What counts as a 'major structural defect' under the Tarion 7-year warranty?

The seven-year major structural defect warranty is Tarion's most comprehensive long-term coverage. A major structural defect (MSD) is defined under the New Home Warranties Plan Act and generally means: a defect in a structural load-bearing component that results in the failure of a load-bearing element, or a defect that materially and adversely affects the use of the building as a home.

Not every crack in a foundation or wall qualifies. The defect must involve a load-bearing element — such as foundation walls, beams, columns, floor systems, or roof structures — and must pose a genuine risk of structural failure or render the home unlivable. Settlement cracks that are cosmetic in nature, for example, typically do not meet the MSD threshold.

Proving a major structural defect usually requires an engineering opinion. If you suspect an MSD, hire a licensed structural engineer to assess the issue and prepare a report before contacting Tarion or the builder. A Tarion field officer will also inspect, and the final determination involves a technical assessment of the building.

Seven years runs from the date of first possession, so even a relatively recent resale home may have remaining MSD coverage if it was built within that window.