Stonecutter

overview

A new office building in Central London reuses the existing foundations of a seven-story 1990s office building. The earlier building was challenged in its construction by a major archaeological dig locating human remains from burials following the Black Death and the Great Fire of London. The new basement for the 350,000-square-foot Stonecutter was therefore planned within the volume of the existing basement, and existing piles were reused to avoid further excavation and mitigate archaeological risks.

We provided structural design and sustainability consulting services for the building, which features 24,000-square-foot floor plates with flexible open space for tenants. The office floors are served by six separate terraces and a pocket park at ground level adjacent to retail spaces and a pavilion café, contributing to a much-improved public realm.

Use of a whole life carbon assessment helped us to focus on materials that would offer maximum benefits to reduce embodied carbon. By specifying very high levels of cement replacement where curing rates would allow it, and through designing in EAF steelwork, we delivered A1-A5 emissions of 550kgCO2e/m2.

highlights

• The existing piles were reused to avoid spoil while also reducing construction programme and cost. By using lightweight materials, we were able to match the weight of the new building with the existing while doubling the height to 14 floors.
• The new build provides long-span floors of 24,000 square feet with internal columns limited to just three (compared to 12 in the original building).
• Through our careful specification of materials, we limited the embodied carbon A1-A5 to 550kgCO2e/m2, which is the lowest published figure for a new build major project in the City of London to date.