One of the most anxiety-inducing questions for Markham homeowners preparing to sell is this: what do I legally have to tell the buyer about my home? Ontario disclosure law is frequently misunderstood — and getting it wrong, in either direction, creates real legal and financial risk. Michael John Lau and Neeraj Moolchandani at Kaizen Real Estate Team walk every Markham seller through their disclosure obligations before any listing agreement is signed.
Important Disclaimer: This blog provides general educational information about seller disclosure obligations in Ontario real estate. It is not legal advice. Every Markham seller's situation is unique. Before listing your home for sale in Markham, Ontario, consult a licensed Ontario real estate lawyer to confirm your specific disclosure obligations and review your listing documentation.
The Legal Foundation of Seller Disclosure in Ontario
Ontario's seller disclosure framework is rooted in common law — specifically the principles of misrepresentation and caveat emptor ("buyer beware"). Unlike some jurisdictions that require sellers to complete detailed mandatory disclosure forms, Ontario takes a more nuanced approach that places different obligations on sellers depending on the type of defect involved.
Under Ontario common law, a Markham home seller has a positive legal duty to disclose known material latent defects — while being under no general obligation to volunteer information about patent defects that a buyer can discover through reasonable inspection. Understanding the distinction between these two categories is the foundation of every Markham seller's disclosure strategy.
Patent Defects vs. Latent Defects: The Critical Distinction
The difference between a patent defect and a latent defect determines whether a Markham seller has a legal obligation to disclose it — and the consequences if they do not.
A patent defect is a defect that is visible and discoverable by a buyer conducting a reasonable inspection of the Markham property — either personally or through a qualified home inspector. Under the principle of caveat emptor, Markham sellers are generally not required to point out patent defects to buyers.
- Cracked driveway or walkway
- Visibly stained carpet or flooring
- Dated kitchen or bathroom finishes
- Worn roof shingles visible from ground level
- Peeling exterior paint
- Broken window — visible to any viewer
A latent defect is a defect that is not visible upon reasonable inspection and that a buyer would not discover without specialized knowledge or testing. Markham sellers have a positive legal obligation to disclose known material latent defects — defects that render the property dangerous, unfit for habitation, or that affect value in ways a buyer would not reasonably anticipate.
- History of basement flooding concealed by recent finishing
- Active mould behind finished drywall
- Vermiculite insulation in the attic containing asbestos
- Underground oil storage tank on the property
- Structural issues concealed by cosmetic renovation
- Known water intrusion through a foundation wall
What Markham Sellers Must Disclose Under Ontario Law
Michael John Lau and Neeraj Moolchandani advise every Markham seller that Ontario law requires disclosure of known material latent defects, and that attempting to conceal or minimize a material defect creates far greater legal and financial risk than transparent disclosure. Here are the most common categories of material latent defects that Markham sellers must disclose:
A history of basement water infiltration or flooding in a Markham home — even if the issue has been remediated — is a material latent defect that must be disclosed to buyers. Concealing a known flooding history is one of the most litigated disclosure failures in Ontario real estate.
The presence — or former presence — of an underground fuel storage tank on a Markham property is a material latent defect. Oil tank contamination can cost tens of thousands of dollars to remediate and creates significant environmental and financial liability for buyers who purchase without disclosure.
If a Markham seller knows that active mould exists behind finished walls, under flooring, or in concealed spaces — and that mould is not visible during a standard inspection — this constitutes a material latent defect that must be disclosed. This includes mould discovered during previous renovations.
Known structural defects in a Markham home — including foundation movement, load-bearing wall compromises, or engineered wood system failures that have been concealed through cosmetic renovation — are material latent defects requiring disclosure under Ontario law.
Unpermitted additions, electrical work, or structural modifications in a Markham home that affect safety or violate the Ontario Building Code — and that are not visible or discoverable through standard inspection — may constitute material latent defects requiring disclosure.
Vermiculite insulation — common in Canadian homes built before 1990, including many Markham properties — may contain asbestos. If a Markham seller knows their home contains vermiculite insulation that has tested positive for asbestos, or that is suspected to contain asbestos based on its age and origin, this is a material latent defect requiring disclosure.
What Markham Sellers Are Generally NOT Required to Disclose
- Patent defects — visible, discoverable issues that any buyer or home inspector would identify during a reasonable inspection of the Markham property
- The sale price of comparable Markham homes — sellers are not required to share their knowledge of recent comparable sale prices
- The reason for selling — Markham sellers are not legally required to disclose their personal motivation for selling (divorce, financial pressure, job relocation, etc.)
- Stigmatized property history in most cases — Ontario courts have generally not required disclosure of non-physical stigmatizing events (e.g., a death on the property) unless the seller has been directly asked
- Neighbourhood characteristics — nearby construction plans, traffic patterns, or community composition are generally not seller disclosure obligations
- Known active or historical basement flooding or water infiltration in the Markham home — even if "fixed"
- Active mould that is not visible or discoverable during a standard inspection
- Known underground oil storage tanks — active or previously decommissioned
- Structural defects that have been concealed by cosmetic renovation or finishing
- Known vermiculite or asbestos-containing materials in hidden or inaccessible spaces
- Any defect that renders the Markham property dangerous or materially unfit for habitation
The Seller Property Information Statement (SPIS): Should Markham Sellers Complete One?
The Seller Property Information Statement (SPIS) is a standardized document created by the Ontario Real Estate Association (OREA) that asks Markham sellers to answer questions about the property's condition. Completing and providing a SPIS is entirely voluntary in Ontario. No Ontario law requires Markham sellers to complete a SPIS.
However, if a Markham seller voluntarily completes a SPIS and provides it to buyers — through their REALTOR® or directly — every representation made in that document becomes legally binding. A misrepresentation on a SPIS, even an inadvertent one, can expose a Markham seller to significant legal liability.
Many Ontario real estate lawyers advise Markham sellers not to complete a SPIS because the document can create legal obligations that are broader than what Ontario disclosure law would otherwise require. Michael John Lau and Neeraj Moolchandani discuss the SPIS question with every Markham seller — and recommend consulting an Ontario real estate lawyer before making any decision about completing one.
Legal Consequences of Non-Disclosure for Markham Sellers
Markham sellers who fail to disclose known material latent defects face serious legal and financial consequences. Ontario courts take disclosure failures seriously — and buyers who discover concealed defects after closing have multiple legal remedies available to them.
Frequently Asked Questions: Seller Disclosure in Markham, Ontario
Under Ontario law, a home seller in Markham or anywhere in Ontario is legally required to disclose known material latent defects — defects not visible upon reasonable inspection that render the property dangerous, unfit for habitation, or that affect value in ways a buyer would not discover without specialized knowledge. Common examples include basement flooding history, active hidden mould, underground oil tanks, structural issues concealed by renovation, and vermiculite insulation. Sellers are not generally required to volunteer information about patent defects visible during a standard inspection.
No. The Seller Property Information Statement (SPIS) is not mandatory in Ontario. Markham sellers are not legally required to complete or provide a SPIS to buyers. However, if a seller voluntarily completes a SPIS, all representations made in it become legally binding. Many Ontario real estate lawyers advise Markham sellers against completing a SPIS because it can create legal liability beyond what Ontario disclosure law would otherwise require.
If a Markham seller fails to disclose a known material latent defect, they may face a lawsuit for misrepresentation, rescission of the sale transaction, and/or financial damages to compensate the buyer for remediation costs. Ontario courts have awarded substantial damages in cases where Markham sellers knowingly concealed material latent defects such as flooding history, structural issues, or hidden mould.
A patent defect in Ontario real estate is visible and discoverable by a buyer through reasonable inspection — such as a cracked driveway or broken window. Sellers are not generally required to point out patent defects. A latent defect is not visible upon reasonable inspection — such as hidden flooding history or mould behind walls. Markham sellers have a legal obligation to disclose known material latent defects to buyers under Ontario common law.