“Existing” is a fact; “legal” is a status that needs records
An older kitchen, separate entrance, tenant history or tax assessment does not by itself establish that a second dwelling was approved. Start by asking the municipality what permits, approved plans, inspections, occupancy records or registrations exist for the property.
Step 1: identify what the municipality recognizes
Compare the current physical layout with the municipal record. Note the number of dwelling units, room uses shown on approved plans, open or expired permits, and any previous suite or enforcement file. If the municipality has an existing-suite or legalization program, use that route rather than assuming the new-construction checklist applies unchanged.
Step 2: confirm current land-use permission
Check whether the current zoning permits the type of suite that exists today. Provincial reforms can expand housing permissions, but they do not automatically certify unpermitted construction. Conversely, an older lawful use can involve legal-nonconforming rules that need municipal confirmation rather than guesswork.
Step 3: let the authority identify the applicable construction review
Existing buildings may be reviewed differently from a brand-new house, depending on the jurisdiction and the scope of work. The municipality can tell you which drawings, investigations and trade permits are needed. Avoid opening walls or doing corrective work solely from a generic checklist before the permit path is clear.
Step 4: close every inspection and keep the evidence
Track deficiencies, revised drawings, trade inspections and the final municipal record. If the municipality requires registration, a licence or another final step, keep that with the permit file. Future buyers, lenders, insurers and contractors may all need to distinguish documented approval from informal use.
What not to assume
- “It has been rented for years” is not proof of approval.
- “The zoning now allows suites” is not proof the construction was permitted.
- “The previous owner did it” does not resolve open permits or deficiencies.