What is the difference between structural and cosmetic stucco cracks in Ottawa?

Knowing the difference between structural and cosmetic stucco cracks saves Ottawa homeowners from either ignoring a serious problem or spending thousands fixing something harmless. The distinction comes down to what's causing the crack, how deep it goes, and whether it's actively getting worse.

Cosmetic Cracks (Low Concern)

Cosmetic cracks affect only the stucco itself and don't indicate any problem with the underlying structure. They're extremely common in Ottawa — virtually every stucco home older than a few years has some. Characteristics include:

• Hairline width: Less than 1/16 inch (1.5mm) wide. You can't fit a credit card edge into them.- Surface-only depth: They affect the finish coat or possibly the top of the brown coat but don't extend through the full stucco thickness.- Pattern cracking (crazing): A spider-web pattern of fine lines, usually caused by rapid drying during application. Very common on sun-exposed Ottawa walls.- Stable over time: They appeared within the first year or two and haven't noticeably widened since.- No displacement: Both sides of the crack are flush — one side isn't higher or more recessed than the other.

Cosmetic crack repair in Ottawa typically costs $2 to $5 per linear foot for surface filling, or $300 to $800 for a full-wall skim coat if the crazing is widespread. Many homeowners simply leave hairline cracks alone — they don't affect water resistance if the stucco has a proper drainage plane behind it.

Structural Cracks (Requires Attention)

Structural cracks indicate movement in the building frame or foundation and require investigation before any stucco repair makes sense. Signs include:

• Width greater than 1/8 inch (3mm): You can easily slide a coin or card edge into the crack.- Diagonal orientation from window/door corners: Classic 45-degree cracks radiating from openings indicate differential foundation settlement.- Displacement: One side of the crack is offset from the other — you can feel a step or ledge with your finger.- Active growth: The crack is wider than it was last season, or new cracks are appearing nearby.- Matching interior cracks: If you see cracks in the same locations inside the house (in drywall), the movement goes through the entire wall assembly.- Full-depth penetration: You can see lath or sheathing through the crack, meaning water is definitely getting behind the stucco.

Structural crack investigation in Ottawa starts with a professional assessment, typically $500 to $1,200 from a structural engineer. Foundation repairs, if needed, range from $5,000 to $25,000+ depending on the issue. Only after the structural problem is resolved does stucco repair make sense — otherwise you're patching cracks that will return within months.

Ottawa's Leda clay soils make structural cracks more common here than in cities built on bedrock. If your home is in Kanata, Barrhaven, or the south end and you see diagonal cracks growing over time, foundation investigation is strongly recommended before spending money on stucco repairs.

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

• Justyn Rook Contracting
• JC Carpentry
• Ottawa Caulking
• The Fixer
• jbstuccodecor

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