Guide to Basement Underpinning in Toronto & Ontario

Real estate is expensive. This is especially true in large cities like Toronto. Basement underpinning solves this problem as it allows to expand the living space, without costly home additions or building anew.

In the past most homes didn’t use basements as living spaces. Basements were often used as storage, while other properties had crawlspaces (ceiling height of 44-48 inches) instead.

As cities continued to grow, more and more property owners wanted to convert their basements or crawlspaces into a livable space. A variety of basement floor lowering techniques were created – underpinning, bench footing, crawlspace transformations etc.

This allowed to convert basements and crawlspaces into habitable dwellings, without costly home additions. Some property owners could expand living space in their homes, others – divided their houses into multiple units with separate entrances, allowing to decrease mortgage payments and generate revenue.

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What is Basement Underpinning?

Basement underpinning is a process of lowering basement floor that involves building new footings underneath existing ones. As a results, foundation of the building goes deeper into the ground and you can now lower the basement floor safely, without structural concerns.

In order to understand the differences between basement floor lowering methodologies, lets first look at how foundations are built.

The sketch above shows that footings are the lowest point of the building. They are connected to the foundation that transfers the weight of the whole building to the footings underneath it. If one of the footings was to be removed, this would compromise the entire structure and can potentially lead to serious damage.

That’s why basement underpinning process involves digging underneath the existing footing and pouring new footing below it. This effectively convert the old footing into the foundation.

Basement underpinning & benching – before and after. Source OREA

Alternatives – Bench Footing vs Underpinning vs Crawlspace Transformation

There is a number of ways to lower the basement floor – basement underpinning, bench footing and crawlspace conversion. All three services add extra height to the basement.

Basement Underpinning – involves digging underneath existing footing of the building, the new footing is then poured underneath it. This extends the depth of the foundation deeper into the ground and allows to lower the floor.

Bench footing – unlike basement underpinning, benching technique does not require digging underneath the existing footing. Instead, the new footing is built besides it.

This results into creating a “bench” inside the basement, the weight of the building is transferred to the newly built “bench”. Basement floor can be lowered to the bottom of it.

This service often costs less compared to underpinning, and oftentimes it won’t require sign off from your neighbours (in case you have a shared foundation).

The main downside of bench footing is that it creates a bench inside the basement, which results in less space inside your basement. In most cases, this bench can be hidden inside the interior features – it can be used as for sitting, covered by furniture etc.

Crawlspace Conversion – is a floor lowering technique widely used for transforming crawlspaces (44-48 inch ceiling height) into basements (8-10 feet ceiling height).

As contractors remove the extra soil from the crawlspace, this will lower the floor. During the this process a new foundation will be planned & poured.



Converting a crawlspace into a finished basement

$50,000 to $150,000

Crawlspace excavation cost

$20,000 to $40,000

Plumbing and drainage installation

$4,000 to $10,000

Pouring foundation

$20,000 to $40,000


$15,000 to $40,000

Crawlspace conversion & other costs. Table source: Home Advisor

How Much Does it Cost to Lower the Basement Floor?

The average cost of basement underpinning (floor lowering) projects will cost from $80 – $350 per linear foor. An average cost of basement underpinning in Toronto in 2023 is around $50,000 to $70,000 per project. Provided that no complications arise along the way.

Basement underpinning projects can include some of the following services:

– Initial site inspection

– Drawings & permits

– Construction site preparation

– Demolition

– Foundation underpinning

– Concrete slab pouring

– Wall crack repairs

Compared to underpinning, bench footing will often cost less as it doesn’t require digging underneath the footing.

Cost of Crawlspace conversion will be similar to the basement underpinning, as it involves a large amount of digging and removing the soil.

Is Basement Underpinning Worth It?

Absolutely, according to VBM Contracting, an average cost of home addition in 2023 can range anywhere from $400,000-$800,000. While an average basement underpinning project costs around $50,000.

In other words, underpinning allows you to achieve the same result for 8x-10x less compared to home additions. Plus, basement underpinning won’t change the footprint of your property and will be easier to obtain a permit for than home additions.

Basement underpinning project in progress at 10 Constance Street, Toronto.

Permits Required for Underpinning Projects

Basement underpinning projects are complex and require professional work to examine the soil, do the drawings, pour the footing, examine the foundation and other steps.

According to the City of Toronto website, basement underpinning projects require a number of forms, approvals and sign offs by the city. See more information here.

– Professional Engineer – has to design & review the foundation “when it is constructed below the level of the footing of an adjacent building and within the angle of repose of the soil.” There are more requirements and steps that need Engineer’s sign off, so do take a look at the link above.

– Drawings – there is a number of requirements for the drawings. For example, they must be drawn on the standard size sheets, be drawn to scale, fully dimensioned, signed, dated, etc.

– Documentation – a number of documents will need to be provided as well.

– Forms – will need to be filled out. For example, the Application to Construct or Demolish, Designer Information Form, Commitment to General Reviews by Architect and Engineer, Tree Declaration form and more.

Different municipalities may have different requirements for basement underpinning projects. We’ve gather a couple of useful links below.

Make sure to talk to professional basement underpinning company to discuss the paperwork required in your area.


Article by Aquamaster Basement Waterproofing & Underpinning. Since 2009 our team has been providing top-quality services. We can help with waterproofing, underpinning, bench footing, crawlspace transformations, basement walkouts and more. Book a FREE estimate today!

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