Client & Scope

• Client: Private homeowner

• Project type: Residential extension

• Services: Structural design, foundation solution, site coordination

• Location : Barnet, London

Key Challenges

• Extension constructed adjacent to an existing basement, requiring careful consideration of load transfer

• Presence of mature trees influencing foundation design

• Existing drainage and manholes located within the extension footprint

• Working within restricted site conditions typical of residential properties

Structural Solution

A practical and robust solution was developed to address the site constraints:

• Deep trench fill foundations designed to suit ground conditions and mitigate the influence of nearby trees

• Reinforced concrete suspended slab, dowelled into the existing structure to ensure continuity and stability

• Concrete lintel detail introduced to bridge over existing drainage runs, preventing load transfer onto buried services

• Heave protection boards designed to protect the reinforced concrete slab from tree-induced subsidence and heave.

Outcome

• Delivered a compliant and buildable structural design despite multiple constraints

• Successfully protected existing drainage infrastructure

• Ensured stability of both the existing basement structure and new extension

• Enabled efficient construction with clear and practical detailing