The sale of marijuana, along with growing a few plants, is now legal. How to manage the sale of marijuana and the potential tax base it will provide is being widely studied and debated across all media platforms and by all levels of government. However, what’s not being as hotly debated is what this could mean for the sale of your house or, worse yet, what happens if you buy a hazardous home.

Growing cannabis indoors requires high humidity and high temperatures. These conditions create perfect conditions for mould and fungus to grow and spread, which is difficult and expensive to remediate. The risk is uncontrivable: mould poses serious health and safety issues for home buyers. This is why cannabis grow-operations, regardless of size, have been villainized in the real estate industry.

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In the past, grow-ops were easier to identify: the home was typically abandoned, boarded and unkept. Heating bills were unusually high and the neighbours, should you ask them, would tell you of their suspicions. This is all about to change.

The federal legislation allows individuals to grow up to four plants in their home. While there are corresponding fire, plumbing and electrical regulations, it’s highly unlikely that everyone will comply. When legalization occurred in Denver, Colo., for example, one in 10 homes grew marijuana and very few complied with the health and safety regulations created to prevent the growth of mould and damage to the structure of the homes.

Limits on home growth and ensuring health and safety compliance in someone’s home – as opposed to a business – is hard to police. If you’re growing four plants, for example, and need to keep a certain level of humidity and heat, how can you prevent mould from building and then spreading?

The risks extend just beyond health. Some Realtors have shared cases with the Ontario Real Estate Association where buyers purchased a home, had the property remediated and brought up to building code standards, but were denied insurance coverage.

There’s serious lack of clarity regarding how home insurance compliance will fit into the legalization puzzle and what level of remediation is acceptable to obtain insurance. What’s also unclear is whether or not legal marijuana “grow-ops” pose a stigma that needs to be disclosed by either Realtors, when appropriate, or by the seller. Who’s responsible, for example, if a seller covers up the legal “grow-op” with a fresh coat of paint? Does that even need to be disclosed? When does a legal grow up become one that needs to be reported due to health and safety issues?

Home inspectors, one could argue, can be the shield to protect an unsuspecting buyer. The problem is that home inspectors do not have any mandatory training on how to identify a former marijuana grow-op – legal or not.

The best solution as a buyer is to ask the seller pointed questions about whether marijuana was grown or known to be grown in the home. Meanwhile, the public should support the real estate associations along with the Canadian Medical Association, the Canadian Association of Chiefs of Police and the Canadian Federation of Apartment Associations’ position that “no personal cultivation of cannabis be allowed inside homes and any provisions related to indoor personal cultivation be removed from the legislation and regulations.”


  1. You’re asking the wrong question! Your connecting with the wrong issue! The issue is not and has never been about pot. The issue is mold. The issue is not about legal or illegal! The issue is about health. Ok, you’re all pretty smart. Let’s focus on the correct terminology. Some of our offers to purchase already address the “is the house fit for human habitation” issue. Ok, my rant…:-)

    • Grant

      I agree entirely, but your post brings another question: who exactly is certified to provide with absolute certainty that the property is habitable from the “safety-no-mold spores” are tucked away in the HVAC systems or in the insulation in the attic or hiding in the electrical pot lights or in the wall receptacles or hiding in the motor in the kitchen fridge? Maybe in the jets in the bathtub, or in the window tracking sliders between the glass? Many places that homeowners typically often never especially clean. Spores feed on themselves. And maybe can only be identified in a Petrie dish.

      No regular building inspector is likely specially qualified, so does this issue you address create a whole new field of occupation expertise that can be government addressed in residential properties about to change ownership?

      And where does REALTOR(r) liability fit into the grand scheme of things? As much as the safety issue, this latter topic might be equally important. And is any relationship that comes unstuck in this regard covered by agency insurance? Who’s there to protect the agent when such surreptitious things are uncovered (pardon the pun) especially after the fact. How are judges equipped to analyze such argument presentations years in the making when the question arises, not unlike the health-related asbestos cases…

      Carolyne L ?

  2. These comments assume that one is buying or selling a home. But how about renting? Is a tenant obligated to report to the owner of the home that he/she is growing pot? Is the owner obligated to tell the potential buyer that he/she is suspicious that his/her past tenant may have been growing it?
    I imagine that the right to grow 4 plants “in one’s home”, includes in one’s rented home.

  3. there is one very large misconception in this article, cannabis should not been grown in high temperature nor in high humidity, it is best grown at 15 degrees C and very low humidity. The plants require water for the roots, not the leaves. The high humidity and high temperature is a result of poor setups. the lights create the high temperature, and the lack of ventilation creates the high humidity, lots of water in the room which evaporates because of the high temperature.

    All plants including cannabis require CO2 and give off oxygen, they can help our homes environment when grown properly.
    If a person grows pot in their home they should ensure the room is kept cool and well ventilated to ensure the ideal conditions for mold and fungus never exist.
    4 plants should be grown the same way as you grow your house plants, lots of light, low heat and dryer air.

    One could also argue that making it legal will stop the grow ops that are not created correctly, because those where created for the illegal drug trade.

    I have seen both the improper setup and the correct method, i have also seen the house where the plant sits in the front window and grows like a regular house plant.
    The illegal operations had setups with no care for the house, they were meant to make money, the legalization is to stop the illegal money making ventures and allow the public to grow their own, not every pot smoker is a drug dealer.

    The best practice for realtors when selling a house that has a grow op is investigate how the owner grew the cannabis, did they do it right or did they cut corners and create an issue for the environment.

    If we educate ourselves on the proper grow methods it gives us the power to understand and then educate our clients.
    If we are worried about a grow op then we should also be worried about the seller who has 50 house plants in their home, no difference if the pot is grown properly.

    Education is a must because ignorance is dangerous.

  4. And, like in the sale of all homes, where does “three times removed” for into the equation, not unlike the 80’s urea formaldehyde fracas?

    A current grow op owner might legitimately declare that no such “growing” had transpired during “his” ownership. But he remains mute that when he actually bought it, he subsequently discovered the property did in fact have a “growing” for personal use history. Now he wants to sell. He cannot speak to what happened before he bought it? Depends largely on how the question is asked, perhaps, of how a would-be disclosure is worded?

    But like the example you stated where a coat of paint can cover a multitude of sins, how does the insurance company know not to insure such properties? “They” must have a means of discovering such, obviously.

    After the urea formaldehyde properties changed hands repeatedly, even where it was well-known in the real estate community, that whole townhouse complexes had government blessings to install the formaldehyde insulation, and further government blessings to have it removed and the property declared “safe,” the properties very often did not come with any sort of historical disclosure, much less current disclosures in the day.

    Whether I did right or whether I did wrong, I avoided those townhouse complexes after I learned their history. I started by telling buyers the history (my full disclosure even if no one else disclosed) during sub-agency days and further in buyer agency. Some agents had disclosed on MLS, and buyers bought them anyhow.

    Investors literally “flew” over certain complexes in the early 1980’s, and there were lawyers in town who participated, buying as many as 85 units at a time.

    Some sellers had put their keys in the door and abandoned properties by the dozens. They became rental properties and in some cases the government even provided all new appliances to the investors. There were tenants who moved out when they discovered what was to be deemed a health hazard, and took all the new government supplied appliances with them.

    Long gone are the disclosures associated with those blocks of townhouses.

    Twenty years down the road, will the same situation show its face?

    Carolyne L ?

  5. You raise some great and very important points Natalka. This is where in Manitoba, “the growing of” is not permitted. Our provincial real estate industry lobbied the provincial government and we were heard and they followed our position to ban the growing. The federal government in my opinion has failed in their responsibility when legalizing it. All stakeholders as you mentioned should have been deeply included in the process to have a plan in place that ensured all aspects of this was considered and clear direction and measures were also in place before moving ahead which is not the place. The “let’s start driving and we will find our way” approach that is apparent is irresponsible. We REALTORS(R) must keep on top of our in-industry training on the subject and be even more diligent with our clients in asking the right questions, drafting the right terms in contract and continue guiding our clients through the process to pick up the new slack. Fortunately our industry has been on top of this for a long time and is educating the members as best as possible. In the end it reinforces why it is imperitive to use a REALTOR(R).


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