Commercial building codes in Ontario are the construction and safety standards set out in the Ontario Building Code, a regulation made under the Building Code Act, 1992 that every commercial build, renovation, and change of use has to meet. Since January 1, 2025 that code is structured differently than it used to be, because Ontario now follows the National Building Code of Canada 2020 with a layer of Ontario amendments on top.
For most business owners the code is not something you read cover to cover. It matters at three specific moments. When you buy or sell commercial property, when you change how a building is used, and when you renovate or fit out a space. This article walks through what the code requires, how the permit and inspection process actually runs, and the legal traps we see catch commercial clients in real transactions.
What are commercial building codes, and what changed in 2025?
Two pieces of law work together. The Building Code Act, 1992 is the framework. It creates the permit system, sets out who enforces the rules, and gives municipalities their inspection and order powers. The Ontario Building Code is the regulation under that Act. It contains the technical detail, meaning the actual standards for how a building has to perform on structure, fire safety, exits, plumbing, electrical work, accessibility, and energy use.
The change worth knowing about took effect on January 1, 2025. Ontario replaced its old standalone code (O. Reg. 332/12) with the 2024 Building Code (O. Reg. 163/24). Rather than maintain a separate provincial code, Ontario now adopts the National Building Code of Canada 2020 together with a set of Ontario specific amendments. A transition window ran until March 31, 2025 for projects already in the pipeline under the old code.
Why this matters to you as an owner or buyer rather than as a builder is simple. Work that was permitted before 2025 was reviewed under the old code, and work permitted after is reviewed under the new one. If you inherit a half finished project or an open permit when you buy, the version of the code that applies depends on when the permit was issued. Most online guides still describe the old standalone code, which is one reason it pays to confirm the current position rather than rely on a generic article.
When do building codes actually affect your business?
You rarely deal with the code in the abstract. It shows up at three moments, and each one carries different legal risk.
When you buy or sell commercial property
This is where we see code issues most often. A buyer needs to know whether past work was permitted, whether any permits are still open, whether the municipality has issued any orders against the property, and whether the way the building is being used is actually legal. A seller needs to be ready to answer those questions. If you are buying a business along with its premises, the same checks belong in your business purchase due diligence.
When you change how a building is used
Turning a retail unit into a restaurant, a warehouse into an assembly space, or an office into a medical clinic is a change of use. A change of use needs a permit, and if it increases the hazard in the building it can trigger upgrades to things like fire separations, exits, washrooms, and accessibility. The zoning bylaw also has to allow the new use in the first place.
When you renovate or fit out a space
Most structural alterations, additions, and significant renovations need a building permit, inspections during construction, and confirmation that the space is safe to occupy at the end. Business owners signing a commercial lease often miss who is responsible for that work and for closing out the permits. That belongs in the lease and in your broader business planning.
The practical takeaway is that the code is a transaction issue as much as a construction issue. The cheapest time to deal with it is before you sign, not after.
Building code versus zoning, and why both matter
Clients often use building code and zoning as if they mean the same thing. They do not, and confusing them is one of the more expensive mistakes you can make. The building code governs how you build and how safe the result is. Zoning governs what you are allowed to do with the land and where on the lot you can build. A project can satisfy one and fail the other.
The two connect through a concept in the building code called applicable law. A building permit cannot be issued until the other approvals listed in the code, including zoning compliance, are in place. So a perfectly safe building plan can still be refused a permit because the use is not permitted under the zoning bylaw. The table below sets out the difference.
| Feature | Ontario Building Code | Zoning bylaw |
|---|---|---|
| Question it answers | How a building must be built and kept safe | What you may do with the land and where you may build on it |
| What it covers | Structure, fire protection, exits, plumbing, electrical, accessibility, and energy use | Permitted uses, density, setbacks, parking, signage, and height |
| Where it comes from | The Building Code Act, 1992 and the Ontario Building Code (O. Reg. 163/24) | Your municipality’s zoning bylaw, made under the Planning Act |
| Who reviews it | The municipal building department, through the building permit | Municipal planning and zoning staff, usually before a permit can issue |
| How it bites in a deal | Open permits, outstanding work orders, unpermitted renovations, and occupancy problems | Your intended use is not allowed and needs a minor variance or rezoning |
One more distinction trips people up. An occupancy permit confirms the building is safe to occupy under the building code. A certificate of occupancy, where a municipality uses one, confirms the use complies with zoning. They sound alike and are often spoken about loosely, even by people in the industry, but they answer different questions. If a salesperson tells you a unit has its occupancy paperwork, it is worth asking which document they actually mean.
How the permit, inspection, and occupancy process works
Permits are issued by your municipal building department, not by the province. The chief building official reviews your application against the building code and applicable law, and either issues the permit or refuses it with reasons. The general path looks like this.
- You submit a complete application with drawings, specifications, and the required forms to the municipality.
- The building department reviews the plans for code and applicable law compliance, and may circulate them to other departments such as zoning or fire.
- The municipality issues the permit, or refuses it and gives you all the reasons in writing.
- Construction proceeds, and you call for inspections at the stages set out in the code.
- After the final inspection and any required certificates, the building can be occupied.
Timelines are set by the code and depend on the building type. The province’s own building permit guidance gives an example of 10 business days for a house and up to 30 days for a more complex building such as a hospital, with commercial projects falling within that range depending on classification. Once construction is underway, a building official is generally required to carry out a requested inspection within two working days. These figures are current as of mid 2026, and you should confirm the current numbers and your municipality’s process before relying on them.
Occupancy is its own step. Under the Building Code Act you cannot occupy or use a newly erected building until the requirements in the Act are met. Some municipalities issue a formal occupancy permit, while others simply treat one of the final inspections as the occupancy sign off. Partial occupancy is common on larger projects, where one finished portion can be occupied while the rest is still under construction.
Where work falls short, municipalities have real teeth. A building official can issue an order to comply, an order not to cover work until it has been inspected, and a stop work order if those are ignored. Building without a permit or ignoring an order is an offence under the Act and can carry significant fines. The more important point for a buyer is the next one.
Buying commercial property and the due diligence that protects you
When you buy commercial property, you are not just buying the building. You can inherit its compliance history. An outstanding order to comply can be registered on title, and once it is there it can hold up a transfer or a lender’s financing until it is resolved. An open permit that was never closed out, or a renovation a previous owner did without a permit, becomes your problem the day you close.
That is why the code belongs in your due diligence, not just in your contractor’s scope. In a commercial purchase, the checks we run typically include the following.
- A building and zoning compliance search with the municipality, to confirm the building and its use line up with the records.
- An open permit search, to confirm no permits are still active or sitting unclosed against the property.
- An outstanding order and work order search, since an order can be registered on title and affect the deal.
- Confirmation that past renovations were permitted and that the permits were closed out by a final inspection.
- Confirmation that the current use, and any use you intend, is permitted under the zoning bylaw.
- Where it fits, title insurance that responds to certain work orders and unpermitted work.
The agreement of purchase and sale is where this gets locked in. Well drafted representations and warranties about code and applicable law compliance, and a condition that lets you walk or renegotiate if a search turns up a problem, are far cheaper than discovering an order after closing.
Changing how you use a commercial building
A change of use is one of the most underestimated code events. The building may look ready for your business, but the law looks at the new use, not the old one. Converting retail space to a restaurant brings in requirements around ventilation, fire safety, and occupant load. Turning storage or industrial space into an area where people gather raises exit and fire separation questions. Adding a medical or personal service use can bring accessibility and plumbing requirements into play.
Two approvals run in parallel. You need a permit for the change of use, and where the change increases the hazard in the building the code can require you to upgrade parts of it. You also need the zoning bylaw to permit the new use, or you will be applying for a minor variance or a rezoning before you can even get the permit. The order matters, because spending money on a fit out before confirming both can leave you with a space you cannot legally open.
The mistakes we see commercial clients make
Most code problems we are asked to fix trace back to a small number of avoidable missteps. These are the ones that come up most often in our practice.
Taking the seller’s word that everything is permitted
Open permits and unpermitted work do not disappear at closing. They transfer with the property, and the cost of closing them out, or undoing work that was never approved, lands on the new owner.
Treating zoning approval as building code compliance
A use being allowed under zoning says nothing about whether the building meets the code. We see buyers assume that because the city confirmed the use, the building is fine. Those are two separate questions with two separate searches.
Signing the agreement without a compliance condition
Once the agreement is firm, leverage is gone. Without a condition tied to a clean compliance and permit search, a buyer who finds a problem after the deal goes firm is often stuck dealing with it themselves.
Starting a change of use or fit out before confirming approvals
Spending on construction before confirming both the permit path and the zoning can mean paying twice, once to build and again to bring the work into compliance or reverse it.
Frequently asked questions
Do I need a building permit for a commercial renovation in Ontario?
Usually yes, for anything structural or anything that alters the building in a meaningful way, and almost always for a change of use. Cosmetic work like paint or flooring generally does not. The line is not always obvious, so the safe move is to confirm with your municipal building department or your lawyer before you start, because doing permitted work without a permit is an offence and can stall a future sale.
What happens if I buy a commercial property with an open permit or work order?
You generally inherit it. An open permit needs to be closed out, which can mean inspections, corrective work, or re engaging professionals, and an order to comply can be registered on title and hold up your financing or a later sale until it is cleared. This is exactly why a compliance and permit search before closing is worth far more than it costs.
Is a building permit the same as zoning approval?
No. Zoning controls whether your use is allowed on that land. The building permit controls how the building is constructed and whether it meets the code. A permit will not be issued until zoning and the other applicable approvals are satisfied, so you can clear one and still be blocked by the other.
Do I need an occupancy permit before opening my business?
You cannot legally occupy a newly built or newly altered space until the building code requirements for occupancy are met. Some municipalities issue a formal occupancy permit and others treat a final inspection as the occupancy sign off, so the document you need depends on where the property is. Confirm the local practice before you plan your opening date, because occupying early can expose you to enforcement.
How long does it take to get a commercial building permit in Ontario?
The review timeframe set in the code depends on the building type, with simpler projects reviewed in around 10 business days and more complex buildings taking up to 30 days, plus any time you spend correcting an incomplete application. Commercial projects sit within that range. The biggest delays usually come from missing documents, so a complete first submission is the surest way to keep things moving.
The information provided above is of a general nature and should not be considered legal advice. Every transaction or circumstance is unique, and obtaining specific legal advice is necessary to address your particular requirements. Therefore, if you have any legal questions, it is recommended that you consult with a lawyer.
