Do I need a soil report before building a house slab?

Yes. A soil report is a required, essential first step before any residential house slab is designed in Victoria — it’s not optional, and not something a builder or engineer can skip regardless of how straightforward your site looks.

The report classifies your site’s soil under AS 2870 (Classes A through E, plus P for problem sites), which directly determines which foundation system your engineer will specify — a waffle slab, raft slab, or a deep foundation system like screw piles or bored piers. Without this classification, there’s no genuine engineering basis for the design at all.

Soil reports are typically arranged early, often before final house design is locked in, since the result can influence overall project cost and, in some cases, siting decisions.

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