Why Duplex Inspections Are Different

A duplex inspection is more complex than a single-family home inspection — you essentially have two homes to inspect, plus the shared systems and the fire separation between them. Hire an inspector with specific experience in multi-unit residential properties. Ask directly: 'How many duplexes and multi-unit properties have you inspected?' A general home inspector may miss critical duplex-specific issues.

Fire Separation: The Most Critical Item

Ontario Building Code requires fire-rated separation between dwelling units in a duplex. This means fire-rated drywall (Type X) throughout the separation wall and ceiling, with no penetrations. Have your inspector specifically check: the separation wall from basement to roof, all penetrations (plumbing, electrical, HVAC), and the underside of the floor between units. Non-compliant fire separation is both a safety issue and a deal-killer for insurance.

Electrical: Two Panels or One?

Each unit in a legal duplex should have its own electrical panel or a properly wired sub-panel. Check: panel amperage per unit (minimum 100A per unit recommended), whether knob-and-tube wiring is present (very common in older Ontario properties — often uninsurable or requires expensive updates), and whether the panels are labeled and accessible.

The 12 Red Flags That Should Kill Your Deal

1. No fire separation or non-compliant separation. 2. Single electrical panel serving both units with no sub-metering. 3. Active knob-and-tube wiring in walls. 4. Evidence of water infiltration in basement unit (efflorescence, staining, active moisture). 5. Shared furnace with no separate zone control for each unit. 6. Only one water heater for both units (who owns it? who pays?). 7. Evidence of pest activity (rodent droppings, insect damage). 8. Asbestos-containing materials in disturbed areas. 9. No working smoke/CO detector interconnection between units. 10. Structural cracks in foundation walls with horizontal cracking pattern. 11. Evidence of prior flood damage — look for water lines above basement floor. 12. Unpermitted additions (additions not matching original construction style/materials).

Negotiating Post-Inspection

A good inspection report on a duplex will almost always find $10,000–$40,000 in deficiencies. This is normal — don't panic, and don't use it as an excuse to walk away from a good deal. Use the report to negotiate: ask for a price reduction equal to the cost of addressing safety-critical items (fire separation, electrical), and accept the deferred maintenance as known risk priced into your reserves. Major structural or fire code issues are legitimate deal-killers — price adjustments and disclosure are the appropriate remedies for everything else.