Understanding Soil Tests & Site Surveys Before Building

Before any foundation design can be calculated, structural engineers require two critical pre-construction reports: a Geotechnical Soil Test and a Land Boundary Survey. Skipping or rushing these assessments can lead to foundation shifting, shifting brickwork, and border disputes.

1. Soil Classification

A geotechnical engineer drills boreholes to analyze soil profile layers and clay content. Soils are categorized into classifications:

• Class A & S: Stable, sandy, or non-reactive soils. Requires standard footing designs.
• Class M & H (Highly Reactive): Clay-rich soils that expand when wet and shrink when dry. Requires stiffer concrete slabs with deeper support beams.
• Class P (Problem Soil): Soft clay, organic silt, fill soil, or shifting sand. Requires concrete piers drilled down to solid rock layers.

2. Land Boundary Surveys

A licensed surveyor uses lasers to map boundary lines, easements, existing fences, and height levels. Fences in older Melbourne suburbs are often offset from the true property lines by several inches. Re-establishing the correct boundaries ensures your walls comply with side setback codes.