Site classification or geotechnical report: which one have you been asked for?

For a house, extension, granny flat or garage on a flat or gently sloping block with no basement. Two boreholes to 2.5 metres, the soil logged and tested where needed, and a site class of A, S, M, H1, H2, E or P under AS 2870 with the reasoning. It is a fixed fee, and it is what a builder or certifier usually means when they say soil test.

For everything the classification cannot answer. The investigation is scoped to the site and the proposal: boreholes or test pits to the depth the design needs, logging to AS 1726, in-situ and laboratory testing, and a report that gives the ground profile, groundwater, allowable bearing pressure, founding levels, and advice on excavation, retaining walls and drainage. It is a custom quote because the scope is.

If any of these apply, a classification will not be enough, and a certifier is likely to send you back for the fuller report.

The fastest way to tell is the document that asked for it. A condition that says soil classification, site classification, soil test, or refers to AS 2870, wants a classification. One that says geotechnical report, geotechnical investigation, slope stability, bearing capacity or refers to AS 1726 wants a geotechnical report. If the wording is ambiguous, send it to us and we will tell you which it is, at no charge.

Sometimes. If a classification finds something that needs more, such as deep fill or a Class P result caused by a slope, the report says so and we quote the investigation to follow. But if the signs above already apply, it is cheaper to scope the geotechnical report from the start than to drill the block twice.