WorkStack in Charlton, London, is an ingenious solution for a compact, urban site – helping to redefine the future of workspace developments. The first lightweight industrial building of its type and scale in the UK, the design adopts overlapping, cantilevering workspaces, which progressively increase in floor area and size, to create 14 new industrial units scaling in size from 55m2 to 110 m2. Manufactured offsite to achieve both speed and accuracy, cross-laminated timber (CLT) was the ideal material to facilitate this unique and optimised inverted form, and specialist timber subcontractor B&K Structures (BKS) were selected to deliver the CLT and structural steelwork package.
The end client Greenwich Enterprise Board (GEB), a social enterprise with more than 20 years of experience, assembled an expert project team for WorkStack, with dRMM selected to head the design team and ARUP acting as structural engineer and fire strategy consultants. F Parkinson was appointed as the main contractor, with B&K Structures (BKS) selected as the specialist subcontractor responsible for the CLT and steelwork package – including the CLT, glulam and steel connection design – enabling the construction of this innovative, cantilevering five-storey structure.
Early engagement and collaboration by the entire team was fundamental to the success of the project. Due to the building’s unconventional form, the design sat outside of existing available test data. As such, dynamic thermal modelling was undertaken to inform the architectural design development and material selection. The subsequent specification of CLT ensured passive measures were adopted, and careful coordination across the project team during construction – including B&K Structures, who brought 20 years of structural timber expertise – ensured a tightly sealed building, delivered on time and to budget.
Alex Brock, BKS Pre-Construction Manager said: “We believe the best way to continue bringing timber technology to the mainstream market is through knowledge sharing and collaborative research and development. WorkStack is another project in our portfolio that continues to push the boundaries of timber construction into new and exciting sectors.”
ARUP collaborated with Building Control and the London Fire Brigade to configure each workspace as a separate fire compartment, augmented by smoke extract and other mitigations, addressing shortcomings in existing standards with respect to the use of mass timber in major buildings.
Simon Bateman, Senior Structural Engineer, ARUP said: “The design included a bespoke smoke ventilation system and stringent fire safety performance criteria for the CLT panels, including the systems that need to interface with the CLT panels, such as fire doors, fire dampers and encapsulation.”
On site, BKS addressed rigorous best practice on site, including a stringent focus on working at height requirements because the jettied structure rapidly began to rise alongside the busy main road. They also ensured moisture protection for the varied CLT elements, including end grain protection, with special emphasis on achieving compartmentation for fire performance.
The offsite benefits of the timber solution played a significant role in the project. BKS’ package included versatile CLT panels forming sheer walls, roof and floor slabs, with steelwork providing extra support around the loading bay and plant room. The interlock between the CLT panels – up to 19.2m in length – enabled continuous spanning and structural robustness, while the team at ARUP simplified the connection details. The offsite delivery model reduced the build phase on site by 25%, lowering waste and provided cost certainty compared to using traditional construction methods. It also enabled effective design clash identification and accurate installation planning – as such, the structural elements of the project were completed on site by BKS in just eight weeks.
Furthermore, the project achieved high levels of energy efficiency and sustainability, with structural timber making significant contributions thanks to the material’s natural ability to capture 297.9 tonnes of carbon within its 391 m3 of CLT walls and floors, whilst emitting only 10% of this during manufacturing and transport (28.8 tonnes CO2e). With full PEFC chain of custody certification, the responsible management of the European forests by BKS’ supply chain ensures that the timber for the project will have regrown in just 66 seconds.
Now complete, WorkStack offers affordability, flexibility and excellent transport links. The 14 new units are ideal spaces to allow new creative enterprises to grow and the project breaks the mould of ubiquitous ‘tin-shack’ industrial units.
Lee Roberts, Pre-Construction Director at B&K Structures, concluded: “WorkStack is designed to create a new class of high-density industrial buildings. We believe there will be ample scope to copy this building’s methodology to other sites while raising the bar on industrial design, in a way that will be of national significance.”
