Welcome to 11 Belgrave Road, London. This major reconstruction and vertical extension of a 1950s office building is a beautiful example of the latest in circular design and construction.

A significant amount of the existing fabric (concrete structure and foundations) were retained as part of an overall strategy to reduce the development's embodied carbon.

The strategy worked with an impressive 466kg CO₂e per m² and 324kg CO₂e per m² for the refurbished areas - beneath the LETI target of 350 kg CO₂ per m². Due to open in 2024, the building transforms the existing site into 108,000 sq. ft (10,033 m²) of premium biophilic offices with ample communal spaces and best-in-class facilities, including a café and gym with spa style changing rooms. The entire space is punctuated with gorgeous light-filled green space throughout (CIBSE journal). 

The specialist timber sub-contractor, G-frame Structures made an excellent application of a prefabricated Sylva kit by Stora Enso which enabled construction of the vertical extension, which includes a private terrace on the sixth floor, multiple terraces on the seventh floor, and a rooftop platform offering 360-degree views over London.

Vertical extensions (sometimes referred to as the Dutch Optoppen) are gaining popularity, particularly in dense urban areas where the only way to build is often up. Adding floors creates value and welcomes green rooftops and flat-packed kits like Sylva are ideal for hard to access sites in congested inner-cities. The elements came with preinstalled lifting devices so the elements could be lifted directly off the truck and maneuvering them into position. The elements also had preapplied moisture prevention membranes which reduced the construction time and need for temporary dry storage on-site.

The end result is that 11 Belgrave Road now achieves some of the highest sustainability and wellbeing credentials, taking its place as one of the capital's most sustainable office buildings which surpasses the RIBA 2030 Climate Challenge target by 38% according to Max Fordham, the engineers behind the beautiful design.

Sustainability certifications designed to achieve include:

• NABERS process

• WiredScore Platinum Certification

• SmartScore Platinum

• BREEAM 'Outstanding' rating

• WELL Platinum

Learn more:

Case study

Planning permission application 

Advantages of building with mass timber 

Flythrough