What Is Basement Underpinning and When Do You Need It?
What Is Basement Underpinning?
Basement underpinning is a structural process that deepens your foundation by excavating below the existing footings and installing new, deeper support. It’s common in Calgary where basements often sit shallower than modern code requires, especially for legal suites or renovations.
When You Need Underpinning
- Legal Suite Development — Calgary requires minimum 2.1 m (6’11”) clear height; most older homes fall short
- Foundation Settlement — Cracks, uneven floors, or structural movement indicate compromised support
- Soil Issues — Poor bearing capacity, expansive clay, or high water table problems
- Renovation Depth — Adding egress windows or increasing headroom below grade
- Building Code Compliance — Alberta Building Code Section 9.8 sets minimum basement standards
Calgary Underpinning Costs (2024)
| Factor | Cost Range |
|---|---|
| Basic underpinning (per linear foot) | $250–$400 |
| Full basement (avg. 1,200 sq ft) | $15,000–$35,000+ |
| Soil remediation (if needed) | +$3,000–$8,000 |
| Structural reinforcement | +$2,000–$5,000 |
The Calgary Permit Process
The City of Calgary requires:
- Structural engineer’s report
- Building permit application
- Geotechnical assessment
- Third-party inspections during work
Permit timelines typically run 3–6 weeks. OAF Construction handles all documentation.
Next Steps
If your basement needs underpinning—whether for a legal suite, foundation repair, or code compliance—schedule a free assessment with OAF Construction. We’ll evaluate soil conditions, measure current depth, and provide a detailed quote.