What 71% of Markham Homes Have Hidden in Their Walls — And Why You Must Get an Inspection

A significant proportion of Markham's housing stock was built between 1975 and 2005 — a thirty-year span that produced detached homes, semis, and townhomes across Greensborough, Wismer Commons, Berczy Village, Cornell, Box Grove, Raymerville, Milliken Mills, and dozens of other communities. These homes are well-built, well-loved, and actively competing for buyers. They are also homes where decades of Ontario building practices, material choices, and maintenance histories mean that what is visible during a showing is not a complete picture of what you are buying.

Michael John Lau, top real estate agent in Markham Ontario, has a consistent message for every buyer he represents on a resale Markham home: include a home inspection condition in your offer. Every time. Without exception. Here is exactly why.

The Hidden Issues Most Common in Markham's Housing Stock

Knob-and-Tube Wiring

Homes built before approximately 1950 in Markham's oldest communities — Markham Village, Bullock, and portions of the original village areas — may still contain original knob-and-tube electrical wiring. Insurance companies routinely refuse coverage or impose significant surcharges. A licensed inspector identifies active knob-and-tube and can quantify remediation cost.

Aluminum Wiring (1965 to 1975)

Homes built in the late 1960s and early 1970s — a meaningful portion of Markham Village and Raymerville's stock — were frequently wired with aluminum rather than copper. Aluminum expands and contracts differently than standard hardware, creating loose connections that generate heat and fire risk. The ESA estimates that approximately 71% of homes with original aluminum wiring have at least one connection that needs remediation. Insurers typically require complete rewiring or approved aluminum-to-copper connections at every outlet before providing coverage.

Galvanized Steel Water Supply Pipes

Homes built before 1960 may have galvanized steel supply pipes that have corroded internally over decades — reducing water pressure, contaminating water with rust, and creating leak risk. The signs are not always visible during a showing. A home inspector tests water pressure at multiple points.

Asbestos-Containing Materials

Homes built before 1985 — a substantial portion of Markham Village, Raymerville, Milliken Mills, and early Unionville — may contain asbestos in floor tiles, insulation, drywall compound, popcorn ceiling texture, and duct wrap. Undisturbed asbestos is not a health hazard but is a renovation-triggering concern.

Polybutylene Water Supply Pipes

Homes built between 1978 and 1995 — a large swath of Markham's detached stock in Milliken Mills, early Cornell, Berczy Village, and Wismer — may have grey plastic polybutylene supply pipes, which degrade over time with chlorinated water, creating spontaneous burst risk that floods finished basements without warning.

Inadequate Attic Insulation and Ventilation

Under-insulated attics create ice dams — when escaping heat melts roof snow that refreezes at the eave, backing water under the shingles and into the ceiling. Ice dam damage is one of the most common and expensive claims in Ontario home ownership.

Foundation Cracks and Water Infiltration

Markham's clay-heavy soils expand and contract significantly with seasonal moisture changes, placing consistent pressure on foundation walls. Horizontal cracks, water staining, efflorescence, and sump pump conditions all tell stories invisible to buyers during a standard showing. A home inspector goes where buyers do not — crawl spaces, behind access panels, and along the full foundation perimeter.

Why the Inspection Condition Is Non-Negotiable in 2026

A home inspection condition in your Agreement of Purchase and Sale gives you the right to renegotiate or walk away if the inspection reveals issues that materially affect the property's value or condition. In the current Markham buyer's market, where sellers are accepting conditional offers routinely, this protection is available to every buyer who asks for it. There is no rational argument for not using it on a resale home.

In the 2021 market, buyers waived home inspections because they had to — competition was so fierce that conditions were used as a differentiator. In 2026, with 755 active listings and 33 days average time on market, you do not have to waive your inspection. If a seller in the current Markham market refuses to accept an offer with a home inspection condition, that refusal is itself a red flag worth investigating.

Michael John Lau, top real estate agent in Markham Ontario, recommends qualified home inspectors to every buyer client and structures every offer on a resale Markham home to include an inspection condition as a baseline protection.

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