Site classification
Site class under AS 2870 runs from Class A (stable rock or sand) to Class P (problem site). The class drives footing design, slab type, and concrete specification.
Ask Chalkline about this →Site classification is the process of grouping a residential building site into one of seven classes (A, S, M, H1, H2, E, P) under AS 2870:2011, based on the predicted movement of the ground surface due to moisture changes in reactive clay soils. The classification is performed by a geotechnical engineer and recorded in the soil report.
The class directly determines the footing and slab design: Class A and S sites can use the ABCB Housing Provisions 2022 Part 4.2 DTS prescriptive tables. Class H1 and above requires structural engineering directly under AS 2870. Class P is a problem site (soft fill, mine subsidence, abnormal moisture) that always requires a custom engineered solution.
Getting the soil report and site classification before quoting a slab is standard practice. A builder who quotes on an assumed Class S and the site classifies H1 wears the extra beam depth and concrete volume unless an explicit allowance was included in the contract.
Also known as: soil classification, site class, AS 2870 site class.
Category: Structural.
Related
- AS 2870:2011 residential slabs and footings
- Pad footings: construction and sizing for residential builds
- Soil report (geotech)
See also
Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.