Your Deck Shifted Again Over the Winter. The Problem Is Below the Frost Line
Every spring somebody discovers that the gate on their deck won't latch anymore. There's a new gap where the stairs meet the landing, one corner sits noticeably higher than it did in October, and by August most of it has quietly settled back. Nothing is broken, exactly. It just moves.
That seasonal rise and fall is one of the most common ways a residential footing underperforms in this country, and it usually has nothing to do with workmanship. It's a question of depth and anchorage.
What’s Actually Lifting Your Footings
Frost heave isn't ice shoving up from underneath. In frost-susceptible soils — the silts and clays that a great deal of southern Ontario is built on — freezing pulls water toward the freezing front and grows ice lenses that expand the soil upward, often by a surprising amount.
There's a second mechanism that catches builders out more often. Soil can freeze directly onto the side of a concrete pier or a steel shaft and drag the whole element up with it, even when the bottom of that footing sits safely below the frost line. Researchers at the National Research Council documented the problem decades ago in Adfreezing and Frost Heaving of Foundations, and it's still why unheated structures — decks, porches, detached garages, carports — wander while the heated house beside them stays put.
Design frost depth is set municipally and varies widely across the country, so there's no single number worth quoting. The principle holds everywhere, though: get your bearing well below the frost zone, and give the element enough resistance in uplift that the freezing soil gripping its sides can't win the argument.
Where a Screw Pile Beats a Sonotube
A helical pile is a steel shaft with one or more helix plates welded to it, turned into the ground with a hydraulic torque motor until the helices reach competent soil. The load transfers through those plates in bearing, not through a slab of concrete sitting on grade.
The cases where that matters are fairly specific. Sites with deep fill or soft organic layers, where you'd otherwise be digging a long way to find anything worth bearing on. Additions and underpinning work beside an existing house, where you can't safely excavate next to a live foundation. Tight urban lots with no room for a machine, which is where low-clearance equipment earns its keep. Waterfront and high-water-table ground. And winter, when concrete work becomes a heating and hoarding exercise.
For a straightforward deck on decent soil with easy access, poured footings are still perfectly good engineering. Nobody should pretend otherwise.
The Honest Comparison
Concrete wins on material cost and on familiarity. Every framer on your crew has poured a pier. Helical piles win on schedule, on site disruption, and on something less obvious: verification.
With a poured footing, you design for an assumed soil bearing capacity, dig, look at the hole, and trust it. With a helical pile, the installation itself is the test. Installation torque correlates to ultimate capacity through an empirically established relationship, so the machine is measuring the soil while it works. If the torque comes up short at the design depth, you add extension and keep going until it doesn't.
That's a genuinely different quality-control model, and it's the main reason helical piles have moved from oil-patch and utility work into mainstream residential construction.
Torque Reports Are the Deliverable
If you take one thing away from this, make it that. The pile is not the product; the documented capacity is.
A properly run installation produces an engineered design matched to the soil and loading, torque readings recorded pile by pile, and a stamped report you can hand to a building inspector. Anyone quoting a flat per-pile price with no mention of design loads, soil review or torque monitoring is selling you steel in the ground, not a foundation. Reputable installers such as the helical pile team at GAMCON treat the engineering paperwork and the load testing as part of the job rather than an upsell, which is the standard worth holding any contractor to.
Corrosion: The Question People Forget to Ask
Steel in soil corrodes. How fast depends on resistivity, pH, moisture, chloride content and whether there's stray current nearby — a pile beside a road that gets salted every winter lives a harder life than one in a back garden.
Hot-dip galvanizing is the usual answer, and shaft wall thickness provides a sacrificial allowance beyond that. Service life projections in the 75 to 100 year range are commonly cited for galvanized piles in ordinary soils, which is a reasonable expectation rather than a guarantee. What you want to avoid is bare black steel in aggressive ground with no corrosion assessment at all, and welded connections that were never touched up after fabrication.
What to Settle Before Anyone Starts
Ask what the design load per pile actually is, and how it was arrived at. Ask whether the design is stamped, and by whom. Ask what happens if the torque target isn't met at depth — the answer should be "we install extensions," not "we stop." Ask how the brackets attach to your structure, because a beautifully installed pile with a poorly detailed connection is still a failure point.
Then ask about locates and access. Helical piles need a machine with room to swing, and the equipment that fits through a 900 mm gate is not the equipment that installs a 75,000 pound commercial pile.
None of this is exotic. It's the same diligence you'd apply to any structural element you're going to bury and never see again. The difference with a screw pile is that, done properly, you get a number on paper telling you exactly what the ground gave back — and that's worth more than a deck that only moves in the spring.
