Underpinning in Toronto and GTA: What You Need to Know

Underpinning in Toronto and GTA: What You Need to Know


In Toronto and the GTA, underpinning presents a cost-effective way to enhance basement spaces without the extensive permits and disruptions of major extensions. VMB Group simplifies the process, guiding homeowners through the specific building code requirements for successful underpinning projects.

What is Underpinning?

Underpinning is the process of reinforcing an existing foundation, either by extending it deeper into the soil or by strengthening the current footings. This method is often employed to increase basement depth, improve structural stability, or add sub-grade entrances to homes.

Determining the Angle of Repose

A critical factor in underpinning is determining the angle of repose, which is the steepest angle at which a soil slope remains stable. Since this angle varies with different soil conditions, it’s pivotal for the design drawings preparation. Disturbing the soil within this angle without proper precautions can lead to soil failure and necessitate extensive repairs.

When is an Engineer Required?


Underpinning in Toronto mandates involvement from a professional engineer, especially when construction occurs below the level of the footings of an adjacent building or within the soil’s angle of repose.

The engineer is required to seal your designs and sign the Commitment to General Review form, which is a part of the permit application. This ensures the underpinning work upholds safety standards, guaranteeing the well-being of your home and the surrounding neighborhood.

General Information for Underpinning

Every underpinning project in Toronto needs to adhere to a set of documentation requirements to ensure compliance with local construction regulations. Here’s a brief overview of what you’ll need:

Comprehensive Drawings

  • Your documentation must include standardized, accurately scaled, and fully detailed drawings of the underpinning work.
  • These drawings should encompass all architectural and structural aspects of the project, from foundation depth to material specifications.

Designer Credentials

  • Projects led by qualified designers must include their identification, showcasing registration and qualifications to attest to the legitimacy and accuracy of the plans.

Digital Submission

  • All drawings, reports, and required forms should be prepared in PDF format for clarity and ease of review.
  • You can submit these documents through digital media like DVD or USB drives, or via email, ensuring an efficient and environmentally friendly process.

What Documentation Is Required For Underpinning?


Completing and submitting a set of documents to the city is a mandatory step for finalizing your basement underpinning project. The required documentation encompasses:

Site Plan: A detailed site plan or survey is needed, showcasing property boundaries, the area of the lot, and any rights-of-way or easements. It should outline both current and planned structures, their dimensions, and setback distances from property lines and neighboring buildings.

Basement/Foundation Plans: Submission must include plans of the existing and planned structure, detailing foundation and exterior walls. It should highlight areas of underpinning, support columns, and overhead structural frames, alongside the underpinning phases, sequentially numbered to display the work order and the linear extent of underpinning intended. Documents should also portray the proximity to neighboring buildings’ foundations and the depth of their footings.

Floor Plans: Required are comprehensively dimensioned floor plans for each level, depicting current and envisioned space utilizations, including smoke detectors, carbon monoxide detectors, and plumbing installations, along with interior wall structures and foundational details. 

Sections: Inclusive in the submission should be cross-sectional diagrams illustrating the construction and material specifics of floors, walls, and roofs. These should detail foundation and wall specs, the external ground level relative to the basement floor, overall heights (from floor to floor and floor to ceiling), and stairways, landings, guardrails, and handrails, not forgetting the projected depth of underpinning.

This data is crucial for the city to verify that the underpinning work complies with municipal regulations.

Construction Details and Notes: Also essential are detailed construction notes and blueprints, listing materials for walls, floors, and roofs, alongside specifics like guardrail connection details. These comprehensive notes ensure clarity on the materials used and structural integrity throughout the project.

The city requires these comprehensive documents to ensure the underpinning process meets all local construction standards and regulations.


Cost Estimates for Underpinning Projects


Determining the cost of an underpinning project in Toronto involves a number of factors, including the scope of the project, soil conditions, property size, and any additional renovations or structural changes required. Here’s a general estimate to give you an idea:

  • Basic Underpinning: For straightforward underpinning projects without significant obstacles or additions, costs can range from $10,000 to $25,000.
  • Moderate Complexity: Projects of moderate complexity that may involve deeper excavation, mild structural adjustments, or moderate soil instability typically range from $25,000 to $40,000.
  • High Complexity: For extensive underpinning involving significant structural modifications, challenging soil conditions, or additional basement lowering, costs can exceed $40,000, sometimes reaching up to $100,000 or more for large properties or those in particularly difficult conditions.

Remember, these are rough estimates. The actual costs can vary based on specific project requirements, unforeseen challenges, and the prevailing market rates for labor and materials. It’s recommended to consult with a professional for a detailed quote tailored to your specific project needs.

The Underpinning Process


Underpinning is a specialized construction procedure aimed at strengthening the foundation of an existing structure. Here’s a concise breakdown of the typical steps involved in the underpinning process:

  1. Assessment and Planning: An initial evaluation by structural engineers to determine the existing foundation’s condition and the underpinning method best suited to the project’s needs.
  2. Obtaining Permits: Securing the necessary approvals and permits from local authorities based on detailed engineering drawings and plans.
  1. Site Preparation: Setting up the work area, which may involve temporary supports for the structure, and ensuring that all utilities are properly identified and protected.
  2. Excavation: Carefully excavating sections beneath the existing foundation in stages, to minimize structural risk.
  3. Foundation Extension: Extending the foundation by pouring new concrete footings or installing piers beneath the existing ones, thereby increasing the foundation’s depth and strength.
  4. Reinforcement: Adding structural supports and reinforcing the new foundation sections as necessary, according to the project specifications.
  5. Backfilling and Cleanup: Filling in excavated areas and cleaning up the site, followed by any required cosmetic repairs to the property.
  6. Inspection and Approval: Final inspections by the relevant authorities to ensure the work complies with all regulations and standards, leading to official approval of the underpinning project.


This process can vary depending on the specific underpinning technique used and the project’s scope, but these steps offer a general guide to what homeowners and property owners can expect.

VMB Group: Hassle-Free Underpinning for Your Toronto Home

Choose VMB Group for your underpinning needs in Toronto and ensure a seamless, worry-free project from start to finish. With our deep understanding of local building regulations and a commitment to excellence, we’re the trusted partner you need to enhance your basement space effectively. Trust VMB Group to deliver superior underpinning solutions that bring your vision to life.

FAQs About Underpinning in Toronto

Signs include cracks in walls, uneven floors, and difficulty operating windows and doors. A professional assessment, which VMB Group can provide, is the best way to determine the need for underpinning.

The process varies, but it generally takes from 4 to 8 weeks. Factors affecting duration include the project's scale, property conditions, and any city permits involved.

While underpinning involves significant work, VMB Group aims to minimize disruption through efficient planning and execution, ensuring homeowners can manage their daily lives with as little inconvenience as possible.

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