An existing building is not exempt from the current building code simply because it predates it. What actually determines how much of the code applies is the scope of work being done to it — and getting that scope question wrong before pricing a job is expensive to fix afterward.
Key takeaways
It is a common assumption that an older building is grandfathered against the current building code, and only a new building has to meet current requirements. That is not how the code is written. The National Building Code of Canada 2020 states plainly that it covers requirements for "the design and construction of new buildings, as well as the alteration, change of use and demolition of existing" ones. An older building is squarely inside that scope the moment a renovation, an alteration, or a change of use touches it — the building's age is not, on its own, an exemption.
This does not mean every renovation of an older building has to bring the entire structure up to the current code from top to bottom. In practice, how much of the code applies is a function of the scope of the specific work — a cosmetic interior renovation and a structural alteration are not treated the same way, and neither is a project that also changes the building's use, which is covered in more depth in this hub's own piece on change of use approvals. The general principle is real; the specific line between "minor alteration" and "full code review" is set by the applicable code provisions and the local building department's interpretation of the specific project, not by a rule of thumb.
Firms researching an older building often go looking for the specific numeric line — a storey count, a floor area, a specific clause number — that determines which part of the building code applies to their project. Those thresholds exist, but the text of the building code itself is not published free online, and no reliable public source carries the specific clause language. The honest answer, and the one worth acting on rather than guessing past, is to confirm the applicable threshold directly with the local building department for the specific project, rather than relying on a remembered figure or a number found informally — a wrong assumption here is the kind of mistake that surfaces expensively, mid-permit-review, rather than early.
If the older building carries a heritage designation, code research has a second layer to work through, on top of the building code itself — the two tracks run in parallel and neither substitutes for the other. This hub's glossary entry on heritage alteration permits covers what that additional review requires and is worth checking early in the code-research process, since a heritage review can affect what alteration options are even available before the building-code question is fully resolved.
An older building with a past industrial or commercial use carries one more question worth folding into code research at the same stage, particularly if the project also changes the building's use: whether that history requires an environmental site assessment before the new use can proceed. This hub's piece on change-of-use approvals covers the Record of Site Condition requirement in full; the short version for code research purposes is that it is worth asking the question for any older building with an unclear or industrial past, rather than assuming it does not apply.
Older buildings are disproportionately likely to need an accessibility retrofit as part of any renovation, simply because they predate current expectations for barrier-free design, and the National Building Code of Canada 2020 introduced updated accessibility requirements among its more than 280 technical changes in the most recent edition — alongside the alteration and change-of-use provisions already covered above. Where the project also touches a public space, this hub's piece on accessibility requirements in a fit-out covers the separate AODA layer that runs alongside the building code question, and is worth reading together with this page rather than treating the two as unrelated research tasks on an older building.
A pre-consultation answer is only useful if it survives the months between the conversation and the permit application. Confirming the applicable threshold verbally and then not writing it down — who said what, when, and against which specific scope of work — is a common way for a firm to end up re-litigating a question it already had answered, sometimes with a different reviewer who reads the same project differently. A brief written summary sent back to the building department after any pre-consultation, confirming the understanding in writing, is a cheap habit that avoids that entire category of mid-project surprise.
The most reliable way to resolve code research on an older building is a direct pre-consultation with the local building department, ideally before the design is finalized rather than after. That conversation, specific to the actual building and the actual scope of work, is what turns "we think this triggers a full code review" into a confirmed answer — and it is a far cheaper step than discovering the answer for the first time at permit submission.
A worked example
A firm is engaged to renovate a two-storey commercial building from the 1960s for a new retail tenant. The scope includes new interior partitions, an upgraded electrical service, and a new accessible entrance — no structural changes and no change of use.
Before finalizing drawings, the firm requests a pre-consultation with the local building department to confirm which specific code provisions the renovation scope triggers, rather than assuming a threshold from a different project in a different municipality.
The building department confirms the property has no heritage designation, and because the renovation does not change the building's use and the prior use was retail rather than industrial, no separate heritage review or Record of Site Condition applies — only the standard building-code review for the renovation scope itself, confirmed directly rather than guessed.
The new accessible entrance is flagged separately as touching the building's accessibility provisions, so the firm confirms the applicable clearances with the building department at the same pre-consultation, rather than treating it as a minor door swap unrelated to the rest of the code review. The firm emails a short written summary of everything confirmed back to its building-department contact the same week, so the answer is on record before drawings are finalized.
Not automatically in full, but it is not exempt either — the National Building Code covers alteration, change of use, and demolition of existing buildings directly, and how much of the code applies depends on the scope of the specific work being done to it.
The local building department, applying the applicable building code to the specific scope of work — this is a locally confirmed question, not one with a single national threshold, which is why a direct pre-consultation before finalizing design is the reliable way to get a firm answer.
A heritage designation adds a separate review track on top of the building code, rather than replacing it — see heritage alteration permit for what that additional layer requires. Both the building code and the heritage review apply; neither substitutes for the other.
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