Rental Properties are more likely to be moldy than other homes.

Rental Properties are more likely to be moldy than other Homes

Rental properties are more likely to be moldy than other homes. This is a concern as excessive mold growth is known to harm human health likely be moldy

Once buildings are infested with mold, the difficult and costly issue of remediation arises,…ng-in-your-condo/    Landlords and tenants are caught in the middle of a tussle over who is responsible for fixing the problem. As one renter and research participant told us;

“The landlord came around [and] walked [into] every room where there’s black mold on the ceiling – like it’s freaking [something out of the TV series] Stranger Things – and she’s like, ‘Oh, a little bit of mold in winter, it’s very normal, it’s fine […] this happens every winter, it’s not a big deal”.

Heading into winter, after three consecutive La Niñasconditions are ripe for a mega-mold season. Combining our expertise in health, law, building and construction, we examine the problem of mold in homes and offer guidance for both renters and landlords,

Ideal conditions for growth

Mold is a fungal growth that reproduces via tiny airborne particles called spores. When these spores settle on moist, plant-based construction materials such as wood, wallpaper or plasterboard, they can form a new colony.

Growth is more likely when homes are cold, humid, lack air flow, or suffer from water damage.

So why is the problem of household mold worse in rentals? Weak regulation of tenancy legislation is just one of many factors. Rental properties tend to be poorly maintained, with structural problems such as leaks. Given this, they can be expensive to heat.


A chart showing the percentage of homes with structural defects in each category

Rental homes have more structural defects than owner-occupied homes.


How mold makes people sick

The World Health Organization recognizes mold can be harmful.

A 2022 Asthma report revealed people living in moldy homes were more likely to have asthma and allergies. A systematic review of peer-reviewed research found children living in moldy homes were more likely to experience asthma, wheeze and allergic irritation of the eyes, nose, throat and mouth (allergic rhinitis).

Living with mold is a source of stress. People worry about the consequences for their health and there is a growing body of evidence describing the negative mental health effects of moldy, damp homes.


Problems with managing mold in the rental sector

There is a gap between building and residential tenancies legislation. A building deemed to meet the minimum standards of the construction code with respect to mold may not meet the minimum standards for rental. That’s because there’s ambiguity in Canada’s National Building Code around the definition of “minimum standards of health”.

Mold remediation can be costly. A study by Victoria, B.C University found half the defects causing mold were water-related. These were more expensive to fix than other problems, by an average of $9500.

Each winter, the Toronto Tenant complaints department deals with a spike in renters seeking legal help to resolve their mold problems.

Despite increased legal protections, renters are still struggling to get mold fixed. For these reasons, many renters find the legal process doesn’t offer a solution to their problem, and instead move to a new property, with all its attendant costs and stresses. Others can’t afford to leave, or live in social housing with limited transfer options.

Where does the responsibility lie?

Tenancy legislation varies by state and territory. Renters should familiarize themselves with the regulations in their jurisdiction.

In Toronto, there is a criteria that “each room in the rented premises must be free from mold and damp caused by or related to the building structure”. Landlords should be forced to disclose if they have treated mold in the past three years.

For the most part, the responsibility for mold in rental properties lies with landlords if the cause is structural –- for example, if a broken or faulty window frame has let rainwater inside.

Requests for urgent repairs can be accompanied by an assessment report by an occupational hygienist, environmental health professional or expert from the local council. People with an existing health condition such as asthma can include a doctor’s report.

What next?

To achieve change across all relevant domains of regulation, construction, natural disaster response and government policy, we need a sustainable, broad healthy housing agenda in Toronto. We also need to consider options for immediate action.

As one renter noted:

“When we buy a car for the purpose of driving on the roads, we’re required to get a roadworthy certificate to make sure it’s safe, because of the risk to other people. Ideally it would be great if there was some kind of ‘rent worthy’ certificate to demonstrate that the property has been inspected, to identify any structural issues that might affect the incoming renter.”


What would be my first steps in order to get this potential issue looked at?

Call us! We can arrange an inspection to suit your schedule. We serve the entire GTA!.


Maple Leaf Mold Inc. is a certified  mold / asbestos removal and air analysis company located in Toronto that uses IICRC technicians for all testing and remediation projects.

We are a professionally licensed firm experienced in testing, verifying  and removing Mold / Asbestos / Lead and other environmental contaminants as well as providing disinfection services to control and kill biological contaminants.

Call 416-254-7256 to talk with us about your issue anytime.




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