Legality decides whether the income counts for anything beyond cash in hand. The City of Saskatoon requires a building permit for a secondary suite, covering egress, ceiling height and fire separation, and only a permitted suite's income can be underwritten by a lender or reflected in an appraisal.
Expenses narrow the gap between gross rent and actual return. Utilities split between units, a share of insurance, ongoing maintenance and vacancy between tenants all come off the top, and a pre-purchase home inspection, typically $400 to $600, is the way to price deferred maintenance before it becomes your problem.
The only way to know what a specific Grosvenor Park property will actually generate is to look at its condition, its permit file and comparable sold rents together. Get your hand-reviewed valuation from Joel Dyck.