The second unit only adds full value if it is legal and documented. A secondary suite permitted through the City of Saskatoon and generating verifiable rent supports a real income-approach valuation, while an unpermitted or undocumented suite is exactly the kind of improvement a standard comparative report misses entirely.
Condition on both units matters just as much as the rent roll. A tenant-occupied unit that has not been updated in years can drag the whole property's value down even if the main unit shows well.
Getting an accurate number on a two-family property means walking both units, not just running comparables. Get your hand-reviewed valuation from Joel Dyck.