AS 3798 is about the ground before the slab. On a greenfield, cut-and-fill lot — common across South East Queensland's growth corridors — the quality of the fill under your slab is as important as the slab itself.
What AS 3798 actually means
AS 3798 provides guidelines for earthworks on residential and commercial developments, including the placement, compaction and testing of controlled (engineered) fill. Its purpose is to give the ground the stability that structures built on it rely on.
Where it applies in your new home
Where a lot has been cut down in one area and filled in another to create a level building pad, part of your slab may sit on that fill. AS 3798 governs how the fill was placed and compacted, and how it is tested — so the slab has firm, non-settling support.
What VG Inspect checks against it
A building inspector does not carry out geotechnical testing — that is the geotechnical engineer's role. What the pre-pour inspection checks is that the fill compaction test reports exist and cover the site. Missing compaction test reports for the fill is a standard pre-pour red flag, because without them there is no evidence the ground beneath the slab will hold.
What it does and doesn't cover
AS 3798 covers the earthworks and fill. The soil-testing methods it relies on come from AS 1289, the residential slab design from AS 2870, and the concrete from AS 3600. Together they connect the ground to the structure.
A VG Inspect QBCC-licensed inspector (QBCC Licence 1318443) checks for the compaction documentation at pre-pour, and reports the same day. Call 07 3180 8041 or book a pre-pour inspection online.