How Much Concrete for a Foundation?
Quick Answer
Width × depth × length. 600mm × 225mm trench: 0.135m³ per metre
Based on: Standard strip foundation for domestic masonry wall, minimum 225mm thick concrete
Important: Foundation design depends on ground conditions, loading, and local requirements. Always consult a structural engineer and comply with Building Regulations (Approved Document A). These figures are general guidance only.
How We Calculated This
- Trench width: 600mm = 0.6m
- Concrete thickness: 225mm = 0.225m
- Volume per metre run: 0.6 × 0.225 × 1 = 0.135m³
- For 20m total trench: 20 × 0.135 = 2.7m³
Standard Foundation Sizes (Approved Document A)
- Single-storey wall: Minimum 450mm wide × 225mm deep
- Two-storey wall: Minimum 600mm wide × 225mm deep
- Cavity wall (two-storey): Typically 600–750mm wide
- Depth below ground: Minimum 450mm (often 600–1000mm depending on soil)
Concrete Per Metre Run
- 450mm × 225mm: 0.101m³/m
- 600mm × 225mm: 0.135m³/m
- 750mm × 225mm: 0.169m³/m
- 600mm × 300mm: 0.180m³/m
Concrete Specification
Foundations typically use:
- Standard: GEN 1 or C20 (ST2) — suitable for most domestic strip foundations
- Sulphate-resistant: Required in areas with sulphate-bearing soils (DS class)
- Ready-mix delivery: Minimum order typically 1m³, delivered by mixer lorry
Cost Guide
- Ready-mix concrete: £80–120/m³ delivered
- Concrete pump (if needed): £200–400 half day
- Hand-mix (bags): Much more expensive, only for very small pours
Add 5–10% extra to account for uneven trench bottoms and minor over-dig.
Last updated: April 2026