Methodology

How we build the record

Every status on The Patina Record comes from a public municipal source, carries that source and its date, and says how it was worked out. This page explains the rules.

1. Registers

Each municipality keeps a register of properties of cultural heritage value or interest (Ontario Heritage Act s. 27): properties designated under Part IV (individually) or Part V (in a heritage conservation district), and listed, non-designated properties. We read each register from the municipality's open data, from the register it publishes (often a PDF), from an extract it sent us, or from its staff through the Register desk. Each record keeps the register's own status and wording, its source link and the date the source was current. We never copy owner names or contact details.

2. When the register lags

Registers are often updated weeks or months after council acts. We also read municipal notices and council and committee agendas, and staff can record a decision the day it happens. The status we show is the register's, updated by the latest of these:

• A notice of intention to designate (published notice, council resolution or staff record) shows a listed property as “notice of intention to designate” for 120 days, the time council has to pass the by-law (s. 29(8)).
• A passed designating by-law shows it as designated.
• The page always says which it is, and that the register itself may still show the older status.

3. January 1, 2027 and removal dates

Under Bill 23 as extended by Bill 200, a listing made before 2023 comes off the register on January 1, 2027 unless council issues a notice of intention to designate first; listings from 2023 on have two years from their listing date. Where a register gives its own expiry date (Hamilton does) we use it. A removed property can't be listed again for five years. See deadlines.

4. Placing addresses on the map

We match each address to the municipality's own address points where they are open, then to Statistics Canada's National Address Register. Only exact civic matches are used; we never guess. A number that matches points more than 1 km apart is left unplaced. Unplaced properties stay searchable by address.

5. Permits, applications and the priority score

Building and demolition permits and planning applications come from municipal open data and are matched to properties by address. The priority score (out of 100) is a triage aid, not a judgement of heritage value: threat (up to 50: a live demolition permit, an application at the address, a council item, rapid transit nearby, zoning that allows more density, a large lot), evidence (up to 35: what the register already says and research under way) and urgency (up to 15: how soon the listing comes off).

6. Checks every day

Imports never delete: a record a source drops is retired with a note, and a source that would lose more than 10% of its rows at once is held for review. A daily quality check compares counts, statuses and placements with the day before and flags anything unusual to us.

7. Corrections

We fix confirmed mistakes within two business days and note the change on the property's page. Use “Report a mistake in our data” on any property page. Municipal staff can confirm and correct records directly from the Register desk; confirmed records say so, with the date.

8. Sources and how current they are

1 source is overdue for a refresh: Town of Milton — Heritage Properties.

Licences and required attributions for every source: data sources and credits.

Not legal advice. Confirm status with the municipality.