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Helical Pile Basics
What Are Helical Piles?
How Screw Pile Foundations Work
A helical pile is a steel shaft with one or more helix plates welded near the tip. Hydraulic equipment turns it into the ground like a giant screw until it reaches soil dense enough to carry the design load, below the frost line. The pile holds weight the moment it is in, so there is no excavation, no spoil pile and no concrete cure time. Helical piles are also called screw piles, helical piers or screw pile footings.
How a helical pile actually goes in
The install looks simple from the driveway. A machine with a hydraulic drive head grabs the pile, lines it up on the mark, and turns. The helix plates pull the shaft down the way a wood screw pulls into a stud. Extensions get bolted on as the pile goes deeper.
What matters is what the machine reports back. The drive head measures how hard it has to work to keep turning, and that installation torque tracks the strength of the soil the helix is cutting through. When the torque climbs to the number the project engineer specified, the pile is in competent ground and the crew stops. Depth is an outcome, not a target. Two piles ten feet apart on the same lot can finish at different depths and both be right.
Once the pile is at capacity, a bracket or cap goes on top and the structure bolts to it. A framing crew can start the same day.
The parts of a screw pile
| Part | What it does |
|---|---|
| Shaft | The central steel tube or square bar that carries load down to the helix. Round shafts handle lateral load and bending better; square shafts drive well through hard ground. |
| Helix plate | The steel disc welded near the tip. It cuts into the soil, pulls the pile down and does the actual bearing. More plates or bigger plates mean more capacity. |
| Extensions | Bolted sections added as the pile goes deeper, so the pile can reach whatever depth the soil demands. |
| Cap or bracket | The connection at the top. A new-build cap takes a beam or post; an underpinning bracket clamps to an existing footing. |
| Coating | Hot-dip galvanizing, which is what keeps a steel foundation from rusting in wet Ontario ground. |
How much weight can one hold?
There is no single answer, and anyone who gives you one without seeing the site is guessing. Capacity comes from three things: the size of the shaft, the size and number of helix plates, and the soil the plates end up in. A small deck pile and a pile under a commercial column are the same idea at very different scales.
The useful part is that capacity gets confirmed on every single pile. Installation torque is correlated to capacity using the method set out in ICC-ES AC358, the acceptance criteria for helical pile systems, and the readings get recorded. Your engineer sets the required number before the crew arrives, and the field report shows whether each pile hit it. Compare that with a poured footing, where nobody measures anything after the truck leaves.
Full material and installation specs are on our helical piles page.
Where helical piles make the most sense
They are not the answer to everything, but in Ontario they solve a lot of expensive problems:
- Frost-prone ground. The pile bears below the frost line, so seasonal heave has nothing to lift.
- Soft, wet or filled soil. The helix keeps going until it finds ground that can carry the load, instead of sitting on whatever happens to be at footing depth.
- Tight access. Compact equipment gets into back yards and between houses without wrecking the lawn or a neighbour’s driveway.
- Winter builds. Nothing has to cure, so cold weather does not stop the schedule.
- Existing buildings. Piles can be installed beside a settling foundation and brackets transfer the load onto them, which is how helical underpinning works.
- Water and shoreline. Docks, boathouses and boardwalks sit on piles because there is no practical way to pour a footing there.
A full concrete basement still makes sense on plenty of builds. If you want the side-by-side, read helical piles vs concrete footings.
What moves the price
We quote per project rather than per pile, because the pile count is only part of it. The things that actually change a number are:
- How many piles the design needs, which comes from the loads, not the square footage
- How deep they have to go before the torque says stop, which is a soil question
- Shaft and helix size, since a commercial column needs more steel than a deck post
- Access, because a machine that can drive into the yard costs less to run than one that has to be craned or hand-carried
- Whether the job needs engineered drawings, a soil report or a permit
If you send us the loads and a site photo we can usually tell you where a project lands. Ask for a quote.
Helical pile questions
Are helical piles and screw piles the same thing?
Yes. Helical pile, screw pile, helical pier and screw pile footing all describe the same product: a steel shaft with helix plates that gets turned into the ground. Engineers and code documents tend to say helical pile. Builders and homeowners usually say screw pile.
How deep do helical piles go?
Deep enough to pass the frost line and reach soil that carries the design load. Across much of Ontario that lands somewhere between about 10 feet and more than 30 feet. The installation torque decides the final depth on the day, not a number on a drawing.
How long does an install take?
Most residential jobs are done in a day. A deck or shed can be a few hours. The pile carries load immediately, so framing can start as soon as the crew packs up.
Do helical piles need a permit?
The foundation follows the structure. If the deck, addition or building needs a permit, the pile foundation is part of that permit, and the municipality will usually want engineered drawings and the installation torque records. We can supply the field report.
Can helical piles be removed?
Yes. They unscrew. That is why they get used for temporary structures, site trailers and staging, and it is one of the reasons they are considered a low-impact foundation.
Do they rust?
The steel is hot-dip galvanized, which is the standard corrosion protection for buried steel. Coating thickness and soil chemistry decide service life, so aggressive soils get looked at case by case.
