Basement Apartment Legalization in Ontario: The 12-Point OBC Checklist
- John Barnhart
- Oct 2
- 3 min read
Turning your basement into a rental apartment can add serious value to your home — and provide a steady stream of income. But here’s the catch: in Ontario, not every finished basement qualifies as a legal secondary suite.
Municipal inspectors follow a strict list of requirements from the Ontario Building Code (OBC). If your space doesn’t check all the boxes, your permit won’t be approved — and you could be on the hook for costly revisions, double permit fees, or even orders to remove finishes.
This guide gives you a 12-point checklist similar to what inspectors use when reviewing a basement apartment for legalization.
The 12-Point OBC Checklist
☐ Minimum Ceiling Height
Ceilings must be at least 1.95 m (6′5″) throughout living areas. Under beams, ducts, or bulkheads, the Code allows clearance as low as 1.85 m (6′1″) in limited spots.
☐ Means of Egress (Exit Route)
Every basement apartment needs a safe way out — either a dedicated exterior door or a fire-separated stairway leading to the outdoors.
☐ Egress Window
On every storey that contains a bedroom, at least one window must provide a clear open area of 0.35 m² (3.77 sq. ft.), with no dimension less than 380 mm (15 in.). If the window is below grade, the window well must provide 760 mm (30 in.) clearance.
☐ Fire Separation
The basement apartment must be separated from the rest of the house with a minimum 45-minute fire resistance rating. This typically means proper drywall assemblies, sealed penetrations, and rated doors.
☐ Smoke Alarms
Smoke alarms are required in each bedroom and in the hallway outside bedrooms. They must be hard-wired, interconnected, and include battery backup.
☐ Carbon Monoxide Alarms
If the home has fuel-burning appliances or an attached garage, carbon monoxide alarms are required outside bedrooms.
☐ Heating & Ventilation
The unit must be capable of maintaining a comfortable indoor temperature year-round. Shared heating systems may require smoke/fire dampers in the ductwork. Some homeowners choose independent systems for simplicity.
☐ Plumbing & Bathroom
Every legal basement apartment must include a full bathroom with a toilet, sink, and shower or tub. Plumbing systems must meet Code requirements for drainage, venting, and backflow prevention.
☐ Kitchen Facilities
A functional kitchen is required, including a sink, counter space, and cooking facilities. Electrical service must support appliances safely.
☐ Electrical Safety
All wiring in the basement apartment must be inspected and approved by the Electrical Safety Authority (ESA). This ensures outlets are spaced correctly, circuits are sized for the load, and the panel has sufficient capacity. Municipal building inspectors typically require proof of ESA approval as part of the permit process.
☐ Soundproofing
Walls and ceilings separating units must provide a minimum STC 50 sound transmission rating — usually achieved with insulation, resilient channels, and multiple layers of drywall.
☐ Shared Exiting Areas
If the basement unit exits through a shared stair or corridor, that route must be fully fire-separated from the main dwelling all the way to the exterior door.
Retroactive Legalization
Many Ontario basements were converted without permits. Municipalities do allow retroactive legalization, but expect to pay double permit fees in many muncipalities — and inspectors may require you to open walls or ceilings so they can verify insulation, vapour barriers, and fire separations.
How The Building Permit Guy Helps
At The Building Permit Guy, we prepare permit-ready drawings that pass inspection. John Barnhart, our lead designer, is a former municipal building inspector who knows exactly what cities look for. We coordinate with engineers where required and take the stress out of the approval process.
📩 Email us at info@thebuildingpermitguy.ca to get started — and check out our
to see how we can help you turn your basement into a legal rental.
