Foundation Piles: Types, Capacity, Selection
Driven, bored, CFA and screw piles compared. What each method does, when it works, and what it costs.
Types of foundation piles
Foundation piles transfer building loads to soil layers deeper than the surface can carry. Four main types: driven, bored, CFA, and screw piles. Selection depends on soil, schedule, and budget.
Driven piles
Steel or concrete sections hammered into the ground by impact or vibratory force. Good in dense soils. Noisy, vibration-producing, needs heavy rigs.
Bored / drilled piles
Hole drilled, reinforcement cage inserted, concrete poured in place. Suitable for very heavy loads. Needs concrete curing, spoil removal, large equipment.
CFA piles (continuous flight auger)
Auger drills to depth, concrete pumped through the hollow stem as the auger withdraws. Good capacity. Needs concrete, heavy rigs, and curing time before load-bearing.
Screw piles (helical piles)
Steel shaft with helical bearing plates, rotated into the ground by an excavator-mounted drive head or a handheld drill. No concrete, no excavation, no curing. Carries load immediately. Fully removable and recyclable.
Where screw piles outperform driven, bored, and CFA
Six measurable differences when comparing screw piles to concrete-based piling methods.
No excavation
Piles rotate into the ground. No digging, no spoil, no backfill. Site stays clean.
No concrete cure
Steel carries load immediately. No 7 to 28 day wait for concrete to reach strength.
Works in difficult soils
Clay, peat, sand, fill. The helix plate anchors into the bearing stratum at depth. Torque verifies capacity at each pile.
Year-round installation
No weather window. Installs in summer heat and winter frost.
Fewer work phases
No frost insulation, no drainage, no formwork, no curing. Fewer trades on site.
about 80% less CO₂ than concrete
No concrete pour eliminates the largest carbon source in conventional foundations. 100 % steel, removable, recyclable.
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Foundation pile FAQ
Foundation piles are structural elements installed deep into the ground to transfer building loads to stronger soil layers below the surface. They are used when the top layer of soil is too weak or compressible to support a structure directly.
The four main types are driven piles, bored (drilled) piles, CFA piles, and screw piles (helical piles). Screw piles are the fastest to install and the only type that requires no concrete, no excavation, and no curing time.
Driven piles are hammered into the ground using impact or vibratory force. They work well in dense soils but produce significant noise and vibration.
Bored (drilled) piles are created by drilling a hole, inserting a reinforcement cage, and pouring concrete. Used for very heavy loads but require large equipment, spoil removal, and curing time.
CFA piles (Continuous Flight Auger) use an auger that drills to depth while concrete is pumped through the hollow stem as it withdraws. Good capacity but dependent on concrete.
Screw piles (helical piles) are steel piles with helical bearing plates, screwed into the ground with an excavator or hand drill. No concrete, no excavation, immediate load-bearing, fully removable and recyclable.
Pile foundation cost depends on pile type, soil conditions, required depth, and project scale. Concrete-based options (driven, bored, CFA) include excavation, formwork, reinforcement, concrete supply, frost insulation, drainage, and curing.
Screw piles eliminate the concrete-related cost lines (formwork, frost insulation, drainage, curing). The remaining cost drivers are pile size and length, quantity, site access, and working space. See screw pile cost for a breakdown.
Pile foundations are needed when the surface soil cannot safely support the structure. Common situations include:
• Soft or compressible ground (clay, peat, organic soil, loose sand)
• High water table or flood-prone areas
• Heavy structural loads that exceed shallow foundation capacity
• Structures subject to uplift or lateral forces (solar panels, masts, noise barriers)
• Sloped or uneven terrain
• Projects where speed is critical and concrete curing is not acceptable
Depends on the pile type. Concrete-based piles (bored, CFA) need controlled conditions for curing and cannot be poured below freezing. Driven piles install in winter but need heavy mobilisation.
Screw piles install year-round. No concrete, no curing window. The drive head pushes the helix below frost depth in a single operation, and load-bearing begins immediately.
Installation method: Screw piles rotate into the ground using torque. Driven piles are hammered in by impact or vibratory force.
Noise and vibration: Screw piles produce no significant ground vibration. Safe to install next to existing structures. Driven piles produce vibration that can affect nearby buildings.
Load direction: Screw piles resist both compression and tension (uplift) loads through the helical bearing plates. Driven piles resist compression but have limited uplift resistance.
Capacity verification: Each screw pile is torque-verified during installation (QT = KT × T). Driven piles are verified by set criteria or PDA testing.
Removability: Screw piles unscrew. Driven piles are permanent.