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What is a basement apartment?

Lindsay Smith

By Lindsay Smith/Columnist

What is a basement apartment called? Straight from an episode of Jeopardy, this is a question that seems to be a mystery for many buyers and sellers. As a real estate broker, I see homes being listed or sold with the definitions, duplex, in-law apartment, accessory apartments, and second living areas. I admit, it can get confusing.

I thought it would be a good time to review what the commonly used terms are, and which truly identify the secondary units that are legal in the eyes of the City of Oshawa.

The reason I chose to clarify this topic comes from my interaction with several buyers I have met over the past few years. I am the chairperson for a committee that reviews applications for minor variances for the City of Oshawa. How this relates, is that some buyers of homes have come before our committee looking for relief from the bylaws after purchasing a home with what they thought was a legal apartment, only to learn it did not meet the city’s requirements. Let us dig into the question of what makes a secondary unit legal.

The province put forth a mandate for municipalities to allow secondary units in all residential zonings. Since this time, many homeowners have created legal units inside existing homes, and many have built legal two-unit homes. In fact, there are approximately 3,500 homes on a registry list of legal secondary units in Oshawa. For the purposes of this article, we will discuss adding an accessory apartment to an existing home.

The rules are in some ways simple, and other ways complex when it comes to creating a legal accessory unit. There are physical requirements that need to fit into the bylaws and then interior changes that can be completed. The physical requirements that the property must have are:

– 11 meters frontage.

– Parking for three cars (two of which are always accessible to the street).

– 6’4” of height in the basement.

– 50 per cent open landscape space in the front yard.

– Compliance with Central Lake Ontario Conservation Authority.

These requirements are fixed or “must haves” and can only be modified by a minor variance. The other requirements can be created. These include egress windows, fire separation, in-furnace smoke detectors, flattening of duct work, and permanent ceiling smoke and carbon monoxide detectors.

I recently constructed a legal accessory apartment in a property I own and found several of the items can be dealt with by a contractor. In my case, the property met all physical requirements, however the height in the basement needed an I-beam to add enough head room and the addition of two egress windows to create both extra light and meet the fire regulations. The other items were regular building code requirements dealing with insulation and fire separation.

The definition of a legal second unit is “accessory unit” or a duplex. When the property is advertised as having an in-law suite, a bachelor or a secondary unit, it typically has a non-licensed unit in the home.

Having a legal accessory apartment is beneficial for two reasons:

– The city recognizes the unit as legal and allows the use to be continued, and

– A lender will include a portion of the rent to be added to the owner’s income to help qualify for a mortgage

The owner knows the unit is safe and meets the fire code.

There is also a monetary value to the certification of legal use. A buyer will typically pay more for a property with a legal unit than one without approvals.

If you have a property with an apartment that has not been certified by the City of Oshawa, now might be the time to bring it into compliance. There is a peace of mind offered when you know you own a safe and legal property. If you are planning on building an accessory unit, most of the information can be found at  (for information purposes only, please confirm any specific inquiries to Planning Services, City of Oshawa.)

If you have any questions about the above information, or if you need help with an investment property with or without a tenant, I can be reached at

Lindsay Smith

Keller Williams Energy Brokerage