Construction · Published September 29, 2026 · 8 min read · By Groupe Nuvem
Two ways to carry a building
A poured concrete foundation (footing + wall, or slab on grade) spreads loads over a wide area below the frost line, about 1.5 m deep in the Quebec City region. A helical pile is a galvanized steel tube with a helix, screwed into the ground with an excavator until it reaches a torque (a resistance) specified by the engineer; the load is transferred to the bearing soil layer, well below frost.
Side-by-side comparison
| Criterion | Concrete foundation | Helical piles |
|---|---|---|
| Finished basement | Yes | No (crawl space or on posts) |
| Time before building on it | 7 to 28 days of curing | Same day |
| Season | April to November (winter possible with heating) | Year-round |
| Sloped, rocky, wooded lot | Heavy excavation, high cost | Ideal, minimal disturbance |
| Lifespan | 75 to 100+ years | 50 to 75 years (galvanized steel) |
| Reversible / adjustable | No | Yes (adjust, add, remove) |
| Typical cost (24 × 32 ft cottage) | $25,000 – $45,000 | $8,000 – $18,000 |
When concrete wins
- Main home with a basement: the living space below grade is well worth the foundation cost.
- Heavy loads: two-storey house with masonry, RV garage, farm building with a loaded slab.
- Clay soil or deep fill: piles would have to go very deep to reach bearing soil; a wide footing may be cheaper.
- Continuous thermal envelope: an insulated basement makes air sealing and frost-protected plumbing easier.
When helical piles win
- Cottage, tiny home, addition, deck, detached garage: no basement needed, the pile is enough.
- Difficult lot: slope, exposed bedrock, lakefront with a protected shoreline strip, narrow access for the concrete truck.
- Tight schedule: screw in the morning, frame in the afternoon, even in January.
- Addition to an existing house: no vibration or excavation near the current foundation.
- Frost-susceptible soils: the helix anchored below the frost line and the smooth shaft resist heaving, where a floating slab moves.
Frost: the real question in Quebec
Frost heave is the number-one cause of moving foundations in the region. A concrete foundation must go below the frost line and be drained (French drain, membrane, granular backfill) so it is not pushed up. A properly designed helical pile is anchored by its helix below frost; the grip of frozen soil on the tube is low and the engineer accounts for it. In both cases, what fails is improvisation: slab on grade with no perimeter insulation, piles that are too short or come with no torque report. Always require the installation report (torque reached, depth, pile number): we provide it every time.
Real 2026 prices
For a 24 × 32 ft cottage in Portneuf: 12 to 16 helical piles, 3 in. (20,000 to 30,000 lb capacity each) installed with an engineer's report, between $8,000 and $18,000. The same footprint on an 8 ft concrete foundation with drain, membrane and slab: between $25,000 and $45,000, more if bedrock requires blasting or access is long. For a 1,500 sq. ft. home with a finished basement, the concrete foundation is roughly 10 to 15% of the total construction cost.
What about hybrid solutions?
They are common: house on a concrete foundation with an addition or deck on piles; garage on an insulated slab on grade with piles at the corners; main building on concrete and equipment shelter on piles. We combine both depending on load and terrain, and we do both in-house, which avoids coordinating two subcontractors.
Our recommendation
Finished basement or heavy loads: concrete. Cottage, addition, garage, difficult lot or tight schedule: helical piles with an engineer's report. When in doubt, a soil study ($800 to $2,000) settles the question and avoids tens of thousands of dollars in mistakes. See our foundations and piles service, or first read how to prepare your lot.