Secondary suites are sizable renovation projects that require careful planning before starting construction. Building codes and municipal by-laws dictate whether or not you can build these multi-unit dwellings and which type of construction is allowed. Additional research and due diligence ensure that your project meets all the necessary provisions so that you can avoid potential blockers or delays along the way.
What are the requirements to build a secondary suite?
Building codes
When planning a secondary suite in Toronto, there are various codes that you need to abide by, namely the Ontario Building Code (OBC), the Fire Code, and the Electrical Code (ESA).
Ontario Building Code (City Building Department)
The Ontario Building Code is a regulation under the Building Code Act. It establishes detailed technical and administrative requirements and minimum standards for building construction.
Fire Code (City Building/Fire Department)
The National Fire Code of Canada 2015 (NFC) is published by the National Research Council of Canada NRC and developed by the Canadian Commission on Building and Fire Codes. It sets out the technical provisions that regulate activities related to the:
- Construction, use, or demolition of buildings and facilities
- Condition of specific elements of buildings and facilities
- Design or construction of specific aspects of facilities related to certain hazards
- Protection measures for the current or intended use of buildings
Electrical Code (ESA)
The Ontario Electrical Safety Code is primarily a technical document and is prescriptive in approach. The Code describes Ontario's standards for electrical installations, products, and equipment in detail. You can decrease the risks of fire, shock, and electrocution by taking steps to ensure those who perform electrical work are qualified, competent, and licensed.
When inspectors check for building permits, they look at whether you are meeting the Building Code and the Fire Code requirements. As for the Electrical Code, inspectors review requirements that are for a separate electrical permit with the Electrical Safety Authority (ESA).
If the space where you want to build a secondary suite doesn’t meet the minimum OBC requirements, you won’t be able to get a building permit. And without a building permit, you won’t receive a legal secondary suite designation. In some instances (e.g., fire issues may prevent you from getting a legal suite status), you may settle on an alternative solution with the inspector. However, the alternative could require extensive renovation work, which may not be worthwhile.
Municipal by-laws
Every city has slight differences within their municipal by-laws when it comes to building secondary suites. You can find these nuances in:
- The number of parking
- Design of the parking — side by side vs. tandem (front/back)
- Maximum suite size
- Minimum suite size
- The maximum number of bedrooms
- Location of entry doors and walkouts
- Additional application fees
What else do you need to research before construction starts?
There are a few more things to keep in mind while doing your research and due diligence. Before adding a secondary suite to your property, make sure to verify:
1. Zoning Destination
Find out what type of zone your property is located in. Whether it’s an R1 or R2 zone, this designation will determine what you are allowed or not allowed to build in the area. Each city has its own set of designations. For example, Toronto works with R, RD, RS, RM, etc.
Most cities have an interactive zoning by-law map or a pdf map that you can refer to (e.g. Toronto’s zoning map). Find your property by inputting its address on this map to find the zoning designation.
2. Zoning bylaw for permitted uses
Once you have your zoning designation, cross-reference the latter with the zoning by-law. For example, if you're in an R1 zone, go to the R1 zoning by-law to see what type of construction is allowed. To see if you can build a secondary unit, look for the following words:
Secondary suitesAccessory dwelling unit (ADU)DuplexTwo-Unit dwellingMulti-Unit dwellingFor the most part, secondary suites are now allowed in Ontario thanks to the government policies and provincial acts mentioned above.
- Secondary suites
- Accessory dwelling unit (ADU)
- Duplex
- Two-Unit dwelling
- Multi-Unit dwelling
For the most part, secondary suites are now allowed in Ontario thanks to the government policies and provincial acts mentioned above.
3. Parking
When building secondary suites, you should consider parking spaces.
First, ensure that you can fit parking on your existing lot — and that it is actually on your lot. While you may think that your property extends at the sidewalk, the first two-to-three feet may be city property (also known as “the boulevard”). Verify the boundaries of your property early on, so that you can plan your parking space within its limits.
Second, even if you have room to add a parking space on your property, you also want to make sure that you meet the landscape area requirements. You can’t pave your entire front lawn and make that a parking space. Usually, at least 50% of your front yard must remain as grass or other softscape, which refers to the live horticultural elements of a landscape (e.g. flowers, plants, shrubs, trees, flower beds).
*** The specifications below are for homes that are over five years old. These homes have special provisions in the Ontario Building Code — Part 11 ***
In Ontario, if your home is 5+ years old, you’re allowed to follow special provisions as stated by Part 11 of the Ontario Building Code. Construction rules for these houses are less stringent than the ones in the Building Code. Inspectors recognize that older homes can’t fully meet the current Building Code, so they are more lenient on certain aspects.
4. Ceiling height
Minimum 6’5” (1,950 mm) under bulkheads
- If you don’t have 6’5” under the bulkhead, you can use a flush beam to raise it into the joist space to get that 6’5” clearance.
- If you can’t meet requirements, underpinning can be a good –– though expensive –– alternative, especially when it comes to older Toronto homes. It would increase the depth or load capacity of existing foundations to support adding another story to the building.
Minimum clearance of 6’8” (2,030 mm) for at least 50% of the ceiling
- In attic spaces, at least 50% of the ceiling should be 6’8” while the rest of the ceiling cannot be less than 4’7”.
Any height less than 4’7” (1.400 mm) cannot be used to calculate minimum room sizes
- Anything less than 4’7” won’t be considered as living space. You can leave it open, but it doesn’t count as part of the room’s size.
5. Exiting requirements
1. A single exit that isn’t shared with another dwelling unit
You could pass building code requirements with one exit if it goes directly outside and if stairs are less than one flight.
2. A shared exit between dwelling units
If two units exit into the same stairwell, you’ll need a second exit, which can be an egress window. The latter is a large window that meets the following dimensions: 3.80 ft² (0.35 m²) and 15” (380 mm) with extra clearance for the window to swing. The egress window should allow space for one person to get out in case of an emergency, such as a fire incident.
The egress window can be located in any room as long as you don’t block access to it. Watch out for kitchen cabinets — some inspectors may consider them as obstructions.
To cover all your grounds, ensure that your unit has a single door exit and a large enough window to act as the second exit.
6. Room sizes
A liveable space is more than tiny rooms squeezed together. According to the Building Code, kitchens, bedrooms, and living rooms each have to meet minimum size requirements. Sizing provisions also apply to an open space with a combined living room/kitchen or a studio space.
- Living room: 145 ft² (13.5 m²)
- Dining room: 75 ft² (17 m²)
- Kitchen: 45.2 ft² (4.2 m²)
- Combined living/kitchen: 118.4 ft² (11 m²)
- Master bedroom without closet: 95 ft² (9.8 m²)
- Other bedrooms without closet: 75 ft² (7 m²)
- Combined sleep/living/kitchen: 145 ft² (13.5 m²)
Note that closets aren’t always necessary in bedrooms. However, size requirements will differ between a bedroom with a closet and a bedroom without a closet.
7. Plumbing facilities
Requirements for plumbing are standard — you’ll need a kitchen sink, toilet, shower or bathtub, and a bathroom sink. Laundry can be in-suite if there’s a private facility for each unit, but it can also be a shared facilities room. The latter would have to meet specific fire separation requirements and be accessible by both units.
8. Natural light
People often think that they need bedroom windows because of egress windows. However, much of the time, it’s for natural light. Having light reach 2.5% of the floor area in older homes is acceptable. However, these provisions are much higher for new builds. For homes that are more than five years old, these are the minimum requirements:
- Living room/dining room: 5% of the floor area
- Bedrooms: 2.5% of the floor area
- Other finished rooms: 2.5% of the floor area
- Kitchen/bathroom/laundry: Not required
9. Fire and sound separation
People are aware of fire separation but often forget about sound separation, which is equally crucial for ceiling and wall assembly and insulation.
Ceiling assembly
For common dwelling splits (a basement unit and a ground-floor unit), the typical ceiling with a joist includes sound insulation and a resilient channel. This ceiling creates a separation between your drywall layer and the rest of the ceiling assembly, which is better for sound rating. A layer of Type X drywall, which has special core additives that lets you use it in fire-rated designs, comes after.
Wall assembly
You might have to go with two layers depending on the type of split. For example, if you have units that are split side-by-side, you’ll have to decide on a wall assembly that meets the minimum 45-minute Fire Resistance Rating (FRR) and the Sound Transmission Class (STC) 50 for the sound rating between dwelling units.
10. Smoke alarms and carbon monoxide detectors
You’ll need a smoke alarm for each bedroom and every other living space, such as a combined living/kitchen/dining room. Each newly created bedroom will require one too.
We recommend hardwired or wireless interconnections for smoke alarms for multi-unit homes, such as secondary suites and duplexes. By being interconnected, if one alarm gets triggered, they all get triggered. Single-family homes don’t require interconnections for smoke alarms. The benefit of having hardwired interconnections is reducing your FRR. Also, though wireless interconnections tend to be cheaper labor-wise, each device is more expensive as you purchase them one at a time.
Additional specifications for smoke alarms in secondary suites:
- One smoke alarm and one carbon monoxide detector within 16’ (5 m) of bedroom doors
- One smoke alarm and one carbon monoxide detector on each floor
- One in-duct smoke detector is required if you’re using a single furnace to heat both units
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Invest in research now to avoid bottlenecks in your project
Though there’s a lot of research to do before starting construction on your secondary suite, we highly recommend taking the time to go through this process. Doing your due diligence ensures that your project has a higher chance of getting a green light from your municipality and that you avoid risky problems later on.
What’s next?
Part Three of our guide series on secondary suites in Toronto will focus on the importance of obtaining a legal building permit and the penalties you may face otherwise.
