Basement Apartment Rules in Ontario — 2026 Update
Ontario changed the rules for second units in 2023. Here's what every Ontario homeowner planning a legal basement apartment needs to know in 2026.
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Ontario's More Homes Built Faster Act (Bill 23) and the subsequent municipal conformity updates changed the rules for second units significantly. If you're planning a legal basement apartment in the Ontario, here's what the regulations actually say in 2026.
Zoning: As-of-right is now the rule
Most Ontario municipalities now permit one additional dwelling unit in a detached, semi-detached, or townhouse as-of-right — meaning no variance or Committee of Adjustment hearing required. This was the single biggest change from the provincial legislation.
Key OBC requirements for basement apartments
Ceiling height
Minimum 1.95 m (6'5") clear height in all habitable rooms and corridors. Below-grade bedrooms require a minimum 0.55 m² unobstructed egress window well area.
Fire separation
The existing floor/ceiling assembly between the basement unit and the ground floor must achieve a 30-minute fire resistance rating. This typically means upgrading ceiling drywall to 5/8" Type X plus firestopping all penetrations.
HVAC
The basement unit requires its own independent heat source and, ideally, an ERV for ventilation. A shared furnace with a separate thermostat-controlled zone is usually acceptable if properly designed.
What the permit package must include
- Floor plan showing the unit layout, egress windows, exit path
- Section showing the fire-separation assembly
- Plumbing plan if adding a kitchen or bathroom
- Electrical panel schedule (verified by ESA)
Skipping any one of these is the most common reason basement permits get returned on first submission.