120,000 sq ft City of London refurbishment innovatively jacks up trading floors in situ, converting 2 floors into 3 using CLT. Navigates constraints from adjacent Bank of America.

20 Giltspur Street is a 120,000 sq ft commercial refurbishment in the City of London that employs innovative structural engineering to jack up existing trading floors in situ, converting the two existing floors into three new floors constructed from CLT. It is a project defined not by what it adds to the skyline, but by the ingenuity with which it unlocks value from within an existing envelope — a genuinely novel contribution to the practice of urban retrofit.

Originally connected to the Bank of America Building but now separated, this project navigates exceptional constraints: the site cannot extend sideways due to the bank, public access and roads, cannot extend downward due to tunnels and archaeological remains beneath, and cannot extend upward due to St Paul’s Cathedral sight lines.

Rather than accepting these constraints as limitations, the design team transformed them into the generative premise of the entire project. The celebrated “floors up” engineering strategy — jacking the existing trading floors in situ to create an additional storey within the same height envelope — is a world-class example of structural innovation in the service of sustainability and value creation.

The scheme intelligently optimises the existing envelope, adding a new floor plate at lower levels while replacing 90% of the façade, which serves to modernise the building while highlighting a preserved section of the historic London Wall. The roof plant has been consolidated to create valuable new office space.

20 Giltspur Street’s innovative “floors up” engineering approach delivers exceptional sustainability credentials while achieving remarkable spatial efficiency — 30% gross and 41% net area increases within the existing envelope. By preserving 80% of the original steel structure, the project achieves an outstanding structural embodied carbon performance of just 89kgCO2/m².

Urban greening via green/blue roofs and landscaped terraces enhances biodiversity, while thoughtful features include a double-height reception, comprehensive end-of-trip facilities, and shell-and-core office delivery to prevent wasteful fit-out cycles.