Soil Classification Reports for NSW Dwellings

A soil classification report (sometimes called a geotechnical or soil test report) identifies how reactive the ground on your site is — in other words, how much it swells and shrinks with changes in moisture. For NSW dwellings, this report is required so that footings and slabs can be engineered correctly under AS 2870 — Residential slabs and footings. Without it, your engineer can't design compliant footings and your certifier can't approve the structural documentation.

Why is it required?

Reactive soils are one of the most common causes of cracking in homes. By classifying the site first, the slab and footing design can accommodate ground movement, protecting the building for its lifetime. A soil report is typically needed as part of the documentation for a construction certificate or CDC for new homes, additions, granny flats and similar Class 1 buildings.

The site classifications

Under AS 2870, sites are classified by their reactivity:

• Class A — stable, non-reactive (mostly sand or rock).
• Class S — slightly reactive clay; minor ground movement.
• Class M — moderately reactive clay or silt.
• Class H1 / H2 — highly reactive clay; significant movement.
• Class E — extremely reactive clay.
• Class P — problem sites requiring special engineering.

What does Class P soil mean?

Class P stands for a "problem" site. A site is classified P when normal designs can't be relied on — for example because of soft or unstable soils, deep fill, landslip, mine subsidence, trees affecting the soil, or abnormal moisture conditions. Class P sites require a site-specific footing design from a structural engineer, often using deeper piers, raft slabs or other engineered solutions. This usually means higher footing costs, so it's important to know your classification early in the budgeting stage.

How Meta Certifiers helps

We make sure your soil classification report and engineering align before your application is lodged, so there are no compliance gaps that delay your certificate. If your site comes back as Class P, we'll help you understand what the engineered design means for your project. Talk to our certifiers about your block in Sydney.