Buying or Selling a Home with Mold in Ontario and Quebec
The home inspection flagged mold and now there is a deadline attached to it. Here is what your conditional period actually lets you do, what a seller has to disclose in each province, and where the two provinces differ more than most people expect.
Most of what you will find searching this question was written for a US market, about US disclosure rules that do not apply here. This guide covers Ontario and Quebec specifically.
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On a conditional period? Tell us your deadline and we will tell you what we can get done before it closes.
Working against a conditional deadline?
Conditional periods in Ontario and Quebec are usually measured in days, not weeks. If mold came up in your inspection report and you need an answer before the condition expires, a free virtual mold inspection can give you a read on the same day, and we can usually get someone on site the next morning.
Book Your Free Virtual Inspection NowDoes a home inspector check for mold?
Not the way most buyers assume. A general home inspection is a visual survey of the whole property, and a home inspector will note visible staining, moisture damage, musty odours, and conditions that tend to produce mold, such as poor grading or a bathroom with no working fan.
What a standard home inspection does not include is sampling. No air test, no surface swab, no lab analysis. So a report can say “possible microbial growth observed in the basement” without anyone establishing what it is, how far it extends, or whether it sits inside the wall assembly.
That gap is the reason a separate mold inspection exists, and it is why the phrase turns up so often in real estate. The home inspector found something and named it carefully. Somebody still has to find out what it is.
What a home inspector does
Looks at the whole property and flags visible damage and moisture conditions. Broad, visual, no lab work.
What a mold inspector does
Air and surface sampling with lab analysis, moisture mapping, and infrared to trace what sits behind finished surfaces.
Why it matters in a deal
A documented scope and cost is what you negotiate against. “Possible microbial growth” is not a number.
See what a full mold inspection covers, or read what a mold inspection costs.
Mold turned up in the inspection. What are your options?
You generally have four, and which one is sensible depends on something you do not know yet, which is how far the mold actually goes. Every one of these is a conversation to have with your own agent and your real estate lawyer, because the wording of your agreement decides what is available to you.
Proceed as agreed
Sometimes what got flagged is surface growth on a cold-water pipe or a bathroom ceiling, and the fix is small and well understood. Finding mold does not by itself mean a problem with the structure.
Renegotiate the price
The common route once there is a written scope and a real number attached to it. A quote is far more persuasive to a seller than a line in an inspection report.
Ask the seller to remediate before closing
Worth agreeing in writing who selects the contractor and what proof of completion looks like. Post-remediation verification testing is the usual proof.
Walk away
If your agreement carries an inspection condition and it has not expired, this is normally available to you. Once the condition is waived, it usually is not. Confirm with your lawyer.
The pattern worth noticing is that three of the four options need a number, and the inspection report does not give you one. That is the actual job in front of you during the conditional period.
Selling in Ontario: what you have to disclose
Ontario draws a line between two kinds of defect, and which side the mold falls on decides everything.
A patent defect is one that, in the words of the Real Estate Council of Ontario, “can be detected by a potential home buyer or their home inspector by reasonable observation and inquiry.” A seller does not have to point out a patent defect. Buyer beware applies. What a seller must not do is conceal it, and painting over active growth before a showing is the example that ends up in court.
A latent defect is one that “would make a property unfit for habitation, dangerous, or potentially dangerous, and is generally not apparent to someone exercising reasonable care in the inspection of the property.” Latent defects must be disclosed.
Whether a given mold situation is patent or latent is decided on its own facts, and it is a question for a lawyer rather than a rule you can apply yourself. Mold behind a finished basement wall sits in very different territory from mold on a window frame.
Where the seller’s duty comes from
This one surprises people. The seller’s disclosure obligation in Ontario comes from case law, not from real estate legislation. RECO states it plainly: “The seller’s obligation to disclose and the facts or defects they must disclose are based on current case law, not TRESA.”
What your agent has to do
Separate duty, and it binds the agent rather than you. Where a fact must legally be disclosed and the agent knows it, the agent must disclose it to every buyer who expresses an interest in the property, and make best efforts to get a written acknowledgement from each one.
The SPIS form is optional, and most sellers skip it
The Seller Property Information Statement, OREA Form 220, is the form where a seller writes down what they know about the property, and it includes questions about moisture and water damage. It is voluntary in Ontario. Outside a small number of local boards that require it for their listings, most sellers in the larger Ontario markets decline to complete one.
Filling one in does not create a disclosure duty you did not already have, and leaving it blank does not remove one. What it changes is the evidence. A completed SPIS is a written record of what you said you knew and when you said it, which cuts both ways depending on how carefully it was filled in. This is a decision to make with your agent and your lawyer rather than a box to tick.
Definitions and the quoted passage above are from the Real Estate Council of Ontario, Bulletin 7.4, Facts a seller has a legal obligation to disclose.
Selling in Quebec: the declaration form is mandatory, and it names mould
This is the difference most people carry across the provincial border and get wrong. Quebec does not leave seller disclosure to a voluntary form.
When a residential property with fewer than five dwellings is sold by an individual through a broker, the OACIQ Declarations by the seller of the immovable form is mandatory. It has been since July 2012. The seller fills it in, and the broker has a duty to gather and verify supporting documents rather than simply accept what is written.
The form asks about mould directly. Not by implication, by name:
D7.3 Have there ever been traces of mould, rot or fungi? □ yes □ no
If so, where? □ windows □ solariums □ walls □ ceiling □ other
D4.1 Have there ever been water infiltrations? □ yes □ no
If so, where? □ basement or crawl space □ roof □ patio □ balcony □ solarium □ skylight □ door □ window □ chimney □ other
D7.2 Has there ever been any unpleasant odour? □ yes □ no
Including dampness.
Quoted from OACIQ form DS 00001 (V17 06/2022).
Three separate questions, any one of which reaches a mold history. A Quebec seller who has dealt with a water infiltration and a musty smell has been asked about both, in writing, on a form they signed.
So the practical comparison is this. In Ontario the disclosure form is optional and frequently skipped. In Quebec it is mandatory and it asks about mould explicitly. Sellers who have moved between the provinces, and buyers comparing listings across them, routinely assume the two work the same way.
Questions quoted from the OACIQ Declarations by the seller of the immovable form. See also the OACIQ guidance on the declarations by the seller.
Buying in Quebec: vice caché and the inspection you decided to skip
Quebec gives buyers a protection Ontario does not, and attaches a condition to it that catches people out.
Under article 1726 of the Civil Code of Quebec, a seller warrants the buyer that the property is free of latent defects, described as defects “which render it unfit for the use for which it was intended or which so diminish its usefulness that the buyer would not have bought it or paid so high a price if he had been aware of them.” Mold inside a wall assembly is the kind of thing this was written for.
Here is the condition. The same article says the seller is not bound to warrant “against any latent defect known to the buyer or any apparent defect,” and defines an apparent defect as one “that can be perceived by a prudent and diligent buyer without the need to resort to an expert.”
A buyer who skipped a reasonable inspection can find that a defect is treated as one they should have seen. The warranty protects you against what was genuinely hidden. It is less help with what a careful buyer would have caught.
That is the honest argument for inspecting before you buy in Quebec, and it is a legal one rather than a sales one. The inspection is part of being the prudent and diligent buyer the Code describes.
If you find it after closing, the clock is already running
Article 1739 requires a buyer who discovers a defect to give the seller notice in writing within a reasonable time of discovering it. Where a defect appears gradually, that time runs from the day the buyer could suspect how serious and extensive it is.
What counts as a reasonable time is interpreted by the courts rather than fixed in the Code, and it depends on the circumstances. We are not going to print a number here, because relying on a number from a web page is exactly how people lose a claim. Notify the seller in writing as soon as you find the problem, keep a copy, and speak to a lawyer straight away. One point worth knowing: a seller who was already aware of the defect cannot rely on your notice being late.
Quoted from the Civil Code of Quebec, articles 1726 and 1739.
You already closed and found mold: do you have a claim?
Whether you have a claim depends on what the seller knew, whether the defect was hidden or visible, what was written in the agreement, and in Quebec how quickly you gave notice. That is a question for a real estate lawyer, and the sooner you ask it the more options you have.
What we can help with is the part that has to happen regardless of whether anyone ends up in a dispute, which is establishing what is actually there. Any claim rests on documentation, and recollection of what a wall looked like on moving day is not documentation.
A lab-backed inspection report gives you the extent, the moisture source, and a written scope. If it does turn into a legal matter, your lawyer has something dated and independent to work from. If it does not, you still need the same information to get it fixed properly.
Does mold reduce what a home is worth?
During a live transaction, what moves the price is not the mold itself. It is the uncertainty around it. A buyer looking at “possible microbial growth observed” with no scope and no number has to price in the worst case they can imagine, and the number they imagine is almost always larger than the number a contractor would write down.
Which is why sellers who get ahead of it tend to do better. A documented scope and a quote replaces an open-ended worry with a figure that can be discussed. Sometimes that figure comes off the price and sometimes the work gets done first, but either way it is being negotiated instead of guessed at.
Actual remediation costs vary widely with the extent of the growth, what it is growing on, and how much of the structure has to be opened up. A small bathroom job and a finished basement with moisture inside the wall assembly are different pieces of work. We quote after seeing it, and we publish general cost ranges for mold removal rather than a price list, because a fixed price before an inspection would be a guess.
If cost is the obstacle to closing, there are financial assistance options worth looking at.
How fast we can get there
Conditional periods do not wait, so the schedule is built around them.
A free virtual inspection can usually happen the same day you call, which is often enough to tell you whether what the report flagged is a small fix or something that needs a proper look. On-site inspections in our Ontario and Quebec service areas are typically available the next morning, and lab results come back with same-day reporting where the timeline requires it.
Tell us your condition expiry date when you book. It changes how we schedule you.
Or call 1-877-566-6653, 24/7.
Working in property beyond your own home
Plenty of people arrive here buying a first home and end up owning more than one property. Two related guides:
Renting it out
If the property becomes a rental, mold obligations shift onto you as a landlord, and both provinces have their own rules about response times and tenant complaints.
Commercial property
Commercial acquisitions carry their own due diligence expectations, usually on a longer timeline and with building science questions a residential inspection does not reach.
Buying in the Toronto area? See mold inspection and removal in Toronto, or read what a full mold inspection covers before you book one.
Since 2005 we have completed more than 15,000 inspections and 5,000 remediation projects across Ontario and Quebec. We are IICRC certified, RBQ licensed in Quebec, and hold an A+ rating with the Better Business Bureau. Samples go to independent testing laboratories accredited by CALA to ISO/IEC 17025:2017, so the results you hand to a lawyer or a seller are not produced in house.
Get the industry-standard mold removal guidelines
These are the same guidelines our certified crews follow on real remediation jobs. Useful if you are assessing a contractor’s proposed scope during a transaction. Enter your details and we will email you the download, no cost.
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Frequently asked questions
It depends on whether the mold is a patent or a latent defect. RECO describes a patent defect as one that can be detected by a buyer or their home inspector through reasonable observation and inquiry, and a seller does not have to disclose those, though they must not conceal them. A latent defect is one that is not apparent to someone exercising reasonable care in the inspection of the property and that makes the property unfit for habitation, dangerous, or potentially dangerous, and those must be disclosed. Which category a specific mold situation falls into is fact-specific, so ask a real estate lawyer about your own property. Note also that this duty comes from case law rather than from TRESA.
A home inspector will note visible mold, staining, moisture damage, musty odours, and conditions that encourage mold growth. What a standard home inspection does not include is air or surface sampling and lab analysis, so it cannot establish what the growth is or how far it extends behind finished surfaces. That is what a separate mold inspection is for.
If your agreement includes an inspection condition and it has not yet expired or been waived, walking away is normally one of your options, alongside renegotiating the price or asking the seller to remediate before closing. Once the condition is waived those options usually close. The wording of your specific agreement governs, so confirm your position with your agent and your real estate lawyer before the condition expires.
Vice caché is the latent defect warranty under article 1726 of the Civil Code of Quebec. The seller warrants the buyer that the property is free of latent defects that render it unfit for its intended use, or that so diminish its usefulness that the buyer would not have bought it or paid as much had they known. The warranty does not extend to defects already known to the buyer or to apparent defects, which the Code defines as those a prudent and diligent buyer could perceive without needing an expert.
Yes. The OACIQ Declarations by the seller of the immovable form has been mandatory since July 2012 for the sale by an individual of a chiefly residential property containing fewer than five dwellings. It asks about mould directly at question D7.3, which reads: Have there ever been traces of mould, rot or fungi? It also asks about water infiltrations and about dampness odours. This differs from Ontario, where the equivalent disclosure form is voluntary.
No. The Seller Property Information Statement, OREA Form 220, is voluntary in Ontario, and in the larger Ontario markets most sellers decline to complete one. A small number of local real estate boards require it for their own listings. Completing one does not create a disclosure obligation you did not already have, and declining does not remove one, but it does change what is on the record. Discuss the decision with your agent and your lawyer.
Speak to a real estate lawyer early, because whether you have a claim turns on what the seller knew, whether the defect was hidden, and what your agreement said. If the property is in Quebec, note that article 1739 of the Civil Code requires a buyer to give the seller notice in writing within a reasonable time of discovering a defect, so do not delay that step. Separately, get the extent documented with a lab-backed inspection. You need that information to fix the problem properly whether or not anyone ends up in a dispute.
There is no fixed percentage, and during a transaction the bigger factor is usually uncertainty rather than the mold itself. A buyer facing an undefined problem prices in the worst case they can picture, which is typically larger than an actual remediation scope. Getting a documented scope and a quote replaces that guess with a figure both sides can negotiate over. Remediation costs vary considerably with the extent of growth, the materials affected, and how much has to be opened up.
A free virtual inspection can usually be arranged the same day you contact us. On-site inspections across our Ontario and Quebec service areas are typically available the following morning, with same-day reporting where a deadline requires it. Tell us your condition expiry date when you book so we can schedule around it.
This guide explains how mold is treated in Ontario and Quebec property transactions. It is general information, not legal advice, and it does not account for the facts of your situation or the wording of your agreement. Speak to a real estate lawyer about your own transaction.
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