How do you fix stucco that is bulging or pulling away from the wall in Ottawa?

Bulging or delaminating stucco is one of the more serious issues you can encounter, and in Ottawa's climate it needs prompt attention. When stucco separates from the wall, it creates a void where moisture accumulates—and once Ottawa's winter freeze-thaw cycles start working on that trapped water, the problem accelerates rapidly. What starts as a small bulge in October can become a large section of failed stucco by March.

The Repair Process

Fixing bulging stucco isn't a surface-level patch job. Here's how it's properly done:

1. Assessment and sounding — A contractor will tap the surrounding area with a rubber mallet or the handle of a tool, listening for hollow sounds that indicate where the stucco has separated. The affected area is almost always larger than what's visible from the surface. Expect the actual delamination zone to extend 6–12 inches beyond the visible bulge.

2. Removal of the failed section — The delaminated stucco is carefully cut out using a grinder or masonry saw, cutting back to where the bond is still sound. This is done in a clean geometric shape (usually rectangular) to make the patch easier to blend.

3. Inspection of the substrate — This is the critical step. Once the stucco is removed, the contractor checks the metal lath, building paper or house wrap, and sheathing underneath. In Ottawa, the most common findings are:

• Corroded or improperly fastened lath- Torn or deteriorated moisture barrier- Wet or rotted sheathing (especially on north-facing walls)- Missing weep screeds at the base, trapping moisture

4. Substrate repair — Any damaged lath, moisture barrier, or sheathing is replaced. New galvanized metal lath is secured with proper fasteners at the spacing required by the Ontario Building Code.

5. Re-application in coats — Stucco is applied in the traditional three-coat system: scratch coat, brown coat, and finish coat, with proper cure time between each (typically 24–48 hours). The finish coat is textured and coloured to match the existing wall.

6. Sealing and blending — The edges where new meets old are sealed, and the entire section may need painting to achieve a uniform appearance.

Cost expectations in Ottawa:

• Small bulge repair (under 10 sq ft): $800–$2,000- Medium section (10–50 sq ft): $2,000–$5,000- Large area or multiple walls: $5,000–$12,000+

This is not a DIY repair. It involves cutting into the wall assembly, inspecting structural components, and re-applying a multi-coat system that must cure properly. If the underlying cause (usually moisture infiltration) isn't addressed, the new stucco will eventually delaminate too.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• Justyn Rook Contracting
• JC Carpentry
• Capital City Drywall
• Diamond renovations
• Regimbal

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