Project NameMultiPly CLT Pavilion at London Design Festival
MultiPly is an interactive exhibition currently on show in the courtyard of the V&A museum in London for the London Design Festival. A collaboration between the American Hardwood Export Council (AHEC), Arup Engineering and Waugh Thistleton Architects, the project aims to showcase the engineered timber product Cross-Laminated Timber (CLT), to the European market.
Previously collaborating on a similar project The Smile, the new CLT project MultiPly aims to further the research into the groundbreaking qualities of CLT in the construction industry, this time showcasing the modular production process, market application, and cost efficiency.
MultiPly comes in the form of a nine metre high maze, made entirely from CLT, and resulting in a carbon neutral structure. The panels used in this structure are the first CLT panels ever produced in the UK.
The MultiPly structure itself appears to be a simple set of stacked boxes, but it’s groundbreaking in its detailing and design. Small overlaps of only 100mm between panels hold the frames together, whilst ambitious cantilevers and high occupancy limits (up to 200 at a time), test the limits of CLT as a structural material. It was essential to test the irregularly-stacked-box design of the maze in order to ensure that whatever path the load of occupants took, no members would fracture or over stress along the way.
The pavilion-like structure also showcases the accuracy of CNC timber cutting to produce strong and beautiful joints to create a demountable structure. Multiply is connected in a way to optimise the speed of assembly and disassembly, with tongue and groove like joinery connecting members. Offsite modular construction is becoming more popular, and Multiply is a great example of the speed and accuracy of this process.
CLT is also optimised for pre-fabrication, as it is generally machine cut by CNC machines. This greatly reduces construction costs and allows structures to be erected on site in a fraction of the time. Wastage is also minimised with machine cutting, and offcuts can be used in other areas like stairs or detailing.
The CLT comprises American tulipwood layers oriented at right angles to each other to produce an engineered product much stronger than normal timber. The thin ‘plys’ are ordered in odd numbers, usually of 3, 5, 7 or 9 layers, with alternating grain directions. Engineered wood products are generally made from softwoods, but this project aims to showcase the structural potential of engineered hardwoods.
The benefit of engineered timber products is the ability to utilise lower grade timbers, which lowers the cost, without compromising the integrity of its structural performance. The structure locks in 30 tonnes of carbon dioxide from the atmosphere, completely offsetting its production emissions and generally achieving a carbon positive result. This means the material locks in more carbon dioxide than is produced during the process of making it. Materials like this, with low embodied energy, could help to lower carbon emissions in the construction industry.
Through 20 years of research and development into the structural potential of American hardwoods, Arup has used the structural quality of American tulipwood for its high strength to weight ratio.
Arup’s timber specialist Andrew Lawrence says Multiply “showcases the ability for Tulipwood CLT to be the structural foundations for multi-level buildings.” Hardwood CLT allows for much slimmer panels than softwood, and can offer an improved appearance for exposed panels.
Lead architect Andrew Waugh of Waugh Thistleton says the project aim to “create debate around how environmental challenges don’t have to be addressed at the expense of innovation and affordability.” Waugh appreciates the precise nature of pre-fabricating CLT off site, to produce a building that accurately represents what is documented, unlike concrete and steel construction which is notoriously imprecise.
American Tulipwood is one of the most abundant hardwoods in the USA and consequently is one of the most sustainably grown.