What fire code requirements apply when converting an attached garage in Ottawa?

Fire separation between an attached garage and the living space is one of the most important safety requirements in the Ontario Building Code, and it is an area where many garage conversions fall short. Whether you are keeping the space as a garage or converting it to something else, understanding these requirements protects your family and keeps your renovation on the right side of the code.

The OBC requires a fire separation between an attached garage and any residential occupancy with a minimum fire resistance rating of 45 minutes. In practical terms, this means the shared wall between the garage and the house, plus the ceiling if there is living space above the garage, must be constructed with fire-rated materials that can contain a fire for at least 45 minutes. The standard approach is 12.7mm (half-inch) Type X fire-rated drywall on the garage side of shared walls and ceilings, with all joints properly taped and mudded. Some builders double up the drywall for extra protection, and this is required in certain configurations.

Every penetration through the fire separation must be properly sealed. This includes electrical boxes, plumbing pipes, HVAC ducts, and any other opening. Fire-rated caulking or fire stop putty pads must be used around electrical boxes. Plumbing and duct penetrations need fire-rated collars or wrap. These details are small but critical, and building inspectors in Ottawa check them carefully during inspections. A single unsealed penetration can allow fire and toxic smoke to spread into the living space in minutes.

The door between the attached garage and the house must be a solid-core door with a minimum 20-minute fire rating, self-closing hardware, and no glass unless the glass is fire-rated. The door must not open directly into a bedroom. Most newer Ottawa homes have a metal-clad or solid-core wood door with a spring-loaded hinge or hydraulic closer, but older homes sometimes have hollow-core doors or doors that do not self-close, both of which are code violations.

If you are converting the attached garage into a living space and eliminating the garage function entirely, the fire separation requirements change. You no longer need the fire separation between the former garage and the house because the space is no longer classified as a garage. However, you need to make sure you are not creating new fire code issues. If the converted space has a furnace, water heater, or any combustion appliance, it needs proper clearances, combustion air supply, and may need its own fire separation depending on the fuel type.

Smoke detectors are required on every level of a home in Ontario, and carbon monoxide detectors are required outside sleeping areas and on every level that has a fuel-burning appliance or an attached garage. When you convert a garage, confirm that your detector placement still meets the code. If you are removing the garage function, you may be able to remove a CO detector from that area, but you still need them near sleeping areas and fuel-burning appliances.

For garage conversions that add a dwelling unit, the fire separation requirements are more stringent. You need a one-hour fire resistance rating between separate dwelling units, which typically means double layers of Type X drywall or other approved assemblies. Sprinkler systems may also be required depending on the building size and configuration.

Always get a building permit for any work that affects the fire separation in an attached garage. The City of Ottawa takes fire safety seriously, and unpermitted work that compromises fire separation can result in orders to remedy, affect your home insurance, and most importantly, put your family at risk.

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