Building permits in Montréal
The Ville de Montréal publishes the permits it has issued since 1990 as open data: construction of a new building, transformation (renovation, extension), demolition and certificates of authorization (for example cutting down a tree). Each permit shows the date, the type and often the nature of the work.
An issued permit does not prove the work was done or that it complies, and work done without a permit appears nowhere. A demolition followed by a construction means the building was rebuilt: the new-home warranty may then apply.
The other cities on the site (Québec, Laval, Gatineau, Longueuil, Sherbrooke) and the linked cities of the island (Westmount, Dorval…) are not covered: ask the municipality for their permits.
General information, not legal or professional advice.