What Exactly Is a Screw Pile? The Complete Technical Guide

Screw piles (also called helical piles) have revolutionized modern construction, yet many homeowners don't understand what makes them unique. At Down Force Piling, we've installed thousands of these engineered foundations across Calgary. This guide breaks down exactly what screw piles are, how they're made, and why they outperform traditional foundations.

What Exactly Is a Screw Pile?

The Anatomy of a Screw Pile

1. Central Steel Shaft

• Material: High-strength carbon steel (ASTM A252 Grade 3)

• Diameter: Typically 2⅞" to 5-1/2"

• Wall Thickness: 0.203" to 0.375"

• Function: Transfers structural loads to soil

2. Helical Bearing Plates

• Shape: Spiral (like a screw thread)

• Diameter: 8" to 20" (soil-dependent)

• Quantity: 1-4 plates per pile

• Purpose: Provides bearing surface in stable soil

How Screw Piles Actually Work

Load Transfer Mechanism

1. Installation: Rotated into ground until reaching required torque

2. Load Path:

   • Structure → Pile Cap → Shaft → Helix Plates → Stable Soil

     
     

Key Engineering Properties

Property	Specification
Tension Capacity	Up to 200 kips
Compression Capacity	Up to 100 kips
Lateral Resistance	20% of vertical capacity
Deflection Limit	L/100 at design load

Manufacturing Process

1. Material Selection

• Domestic steel only

• Mill test reports verified

• Traceability maintained

2. Precision Fabrication

• CNC-cut helix plates

• Robotic welding (AWS D1.1)

• Dimensional tolerance ±1/8"

3. Quality Control

• 100% visual inspection

• Random destructive testing

Why Screw Piles Outperform Alternatives

Advantages Over Concrete Piers

✔ No curing time - build immediately

✔ Adjustable after installation

✔ Verifiable load capacity

✔ Works in all soil conditions

Advantages Over Driven Piles

✔ Minimal vibration

✔ No soil displacement

✔ Precise depth control