Major Structural Defect (MSD) — three-test framework (failure / function / use) defines what qualifies for year 3-7 coverage
Claim: A Major Structural Defect (MSD) under Tarion's 7-year warranty is any defect in work or materials that meets any one of three tests:
- Failure test — results in failure of a structural load-bearing element of the building.
- Function test — materially and adversely affects the ability of a structural load-bearing element to carry, bear and resist applicable loads for its usual service life.
- Use test — materially and adversely affects the use of a significant portion of the building for usual residential purposes.
Source: Tarion Registrar Bulletin 03 (Major Structural Defects); Builder Bulletin 24R supplements.
Confidence: Verified.
Examples that qualify: significant damage from soil movement, major basement-wall cracks compromising the structure, collapse or serious distortion of joists or roof structure, chemical failure of materials (e.g., excessive radon ingress affecting habitability).
Examples explicitly excluded from MSD: cosmetic dampness, damage to drains, damage to finishes, condensation issues not tied to a structural failure.
Coverage cap context: A post-July 2023 freehold home has up to $400K total post-possession coverage (the same pool covers MSD and earlier-year claims combined). The $50K environmentally-harmful-substances sub-limit (radon, mould) applies for APS on/after Feb 1, 2021. See Tarion coverage caps: APS on/after July 1, 2023 — $400K freehold / $300K condo unit / $100K × units common elements to $3.5M cap; $50M project cap.