Should I repair all drywall cracks before repainting my Ottawa home interior?

The short answer is yes, you should repair drywall cracks before repainting — but the repair method depends entirely on what's causing the crack. In Ottawa, we deal with cracks that most other Canadian cities don't because of our extreme climate swings and the seasonal ground movement that comes with them.

Why Ottawa Homes Crack More

Ottawa sits on Leda clay (also called Champlain Sea clay), one of the most problematic soil types in Canada. This clay expands when wet and shrinks when dry, causing subtle but persistent foundation movement that telegraphs into your drywall. Add to that:

• Temperature cycling from -30C to +35C that causes framing lumber to expand and contract
• 6-7 months of heating that dries out interior wood framing, shrinking it
• Spring moisture surges when snowmelt raises the water table and re-expands clay soils

The result is that almost every Ottawa home develops drywall cracks over time. It doesn't necessarily mean something is structurally wrong — but you need to know the difference.

Types of Cracks and How to Handle Each

Hairline Cracks Along Drywall Seams

What they are: Thin cracks that follow horizontal or vertical lines — these run along the joints where drywall sheets meet. They're the most common type in Ottawa homes, caused by seasonal framing movement and sometimes by original taping that wasn't done perfectly.

Repair method: For cracks that have been stable (not getting bigger), apply a thin coat of setting-type joint compound (like Durabond 45 or 90), feather it out 4-6 inches on each side, sand smooth when dry, and prime before painting. Cost: under $20 in materials per room.

For recurring cracks that reappear every year, apply fibreglass mesh tape over the crack before mudding. The mesh adds flexibility and prevents the crack from telegraphing back through. This is extremely common in Ottawa — I'd estimate 60-70% of homes over 15 years old have at least one recurring seam crack.

Nail Pops

What they are: Small circular bumps or cracks where drywall nails have pushed outward through the surface. Ottawa homes are plagued by these because our seasonal wood shrinkage literally pushes nails out of the studs.

Repair method: Drive the popped nail back in, then install a drywall screw 2 inches above and below the nail to hold the drywall firmly. Apply two thin coats of joint compound over each spot, sand, and prime. Budget $2-$5 per pop in materials.

Corner Cracks (Where Walls Meet Ceiling)

What they are: Cracks along the ceiling-wall junction, often running the full length of the room. Caused by truss uplift or differential settling between ceiling joists and wall framing — both exacerbated by Ottawa's climate.

Repair method: For minor cracks, flexible paintable caulk is often the best solution because it accommodates ongoing movement. For larger cracks, re-tape with paper tape and compound, then finish with caulk along the very edge. This is one area where a professional's touch makes a real difference — sloppy ceiling-line repairs are very visible.

Diagonal Cracks From Window/Door Corners

What they are: Cracks that radiate diagonally from the corners of windows and doors. These are stress cracks caused by the natural concentration of structural stress at opening corners, amplified by Ottawa's temperature-driven movement.

Repair method: Apply setting compound (not premixed — it's stronger), feathering well beyond the crack. For recurring ones, use a stress-crack repair clip or fibreglass tape before mudding.

Wide or Growing Cracks (Red Flag)

What they are: Cracks wider than 1/4 inch, cracks that are clearly getting larger over time, stair-step cracks, or cracks accompanied by doors/windows that stick or floors that slope.

These may indicate a structural issue — foundation settlement, bearing wall problems, or significant soil movement. In Ottawa, Leda clay subsidence is a real concern in certain areas. Do not just patch and paint over these. Have a structural engineer assess the situation before cosmetic repairs. An engineering assessment typically costs $300 to $600 in Ottawa.

Repair Costs: DIY vs. Professional

DIY materials for a typical Ottawa home interior (10-20 cracks across various rooms):

• Setting compound: $15-$25


• Fibreglass mesh tape: $8-$12


• Sandpaper (150-220 grit): $5-$10


• Primer for repaired areas: $30-$40 per gallon


• Total: $60-$90

Professional drywall repair before painting:

• Most Ottawa painters include minor crack repair (10-15 small patches) in their painting estimate


• Extensive repair work adds $200 to $600 to a whole-house interior paint job


• Major drywall repair or replacement: $3 to $6 per square foot

The Ontario Building Code Connection

If crack repair reveals underlying moisture issues (common in Ottawa basements and exterior walls), the Ontario Building Code requires addressing the moisture source before refinishing. Simply patching wet or mould-affected drywall violates code and creates health hazards. WSIB-covered contractors should handle any work involving mould remediation.

The Bottom Line

Paint will not hide cracks. Even high-build primers and thick paints will show underlying cracks within weeks as the coating settles into the depression. Spending an extra day on crack repair before painting saves you from looking at imperfections for years.

The Ottawa Construction Network directory is a good place to find painters who include thorough prep work in their process. And if you're unsure whether your cracks are cosmetic or structural, Ottawa Paint Contractors' Paint IQ can help you figure out the right next step.