Catherine Field Building
Inspections

The driveway, the grading and where the water goes

Two items that decide what happens to a slab over twenty years.

Owner Inspections · Catherine Field 2557 · 2026-08-04

In short: Driveway and site grading recorded on Austral handover and fixing work.

What was recorded

A driveway item at an Austral practical completion inspection, and grading required at both a fixing stage visit and a lock-up on the same suburb's jobs.

Why grading is not landscaping

The fall of the finished ground away from the house is designed, not decorative. It is what stops surface water collecting against a footing every time it rains.

The driveway's part in it

A driveway is a large impermeable surface right beside the house. Where it falls decides whether that water reaches the street or the slab edge.

Reactive ground

Soil that gains and loses moisture moves. Slab engineering is sized to resist that movement, not to absorb an unlimited amount of it, which is why persistent water at a footing is a genuine risk rather than a tidiness complaint.

The timing

Grading belongs before the landscaper. Once turf and garden beds are down, correcting the fall is earthworks.

Written by the Owner Inspections team from inspections carried out in Catherine Field. Licensed building practitioners, NSW Fair Trading licence 366177C.

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FAQ

Questions Catherine Field owners ask about this

Whose job is grading?

The builder's at handover, under the contract. Anything an owner changes afterwards is the owner's, which is where a lot of correct grading gets undone.

How do I check it?

Walk the perimeter and look at where the ground sits relative to the slab edge, and imagine where water goes in heavy rain. It is one of the more accessible checks for an owner.

Does it cause slab movement on its own?

Treat it as one factor among several rather than the sole cause. Repeated moisture change at a footing on reactive soil is a known risk.

Which standards apply?

AS 3500 for plumbing and drainage, with the National Construction Code and ABCB Housing Provisions for site drainage, and AS 2870 for what the slab was designed to tolerate.

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