A site classification is a systematic categorisation of the soils found on your site. Soil samples are taken to assess their distinguishing characteristics which will determine their ‘Class’, and ultimately inform correct footing design by the structural engineer.
The classification of the site is based on the expected reactivity, or movement (shrink or swell) of the foundation soils.
Site Classification Assessments are in accordance with the following Australian Standards;
- AS2870-1996: “Residential Slabs and Footings – Construction”
- AS1726-1993: “Geotechnical site investigations”
Your site should be in one of the following classifications:
Slightly reactive clay sites. Only slight ground movement from moisture changes expected.
Moderately reactive Clay or Silt sites which can experience moderate ground movement from moisture changes
Highly reactive clay sites. Can experience high ground movement from moisture changes.
Extremely reactive sites. Can experience extreme ground movement from moisture changes.
A problem site. This can include soft soils, such as soft clay or silt, varying depths of Fill, loose sands, landslips, mine subsidence, collapsing soils, soils subject to erosion, reactive sites subject to abnormal moisture conditions, or sites which cannot be classified otherwise.
Soil types M, H, and E may also have an added classification of ‘D’. This indicates deep seasonal moisture variation which can mean significant expansion and contraction.