Stucco and cladding failures are a major source of water damage in Ontario homes. This guide covers failure modes by cladding type, repair vs replacement decision criteria, and 2026 GTA contractor cost ranges.
One-Coat vs Three-Coat Stucco
Three-coat traditional stucco (pre-1970s homes): Most durable. Repair with lime-based finish coat. 25-38mm total thickness over metal lath.
One-coat synthetic stucco (1990s-2000s homes): Often installed without drainage plane — notorious for water entrapment and concealed rot behind cladding. If your GTA home has this cladding, assume concealed moisture damage until moisture-metered and proven otherwise.
Common Failure Modes
Cracks at window/door corners: Stress concentration. Seal with elastomeric caulk annually. Wide (>3mm) or recurring cracks may indicate structural movement.
Staining below penetrations: Indicates flashing or sealant failure. Requires immediate investigation — stucco conceals damage until extensive.
Bulging or delamination: Stucco separated from substrate. Indicates water behind cladding. Remove and inspect substrate before re-stuccoing.
Repair vs Replacement
Repair: cosmetic cracks, sound substrate, no infiltration evidence, system under 20 years old.
Replace: moisture meter >19% in framing, soft spots in OSB substrate, visible mould at wall cavity, EIFS system with no drainage plane.
Cost Ranges (GTA 2026)
- Crack repair (caulk and paint): $500-$2,000 per elevation
- Partial patch and blend: $1,500-$5,000
- Full removal and re-cladding (Hardie, Maibec, new stucco): $20-$45/sq ft installed
- Substrate repair if moisture damage found: $3-$8/sq ft additional
Full guide with material specs: https://telegra.ph/Ontario-Stucco-and-Cladding-Repair-Guide-2026---Costs-Water-Damage-and-Replacement-04-26