Change of Use Permits for Commercial Properties in Ontario: When You Need One and How to Apply

Short answer: an Ontario commercial property may need a change of use permit even when no construction is planned. Section 10 of the Building Code Act, 1992 requires a permit where changing the use of a building or part of a building would create an increase in hazard as determined by the Building Code. If renovations are also proposed, the work and the new use are usually reviewed together through the applicable building-permit process.

A new tenant, business name, or lease does not automatically answer the permit question. The current approved use, proposed operation, Building Code major occupancy, zoning permissions, occupant load, exits, fire protection, washrooms, ventilation, accessibility, and construction scope all matter.

This guide explains how to apply for a change of use on a commercial property in Ontario. Municipal procedures and required documents vary, so the local building department must confirm the application route for the specific address.

When Is a Change of Use Permit Required in Ontario?

The Building Code Act uses an increase-in-hazard test. The current Ontario Building Code identifies prescribed changes that require a permit under Section 10, including major-occupancy transitions marked in the Code's change-of-use table and certain other changes described in Division C, Article 1.3.1.4.

This is more precise than saying every change of tenant needs a change-of-use permit. A clothing store replaced by another clothing store may remain within the same use and occupancy conditions. A retail unit converted to a restaurant, an office converted to a clinic, or a warehouse converted to an assembly venue can affect occupancy classification and life-safety requirements even when the floor area stays the same.

The analysis should distinguish three separate questions:

• Is the proposed business permitted by zoning? Municipal zoning regulates land use, parking, loading, location, and other property matters.
• Does the proposed use trigger a Building Code change-of-use permit? This depends on the approved existing use, proposed major occupancy, and the Code's increase-in-hazard rules.
• Will construction require a building permit? New partitions, plumbing, ventilation, structural alterations, fire separations, exits, or accessibility work may require a construction permit regardless of how the change-of-use question is classified.

Zoning terminology and Building Code major-occupancy classifications are not interchangeable. A municipality may describe a business as retail, personal service, medical office, restaurant, place of worship, or recreation for zoning purposes, while the Building Code analysis places the space within an occupancy group based on how it is used and the hazards involved.

Ontario's building-permit guidance recommends contacting the municipal building department because a building evaluation may be needed even when construction is not initially planned. Permit Works' Change of Use Permit service can help organize the existing-use research, proposed-use description, drawings, and application support.

What Should You Check Before Signing a Lease?

A commercial lease should not be treated as proof that the proposed business is permitted or that the unit is ready for occupancy. Before making the lease unconditional, confirm the municipal history and compare the proposed operation with the space that actually exists.

Start with the following information:

• the municipal address, unit number, legal property information, and landlord contact;
• the current approved use and most recent occupancy or permit records;
• a detailed description of the proposed business, products or services, hours, staffing, customers, equipment, storage, and deliveries;
• the expected occupant load and whether the public will gather, dine, receive treatment, exercise, worship, or participate in instruction;
• existing floor plans, base-building drawings, fire-alarm and sprinkler information, HVAC capacity, plumbing, and electrical service;
• landlord design criteria and responsibility for work outside the tenant unit; and
• any zoning, site-plan, heritage, conservation, environmental, or other applicable-law issue connected with the property.

Confirm the zoning route with the municipality. Requirements differ across Ontario. For example, Mississauga uses a separate Zoning Certificate of Occupancy for a new or changed use and expressly notes that the certificate does not approve a Building Code change of use or authorize construction. A building permit may still be required.

Ask for property records early. The previous tenant's activity may not be the legally approved use, and the visible construction may not match the latest approved plans. When the prior occupancy cannot be established, the Building Code's change-of-use provisions may require additional review.

Assess feasibility before committing to a detailed layout. A proposed restaurant may need commercial kitchen exhaust, grease management, additional plumbing, a controlled garbage area, fire separations, or mechanical upgrades. A clinic may create different accessibility, plumbing, privacy, ventilation, or life-safety considerations. An assembly use may change occupant load, exiting, door hardware, fire alarm, and washroom requirements.

A permit contingency in the lease should clearly address who is responsible for applications, drawings, base-building upgrades, landlord approvals, municipal comments, and costs. Permit Works' Commercial Renovation Permit service and Retail and Office Renovation Permit service support projects where the proposed use and construction scope need to be evaluated together.

What Drawings and Documents Are Typically Required?

The application package must give the municipality enough information to establish the current use, understand the proposed operation, classify the occupancy, and determine whether the existing building can safely accommodate it. The exact list depends on the municipality and scope.

A commercial change-of-use submission commonly includes:

• Application forms: municipal building-permit information, designer schedules, applicable-law documentation, and owner authorization where the applicant is not the owner;
• Letter of use: a detailed description of the business, activities, employees, customers, hours, equipment, materials, storage, processes, and expected occupant load;
• Key plan or site plan: the project location, unit number, property context, parking, entrances, and adjacent tenant occupancies;
• Existing and proposed floor plans: room uses, dimensions, floor area, partitions, doors, exits, washrooms, barrier-free paths, and construction scope;
• Building Code information: existing and proposed major occupancy, occupant load, construction type, fire separations, travel distances, exiting, spatial or building-system considerations, and the change-of-use analysis;
• Mechanical, plumbing, sprinkler, fire-alarm, electrical, or structural information: where the new use or proposed work affects those systems; and
• Supporting approvals: zoning confirmation and other applicable-law documents required before permit issuance.

A municipal change-of-use review may identify upgrades even when the applicant initially expects little or no construction. Depending on the existing building and proposed use, the review can address fire separations, exits, door hardware, washrooms, ventilation, emergency lighting, fire-alarm systems, and other life-safety or accessibility requirements. The municipality may also request a detailed letter of use and coordinated plans. Confirm the exact submission requirements for the property and project rather than treating any one municipality's checklist as a province-wide standard.

Do not copy the previous tenant's drawings and simply change the business name. Drawings should reflect field conditions and use consistent room names, dimensions, door swings, exit information, and system layouts. If consultants are involved, their plans should coordinate with the same architectural layout.

The required professional disciplines are project-specific. A structural engineer may be needed for structural modifications. Mechanical, electrical, fire-protection, or other professional design and review may apply to more complex systems or occupancies. A professional seal does not, by itself, mean that every project follows an identical general-review process; confirm the permit's required commitments, inspections, and reports with the municipality.

How Does the Application, Review, and Occupancy Process Work?

A practical application sequence is:

1. Confirm the existing approved use. Review available permits, occupancy information, approved drawings, and municipal records rather than relying only on the current tenant or listing.
2. Describe the proposed operation. Prepare a complete letter of use and preliminary layout.
3. Check zoning and applicable law. Confirm that the proposed use is allowed and identify any separate approvals.
4. Determine the permit route. Ask the municipal building department whether the project requires a Section 10 change-of-use permit, a construction permit under Section 8, or another application path.
5. Assess the existing building. Review occupancy classification, occupant load, exiting, fire safety, accessibility, washrooms, mechanical systems, and other relevant conditions.
6. Prepare coordinated documents. Complete the drawings, forms, letter of use, consultant information, and owner or landlord authorizations.
7. Submit and respond. Address completeness comments, zoning questions, Building Code review items, and requested revisions with one coordinated package.
8. Complete required work and inspections. Build from issued documents, arrange inspections before work is covered, and submit required reports.
9. Confirm occupancy requirements. Do not open or occupy the space until the municipality's permit and occupancy conditions have been satisfied.

If no construction was initially proposed, the evaluation can still identify upgrades required to support the new use. Once construction becomes necessary, confirm whether the municipality will convert or coordinate the application with a construction permit. Do not assume that a change-of-use approval authorizes unshown renovation work.

During construction, review the permit card and approved documents with the contractor and consultants. Ask the assigned inspector which inspection stages, professional reviews, and reports are required before work is concealed. Field changes to exits, walls, ceilings, fire separations, washrooms, or mechanical systems can affect the approved analysis and may require a revision.

Municipal processing times and fees vary, and additional approvals can affect the schedule. A complete application improves review readiness but does not guarantee a permit or opening date. For help assessing a proposed commercial use, preparing the drawing package, and responding to municipal comments, use the Permit Application Support service or contact Permit Works.

Official sources

• Ontario: Building Code Act, 1992, Section 10
• Ontario Regulation 163/24: Building Code
• Ontario: 2024 Building Code Compendium, Volume 1
• Ontario: Building Permits and Changes in Use
• City of Mississauga: Zoning Certificate of Occupancy

Related Articles and Permit Services

• Change of Use Permit
• Commercial Renovation Permit
• Retail and Office Renovation Permit
• Restaurant Permit
• Permit Application Support
• Building Without a Valid Permit
• Contact Permit Works

Important Notice

This article is provided for general informational purposes only and is not a substitute for project-specific professional or municipal advice. Building Code, zoning, permit, and inspection requirements vary by property, project scope, and municipality and may change over time. Information that was accurate when published may be outdated when you read it. Before making design or construction decisions, confirm current requirements with the applicable municipality and consult a qualified professional where appropriate.