Construction is underway on Xylo, a landmark nine-storey office development in Clerkenwell and what is due to be the UK’s largest consented all-timber frame office building. The scheme is being developed by Global Holdings Management Group, with McLaren Construction appointed as main contractor, alongside architects Piercy&Company and structural engineers Heyne Tillett Steel.
All CGI images: Global Holdings Management Group
Replacing a former 1960s town hall building, the 9,300m² development will deliver high-quality, open-plan workspace alongside a range of amenities including a vaulted entrance lobby, rooftop garden, town hall space, and landscaped terraces.
A pioneering mass timber structure
At the core of Xylo is a fully expressed engineered timber superstructure spanning nine storeys. The building is constructed using a combination of glulam beams and cross-laminated timber (CLT) floor slabs, forming a regular 9m x 7m structural grid that enables flexible, open-plan office layouts.
The structural design optimises the use of timber to achieve both structural efficiency and architectural clarity. Working closely with the wider design team, Heyne Tillet Steel have developed a streamlined solution that integrates shallow foundations with optimised use of all materials across the structure.
The building’s glulam and CLT frame is being delivered by Hybrid Structures, bringing specialist expertise in off-site fabrication and installation. The use of prefabricated timber elements enables increased precision, reduces waste, and supports a faster, more controlled construction programme – an important factor on a constrained central London site.
Embodied and stored carbon
A key driver behind the adoption of mass timber at Xylo is its environmental performance. The building’s timber structure is expected to store more than 2,400 tonnes of CO₂, while significantly reducing embodied carbon compared to conventional steel or concrete alternatives.
Overall, the development aims to deliver embodied carbon levels approximately 50% lower than a typical London office building, while reducing operational emissions by up to 82%. With energy-efficient systems, low-VOC materials and natural finishes throughout, Xylo is also targeting some of the best indoor environmental quality metrics in the UK.
Future flexibility
The modular timber structure also supports long-term flexibility, as it can be easily reconfigured over time to adapt to changing occupier needs. This approach will allow Xylo to accommodate a wide range of uses over its lifespan.
As construction progresses, Xylo is emerging as a flagship example of how large-scale commercial buildings can successfully adopt mass timber.
