Screw piling is a foundation method where steel piles fitted with helical plates are rotated into the ground like giant screws, using a hydraulic drive head mounted on an excavator. Each pile is wound down until the measured installation torque confirms it has reached the load-bearing capacity specified by the engineer. The structure is then built directly off the pile heads. Screw piles (also called screw piers, helical screw piles or helical piers) install quickly with no excavation, no spoil removal and no waiting for concrete to cure, and they are certified by torque records as they go in. They are widely used across Queensland for new homes, swimming pools, extensions, granny flats and commercial buildings.
How screw piles work
You will hear them called screw in footings or screw in foundations on site. It is the same product, and it has three working parts:
- The pile: a galvanised steel tube that carries the load from your structure down through the weak upper soil.
- The helical plates (helices): one or more circular steel plates welded to the pile in a spiral form. These do two jobs: they pull the pile into the ground as it rotates, and once installed they act as the bearing surface that transfers the structure's weight into competent soil.
- The pile head or cap: the connection point at the top, matched to what is being built: a bearer bracket for a deck, a starter bar cage for a concrete slab, or a bolt-down plate for steel posts and frames.
The engineering principle is simple: the upper metre or two of most Queensland sites is topsoil, fill or reactive clay that moves with moisture. A screw pile bypasses that unstable layer entirely and founds the load on deeper, stronger material. Because the resistance the pile meets while being wound in (its installation torque) correlates directly with its final load capacity, every single pile is effectively load-tested during installation. Concrete footings can only claim this with separate, expensive testing.
How screw piles are installed
Installing screw piles runs like this on a typical residential site:
- Set-out. Pile positions are marked from the engineer's footing plan.
- Winding in. An excavator-mounted hydraulic drive head rotates each pile into the ground. A load cell on the drive attachment feeds the torque reading to a computer on the machine, so the operator watches actual load build continuously against the engineer's target, and against a maximum, because over-torquing a pile can snap it.
- Torque verification. Each pile must reach the minimum torque specified for its design load. If it gets there shallower than expected, it is extended deeper anyway to design depth; if the ground is softer than expected, extension sections are added until the torque target is met in deeper material.
- Trim and cap. Piles are cut to exact level and fitted with the specified head: bearer brackets, slab starter cages or bolt plates.
- Records and certification. Depth and torque are recorded for every pile, and this log supports the engineer's certification (Form 43/12 inspection certificate in Queensland, where required).
Most residential jobs, a deck, a granny flat, a house extension, are piled in a single day, and the piles can be built on immediately. There is no spoil to cart away and no concrete cure time, which is why builders often use screw piles to hold a program together in wet weather. Read more about how this works for your project type on our new home builds, swimming pool piling and commercial and industrial screw piling pages.
Screw piles vs concrete footings vs bored piers
This is the decision most people are actually trying to make, so here is the honest comparison. All three systems work when they are designed and installed properly. The question is which one suits your ground, your access and your budget. For the full breakdown with a decision guide for each system, see screw piles vs concrete footings vs bored piers.
| Factor | Screw piles | Concrete strip / pad footings | Bored concrete piers |
|---|---|---|---|
| Installation time | Hours. Ready to build on immediately. | Days: excavate, form, pour, then cure 3 to 7 days. | Days: drill, cage, pour, then cure before loading. |
| Site disturbance | Minimal. No excavation, no spoil removal. | High. Trenches, spoil heaps, truck and pump access. | Moderate. Drill spoil to manage, concrete access needed. |
| Wet weather | Can usually install in and after rain. | Trenches flood and collapse; pours get delayed. | Holes can collapse or fill; often needs lining. |
| Reactive clay (most of SEQ) | Excellent: founds below the movement zone. | Vulnerable to seasonal heave unless very deep. | Good, when drilled below the active zone. |
| Sloping or tight-access sites | Excellent: installed by compact machines close to boundaries. | Difficult and expensive: benching and formwork. | Possible, but rig access limits steep sites. |
| Load verification | Every pile proof-tested by torque as installed. | Relies on inspection of the excavation only. | Relies on inspection; testing costs extra. |
| Shallow rock sites | Poor: cannot wind into rock without pre-drilling. | Good: footings can bear directly on rock. | Good: piers socket into rock. |
| Very high single-point loads | May need pile groups or larger shafts. | Simple to upsize. | Excellent for heavy point loads. |
When screw piles are the wrong choice
Not every site suits screw piles, so here is the honest list. Screw piles are not the right system when:
- The ground is full of obstructions. Uncontrolled fill containing concrete rubble, old footings or large floaters can deflect or damage piles. Sometimes we can work around it; sometimes bored piers are more practical.
- There is no competent stratum within economic reach. In very deep, very soft profiles, piles may need so many extensions that an alternative system becomes more cost-effective. A soil report tells us this before anyone spends money.
- Highly aggressive soils are present and unprotected. Some acid sulfate and saline coastal soils demand specific corrosion protection. It is routinely engineered for, but it has to be designed, not ignored.
If your site has any of these conditions, we will tell you at the assessment stage and point you to the right system instead. A foundation contractor who says yes to every site is a foundation contractor to avoid.
Queensland soil types and site classification
Under AS 2870 (the Australian residential slabs and footings standard), every building site is classified by how much the ground moves with moisture changes:
- Class A / S: stable sand or rock, or slightly reactive clay. Most footing systems work here.
- Class M: moderately reactive clay, common across Brisbane, Ipswich and inland Sunshine Coast suburbs.
- Class H1 / H2: highly reactive clay that swells and shrinks significantly through wet and dry seasons.
- Class E: extremely reactive sites.
- Class P: problem sites: uncontrolled fill, soft ground, landslip zones and steep slopes. Much of the Sunshine Coast hinterland and many coastal blocks are Class P.
The more reactive or problematic the classification, the stronger the case for screw piles, because they found the structure below the moisture-active zone rather than inside it. On the coastal strip, deep sandy profiles suit screw piles well as the helices develop capacity in dense sand at depth. In hinterland towns like Woombye, Palmwoods and Maleny, where steep slopes and Class P ground are the norm, screw piers are often the only footing system that avoids massive excavation, and it is exactly the ground we work in every week from our own base. Reactive clay is more the story out through Ipswich and Brisbane, where the ground swells and shrinks with the seasons. See how this plays out for sloping and difficult site foundations.
For the full picture, coastal sand and coffee rock, reactive clay, hinterland Class P slopes and rocky ground, read our area-by-area guide to QLD soil types and ground conditions.
What screw piling costs in Queensland
Foundation contractors in Queensland almost never publish prices. Here is honest guidance, with the caveat that every figure below is indicative and your quote depends on load requirements, pile depth, access and pile count.
- Light-duty piles (decks, pergolas, stairs, small sheds): typically in the range of a few hundred dollars per pile installed, at the lower end of the scale.
- Structural piles (granny flats, extensions, new dwellings, pole homes): meaningfully more per pile, reflecting larger shafts, deeper founding and engineer-specified capacities.
- Commercial piling: priced per project, where volume brings the per-pile rate down considerably.
What actually drives your price:
- Design load: a pile holding a corner of a two-storey extension needs more steel and more depth than one holding a deck bearer.
- Founding depth: the deeper the competent stratum, the more pile sections needed.
- Pile count: mobilisation is a flat cost, so per-pile pricing improves with quantity.
- Access: tight backyard access needs smaller machines and more time. Still cheaper than excavating that same backyard for concrete.
- Engineering and reports: if you already have a soil report and footing design, quoting is fast. If not, we can arrange them and include the cost transparently.
When comparing quotes against concrete, compare the finished job: excavation, spoil removal, formwork, steel, concrete supply, pump hire, cure time and the builder's program delay all sit on the concrete side of the ledger. Screw pile quotes are one line: piles, installed and certified.
Lifespan, removal and reuse
How long do screw piles last? Properly specified galvanised steel piles are routinely designed for a 50-year-plus service life, and the design process under AS 2159 (the Australian piling standard) accounts for soil corrosivity by specifying coating systems and sacrificial steel thickness. In benign soils, actual life is typically well beyond design life.
Can screw piles be removed? Yes, they are one of very few foundation systems that can be unwound and extracted, leaving almost no trace. That matters for temporary structures, mining and event infrastructure, and any site where full reinstatement is required.
Can they be reused? Extracted piles in good condition can often be reinstalled, which is one reason screw piles are the default for relocatable buildings and temporary works, and a genuine sustainability advantage: less concrete poured, less steel wasted, no spoil to landfill.
Licensing, council approval and certification in Queensland
Three things protect you on a Queensland piling job:
- QBCC licensing. Foundation and piling work is building work, and in Queensland it must be carried out by a QBCC-licensed contractor. Core Screw Piling works in partnership with Screw Piling QLD, QBCC Licence 15036577. You can verify any licence free on the QBCC's online register.
- Engineering design. Structural screw piles are installed to a footing design prepared by a registered professional engineer (RPEQ), typically documented for your building approval (Form 15 design certificate).
- Installation certification. Torque and depth records for every pile support the engineer's inspection certification (Form 43/12) that your building certifier needs before work continues.
The screw piling itself does not usually need its own separate council approval; it is part of the building work approved for the overall structure (your deck, granny flat or dwelling). Whether that structure needs approval is a planning question, and for granny flats in particular Queensland's rules have relaxed significantly since 2022. There is more on that on our granny flat foundations page.
Screw piling FAQs
What are screw piles?
Screw piles are steel shafts fitted with one or more helical plates that are wound into the ground like a giant screw, so a building's load is carried on competent soil below the surface. They are also called screw piers, helical screw piles or helical piers. Each pile is turned down until the measured installation torque proves the load the engineer specified, then cut to height, and the structure is built directly off the pile heads.
What are screw piles used for?
Screw piles are used to found new homes, swimming pools, extensions, decks, granny flats, sheds, commercial buildings and civil structures, and to re-support existing footings that have sunk or cracked. In South East Queensland they are used most where reactive clay, loose coastal sand or fill sits over the good ground, and where access, spoil or the build program rules out concrete footings.
How many screw piles do I need?
The number comes off your engineer's footing plan, not a rule of thumb. It depends on the total load, how that load runs through the walls and beams, and how much each pile can carry in your ground, which the soil report sets. A small deck might need six to ten. A standard new house is commonly in the twenties to forties. Send us the footing plan and we will count them and quote.
Are screw piles cheaper than concrete footings?
On many sites, yes, once you count the whole concrete job: excavation, spoil removal, formwork, steel, concrete, pumping and cure-time delays. On flat, stable, easy-access sites with shallow good ground, concrete can still be the cheaper option. The comparison table above shows where each system wins, and a quote costs nothing.
How deep do screw piles go?
As deep as the torque target demands. Typical residential piles in South East Queensland found at roughly 2 to 6 metres, but the honest answer is: to the depth where the measured torque proves the specified capacity. Extensions are added until the pile gets there.
Can screw piles hold up a house?
Yes. Screw piles routinely support new dwellings, two-storey extensions, pole homes and commercial buildings. Each pile is engineered for its share of the structural load, and larger loads use bigger shafts, more helices or pile groups.
Do screw piles work in sandy coastal soil?
Generally very well: helices develop strong capacity in dense sand at depth. Loose surface sand is bypassed, exactly as reactive clay is. Aggressive saline conditions are handled through corrosion protection specified in the design, which is standard practice near the coast.
Can screw piles fix my sinking foundations?
Often, yes. Screw piers are one of the main systems used to underpin sunken or cracked footings: piles are installed beside the affected footing and connected with brackets to re-support it. It always needs a structural engineer's assessment first. See underpinning with screw piers.
How long does installation take?
Most residential jobs are piled in one day. A deck might take a morning; a granny flat is typically a day; larger or difficult-access jobs run longer. You can build on the piles the moment we finish.
Sources and standards referenced
- AS 2870: Residential slabs and footings (site classification A, S, M, H1, H2, E, P)
- AS 2159: Piling: design and installation
- Queensland Building and Construction Commission (QBCC): licence requirements and free licence register
- Queensland planning framework: secondary dwelling reforms, 2022 onward