Underpinning in Wollongong

What underpinning in Wollongong actually involves

The NSW Government defines underpinning as building a new support structure under a wall, column or footings without removing the superstructure, to stop a collapse from excessive settlement or another failure, to let the loads on a building increase, or to let the ground level inside or outside it be lowered. CSIRO's footing guide lists what usually takes a footing's ground away: clay that swells and shrinks, erosion, saturation, tree roots and leaking pipes.

Digging beside a footing

CSIRO says excavation around footings must be properly engineered. Guidance from the Welsh Government, which is outside NSW, describes the usual method as digging short sections under the footing one at a time and filling each with concrete, and warns that voids can be left between the new work and the old footing. It says the first step is generally a trial hole beside the footings, assessed by an engineer or surveyor. So ask a provider what they will dig first, and who will read what it shows.

Wollongong has no single rule for a dig beside a footing, and none of the instruments we read says underpinning as such does or does not need consent. Wollongong Local Environmental Plan 2009 attaches consent to land and to kinds of work: works below the natural ground surface on land its acid sulfate soils map puts in a class, and any works on Class 1 land, unless a preliminary assessment shows no management plan is needed or the works disturb under a tonne of soil, with foundations among its examples; earthworks that are not minor; and exterior alterations inside a mapped heritage conservation area, where the state's exempt-work entry for repairing foundations does not apply. The council or a certifier can say whether a given job meets any of it.

Underpinning in Wollongong — common questions

Do I need a licensed contractor for underpinning?

Above A$5,000 in labour and materials, yes. Ask for a licence number and the categories it covers.

Does underpinning need council approval?

That depends on the land and the work, and the documents we read do not settle it for underpinning. Ask the council or a certifier.

How much does underpinning cost?

We set no price. The costs page shows the bands three businesses publish, with the date each was read.