If you’re a homeowner in the GTA, chances are your basement is underutilized. Basement underpinning offers an effective way to turn low-ceiling spaces into fully livable, legal dwellings without expanding your home’s footprint. Whether you’re planning to finish your basement, create a rental suite, or simply improve your home’s value, this in-depth guide walks you through everything you need to know about basement underpinning in Ontario.
Learn more about our basement underpinning services in Toronto to see if this renovation is right for you.
What Is Basement Underpinning?
Before you can weigh the pros and cons of underpinning, you need to understand what it actually involves. Basement underpinning is a structural process where the existing foundation is excavated and reinforced at a deeper level. This allows the basement floor to be lowered—typically by 24 to 36 inches—creating greater headroom and more usable square footage.
The technique is especially valuable in older Toronto homes, where basements were built with limited ceiling height and not intended for habitation. If your space suffers from height restrictions, consider the strategies we cover in our guide on how to increase the height of your basement.
Key benefits:
Safe, code-compliant ceiling height
Greater usable living space
Improved home resale value
Stronger, deeper foundation
Now that you know what basement underpinning is, let’s look at how it’s done—from start to finish.
Step-by-Step Process of Basement Underpinning
Basement underpinning is more than just digging—it’s a carefully engineered process. Understanding the full sequence of work will give you a clearer picture of timelines, disruptions, and required professionals.
Site Evaluation & Soil Testing – Performed by engineers to determine feasibility
Engineering Drawings – Required by most municipalities before permitting
Permit Application – Including forms like the Commitment to General Review
Excavation in Sections – To preserve structural integrity throughout
New Footing Installation – Deeper concrete footings poured under existing ones
Soil Removal – Basement lowered by up to three feet
Slab Re-pouring – New concrete basement floor installed
Waterproofing & Drainage – Optional but highly recommended for longevity
We explore project timelines and duration more deeply in our underpinning and waterproofing duration guide.
Once you know how underpinning works, the next thing every homeowner wants to know is: How much will this cost?
How Much Does Basement Underpinning Cost in Toronto
Underpinning is a serious investment, but the return in usable space and property value often justifies the cost. In Toronto and most of Ontario, expect the following price ranges:
| Project Type | Average Cost per Sq. Ft | Total Estimate (600–800 sq. ft) |
|---|---|---|
| Underpinning Only | $90–$150 | $60,000–$120,000 |
| With Crawlspace Conversion | $100–$160 | $70,000–$130,000 |
| Bench Footing Alternative | $70–$110 | $45,000–$80,000 |
The total cost can vary based on excavation depth, soil conditions, permit requirements, and whether you’re also adding waterproofing or drain upgrades. For a full breakdown, see our dedicated post on basement underpinning costs in Toronto.
Now let’s compare underpinning to its alternative.
Underpinning vs Bench Footing vs Crawlspace Conversion
Not every basement needs underpinning. Sometimes bench footing or crawlspace conversion may be more suitable depending on your home’s structure and your goals.
| Method | Floor Lowering | Space Lost | Cost | Use Case |
| Underpinning | Yes | None | $$$$ | Best for full basement conversions |
| Bench Footing | Yes | Yes | $$$ | Affordable option with some trade-offs |
| Crawlspace Conversion | Yes | None | $$$$ | Turns low-clearance crawlspaces into basements |
Learn more about bench footing or crawlspace encapsulation to compare options before you commit.
Do You Need a Permit for Basement Underpinning?
In almost all cases—yes. Basement underpinning is a structural renovation that requires city permits and engineering oversight.
You’ll need:
Structural drawings by a licensed engineer
Permit application package with required forms
Commitment to General Review (engineer oversight)
Site inspections during and after construction
Permit requirements vary by location. If you live in Vaughan, Richmond Hill, Oshawa, or Niagara, check our service area pages for local guidance.
How Long Does Underpinning Take?
A typical basement underpinning project takes 4 to 8 weeks depending on size, permit approval time, and soil conditions.
| Basement Size | Duration |
| Small (400–600 sq ft) | 3–4 weeks |
| Medium (800 sq ft) | 5–6 weeks |
| Large (1000+ sq ft) | 6–8+ weeks |
This does not include permit approval time, which can add 2–3 weeks. If you’re waterproofing at the same time, total duration may extend.
We break this down more in our guide on underpinning and waterproofing timelines.
Conclusion: Is Basement Underpinning Worth It in 2025?
If you’re living in Toronto or the GTA and want more space without a costly addition, basement underpinning is a smart move. It adds value, solves ceiling height issues, and opens the door to legal basement apartments or comfortable family spaces.
Make sure to consult experienced professionals, secure all necessary permits, and plan your budget in advance. Ready to explore what’s possible in your basement?
Start with a free estimate from Aquamaster and find out how we’ve helped homeowners across Toronto, Mississauga, Vaughan and beyond.
