Ask a Wahi REALTOR®: What To Check Before Buying a Home With a Basement Apartment

From compliance to amenities, here’s what Canadian homebuyers should consider before purchasing a property with a secondary suite, or “mortgage helper.”

By Josh Sherman | 2 minute read

A secondary suite is one of the most common ways for homebuyers to afford a single-family home — so common that these in-house apartments are known as mortgage helpers.

The income from a secondary suite can go towards mortgage payments, supplementing a household’s take home pay and offsetting the burden of higher carrying costs associated with a ground-oriented dwelling.

Wahi data suggests this approach is top of mind for homebuyers. For instance, in recent years “secondary entrance” has been the most popular search term on the listings portal (a secondary entrance is an indicator that the home has, or is capable of supporting an apartment, typically in the basement). And the results of Wahi’s 2025 What Homeseekers Want Survey reveal that 42% of Canadians who would prefer to purchase a single-family home want one with a finished basement.

However, not all basement apartments are created equal. For homebuyers seeking a property with a basement apartment, there is a lot to consider — not least of all whether or not the local municipality recognizes the suite to begin with. “A suite’s legal status can make a significant difference for Canadian mortgage lenders in deciding whether or not to count basement-suite rental income during the qualification process,” says Wahi Broker of Record Anne Alkok. “A property could generate rental income in practice without that income necessarily being accepted for mortgage qualification,” she continues.

Even if an apartment is legal, it still may not attract the type of tenant or income required for the endeavour to pan out. A cramped, dimly lit space won’t command the same rent as a recently renovated walk-out suite. To assist homebuyers who may be in the market for a home with a secondary suite, here’s what to check before buying a home with a basement apartment. 

1. Monitor the local rental market.

As with the ownership market, supply-and-demand conditions in the rental segment vary from location to location, right down to the neighbourhood. Before searching for a home with a basement, read up on the local market. Here’s how:

• At the macro level, rentals.ca releases a monthly report with the latest average asking rents in major cities across Canada. 
• Scan rental listings to see what rents are being advertised in your city or town at a more local level. 
• Take stock of local amenities, both existing and proposed. Transit accessibility, proximity to parks, essential services, and shopping can all boost the rent potential for a basement apartment. 
• Get in touch with a formal landlord association or a more casual group on social media. These communities can provide valuable on-the-ground insights from people who have already gone through the process of buying a home with a basement apartment. 
  

2. Confirm the apartment’s legal status. 

If the rental market looks like it could support your plans for a home with a basement apartment, it’s critical to ensure that the unit you’d like to rent out is legal before signing a purchase agreement.

The language in real estate listings can provide some clues. While some listings may explicitly state that the apartment is legal, others may use vaguer language such as “in-law suite.” Note that in either case, due diligence is required. Homebuyers cannot take the listing at face value. Due diligence can include one or more of the following:

• Many municipalities — such as Brampton, Mississauga, and Vaughan, in Ontario, and Surrey and New Westminster, in B.C. — require homeowners to formally register their secondary suites. In some cases, you can check these registries for free to confirm an apartment’s legal status. (Note that there are often nominal registration costs. For example, in Surrey, small landlords must obtain a secondary suite business license, which costs $170 annually.)

   

• Where public registries are not available, contact your local municipality’s building department to pull the address’s building-permit history.

   

• Consult the relevant building code. Knowledge of the national building code — or one of its provincial variants — can sometimes help you quickly determine whether a secondary suite is legal or not. For instance, the Ontario Building Code requires all habitable rooms in a basement apartment to have a ceiling height of at least 1.95 metres, or 6.5 feet (bring your measuring tape to showings). It also dictates that all bedrooms must have a window for escape in the event of a fire or other emergency. Regulations may vary somewhat from province to province, though many rules — such as ceiling heights and window requirements — are generally consistent.

3. Consider the intended use.

Homeowners should ask themselves what sort of tenant they are aiming to rent to and seek out apartments that reflect this. Different types of apartments work for different tenants. What is acceptable for a student or young professional might not be for a family or older relative. “It is important to view the unit closely,” says Alkok. When attending showings, you’ll want to pay special attention to how noise carries between the unit and the rest of the house to avoid future headaches.

4. Note the unit’s features.

How much rental income your basement generates depends on a variety of factors in addition to location. To maximize potential rental income, you may want to prioritize units with specific features and offerings, keeping in mind your intended use.

According to rentals.ca’s Summer 2025 Renter Preference Survey, tenants were most willing to pay higher rents for units in-suite laundry (57% of respondents), followed by air conditioning (44%), parking (43%), private outdoor space (34%), and pet-friendly policies (31%).