Saskatchewan has no ADU category; a Fairhaven basement suite is a secondary suite under City of Saskatoon zoning, and the requirements cover egress windows, fire separation, a separate entrance and proper ventilation regardless of the house's age.
An older, unpermitted conversion is common in established neighbourhoods precisely because the work predates current record-keeping, and that gap between what is built and what is on file is exactly what an automated estimate cannot see.
Joel checks the permit file directly rather than assuming a suite is legal because it looks finished. Get your hand-reviewed valuation from Joel Dyck.