New Build Structural Design

This project in Truro involved two high-end bespoke new builds in an exposed countryside location. The developer needed a structural design that could support an ambitious architectural layout – open-plan spaces and a mezzanine level – while remaining practical to build and commercially viable within the programme.

Structural challenges

The site presented a different set of constraints from a typical residential project. Granite ground conditions removed the usual concerns about subsidence and foundation depth, but the exposed countryside location and the open-plan structural arrangement introduced a more significant challenge: lateral stability. Open-plan spaces and mezzanine levels reduce the number of walls available to brace a building, and an exposed site increases the wind loads that bracing has to resist. The structural strategy had to address both.

Structural approach

We designed a series of steel portal frames to provide lateral stability in the primary direction, infilled with structural timber to allow faster construction and better coordination with other trades on site. The foundation strategy used shallow trench foundations suited to the granite ground conditions, combined with the lateral resistance provided by the portal frame system to prevent overturning under wind load. The combination of steel and timber kept the structure responsive to the site conditions without introducing unnecessary complexity into the build.