38 Berkeley Square

A landmark development delivering 83,000 square feet of ultra-prime workspace in one of Mayfair’s most prestigious squares. Completed in late 2024, the scheme includes premium office, retail, and gallery spaces, as well as 7,500 square feet of landscaped gardens.

The workspace exceeds the client’s ambitions for a ‘beautiful, sustainable and human workspace’. Replacing a dilapidated office building and adding a basement level, the new 12-storey development is supported by a steel frame with exposed cross-laminated timber floor panels. It is the first commercial CLT building to achieve SWECO Building Control compliance since UK fire regulations became more stringent in 2021.

Fashion House Chanel has signed a 20 year lease on the building for their new London HQ.

Workplace

Architect: Piercy&Company
Client: Berkeley Estate Asset Management
Location: London, UK

Context

Occupying a commanding position in one of Mayfair’s most prestigious squares, 38 Berkeley Square sits proudly above the surrounding buildings and offers panoramic views across the London skyline.

In 2019, we were appointed to the scheme following a competition win alongside architects Piercy & Co. The brief: to reimagine the site, previously occupied by a neglected, poorly serviced office building, into a best-in-class and highly sustainable workplace.

The result is a confident and contextual building — distinct from the “white boxes” that dominate Mayfair’s commercial architecture — that complements the built heritage of the surrounding conservation area.

Our Approach

Navigating CLT Compliance

Timber quickly emerged as the best material to deliver a highly sustainable, best-in-class workspace. However, following the release of new guidance in 2020, CLT buildings faced heightened regulatory scrutiny.

Through close collaboration with The Fire Surgery and IGNIS — drawing from over 25 years of mass timber testing experience — we provided stakeholders and insurers with confidence in our use of exposed timber. This approach allowed us to justify the CLT design and achieve compliance, making 38 Berkeley Square the first commercial CLT building to achieve Building Regulation approval during this challenging period.

2.8m Floor-to-Ceiling Heights

Achieving generous 2.8 metre floor-to-ceiling heights was essential for the best-in-class workplace and future occupants of 38 Berkeley Square. However, achieving this within the constraints of the planning envelope presented a significant design challenge.

Our solution included a 400mm raised floor plenum, with services integrated within upstand castellated steel beams, eliminating the need for a traditional ceiling void. These beams supported notched CLT panels on their bottom flanges, creating a flat, exposed CLT soffit and maximising visual height across the floorplates.

Raft Foundations, Reduced Carbon Impact

With a lightweight superstructure, we were able to design a raft foundation system and eliminate the need for piles. An advantage due to the site’s proximity to a neighbouring Grade II listed building.

By minimising the frame weight, we were able to design out deep piles and use a shallow raft foundation, possible only due to the introduction of timber into the frame. Resulting in a reduction of concrete volume in the ground by approximately 50%, a 3-month reduction in the programme and significant savings to the cost plan.

Integrated Blue & Green Roof System

Our Development Infrastructure team developed a surface water drainage strategy centred on a fully integrated blue and green roof system. This replaced the need for traditional bulky attenuation tanks in the basement, managing water at source in line with the London Sustainable Drainage Action Plan. In addition to their functional role, the roof systems add ecological and aesthetic value to the project.

To protect the CLT structure, a robust waterproofing strategy and management plan were implemented, both during construction and in the permeant case, reducing moisture risk and ensuring durability.

The building’s drainage strategy also includes a greywater harvesting system, reducing water demand by 60%. All water-efficiency and drainage measures were embedded early in the design process, resulting in a future-proof, resilient building that maximises performance while minimising environmental impact.

Impact

Lessons learned during the path to compliance at 38 Berkeley Square directly informed the Commercial Timber Guidebook, which was published in 2024.

Developed by Elliott Wood, Waugh Thistleton Architects, OFR and Lignum Risk Partners — with the backing of the UK’s largest investors, developers and asset owners — the technical resource addresses insurance challenges for mass timber buildings. Focusing on durability and fire safety, it provides clear technical guidance for mitigating the key risks associated with CLT in commercial developments.

By collating cross-industry expertise, the Guidebook addresses the greatest challenge to the widespread adoption of mass timber construction in the UK: insurability.

Engineering Solutions

By minimising the frame weight, we were able to design out deep piles and use a shallow raft foundation, possible only due to the introduction of timber into the frame. It is the single largest contributor to a low-carbon building, resulting in a reduction of concrete volume in the ground by approximately 50%, a 3-month reduction in the programme and significant savings to the cost plan.

We achieved 2.8 metre floor to ceiling heights by eliminating the need for a traditional ceiling void. Designing a 400mm raised floor plenum, with services integrated within upstand castellated steel beams. These beams supported notched CLT panels on their bottom flanges, creating a flat, exposed CLT soffit and maximising visual height across the floorplates.

The raised floor also enabled a pressurised displacement ventilation system, where fresh air is introduced at floor level, rises through the space, and is extracted at a higher level through vertical risers. This solution improves air quality by removing toxins and producing more fresh air than conventional ventilation systems.

To protect the CLT structure, a robust waterproofing strategy and management plan were implemented, both during construction and in the permeant case, reducing moisture risk and ensuring durability.