How to Build a Legal Second Unit in an Existing House

Home ownership prices in Canadian metropolitan areas have increased to unprecedented levels. Lack of affordability has also led to a competitive rental market with Toronto having a vacancy rate of less than 2%. Many existing home owners have started to rent out spare bedrooms, basement units or attic spaces to generate extra income.

Did you know that the space must first be legalized as a secondary unit before renting it out? A legal secondary unit needs meet the Municipal Zoning By-Law, Building Code and Fire Code requirements. So, whether you are looking to purchase, rent or renovate a space to your existing house, there are things to consider. Our Go-To Team has compiled the Fire Code and Building Code requirements that to be met for the space to be considered a Legal Secondary Unit.

Contact our expert team for Building Code support;

Fire Safety

Smoke Alarm – Devices installed in the sleeping room and interior shared spaces, including hallways which serve the sleeping rooms.

Carbon Monoxide Alarm – Devises installed adjacent to each sleeping area where there are fuel-burning appliances such as a furnace or gas stove.  

Fire Separation – Minimum 30-minute fire rated floor and wall assemblies between units and also units and common area. The fire rating can be reduced if the entire house has interconnected smoke alarms.

Egress Distance – Maximum distance to egress doorway to code requirements (typically 15 m).

Parking

There should be minimum one (1) parking space per unit available.

Minimum Room Area

Living Room or Spaces – Minimum area of 13.5 m2 if it’s a separate room or in a combination with other space. If living area is combined with kitchen and dining area, the space requirements can be reduced to 11 m² for a two (2) person or less unit. 

Dining Room – The dining area in combination with other spaces needs to have an area of not less than 3.25 m².

Kitchen – Minimum area of 4.2 m². For a two (2) person unit or less, the kitchen can be as small as 3.7 m².

Bedrooms – No smaller then 7 m² if it doesn’t have a closet and 6 m² when a closet is provided.

Bathrooms and Water Closets – No minimum size requirement but it should have sufficient space for a water closet, lavatory and bathtub or shower stall.

Doorways and Ceiling Height

Doorway – Minimum width of 610 mm (or greater) and height of 1980 mm.

Ceiling Height – Room height needs not be less than 1950 mm for a basement unit. For attic spaces, 50% of required floor area to have a ceiling height of at least 2.03 m and 50% may have a ceiling between 1.4 m and 2.03 m. 

Window Area

The rooms of the second unit shall have sufficient window openings as follows:

Living and Dining Rooms – 10% of area served

Bedrooms – 5%

Laundry Room, Kitchen and Bathroom – not required

Plumbing

Fixture – the unit needs to have a kitchen sink, lavatory, bathtub or shower stall and a water closet or drainless composting toilet.

Arrangement of Piping – Separate shut off valves for the hot and cold-water supply. 

Ventilation

Fresh Air Intake – In the service room, the combustion air needs to be brought directly from the outside for proper combustion and safe operation of the appliance

Ventilation - Required ventilation of bathroom and kitchen of second unit, either by a ceiling exhaust fan or a window that opens to the outside.

Lighting

Outlets - Outlet with fixture controlled by a wall switch need to be provided in kitchens, bedrooms, living rooms, utility rooms, laundry rooms, dining rooms, bathrooms, water closet rooms, vestibules and hallways in a house or an individual dwelling unit.