Secondary Suites - Information

Secondary Suites

The term “secondary suite” is generally used to describe a self-contained dwelling unit with its own kitchen and bathroom, which is separate from the principal dwelling in a house. It can be located either within the principal dwelling or in an accessory building on the same lot as the principal dwelling. These units are also known as “accessory apartments” and “in-law suites.” Basement apartments are the most common type. Aside from being affordable to renters, they also provide income and extra security for the home owner who has more space than is needed, and make entering the housing market easier for first-time buyers who may use the rental income to offset their mortgage costs.

Secondary suites are an affordable housing option that meets the needs of many people, including members of an extended family, singles, seniors and people with low or fixed incomes. Since they are usually constructed inside existing buildings, they help optimize the use of existing housing stock and infrastructure, and re-populate neighbourhoods with declining populations.

Photo by: John Burrows

Figure 1 Living-work area in a basement secondary suite

What Regulations Apply to Secondary Suites?

Whether you intend to renovate an existing secondary suite or add a new one, the secondary dwelling unit must conform to all zoning, building and fire code requirements.

Building Code Requirements

Building codes that govern the design and construction of building are enacted by the provinces and territories to protect the health and safety of occupants. In most cases, building codes are administered and enforced by the municipalities. Secondary suites were not specifically identified in building codes until around 1990. Where building codes contain no specific provisions for secondary suites, they are usually covered by those that apply to duplex dwellings and small apartment buildings, which can be more onerous and costly than necessary.

Design and construction requirements for secondary suites vary by province or territory. Some provinces, such as British Columbia and Ontario, have added parts to their codes to address alterations and renovations to existing buildings separately that can apply to secondary suites.

British Columbia and Alberta have created specific regulations for the construction of secondary suites as distinct from a duplex or apartment building.

Alberta changed its 2007 Building Code to regulate the construction of secondary suites in new and existing buildings. Although these requirements apply only to that province, they are similar to the code provisions that other provinces are considering or are currently enforcing and can therefore serve as an example of the kind of regulations affecting secondary suites in other provinces and territories. The Alberta requirements address the need for the following features: safe egress and exiting, adequate fire separation, proper size and height of rooms, stairs and passages, and early warning of fire emergencies. They include provisions listed below:

Safe egress and exiting

    • There shall be a separate exit from the secondary suite to the outside. Occupants of each suite must have a direct path to the outside without having to go through another dwelling.
    • Each bedroom should have at least one outside window that can be opened from the inside, which shall provide an unobstructed opening of at least 0.35 m2 (3.75 sq. ft.) and with no dimension less than 380 mm (15 in.).
    • There is no requirement for windows in rooms other than bedrooms.

Adequate fire separation

    • Fire protection, such as 12.5 mm (½ in.) gypsum board, is needed for the walls and ceiling to inhibit the passage of fire between the secondary suite and the principal dwelling.
    • Fire protection, such as 12.5 mm (½ in.) gypsum board, is needed for the walls and ceiling of the furnace room.
    • For new homes or new construction, separate heating and ventilation systems are required for the secondary suite and the principal dwelling. Common heating and ventilation systems are permitted for houses with a pre-existing secondary suite.

Adequate size and height of rooms, stairs and passages

    • Rooms and spaces shall have a height of at least 1,950 mm (6 ft. 5 in.).

Early warning of fire hazard

    • Every house with a secondary suite shall have smoke alarms that are interconnected between both dwellings. The smoke alarms shall be permanently connected to an electrical circuit (hard wired), and one smoke alarm is required within 5,000 mm (16 ft. 3 in.) of each bedroom.

Additional Municipal Requirements

Some municipalities have enacted by-laws to regulate the design and construction of secondary suites. These include Surrey, Sidney and Vancouver, British Columbia; Saskatoon, and Montreal. Vancouver and Saskatoon have developed provisions in their by-laws which enable them to address existing secondary suites that may or may not conform to building code requirements and other municipal requirements. These provisions focus on major fire and life-safety features such as:

    • Fire separation of dwelling units, service rooms (such as furnace and laundry), exit stairs and corridors.
    • Egress and exiting features within the dwelling unit, including stairway and corridor dimensions and heights, handrail and guard dimensions, and egress features that serve more than one dwelling.
    • Smoke alarms permanently connected to an electrical circuit (hard wired) and required in each dwelling unit.
    • The number and size of unobstructed window openings.

If you are considering adding a secondary suite in your house or modifying an existing apartment that might serve as a secondary suite, you should review the building code requirements for your jurisdiction and consult a Development Information Officer. This way, you can be sure that your design conforms to the health and safety requirements of the building code and complies with zoning requirements.

You may have to obtain building and utility permits if your plans involve an alteration to the structure of your house, an increase in the size of windows or exterior doors, or changes to mechanical and electrical services. The permit process, which may include visits by building and utility inspectors, helps to ensure that the newly created secondary suite and attached dwelling meets building code requirements as well as any utility-related regulations. When the work is completed to the satisfaction of the municipality, an occupancy permit may be issued that entitles you to use the secondary suite.

Is My House Suitable for a Secondary Suite?

Building a secondary suite in your house can be a cost-effective way to provide accommodation for a family member or create new rental space. But you must ask yourself whether your house is a good candidate for such a project. If the space you intend to use is not high, dry and sound, you should correct these problems before or during construction of your secondary suite. The following questions may help you decide whether it is a good idea to add a secondary suite to your house:

    • Must you stoop to avoid bumping your head on a beam, pipe or duct? You might have to raise a beam, relocate ductwork and plumbing or lower the floor.
    • Are there intermittent or permanent traces of moisture or mold on the floors, walls or ceiling? Is there a persistent musty odour in clothing and other objects that are stored there? Repairs to the roof, walls or foundation might be necessary and you might need additional mechanical ventilation in the space.
    • Are there newly formed cracks or other foundation damage to the walls or on the floor? You might need to repair a structural problem.
    • Is there a door that opens directly from the secondary suite to the outside? This is the safest means of egress and provides the most privacy to the occupants.
    • If no door opens directly from the secondary suite to the outside, can you enter the secondary suite without going through the principal dwelling? Some jurisdictions permit a common entry serving the principal residence and a secondary suite, provided it is enclosed in fire-resistant material and closed off from both dwellings by smoke-tight doors.
    • Is there an operable window of sufficient size in each bedroom? In addition to providing light and ventilation, it might have to be used as an exit during an emergency. If it opens into a window well, as is common in basements, be sure there is enough space in the well to allow a person to crawl out through the window in an emergency.
    • Is there sufficient capacity in your electrical panel for the additional lights, plugs and heating appliances needed for the secondary suite? You might need to enlarge your panel or add circuits.
    • Is there radon gas in your basement? Radon is a radioactive gas that is colourless, odourless and tasteless. The known health risk associated with exposure to radon is an increased risk of developing lung cancer. Consider testing for radon before construction to determine whether or not remedial measures are required to protect occupants. See CMHC’s Radon: A Guide for Canadian Homeowners for more information.

Photo by: Barry Craig

Figure 3 Basement bedrooms with large windows

Can I Create a Safe, Healthy and Comfortable Living Environment?

Good design and careful attention to detail can make the difference between a secondary suite that is a pleasure to live in and one where living is an ordeal.

First and foremost, secondary suites should be healthy and safe to live in. If located in a basement, any pre-existing moisture problem should be resolved. Excessive moisture can damage finishes, framing and personal belongings and contribute to conditions that promote mold growth — a health concern for many Canadians. A safe and healthy suite has space that is large (and high) enough, sufficient natural light, heating and ventilation, adequate thermal and sound insulation, good fire protection, and reliable heat and smoke alarms.

Rooms should be high enough to permit ceiling fixtures or fans with space beneath for occupants to pass unhindered. Some jurisdictions allow limited obstructions such as beams and bulkheads containing services within the space provided they are not in a path to an exit. Ask your building official what minimum heights are required.

Exterior walls and roofs should be insulated and air sealed to current building code requirements to reduce heat loss and energy consumption while enhancing occupant comfort. Walls and floors separating the secondary suite from the principal dwelling should contain acoustic insulation and be covered with tightly-fitted gypsum board, with all joints taped and holes filled. Cracks beneath baseboards and around outlets and fixtures in separating walls and floors should be caulked.

This will help to reduce both noise and odour transfer between the principal residence and secondary suite.

The walls and ceiling that separate the secondary suite from the principal residence must be fire protected and, most important, smoke-tight. Openings between the secondary suite and principal residence must be covered with fire-resistant material so that smoke or flame cannot pass from one dwelling to the other. A tightly-fitted layer of gypsum board with joints and corners taped provides sufficient protection in most jurisdictions. Ducted air handling systems serving both dwellings should be removed and replaced with individual systems, unless common systems are permitted.

Research has shown that the widespread use of smoke alarms is the main reason for the decrease in fire deaths in Canadian houses during the last three decades. In some jurisdictions, smoke alarms in houses with secondary suites are required to be interconnected so that the occupants of both dwellings are alerted to a fire or smoke hazard in either dwelling and can respond appropriately.

It is also a good idea to install a carbon monoxide (CO) detector near a fuel-fired appliance such as a fireplace or furnace and near a doorway to an attached garage. CO gas is odourless and heavier than air, and can collect in low areas, such as in basement living spaces.

Photo by: John Burrows

Figure 4 Enlarged window and bulkhead 1,950 mm (6 ft. 5 in.) above floor

Other Considerations

Property Tax

Adding a secondary suite will likely increase the value of your property, and may result in a small increase to your property tax.

Income Tax

Any rent that you collect must be declared as income under the Income Tax Act. Reasonable operating expenses may be declared as deductions.


Your insurance company should be notified if you intend to build an accessory suite. Additional occupants, cooking facilities and living space may increase the potential for an accident to occur and this could affect your insurance premium. The change in value of your property should also be reflected in your insurance policy.

Financial Help

Canada Mortgage and Housing Corporation (CMHC) offers financial assistance to owners who build secondary suites for adults with disabilities and seniors with low-incomes. If you meet the criteria, you may be eligible for a forgivable loan through CMHC’s Residential Rehabilitation Assistance Program (RRAP) for Secondary/Garden Suites.


Secondary suites can provide affordable living space and intensify urban development without adding new buildings to the landscape. Requirements for secondary suites vary from one province or territory to another, and sometimes between cities. They have been put in place to protect the occupants of both the principal residence and the secondary suite. Homeowners who intend to modify an existing secondary suite or build a new one should first consider whether the house is suitable for the intended changes and then consult with the municipal zoning department and the building permit office to be sure that the project complies with all requirements.