AS 2870 is the Australian Standard for Residential Slabs and Footings. It sets out how footings and slabs for houses and other Class 1 and 10 buildings must be designed and built, based on the site's soil classification. The current edition is AS 2870-2011, and it is referenced by the National Construction Code, which makes compliance effectively mandatory for residential footing work in Australia.

What are the AS 2870 soil classifications?

AS 2870 classifies sites as: Class A (stable sand/rock, little movement), Class S (slightly reactive clay), Class M (moderately reactive clay or silt), Class H1 and H2 (highly reactive clay), Class E (extremely reactive clay), and Class P (problem sites - fill, soft soils, trees, abnormal moisture conditions). More reactive classes require deeper, stiffer footings.

Do I need a soil test to get a building permit?

In practice yes. A geotechnical soil report classifying the site to AS 2870 is required before footings can be designed for a building permit in Victoria and most of Australia. Soil tests typically cost $400-$800 for a residential block and involve boreholes drilled on site.

Do screw piles and steel footings comply with AS 2870?

Yes, when designed and certified by a structural engineer. AS 2870 permits engineered footing solutions, and screw piles and driven steel footings such as SurePile, RapidStump and StumpRite are certified to found below the reactive zone, satisfying AS 2870 performance requirements. Building surveyors across Victoria accept these certified designs routinely.

What is a Class P site?

Class P (problem) covers sites that can't be given a standard reactive classification: uncontrolled fill, soft or collapsing soils, sites subject to erosion or abnormal moisture, and sites affected by trees. Class P sites always require an engineered footing design - commonly deep bored piers or screw piles that bypass the problem material.

What is the difference between Class M and Class H soil?

Both are reactive clays that swell when wet and shrink when dry. Class M (moderate) sites expect characteristic surface movement up to about 40mm; Class H1/H2 (highly reactive) sites expect 40-75mm. The higher the class, the deeper and stiffer the footing design must be - or the more attractive it is to bypass the movement zone entirely with piles.

Standards

AS 2870 Explained: Soil Classes, Footing Types & Compliant Design

By Easy Footings • 26 July 2026 • 8 min read

AS 2870-2011, Residential Slabs and Footings, is the Australian Standard that governs how house footings and slabs are designed and built. If you're building, extending or restumping a home anywhere in Australia, your footings must comply with it — it's referenced by the National Construction Code. This guide explains what the standard covers, what your soil classification actually means, and how modern footing systems comply.

What is AS 2870?

AS 2870 sets out the design and construction requirements for footing systems supporting houses and other Class 1 and Class 10 buildings — slabs, strip footings, pad footings, stumps and piers. The current edition is AS 2870-2011. Its core idea is simple: Australian soils move, particularly reactive clays that swell when wet and shrink when dry, so footings must be matched to how much the site is expected to move.

The standard does three things: it defines how sites are classified by reactivity, provides standard (deemed-to-comply) footing designs for each class, and sets performance requirements that engineered alternatives must meet.

AS 2870 Soil Classifications

Every residential site is assigned a class based on a geotechnical investigation. This is the single most important input to your footing design — and your footing budget:

Class	Site type	Expected surface movement
A	Stable sand or rock	Little or none (0–10mm)
S	Slightly reactive clay	10–20mm
M / M-D	Moderately reactive clay or silt	20–40mm
H1 / H1-D	Highly reactive clay	40–60mm
H2 / H2-D	Highly reactive clay	60–75mm
E / E-D	Extremely reactive clay	75mm+
P	Problem site: fill, soft soil, trees, abnormal moisture	Engineer assessment required

The "-D" suffix indicates deep-seated movement, common in dry inland areas. Much of Melbourne's west and north sits on basaltic clay classified M to H2; parts of regional Victoria classify E. Trees near footings can push an otherwise straightforward block into Class P — see our guide to footings near trees.

Soil Tests & Building Permits

The classification comes from a soil report (geotechnical investigation): boreholes are drilled on site, samples are assessed, and a classification is issued. For a residential block expect to pay roughly $400–$800, and allow 1–2 weeks for the report. Your building surveyor will require it — footings can't be designed or a building permit issued without it.

Footing Types Under AS 2870

Slab-on-ground — stiffened raft and waffle slabs, with edge beams sized to the soil class.
Strip footings — continuous reinforced concrete strips under loadbearing walls.
Pad footings — isolated pads under stumps, piers or posts.
Stumps and piers — discrete vertical supports for framed floors; see our concrete piers guide.
Piled footings — bored piers, screw piles or driven piles that carry loads below the reactive zone, used on H, E and P sites or wherever movement must be minimised.

Standard Designs vs Engineered Designs

AS 2870 offers two paths to compliance:

Deemed-to-comply designs. The standard includes pre-engineered slab and footing details for Class A to H2 sites. Use the tabulated design for your class and you comply — no further engineering needed for conventional construction.
Engineered designs. For Class E and P sites, unusual structures, or alternative footing systems, a structural engineer designs the footings to meet the standard's performance requirements and certifies the design. This is the path used for screw piles, driven steel footings and most difficult sites.

How Steel Footings & Screw Piles Comply with AS 2870

A common misconception is that only concrete complies with AS 2870. In fact the standard is performance-based: any footing system that an engineer certifies to meet its requirements complies. Concrete-free systems typically comply more easily on reactive sites, because they found below the movement zone instead of fighting it:

SurePile screw piles are wound in until a verified installation torque confirms bearing capacity — effectively load-testing every pile as it goes in. Ideal for H, E and P sites.
RapidStump driven steel footings are mechanically driven to refusal below the reactive zone, combining footing and stump in one certified unit.
StumpRite adjustable steel stumps add up to 120mm of screw height adjustment above certified bases — so minor residual movement can be corrected in minutes, for the life of the building.

Every Easy Footings installation is backed by engineer certification that your building surveyor can accept for permit purposes, across Melbourne and Victoria.

AS 2870 FAQs

Is AS 2870 mandatory?

Effectively yes. The National Construction Code references AS 2870 as the acceptable construction manual for residential footings, so building surveyors require compliance — via a deemed-to-comply design or an engineer-certified alternative — before issuing a permit.

What is the current version of AS 2870?

AS 2870-2011 is the current edition, and the one your soil report and engineering drawings will reference.

What does a Class M classification mean for my build?

Class M (moderately reactive) is the most common classification across suburban Melbourne. Expect standard stiffened slab or strip footing designs to work, with edge beams and reinforcement sized up from Class S. For stumped floors, footings typically need to found around 1–1.5m deep — or use driven steel or screw pile footings that bypass the movement zone.

My block is Class P — what now?

Class P just means "engineer required", not "unbuildable". Fill, trees or soft ground rule out the standard designs, so an engineer will design piers, screw piles or driven footings that reach competent material. On many Class P sites, screw piles are the cheapest compliant option because they avoid bulk excavation entirely.

Does restumping have to comply with AS 2870?

Yes — replacement stumps and footings are structural work under a building permit and must comply. See our restumping cost guide for what's involved.

Need AS 2870 compliant footings?

Easy Footings installs engineer-certified screw piles, driven steel footings and adjustable stumps across Melbourne and Victoria — compliant on any soil class, installed in any weather.

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