76 mm screw pile
Round shaft with a 300 mm helix. Driven to 6,000 N·m — 180 kN ultimate, 90 kN working at a factor of safety of 2.0. Supplied and installed to 6 m.
$420 eachfirst 6.0 metres included
Helical screw piling · installed to AS 2159
We drive to torque. The ground decides the depth.
Footings, second storeys, decks and underpinning — Bibra Lake sand to Midland clay.
- Piling since 2014
- Torque logged per pile
- $20m liability
Depth to torque · Bassendean sand
6.5m
to 10,000 N·m
6 piles114 mm shaft
$7,698installed, ex GST
7 mbilled a pile
$7,698 · 6 piles to 6.5 m
10,000 N·m target · Kt 23 · 115 kN working per pile at FoS 2.0
Your engineer's number, not ours.
inside the included 6 m
The Log · set the job
Ground, shaft, rig and load
Left of the drawing above is the ground on a fixed twelve-metre axis. Right is the torque trace: torque across, depth down. The pile goes in until the trace crosses the amber target line — that crossing is your depth, and nobody can tell you what it is before the pile is in the ground. Change the soil below and watch the same pile need a different depth. That is the whole job.
Shafttorque is the design input
Groundfrom your bore logs
Rigwhat the head can deliver
Loadyour engineer's number
600 kNtotal vertical
Sitehow we get the rig in
Underpinning is a mini-rig job in practice — check the headroom before you pick a shaft.
Torque tells us what the pile is holding on the day we screw it in; what it has to hold is your engineer's number, off your geotechnical report — we install to it and we log every pile.
The same numbers, in words
The one thing this page exists to say
You can't buy your way out of soft ground with a fatter shaft
A 168 mm shaft has to be driven to 30,000 N·m before its capacity means anything. Of the four ground profiles we work in, only the Spearwood limestone gives that inside twelve metres — and only the 13-tonne rig has a head big enough to deliver it. On Bassendean sand, on Guildford clay and on the peaty flats, the 168 never reaches its torque and the chip goes dark, with the reason printed under it. Everywhere else, the answer is more piles, not bigger ones.
Ground is free to six metres. The 76 mm reaches torque inside that on both sand profiles — 5.0 m at Bibra Lake, 3.6 m at Hamilton Hill — and those two jobs cost exactly the same. Past six metres we bill the metre, and the page shows you which metres and why.
Which means the ground is not free once you are past it, and we print the counter-example rather than hide it. The same 114 mm pile at 600 kN needs 6.5 m in Bassendean sand and 4.2 m in Spearwood. Spearwood finishes inside the included six metres and bills $7,290; Bassendean crosses into a seventh billed metre, and that metre is $68 on each of six piles — $7,698. Same pile, same rig, same day rate: $408 apart, and every dollar of it is metres of steel in the ground.
Rates
What it costs
Supplied and installed, ex GST, Perth metro. Every pile is driven to its target torque and every pile's torque is logged and handed to your engineer with the depth it reached.
114 mm screw pile
Round shaft with a 400 mm helix. Driven to 10,000 N·m — 230 kN ultimate, 115 kN working at a factor of safety of 2.0. Our standard residential pile.
$610 eachfirst 6.0 metres included
168 mm screw pile
Round shaft with a 600 mm helix. Driven to 30,000 N·m — 390 kN ultimate, 195 kN working at a factor of safety of 2.0. Limestone and a 13-tonne rig only.
$1,180 eachfirst 6.0 metres included
Depth beyond 6 metres
Piles come in extensions and we bill the metre you use, rounded up to the whole metre the pile actually finished on. The ground decides this, not us.
+$46 / +$68 / +$124per metre · 76 / 114 / 168 mm
Test pile & torque log report
One test pile before the run, then a logged torque and finished depth for every pile on the job, issued as one report to your engineer. On every job — it is how the design gets closed out.
$980 per jobmandatory, never optional
Mobilisation
Float in, set up, float out. The mini rig fits a 900 mm side gate; the 13-tonne needs an open block and a truck turn.
$1,850 – $4,900minimum job $4,500
Torque tells us what the pile is holding on the day we screw it in; what it has to hold is your engineer's number, off your geotechnical report — we install to it and we log every pile. Every working load above is the torque correlation divided by a factor of safety of 2.0. It is a design input, not a test result.
- Screw piling in Perth since 2014 — about 240 jobs a year
- Installed to AS 2159 piling design and installation
- Torque logged per pile and handed to your engineer
- Registered building contractor BC00000 (placeholder)
- $20m public liability and contract works cover
- ABN 00 000 000 402 (placeholder)
What builders say
Three jobs
Written as demonstration copy for this build — Groundset Screw Piling is a fictional business and these are not real customers.
"Eighteen piles under a suspended slab and the torque log was in my engineer's inbox the same afternoon, pile by pile, with the depth each one finished on. He signed it off without a site visit. That has never happened to me before."
"I asked for the big shaft because the second storey scared me. They told me the 168 needs 30,000 newton-metres and my clay gives about 16,000 at twelve metres, so it would never get there — and then showed me the trace. Nine 114s instead. Cheaper and it actually works."
"Two mobs had already looked at the peat and said no. Groundset drove past it into the sand underneath, eight point eight metres, and the studio has not moved a millimetre in two winters. They were also the only ones who put the depth in writing before they started."
Where we work
Southern and eastern metro
On this job the geology is the map. The Spearwood limestone ridge runs down the coast, the Bassendean sand fills the middle, the Guildford clay follows the river, and the peaty flats sit in the low ground south-east. Tell us the suburb and we can usually tell you the profile before we see your bore logs — then the bore logs decide.
- Spearwood over limestone
- Bassendean sand
- Guildford clay
- Peaty flats
- Suburbs we work in
Get a pile count
Send us the job
If you have an engineer's footing plan and a geotechnical report, attach them when we reply and we will price the run off your numbers rather than ours. If you don't have them yet, tell us the suburb and what you're building and we'll tell you what you need.
We answer the phone 6:30 to 5:00, Monday to Saturday. Enquiries that come in before 3pm get a call back the same day; anything later, first thing the next morning.
We do not design footings and we are not geotechnical engineers. We install to your engineer's number and we log every pile.
Got it — we'd call you back
On the real site this lands in the office inbox and on the yard phone. Before 3pm we ring back the same day; after that, first thing next morning. Here is what you'd have sent us:
Torque tells us what the pile is holding on the day we screw it in; what it has to hold is your engineer's number, off your geotechnical report — we install to it and we log every pile.
Questions we get
Six answers
What is a screw pile, and why is torque the measurement?
A screw pile is a steel shaft with one or more helical plates welded near the tip. A hydraulic torque head on an excavator winds it into the ground; the plates pull it down and the soil resists. The harder the soil resists, the more torque the head has to apply — and that resistance is the same resistance the pile will use to hold your building up.
The relationship between installation torque and capacity was published by Hoyt and Clemence and is carried in ICC-ES AC358 as a torque factor, Kt: ultimate capacity is roughly Kt multiplied by the installation torque. Our Kt values are 30 per metre on the 76 mm, 23 on the 114 mm and 13 on the 168 mm — the fatter the shaft, the lower the factor, which is exactly why the big shaft needs so much more torque to say anything.
Torque tells us what the pile is holding on the day we screw it in; what it has to hold is your engineer's number, off your geotechnical report — we install to it and we log every pile.
What does my engineer have to give me before you can start?
A footing plan with the pile positions and the vertical load per pile in kilonewtons, and a geotechnical report with bore logs to the depth you expect to go. That is it. The load tells us the pile count; the bore logs tell us which profile to expect and roughly where the torque should come from.
If there is uplift, lateral load or a raft above, your engineer needs to say so — the numbers on this page are vertical compression only, at a factor of safety of 2.0 on the torque correlation.
Why is the depth the ground's decision and not yours?
Because we drive to a torque, not to a depth. Bassendean sand gives about 90 N·m per hundred millimetres for the first four metres and then stiffens up sharply; Guildford clay gives about 50 for the first six; the peaty flats give about 18 until you get through the peat at five metres. The pile goes in until the head reads the target. On a 114 mm that is 10,000 N·m, and it arrives at 6.5 m in Bassendean sand, 4.2 m in Spearwood, 8.8 m in peat and 9.2 m in Guildford clay.
Anyone who quotes you a depth before the first pile is in the ground is quoting you a guess. We quote you a torque and a rate per metre past six, and the Log above shows you the arithmetic.
Why isn't a bigger shaft the answer to soft ground?
Because capacity comes off torque, and a bigger shaft needs more torque to earn its capacity. The 168 mm has a torque factor of 13, so to reach its 390 kN ultimate it has to be driven to 30,000 N·m. Bassendean sand tops out around 24,400 N·m at twelve metres. Guildford clay reaches about 16,200. The peaty flats reach about 17,700. None of them get there.
Only the Spearwood limestone gives 30,000 N·m — at 7.3 m — and only the 13-tonne rig has a head that can deliver it. Everywhere else the honest answer is more piles at 114 mm, which is usually cheaper anyway.
What happens if you don't reach torque at twelve metres?
We stop, we tell you, and it goes back to your engineer. We do not keep adding extensions past twelve metres hoping the number turns up, and we do not sign off a pile that did not reach its target. The torque log for that pile shows exactly where it stopped and what it read, which is what your engineer needs in order to redesign — usually more piles at a lower working load, occasionally a different footing system altogether.
You pay for the metres we drove and the mobilisation. You do not pay for a pile we could not deliver.
What do you not do?
We do not design footings and we are not geotechnical engineers. We do not do bored piers, driven timber or CFA. We do not certify a capacity from this page or any other page — the figures on the Log are the torque correlation at a factor of safety of 2.0, which is a design input, not a test result. What the pile has to hold is your engineer's number.
We also do not work north of the river past Bassendean or east past Midland. There are good screw piling mobs up there and we will give you their numbers.