What underpinning costs in Canberra, and when you don't need it

How much does underpinning cost in Canberra?

Published figures put an average residential underpinning job in Canberra at $4,000 to $15,000, with bigger jobs well beyond that. These ranges come from two figures published online in 2026: an underpinning contractor's Canberra average and a quote marketplace's ACT ranges.

Published ranges, not quotes. Neither publisher states whether GST is included.

Our part is smaller, and it comes first. An independent second opinion on a quote, from your photos and any reports, starts at $390 + GST ($429 inc GST). We never quote, sell or carry out underpinning, and we don't recommend contractors. Contractors who sell underpinning often assess for free because they sell the fix; we're paid for the advice, not the repair.

What are the main underpinning methods?

Underpinning means extending or strengthening a footing so it bears on firmer ground. Three methods are common, and the published price ranges differ between them.

The right method depends on the soil, the cause of the movement and the building. Price is the last question, not the first.

When don't you need underpinning?

When the cause is something you can fix, or the movement has stopped. Underpinning answers one problem: a footing that has lost support or sits on ground that keeps settling. It doesn't fix a leak.

In Canberra, seasonal movement deserves a hard look before anyone digs. Most suburbs sit on soils mapped with widespread seasonal waterlogging, and rainfall at the airport swung from 359 mm in 2019 to 913 mm in 2021. Our guide to cracks in walls in Canberra explains how to tell what's moving and why.

How does an engineer decide whether you need underpinning?

By working through the evidence in order, and leaving the method and price until last. Each step can end the question early.

1. Read the damage

   The width, pattern and location of the cracks, graded against the AS 2870 damage categories, and what the doors, windows and floors are doing.

2. Check whether it's still moving

   Dated photos and measurements, ideally across a wet and a dry season. If it has stopped, the question is repairing the damage, not the footings.

3. Find the cause

   Leaks, drainage, trees, poorly compacted fill or seasonal clay movement. If the cause can be removed, that comes first.

   Cause fixed and movement stops: no underpinning

4. Look at what the footings sit on

   Only if movement continues: how deep firm ground is, and whether a footing has lost support.

   Footing support is the problem: now the method and scope matter

A quote that skips straight to the last step hasn't answered the first three. That's the gap an independent second opinion fills.

Does underpinning need approval in the ACT?

Usually, yes. Underpinning usually needs building approval, and your certifier confirms. Work is only exempt from building approval if it doesn't affect "the structural integrity of any part of a building", and underpinning alters the footings.

The price affects your protections too. Part 6 of the Building Act, which covers statutory warranties and residential building insurance, doesn't apply to residential work costing less than $12,000, or to owner-builder work. On a job above that threshold, ask the contractor which warranty and insurance apply.

Why do Canberra underpinning quotes vary so much?

Because nobody knows how deep the firm ground is until they dig. Canberra's rock is often deeply and unevenly weathered, and rock can be near the surface on one part of a block and metres down on another. That changes how deep each pier has to go.

Geoscience Australia's notes on Canberra's geology record that where hard rock is near the surface, "the necessary blasting adds to excavation costs". In Tuggeranong, a 1976 study found weathering "generally less than 15 m", but excavation conditions variable because the weathering is irregular. Our Tuggeranong page covers that district's ground.

Before you sign any underpinning quote, ask these questions:

• What's causing the movement, and how do you know?
• Has the leak, drainage or tree been dealt with first?
• Is the movement still happening, and how was that checked?
• How many piers, how deep, and down to what material?
• Who designed the work, and will there be engineering drawings for the certifier?
• Does it need building approval, and who applies for it?
• If the price is $12,000 or more, what warranty and insurance apply?
• What happens to the price if you hit rock, or deeper clay, than expected?

When to call a structural engineer

Call an independent engineer before you pay a deposit on underpinning, resin injection or re-levelling, and whenever a quote arrives before anyone has explained the cause.

• Underpinning second opinion: from $390 + GST ($429 inc GST). We review the quote, photos and reports, and tell you in writing whether the movement calls for underpinning and whether the scope fits.
• Crack and footing movement report: from $1,090 + GST ($1,199 inc GST). An engineer visits, inspects, and reports the findings, the likely cause and what to do next.
• Structural inspection and report: from $1,090 + GST ($1,199 inc GST), when the cracks are part of wider concerns about the house.

All our fees are on our prices page, and they're the same across Canberra and the Queanbeyan side. Because we don't sell, carry out or recommend underpinning, our advice doesn't depend on whether you buy it.