How much for a fresh sub-base on my Ottawa driveway?

A fresh sub-base for an Ottawa driveway typically costs $8 to $15 per square foot for excavation, materials, and compaction. For an average 500 square foot driveway, expect $4,000 to $7,500 depending on excavation depth, soil conditions, and access.

The cost breakdown includes several critical components specific to Ottawa's extreme climate. Excavation and disposal runs $3 to $6 per square foot depending on depth and existing material removal. Ottawa driveways require excavation to at least 450mm (18 inches) total depth to accommodate proper sub-base below our 1.2 to 1.5 metre frost line. If you're dealing with Ottawa's prevalent clay soils — common in Barrhaven, Orleans, Gloucester, and Riverside South — you may need to excavate deeper and add geotextile fabric at $0.50 to $1.50 per square foot to prevent clay migration into your granular base.

Granular materials represent the largest cost component. You'll need a minimum 300mm of compacted Granular B sub-base ($20 to $30 per tonne delivered) plus 150mm of Granular A base course ($22 to $35 per tonne). A typical 500 square foot driveway requires 15 to 20 tonnes of Granular B and 8 to 12 tonnes of Granular A. Compaction is critical — the granular base must be placed and compacted in 150mm lifts using a plate compactor or vibratory roller. Proper compaction prevents the settling and heaving that destroys Ottawa driveways within 2 to 3 freeze-thaw seasons.

Additional costs include equipment access — if your driveway location requires hand excavation or small equipment due to tight access, costs increase 30 to 50 percent. Disposal fees for old asphalt or concrete add $15 to $25 per tonne. If your existing driveway has contaminated soil or requires environmental testing, factor additional costs.

The investment in proper sub-base preparation is the foundation of driveway longevity in Ottawa's brutal climate. A sub-base that extends below the frost line and is properly compacted will support your driveway surface for 20 to 25 years. Cutting corners on sub-base depth or compaction to save $1,000 to $2,000 upfront typically results in complete driveway failure within 5 years, requiring expensive tear-out and replacement.

This is definitely professional contractor work — proper excavation requires heavy equipment, precise depth control, and expert compaction technique. The sub-base is invisible once your surface is installed, but it determines whether your driveway survives Ottawa winters or becomes a cracked, heaving mess.

Need help finding a qualified excavation and paving contractor? Ottawa Driveways can match you with local professionals who understand Ottawa's soil conditions and frost depth requirements.