timber, and its pattern is followed in railway stations across Norway.
Switzerland is particularly strong in developing engineered timber products. Steko timber building blocks, for rapid construction of load-bearing external walls up to five storeys, were developed there to make use of softwood off-cuts. Lignatur floor, roof and wall elements, also from Switzerland, are hollow structural timber cassettes made up of four boards. The offer the strength of solid timber without the problems of weight and deforming.
There are signs, however, that the UK is becoming more receptive to these products, with the new music centre at Shrewsbury School and the Winter Garden in Sheffield among the early examples of engineered timber buildings on the Continental pattern.
Interbuild 2002 also saw the UK launch of German LenoTec and LenoPlan structural cross laminated timber panels for walls, floors, ceilings and roofs. The products come up to 297mm thick, depending on the spans and loading required. LenoPlan panels are available in a range of sizes, while LenoTec elements are cut to the dimensions required, up to 15m long by 5m wide, with pre-cut openings for doors, windows, stairs and even wiring channels.
Recommendations in the Egan report and the follow-up Accelerating Change were for the building industry to strive for short construction times, predictable on-site programming, high productivity and safety. Few products enable contractors to satisfy these recommendations as well as engineered timber products like LenoTec. Even fewer offer the environmental benefits, in terms of the health of the indoor environment, and as renewable, recyclable,CO2-neutral materials.
Like timber frame, LenoTec can provide an all-timber, breathing structure, but it is easier and faster to erect. For a typical house, LenoTec elements are assembled in a day. They require only standard, non-proprietary screws, bolts and angle brackets and work can be completed in virtually any weather. With no drying-out time required, internal fit-out can start on day two.
To resolve the UK housing deficit, we must look to such structural systems to provide durable, quality buildings that can be built rapidly and reliably, while meeting requirements on sustainability.
