Should I fill cracks under 1/4 inch on my Ottawa asphalt driveway?

Yes, you should fill cracks under 1/4 inch (6mm) on your Ottawa asphalt driveway. Even small cracks allow water penetration, and Ottawa's 50+ freeze-thaw cycles per winter will rapidly expand these hairline cracks into major structural damage within 1-2 seasons if left untreated.

Why small cracks matter in Ottawa's climate: Water enters even the tiniest surface cracks, freezes and expands by 9 percent, then thaws and allows more water to penetrate deeper. Each freeze-thaw cycle widens the crack and extends it further into the asphalt structure. What starts as a hairline crack in spring becomes a 10-15mm crack by fall, and a major structural crack requiring expensive repair within two winters. Ottawa's extreme temperature swings from -30°C to +35°C create relentless expansion and contraction that stresses these weak points.

For cracks under 6mm, use liquid crack filler — available at Canadian Tire, Home Depot, or paving supply stores for $15-25 per bottle. Clean the crack thoroughly with a wire brush or compressed air to remove debris, vegetation, and loose asphalt. Apply the liquid filler directly from the squeeze bottle, slightly overfilling to account for settling. Smooth with a putty knife and allow 24-48 hours to cure before vehicle traffic. This creates a flexible seal that moves with the asphalt through temperature changes.

Timing is critical in Ottawa — fill cracks during warm, dry weather (above 15°C) with no rain forecast for 24 hours. Late spring through early fall provides the best conditions. Avoid filling cracks when temperatures are below 10°C, as most crack fillers won't cure properly in cold conditions. If you're planning to sealcoat your driveway, fill all cracks first and allow them to cure for at least one week before applying sealer.

When to call a professional: If you have numerous cracks or any cracks wider than 6mm, consider hiring a paving contractor with hot-pour crack filling equipment. Hot-pour rubberized crack filler costs $2-5 per linear foot professionally applied but remains flexible through Ottawa's extreme temperature cycles and lasts 3-5 years versus 1-2 years for cold-pour DIY products. Professional crack filling before sealcoating extends your driveway's life significantly and prevents the need for expensive overlay or replacement work.

The small investment in crack filling now prevents major structural damage that would require costly repairs within a few Ottawa winters.