Structural Award Winner 2008
Location: Murray Grove, London
Building Owner: Telford Homes PLC
Architect: Waugh Thistleton Architects
Builder/Main Contractor: Telford Homes PLC
Structural Engineers: Techniker LTD
Wood Species: European Whitewood
Constructed entirely in timber, the nine-storey high-rise in Hackney is the tallest timber residential building in the world. Comprising both private and affordable housing, Murray Grove will provide twenty nine apartments.
The building has been assembled using a unique structural system pioneered by KLH of Austria. The panels have been formed using timber strips glued together into a solid mass element with minimal movement characteristics. Prior detailing experience has been gained through applications in a variety of projects including housing, commercial developments, schools and industrial units. Our interest in using KLH came from an environmental position and a drive to get timber more readily accepted in the UK construction industry.
The concept design had been developed with this in mind, with the flats generated in a honeycomb pattern around a central core. We worked very closely with Techniker structural engineers and KLH to integrate the technology without sacrificing the design principles. The cross laminated solid timber panels form a cellular structure of timber load bearing walls, including all stair and lift cores, with timber floor slabs, and as such will be the tallest pure timber building in the world.
Each of the panels is prefabricated including cut-outs for windows and doors. As the panels arrived on site they were immediately craned into position, dramatically reducing the time on site. The entire nine storey structure was assembled within nine weeks. A ‘platform construction’ configuration is used throughout this structure. Each floor is set on the walls below, and then another storey of walls is raised and so on up the building. Joints are secured with screws and angle plates. Stresses are generally very low throughout the structure and at points where cross-grain pressures are high screws have been added to reinforce the timber locally. Progressive collapse is avoided by providing sufficient redundancy so that any single element can be removed.
Maintaining a high acoustic performance for Murray Grove was a key issue for us. Timber buildings have always been classified as poor in terms of their acoustic performance due to their super light structures compared with reinforced concrete and masonry. Cross-laminated solid timber KLH panels have a significantly higher density than timber frame buildings. They provide a solid structural core on which different, independent and separating layers can be added. The layer principal overcomes any acoustic or sound transfer issues. With a consistent and economic layering strategy of stud walls with gaps in front of the party walls, floating floor build-ups and suspended ceilings, u-values that exceed UK requirements have been achieved.
The timber is untreated and relies on the building envelope for protection from damp and rot. The construction process is entirely dry and the site remains very neat and clear of superfluous materials throughout first and second fix stages.
Timber absorbs carbon throughout its natural life and continues to store that carbon when cut. The fabric of our Murray Grove tower will store over 181 tonnes of carbon. Additionally, by not using a reinforced concrete frame, a further 125 tonnes of carbon are saved from entering the atmosphere. This is equivalent to 21 years of carbon emissions from a building of this size, or 210 years at the current requirement of 10% renewable.
The facade was created by recording the changing light and shadows formed on the empty site by the surrounding buildings and trees; the pattern was captured through a sun-path animation. The resulting image was pixilated, picked up, stretched and wrapped around the building. The exterior cladding forming this pixilated image is made up of over 5,000 individual panels across the building in three shades: white, grey and black. The 1200×230mm panels are manufactured by Eternit and made up of 70% waste timber.
Each apartment has its own internal balcony and with the windows these will appear as the ‘missing pieces’ on the façade; an additional punctuated rhythm over the abstract image of the façade.
Regulations in Europe have meant there are no precedents for our scheme. Finland allows only three storey timber buildings. Austria prohibits timber housing above five floors. However, engineering methods of timber construction pioneered by Waugh Thistleton and Techniker are now being added to UK Building Regulations in annexe form. For the moment, UK remains the country to produce the tallest crosslaminated high-rise across the continent.