A footing inspection (also called a foundation inspection or footing trench inspection) is a site visit conducted by a geotechnical engineer or technician to verify that excavated footing trenches are suitable for concrete placement.
What Is a Footing Inspection?
A footing inspection involves the visual and physical assessment of excavated footing trenches to confirm they meet the geotechnical and structural requirements specified in the site classification report and engineering drawings. The inspection ensures the ground conditions exposed during excavation match those assumed in the design.
Why Is a Footing Inspection Required?
- Validation — Confirms the soil conditions at footing level match the geotechnical report
- Compliance — Ensures footings are excavated to the correct depth and width
- Safety — Identifies unexpected ground conditions (soft soil, rock, water, fill)
- Council approval — Many councils require footing inspection records as part of certification
- Warranty — Builder warranties often require footing inspection documentation
What Does a Footing Inspection Cover?
Before Concrete Placement
- Trench dimensions — Verify depth, width, and length match engineering drawings
- Trench cleanliness — Remove loose material, standing water, and debris
- Soil condition at bearing level — Check for soft spots, loose material, or unexpected changes
- Water ingress — Assess groundwater seepage and drainage requirements
- Rock intersections — Verify rock quality and bearing capacity if rock is exposed
- Adjacent excavations — Check for disturbance to nearby footings or structures
For Stiffened Raft Slabs (Waffle Pod / Raft)
- Subgrade preparation — Verify the ground is level and properly compacted
- Beam trench depth and width — Confirm dimensions match design
- Pod layout — Check pod placement and spacing
- Reinforcement — Verify steel placement (if specified before concrete)
- Moisture condition — Assess if the subgrade is too dry or too wet
Common Issues Found During Footing Inspections
| Issue | Consequence | Action Required |
|---|---|---|
| Soft / loose soil at base | Excessive settlement | Over-excavate and backfill with compacted fill or concrete |
| Standing water in trench | Weak concrete / soil softening | Pump out, install drainage, or use blinding concrete |
| Unexpected fill material | Variable settlement | Further investigation or redesign |
| Rock shelf at shallow depth | Difficult trenching, potential differential movement | Review footing design with structural engineer |
| Tree roots present | Future heave / settlement from root growth | Remove roots, review design for moisture effects |
| Over-excavated trench | Extra concrete cost | Backfill with compacted fill to correct level |
The Inspection Process
Step 1: Pre-Inspection Preparation
- Review the site classification report
- Review structural engineering footing drawings
- Confirm inspection requirements with the certifier / council
Step 2: Site Visit
- Excavated trenches are inspected before steel placement and concrete pour
- Measurements are taken and recorded
- Soil at bearing level is assessed
- Photographs are taken for documentation
Step 3: Assessment & Decision
- If conditions match the geotechnical report — the inspection passes
- If unexpected conditions are found — the geotechnical engineer provides direction (over-excavate, redesign, etc.)
Step 4: Reporting
A footing inspection report typically includes:
- Date, site address, and personnel
- Trench dimensions and locations
- Soil conditions observed
- Photographs
- Pass / fail determination
- Recommendations if conditions differ from design
Australian Standards
| Standard | Relevance |
|---|---|
| AS 2870-2011 | Residential slabs and footings — footing requirements |
| AS 1726-2017 | Geotechnical site investigations — field inspection methods |
| NCC | National Construction Code — foundation compliance |
Footing Inspection Timing
The inspection must occur after trench excavation but before steel placement and concrete pouring. Once concrete is poured, the condition of the bearing surface cannot be verified.
Typical inspection windows:
- Strip footings — after excavation, before steel
- Raft slab beam trenches — after excavation, before pods and steel
- Pier / pile excavations — after drilling, before concrete
- Pad footings — after excavation, before formwork