In Ontario, the municipal heritage register is an important record to check, but an entry does not always mean that a property is designated. The Ontario Heritage Act requires each municipal register to include properties designated under Part IV by the municipality or the Minister. A municipality may also include some non-designated properties that council believes have cultural heritage value or interest and that meet prescribed criteria. Those entries have different status and consequences, so identify the exact record before drawing conclusions about an ADU.
Find the municipal record and identify its status
Use the municipality’s heritage or planning pages to search the register by civic address, legal description, or parcel identifier. Ontario guidance says the register must be available electronically; a copy can also be requested from the municipal clerk, potentially for a fee. Confirm that the result belongs to the correct parcel and request the full entry, including the legal description, reasons or heritage attributes, by-law, and any notice or decision connected to it.
Ask whether the property is formally designated under Part IV, is included as a non-designated property, or appears in another local inventory. If it is designated, obtain the designation by-law or ministerial record and ask the municipality which approvals or heritage review apply to the specific proposed work. If it is listed as non-designated, do not treat the listing itself as a designation or assume that it has no planning relevance; ask staff how the current register entry is used in development and permit reviews. The result depends on the property’s current status, proposed work, and applicable law.
Check dates and notices for non-designated entries
Ontario’s Act and current provincial guidance set review and removal rules for non-designated properties on municipal registers. For entries added on or after January 1, 2023, municipalities must review the entry within two years. Legacy entries that were on a register on December 31, 2022 have a January 1, 2027 review deadline. If council does not issue a Notice of Intention to Designate within the applicable period, the property must be removed as a non-designated entry and generally cannot be re-added in that status for five years. Prescribed-event rules and other statutory conditions can affect the designation process, so verify the current Act and the municipality’s latest record rather than relying on a dated map or old list.
Confirm the proposal’s route
Give municipal heritage and planning staff the parcel identifier, the register record, and a concise description and location of the proposed secondary dwelling or alteration. Ask whether designation applies, whether heritage permit, planning, or other approvals are required, which heritage attributes or setting need to be addressed, and what plans or reports staff need. Check zoning and building requirements separately: a register search does not decide whether an ADU is permitted, and a heritage status alone does not answer every planning or building question.
Record the date and source of the entry, its designation status, the supporting by-law or notice, and the municipality’s response. If the parcel match, status, or removal history is unclear, ask the clerk or municipal heritage staff to resolve it before relying on the result. This guide describes a records workflow and does not determine the status or approval route for an individual property.