Restumping fixes the foundations a house already has. Bored piers and pad footings are for what comes next — the extension off the back, the second storey, the new deck or garage — where new loads need new, engineered support in the ground. It's the same trade skills, the same soils, and the same rule: the ground decides the design.
What bored piers are
A bored pier is a deep, drilled concrete column: an auger bores a round hole — commonly 300mm to 600mm in diameter — down through the unstable surface layers to competent ground, a steel reinforcement cage goes in, and the hole is filled with concrete. The pier carries its load past the topsoil and the seasonal "movement zone" of reactive clay down to stratum that doesn't shift between wet winters and dry summers. On the reactive clays of the Wimmera, the Latrobe Valley and much of the North East — where the top metre or more of ground swells and shrinks every year — that depth is the whole point.
What pad footings are
A pad footing is the shallow cousin: an excavated square or rectangular pad of reinforced concrete that spreads a concentrated point load — a stump, a steel post, a verandah column — over enough ground to carry it. Pads suit stable soils and lighter loads; piers suit reactive soils, sloping blocks and heavy point loads. Plenty of jobs use both: piers under the structural posts, pads under the light ones, exactly as the engineer draws it.
When you need them
- Extensions and new additions. Every new room needs its own footing system, designed for the soil under it — not for the soil the original house was guessed onto in 1962.
- Second storeys. Going up roughly doubles the load going down. Existing footings often need supplementing with new piers before the frame goes up — sometimes alongside underpinning of the original footings.
- Decks, verandahs and carports. Smaller loads, same physics — undersized footings are why ten-year-old decks lean.
- Reactive clay and sloping sites. Where slab-on-ground or shallow strip footings would ride the seasonal soil movement, piers found the structure below it.
- Rebuilding after removal or raising. In Queensland especially, raised homes and build-unders often land on new engineered piers rather than traditional stumps.
The engineering (why you can't skip it)
Footing design in Australia runs through AS 2870, the residential slabs and footings standard. Your block gets a soil classification — from stable A/S sites through M (moderately reactive) to H1, H2 and E (highly and extremely reactive) — usually off a geotechnical report with bore holes. The classification, the loads and the wind rating drive the engineer's design: pier diameter, depth, spacing, reinforcement and concrete spec. Council or the building surveyor (private certifier in Queensland) then requires an inspection of the drilled holes before the pour, so the founding depth and bearing are verified while anyone can still see them. That inspection paperwork is the difference between a foundation and a rumour — keep it with your title documents.
Indicative 2026 costs
Bored pier pricing splits into the drilling and the rest (cage, concrete, pump and engineering). Published Australian drilling rates run roughly:
| Pier diameter | Drilling, typical (to ~3m depth) |
|---|---|
| 300mm | $300–$450 per pier |
| 450mm | $450–$650 per pier |
| 600mm | $650–$900 per pier |
As a worked example from published rates: 47 pier holes at 450mm diameter and 2m depth prices out around $19,000 drilled. Steel, concrete, pump hire, the geotech report ($1,000–$3,000) and engineering design ($1,500–$3,000+) go on top, and access, rock or collapsing sand can add more — which is why we quote fixed, per job, off the engineer's drawings rather than off a rate card. A typical extension needing six to twelve piers is a far smaller number than a house-sized grid; the drawings decide it.
How a pier and footing job runs
- Site assessment and geotech: soil classified, founding depth established.
- Engineering: pier/pad layout, sizes and reinforcement designed to AS 2870 for your loads and wind rating.
- Approval: the footing design goes through your building permit (VIC) or certifier approval (QLD) — usually as part of the wider extension approval.
- Drill and inspect: holes bored to depth, cleaned, and inspected by the surveyor or engineer before any concrete is ordered.
- Cage and pour: reinforcement set, concrete placed and vibrated, starter bars or brackets cast in for what's being built on top.
- Certification: inspection records and the engineer's sign-off complete the paper trail.
If you're extending an older weatherboard, there's a bonus move: restump and level the original house before the new footings go in, so the builder isn't matching new level floors to an old sagging frame. We do both in one visit of paperwork — one soil report, one engineering package, one mobilisation.