16 Chart Street is a redevelopment project of a 1930s furniture warehouse in Hoxton.
Designed by Ian Chalk Architects in collaboration with Heyne Tillett Steel (client and engineers), the four-storey building has been repurposed and remodelled into a sustainable and collaborative workspace with new components using cross-laminated timber (CLT) and glue-laminated (glulam) beams.
Combining different materials
During the design process, the architects and engineers combined their collective knowledge of the potentially complicated issues of using different materials and the varying tolerances between new and existing masonry, steel, and timber.
The building was extended sideways and upwards to create an open studio space and light-filled flexible spaces for meetings. Extending the existing building sideways, a vertical lightweight CLT structure was added alongside a new stair and lift core. Meanwhile the new third floor level features a large, column-free space with natural lighting provided by four rows of 10m long north-light windows supported by LVL Baubuche beams.
Circularity and Sustainability
The approach to the redevelopment was to reuse and extend the existing building whilst retaining its unique character. Heyne Tillet Steel used its HTS+ Carbon Calculator and worked closely with sustainability advisors KLH Sustainability to measure and accurately report the building’s environmental performance.
By reusing 86% of the existing structure and constructing 46% of the new extensions using timber, the total embodied carbon for the development of 16 Chart Street is 171kgC02e/m2. This means the building outperforms the RIBA, LETI, and iStructE targets.
Use of timber
An additional storey was added to the existing building using a combination of CLT, glulam and high-strength laminated veneer lumber (LVL timber). This all-timber solution allowed the architects and engineers to showcase timber’s unique design potential while extending the life of the existing structure.
The building extensions were built using engineered timber due to their lightweight qualities without the need for additional strengthening. Adding the timber element to the building also allows the timber to act as a natural carbon store and reduces the project's overall carbon cost.
The top floor incorporates a striking sawtooth roof which was constructed using hardwood BauBuche LVL beams to support the northlights and CLT panels. This combination provides the natural strength to support the angular roof while also delivering a clean, open plan space for events, collaboration and creativity.
With biophilic principles in mind, timber is left exposed throughout the interior with the architects opting for Norwegian Spruce for its soft colouring and natural aesthetic qualities. All exposed timber elements were whitewashed with intumescent paint, delivering a beautiful, tactile interior.
The project won the Structural Timber Awards Commercial Project of the Year 2021 and the AJ Retrofit Building of the Year 2022.