Protheroughs carried out the structural engineering for a residential development of six new-build dwellings on an infill plot in Worcestershire. Positioned at the head of an established cul-de-sac, the site required a coordinated substructure and retaining strategy to manage severe level changes across the plot while maintaining access between individual properties and avoiding complications with party wall awards.

Positioned closely together on a sloping site, the proposed dwellings faced two distinct substructure constraints. Firstly, providing steady rear access paths required setting internal finished floor levels (FFL) lower than the surrounding external ground, leaving higher passageways running directly against the building perimeters. Secondly, desiccated clay and tree roots extending past 2m depth made traditional trench foundations technically unsuitable and logistically impractical due to spoil disposal limits through the narrow residential entrance.

To resolve these constraints, a bored pile system was specified to transfer superstructure loads through the unstable upper soil layers directly into competent strata below 2m depth. Reinforced concrete ground beams were engineered and installed at a level to allow for the natural contour of the slope, keeping excavation depths controlled and minimising spoil removal off-site.

Retaining walls were incorporated directly into the substructure design to absorb level changes between individual plots and side access passages. Low-vibration installation methods were specified along property boundaries to limit ground movement near adjacent party walls in accordance with UK Party Wall requirements.

Finally, early coordination with the architectural layouts ensured load-bearing walls aligned directly with the ground beam span arrangement. Utilising traditional load-bearing masonry superstructures with rationalised floor spans kept structural steel requirements to a minimum and simplified site assembly for the main contractor.

The resulting structural design resolved the steep plot topography through ground beams and built-in retaining elements, delivering a stable, cost efficient layout that maintained access across all six plots.