Legal Basement Apartments In Ontario

A Legal basement apartment in Ontario is a form of second dwelling unit that meets the Ontario Building Code Requirements for Second Units, The Ontario Fire Code, and local municipal zoning by-laws.
By: Baron Alloway

Basement Apartments are growing in popularity in Ontario. If you’re looking to buy a home in Toronto, a basement apartment represents the opportunity to make a little extra money, pay off the mortgage quicker, or perhaps more room for extended family. Those getting started in life typically prefer basement apartments for their lower entry cost and lack of maintenance. But is the basement apartment you have a legal basement apartment? In this guide, we’ll break down the core components of a legal basement apartment, provide examples, and hopefully provide guidance about the legalities of basement apartments.

An Introduction

The Basement apartment plays a significant role in the Toronto Real Estate Market. In the GTA in 2020, 1430 houses were sold that advertised some form of “basement apartment”. However, of those 1430, only 303 (or 21%) advertised the basement apartment as “legal”. (Source: Toronto Regional Real Estate Board)

The basement apartment plays a significant role in the Toronto Leasing Market, with 6440 basement apartments reported leased in 2020. (Source: Toronto Regional Real Estate Board)

It’s pretty clear that, even amongst real estate professionals, there’s significant confusion regarding what constitutes a legal basement apartment. There’s good reason for this: the rules concerning basement apartments are complex. Multiple codes and regulations across different levels of government make Basement Apartments an immensely confusing topic!

What is a Legal Basement Apartment

A Legal basement apartment in Ontario is a form of second dwelling unit that meets the Ontario Building Code Requirements for Second Units, The Ontario Fire Code, and local municipal zoning by-laws.

There’s a lot to unpack there. The First, and likely most important point to note about Basement apartments is that they are actually referred to as a “Second Unit” in the Ontario Building code. By omitting the location identifier of “Basement”, the code is able to address the minimum requirements for an additional dwelling space, regardless of the location within the home.

The Ontario Requirements for Second Units only apply in existing houses that are older than 5 years. If your house is less than 5 years old, it may be considered “new” and should comply to the new Ontario Building Code. For this, we’d recommend contacting an architect, planning official, and other professionals in the building industry.

However, if your house (or the house in which your basement apartment is located) is older than 5 years, the following will apply to you.

There are four standards that Second Units in Ontario must meet:

A note about “Retrofit”

When browsing listings on the MLS, one might typically see the advertisement (or disclaimer) that the basement apartment does (or does not) meet Fire Retrofit Requirements.

The term Retrofit (or Fire Retrofit) applies only to the Ontario Fire Code for second units. A basement apartment can meet retrofit requirements, but fail to meet the other standards, and still be deemed illegal. See Ontario Fire Code Retrofit Requirements.

Second Units and Zoning

Local Municipalities have the authority to allow or prohibit basement apartments (Second Units) in their zoning Code. Before undergoing the process of converting the Legal Basement Apartment, it’s important to ensure your local municipality allows them. This will vary by Municipality.

Toronto Zoning Requirements

Chapter 150 of the Toronto Zoning By-Law 569-2013 regulates Legal Basement Apartments in Ontario.

In General:

  • Allowed in Detached Homes, Semi-Detached, and Townhouses
  • Allowed in Townhouses to a maximum of one (1)
  • There are additional Parking, Entrance, and Building Requirements that may be more restrictive than Ontario Codes. Its best to read the chapter of the By-Law for more information.
Some Example Locations of Second Suites. Source: Ministry of Municipal Affairs and Housing

Requirements of a Legal Basement Apartment

Assuming you meet the applicable Zoning Codes for your area, you’ll likely wonder how to make a legal basement apartment.Below are the building requirements for a legal basement apartment (Building older than 5 years).

General Building Restrictions

The Minimum size of a basement apartment varies depending on the number of bedrooms contained. However, the minimum size for a bachelor second unit (with combined eating, living, and sleeping areas), is 145 square feet.

Measurements are from finished surfaces, and do not include closets.

Minimum Size Requirements of Second Units. Source: MMAH

The Minimum Ceiling height for a Legal Basement Apartment is 1.95M.

In situations where the ceiling of the Second Unit has a slope (in, for example, attic Second Units), 50% of the floor area must have a ceiling height of 2.03M. This area excludes the floor area where ceilings are less than 1.4M high.

If your basement is less than this height, you may have to undergo basement underpinning.

Window Requirements

Typically, the larger the unit, the bigger the windows required. Generally the following guidelines apply when the window is NOT being used as an exit:

  • Window size must be 5% of the floor area for the living and dining room
  • Window size must be 2.5% of the floor area for bedrooms
  • Windows not required in Laundry, Kitchen, or bathrooms

Plumbing Requirements

Legal basement apartments must have:

  • Hot/Cold water
  • Sink
  • Kitchen Sink
  • Access to laundry (shared is ok)
  • separate water shut-off valves from the main unit, and
  • may need a backwater preventer valve (depending on the situation).
  • Can exist in homes with septic service, but the current septic system must be able to support the additional load.

Heating and Cooling

Legal Second Units can share the furnace and ducts with the main unit. However, they must possess special smoke detectors (comply with UL268A) in the ducts that shut off the furnace in the event of an emergency.

Duct Smoke Detectors usually analyze air via sampling tubes, like This One Available on Amazon
Special Duct Photosensitive Smoke Detectors cut off the furnace if smoke is detected.

Ventilation is required for the bathroom and kitchen of the second unit. Bathroom ventilation may be in the form of a window or an exhaust fan.


Legal Second Units must have a light switch in every room & a switch at the top and bottom of the stairs, if applicable.

Legal Second Units must be inspected and approved by a licensed Electrical Safety Authority (ESA) Electrician. The electrician will either deliver a certificate or place a special sticker on the main breaker panel for the unit.

Fire Safety

Legal Second Units must have 30 minutes of fire separation between itself and the main unit. This fire separation can be in the ceiling or the walls, depending on the orientation of the Second Unit.

Examples of Fire Separation between units. Source: MMAH

If the whole house has interconnected smoke alarms, the minimum required fire separation is reduced to 15 minutes.

As with homes, smoke alarms are required:

  • On every level of the home or unit
  • In the common area outside sleeping areas
  • In each bedroom
  • In any other shared or Common areas (Laundry, for example)
  • In the Furnace Room, if it is separate for the Secondary Unit
Smoke Alarm Placement Requirements


Legal Basement Apartments may have a common exit with the main dwelling unit only if the smoke alarms are interconnected.

All Legal Second Units must have a second means of escape, if the primary entrance is through the main unit. This is the most common violation of basement apartments. The diagram below illustrates an acceptable window exit.

Secondary Exits in Second Units. Source: MMAH

How Do I know if my Basement Apartment is Legal?

Owners of Legal Basement Apartments should possess and be able to present, upon demand, the following proof that the Basement Apartment is Legal:

  • Fire Certificate from Local Fire Authority (or Fire Chief)
  • ESA Certificate, or ESA Sticker
  • Building Permit Completion or Certificate of Compliance from the Municipal Building Department – In some Municipalities this could also be proof of Registration

If you’re planning to rent a basement apartment, it’s prudent to ask the landlord for all 3 proofs. Failure to present could mean you are renting an illegal basement apartment.

Illegal Basement Apartment

There are unfortunate occasions in which you might end up unknowingly renting an illegal basement apartment. Your safety and wellbeing should always be your number one priority. While low rent might seem attractive, is the couple hundred dollars per month you save worth risking your life where you sleep?

The first step if you discover that your basement apartment might be legal should be to talk to The Landlord. Most issues with basement apartments are minor, since homes operating basement apartments typically historically complied with outdated codes. The requirements to adjust for the new regulations are typically minor in nature.

Even if the municipality considers the basement apartment “legal” by building code standards, it could still be illegal. In Toronto, it is illegal to have a basement apartment as a short term rental.

How to Report an Illegal Basement Apartment

If your landlord is unable or unwilling to produce proof the basement apartment is legal, contact your local municipality for further assistance and to report it. The City or Town is required to investigate the complaint and, if found to be illegal, remedy the situation.

There are strict penalties on the Landlord for operating an illegal basement apartment. The Municipality can:

  • Force the Landlord to fix the issues
  • Force the Landlord to evict the Tenant and pay for a portion of the Moving Costs and difference in rent
  • Force the Landlord to remove features that designate it as a Second Unit.
  • In cases where the Tenant is injured due to the illegal unit, the Landlord will receive criminal charges and face jail time.

Tenant Rights

Landlord-Tenant Relationships are governed by the Residential Tenancies Act, 2006, Ontario. (RTA). The RTA dictates that the tenant shall receive rights and protections under the RTA if the unit has its own Kitchen and Bathroom facilities.

Even if your basement apartment is deemed “illegal”, the lease and protections granted thereunder are not automatically deemed null and void. The Tenant would still receive the same rights owed to them as any other residential tenant in Ontario.

The Cost of A Legal Basement Apartment

Renovations to convert a basement into a Legal Basement apartment can be costly. The Average 1 bedroom basement apartment in the GTA leased for $1,110 in 2020 (Source: Toronto Regional Real Estate Board). It’s important to financially plan to ensure that you will receive sufficient return on your investment.

In addition to renovation costs, or if you’re planning to purchase a home with a basement apartment, you will likely be responsible for the costs of inspection, certification, and renovation of the Basement Apartment. If the seller does not have proof of the legal basement apartment, some certified home inspectors might be able to give you a good idea.**However, remember that a Home inspection report is not an adequate substitute for the required certification documentation.**

A significant renovation to your home could cause the property to be reassessed by the city. This could result in an increase in your property taxes.


Legal Basement Apartments in Ontario is a tricky topic. While this guide provides a detailed look at Basement Apartments and their legalities, it is not, by any means, all encompassing.

If you have additional Questions, Contact Catalyst with your questions.

Baron Alloway
Baron Alloway is the Broker of Record at Catalyst. As a trained engineer, Baron brings with him an extensive by-the-book amount of knowledge to the Real Estate World. Contact Baron today and have him help you buy or sell your next home.

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