How much does it cost to fix stucco blistering caused by moisture in Ottawa?

Stucco blistering—those bubbled, raised areas that eventually pop and flake off—is almost always a moisture problem, and in Ottawa's climate it's one of the most common stucco issues homeowners face. The repair cost depends entirely on whether you're treating the symptom or fixing the root cause.

Repair Cost Ranges

Surface-level blister repair (cosmetic only):

• Small area (under 20 sq ft): $400–$1,000- Moderate area (20–80 sq ft): $1,000–$3,000- Large area (80+ sq ft): $3,000–$6,000

This involves removing the blistered stucco, applying a bonding agent, and reapplying fresh stucco with colour matching. However, if you only fix the surface without addressing the moisture source, the blistering will return—often within one to two Ottawa winter cycles.

Full repair with moisture remediation:

• Small area with localized moisture fix: $1,500–$4,000- Moderate area with drainage plane repair: $4,000–$8,000- Extensive repair with full wall assembly correction: $8,000–$18,000+

Common moisture sources behind Ottawa stucco blistering:

• Missing or failed building paper/house wrap: This is the most common culprit, especially on homes built in the 1980s and 1990s when stucco was sometimes applied directly over sheathing without a proper drainage plane. Repair means removing stucco, installing a proper weather-resistive barrier, new lath, and re-applying stucco.- Failed caulking at penetrations: Windows, electrical outlets, hose bibs, and light fixtures that weren't properly sealed let water behind the stucco. This is the cheapest fix—re-caulking costs $200–$500, but the stucco damage repair adds $500–$2,000.- Ice dam related: Ottawa's freeze-thaw cycles create ice dams that force water up under roof edges and behind stucco at the soffit line. Addressing this may require improved attic insulation and ventilation alongside the stucco repair.- Splash-back and grade issues: Stucco that extends too close to grade (below the required 6" clearance per Ontario Building Code) absorbs ground moisture and road salt spray. Trimming the stucco back and installing a proper weep screed is essential.

Diagnosis before repair: A qualified contractor should use a moisture meter to map the wet areas behind the stucco before proposing a repair scope. This costs $150–$300 for a diagnostic visit but prevents you from paying to fix a 20 sq ft blister area when there's actually moisture damage across 100 sq ft that just hasn't blistered yet.

In Ottawa's climate, moisture behind stucco is never a static problem—it always gets worse through each freeze-thaw season. The water expands as it freezes, pushing the stucco further from the substrate, allowing more water in during the next thaw. If you've noticed blistering, address it before the next winter. The cost difference between catching it early and waiting a year can easily be $3,000–$5,000.

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