Underpinning in Brisbane

What underpinning in Brisbane actually involves

A footing carries a house's weight into the ground. It needs underpinning when the ground beneath part of it has moved or can no longer carry the load. CSIRO's guide to footing performance names the usual reasons: clay swelling and shrinking with moisture, erosion, saturation, tree roots and leaking pipes. What a household sees is step cracks through brick mortar, doors that bind, and floors that dish or bounce.

Digging beside a footing

CSIRO is direct about the dig: excavation around footings must be properly engineered, because removing soil within the angle of repose will cause subsidence. Brisbane City Council's guideline treats that excavation as part of the job, classing digging directly related to underpinning as building work and giving underpinning works below an existing building as its own example. The Regulation's scope for this licence class also lists excavation and support, concreting for foundation work and several kinds of pile, screw piles among them.

Council says filling or excavating more than one vertical metre for a building or structure needs building approval, and its page points to a licensed building certifier to organise it. Up to one vertical metre needs no planning approval unless the site is in a neighbourhood plan area or affected by an overlay, and some overlays change the amount. Landslide and flood overlays are mapped over parts of several suburbs on this site, so look your lot up on City Plan online before assuming the allowance applies.

Underpinning in Brisbane — common questions

Do I need a licensed contractor for underpinning?

Yes, above A$3,300. Queensland's Regulation excludes work valued at A$3,300 or less from building work, and the value counts materials. The licence class that names underpinning is Foundation work (piling and anchors), so ask any provider for a licence number and class before you compare quotes.

Does underpinning need Council approval?

Council counts the excavation as building work, so the person to ask is a licensed building certifier, whom Council names for building approval. Whether a given job needs an approval depends on the job.

How much does underpinning cost?

This site sets no price. Two businesses publish bands that differ widely, and neither is a Brisbane figure; the costs page sets them out with their dates and what each is a price for.