House Levelling in Sydney

What house levelling in Sydney actually involves

Two concrete slabs meeting at a step could mean either of them has moved, and a picture of the step does not say which. CSIRO's footing guide explains both: swelling clay pushes up on footings, shrinkage takes support away, and erosion or saturation removes it. Which one applies decides whether the fix is to lift the low slab, support what is failing, or stop the water first.

Why not just pack it up

On a raised timber floor, CSIRO says isolated piers affected by erosion or saturation will eventually lose contact with the bearers they support, and the floor turns bouncy. It also warns that when a gap opens between a bearer and a pier, adding blocking can backfire: when the next swell part of the cycle arrives, the extra blocking pushes the floor up. Resin injection is one method used to lift a structure to a desired level, and it has its own page.

In NSW, altering or repairing a dwelling is residential building work, and a contractor licence is needed for residential building or trade work valued above A$5,000 in labour and materials. Underpinning or piering is a prescribed trade category; the Regulation names neither levelling nor slab lifting, so ask a provider what category a levelling job is done under.

House Levelling in Sydney — common questions

Is house levelling the same as underpinning?

They overlap. Levelling describes the result, a level floor or slab; underpinning describes one way of supporting a footing that has lost its ground. Which applies depends on why the level was lost.

Can a sloping floor be fixed by adding packing?

CSIRO warns against it where clay is swelling and shrinking under the piers: the extra blocking can push the floor up when the next swelling stage arrives. Ask what has been found to be the cause first.

How is a slab lifted?

One published method is injecting expanding polyurethane resin under the structure a little at a time, described on our resin injection page. Other methods exist; the provider names the one it proposes.