Guide to Basement Underpinning in Toronto & Ontario

Basements in Toronto and across Ontario often serve as valuable living space, but many older homes were built with shallow foundations and low ceilings. As families grow and housing costs rise, homeowners increasingly look for ways to maximize existing space. One of the most effective methods is basement underpinning—a process that not only lowers the basement floor but also strengthens the entire foundation.

At Leaquida Waterproofing, we specialise in basement renovations that improve safety, comfort, and long-term property value. This guide explains what basement underpinning is, how it works, what’s included in the process, and what homeowners in Ontario need to know before starting.

What Is Basement Underpinning?

In simple terms, basement underpinning is the process of extending or deepening a home’s foundation to create more usable basement space. Typically, this is done by carefully excavating below the existing footing and pouring new concrete to support the structure at a lower depth.

For homeowners, the benefits are significant:

• Increased ceiling height – A cramped 6-foot basement can be transformed into a comfortable 8- or 9-foot living space.
• Stronger foundation – Underpinning stabilises older homes with weakened or shallow footings.
• Higher property value – A finished, full-height basement adds square footage and improves resale appeal.
• Opportunity for upgrades – While lowering the floor, contractors can also modernise plumbing, insulation, and flooring.

So when people ask, “What is basement underpinning?”—it’s both a structural reinforcement and a transformation project that turns underused space into a functional part of the home.

What Is Included in Basement Underpinning?

Underpinning is not a single step but rather a carefully phased process. Safety is the top priority, since the home’s weight must always remain supported during excavation.

Here’s what’s typically included in a professional underpinning basement foundation project:

1. Initial Assessment and Engineering Plans

Every project begins with an on-site inspection by structural engineers. They evaluate the soil, foundation condition, and load-bearing points. Detailed plans are then created to guide excavation and ensure stability.

2. Excavation in Stages

The basement floor is removed, and soil beneath the foundation is excavated in small, alternating sections. This staged approach prevents destabilising the entire structure at once.

3. Concrete Footing Extensions

Once a section is dug out, new concrete is poured beneath the existing footing to extend it deeper. After curing, the next section is excavated and underpinned, gradually completing the entire perimeter.

4. Basement Lowering

After underpinning, contractors excavate additional soil to lower the entire basement floor. This is where the term basement lowering and underpinning comes from. The result is significantly increased headroom.

5. Installation of Drains and Flooring

With the new depth established, subfloor drainage systems (such as weeping tile) and sump pumps may be installed. A reinforced concrete floor is then poured, forming a solid, level surface for finishing.

6. Finishing Upgrades

Many homeowners use underpinning as an opportunity to add insulation, radiant floor heating, or upgraded plumbing. Since the basement is already open, these upgrades are cost-efficient at this stage.

This detailed process ensures not only more space but also a foundation that meets modern building standards.

Why Homeowners in Toronto Choose Basement Underpinning

In cities like Toronto, where land is limited and home additions are expensive, underpinning provides a cost-effective alternative. Instead of building outward or upward, homeowners can create more living space without altering the footprint of their lot.

Older Toronto homes, especially those built before the 1960s, often have shallow foundations and low-ceiling basements. These spaces may work for storage but aren’t comfortable for living. Basement underpinning transforms them into bright, livable areas—perfect for family rooms, rental units, or home offices.

Additionally, underpinning strengthens the home against soil movement and settlement, a major benefit in Ontario’s varied climate.

Basement Underpinning Cost in Toronto & Ontario

One of the most common questions homeowners ask is: “How much does underpinning cost?” The answer depends on several key factors, but understanding the ranges helps set realistic expectations.

Average Underpinning Costs

• Underpinning basement cost per foot: typically $350 – $500 per linear foot in Toronto and most Ontario cities.
• Full project cost: for an average home, this ranges from $35,000 to $70,000+, depending on size, depth, and complexity.

Factors That Influence Cost

1. Depth of lowering – Reducing the basement by one or two feet is less expensive than going deeper to create high ceilings.
2. Soil conditions – Clay-heavy or rocky soils require more excavation and reinforcement.
3. Accessibility – Tight urban lots may need manual excavation, increasing labour costs.
4. Additional upgrades – Installing new drains, radiant floors, or insulation adds to the budget.
5. Permits and engineering – Professional plans and city permits are mandatory, and these costs must be factored in.

While the cost is significant, homeowners should view underpinning as both a structural reinforcement and an investment that adds lasting value to their property.

Alternatives: Bench Footing vs Underpinning vs Crawlspace Transformation

Not every home requires full underpinning. Depending on budget, foundation type, and intended use of the basement, there are alternatives.

Bench Footing

Instead of digging below the foundation, a new bench of concrete is poured inside the basement along the perimeter. This allows the floor to be lowered without undermining the existing footing.

• Advantages: Lower cost, less structural risk.
• Disadvantages: Reduces floor area because the bench creates a ledge around the room.

Basement Underpinning

The most complete solution, underpinning basement foundations creates maximum ceiling height and reinforces the structure.

• Advantages: Adds the most usable space, strengthens the foundation.
• Disadvantages: Higher cost, longer project timeline.

Crawlspace Transformation

For homes with crawlspaces, underpinning can be used to convert the space into a full-height basement.

• Advantages: Creates entirely new living space.
• Disadvantages: Complex, often requires extensive excavation.

Homeowners should discuss these options with experienced contractors to determine which method balances cost, space, and structural integrity.

Permits Required for Underpinning Projects in Ontario

Because underpinning directly affects a home’s structural foundation, permits are mandatory. In Toronto and most Ontario municipalities, you cannot begin underpinning without approval from the building department.

Key requirements:

• Engineering plans – A licensed structural engineer must prepare detailed drawings.
• Permit application – Submitted to the city, including fees and project specifications.
• Inspection stages – City inspectors visit during excavation, concrete pouring, and completion to ensure compliance.

Failing to obtain permits can result in stop-work orders, fines, and potential safety risks. At Leaquida Waterproofing, we handle the permitting process on behalf of clients to ensure smooth, compliant projects.

Why Choose Leaquida Waterproofing for Basement Underpinning

Choosing the right contractor is as important as choosing the right method. At Leaquida Waterproofing, we bring decades of experience in basement lowering and underpinning across Toronto and the GTA.

Here’s why homeowners trust us:

• Expert engineering partners – We collaborate with licensed structural engineers to design safe, effective plans.
• Transparent estimates – We clearly outline underpinning basement cost, so there are no surprises.
• Local expertise – Our team understands Toronto’s soil conditions, bylaw requirements, and construction challenges.
• Long-term value – We don’t just lower basements; we build strong, dry, and comfortable living spaces that last.

Conclusion

Basement underpinning is more than a renovation—it’s a structural upgrade that transforms underused basements into valuable living space. By extending the foundation deeper, underpinning increases ceiling height, reinforces stability, and boosts property value.

While the underpinning cost per foot may seem high, the long-term benefits outweigh the investment. Alternatives like bench footing may work in some cases, but underpinning remains the gold standard for creating full-height, livable basements in Toronto and Ontario.

Before starting, homeowners must secure permits and work with qualified professionals. With expert planning and experienced contractors like Leaquida Waterproofing, you can achieve a stronger foundation and a basement that truly enhances your home.