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Site classification

Soils are classified according to their stability. Soil samples are taken on the site to determine soil class. A geotechnical engineer's report will clearly state the likely soil conditions and recommend a suitable footing system.

Photo of a soil drilling machine. Photo of a hole which has been dug by machine.

Type of soil Description Class
Rock Rock sites have no ground movement A
Sand Sand has little or no movement A
Clay, slightly reactive Slight ground movements due to moisture changes S
Clay, moderately reactive Moderate ground movements due to moisture changes M
Clay, highly reactive High ground movements due to moisture changes H
Clay, extremely reactive Extreme ground movements due to moisture changes E
Problem Sites which include soft soils, loose sands, landslip, mine subsidence, collapsing soils, erosion, fill and abnormal moisture conditions P
Table 1: Site classification