How do I DIY caulk the joints on my Ottawa concrete driveway?

Caulking concrete driveway joints is a straightforward DIY project that can prevent water infiltration and extend your driveway's lifespan in Ottawa's harsh freeze-thaw climate. You'll need polyurethane or silicone-based concrete caulk, a caulk gun, backer rod for wider joints, and basic prep tools.

Proper joint sealing is critical in Ottawa because water that penetrates control joints freezes and expands during our 50+ annual freeze-thaw cycles, widening cracks and causing spalling. Concrete driveways have control joints (the intentional grooves cut every 3 metres) that are designed to crack in a controlled manner, but these joints must be sealed to prevent water infiltration.

Start by cleaning the joints thoroughly — remove all old caulk, debris, weeds, and loose concrete with a wire brush, scraper, or pressure washer. For joints wider than 6mm, install closed-cell backer rod (foam rope) to the proper depth before caulking. The backer rod should sit about 6-13mm below the surface, creating the right depth for caulk adhesion. This prevents the caulk from bonding to the bottom of the joint, which would cause it to tear when the concrete moves.

Use high-quality polyurethane or hybrid polymer caulk specifically designed for concrete and exterior use. Avoid cheap acrylic caulks that become brittle in Ottawa's temperature extremes. Apply the caulk in temperatures between 5-30°C with no rain forecast for 24 hours. Cut the caulk tube tip at a 45-degree angle to match your joint width, load it in the caulk gun, and apply steady pressure while moving along the joint. Tool the caulk smooth with a wet finger or caulk tool immediately after application.

Timing matters significantly in Ottawa's climate — avoid caulking during extreme temperature swings when concrete expansion and contraction are most active. Late spring through early fall provides the most stable conditions. The caulk needs to cure undisturbed, so avoid driving on the driveway for 24-48 hours depending on the product specifications.

Expect to recaulk every 3-5 years as Ottawa's freeze-thaw cycles gradually break down even high-quality sealants. Regular joint maintenance prevents minor water infiltration from becoming major structural problems. Well-sealed control joints can add 5-10 years to your concrete driveway's functional lifespan by preventing freeze-thaw damage from spreading beyond the intended crack locations.

If your control joints are severely deteriorated, wider than 25mm, or if you're seeing significant spalling around the joint edges, the damage may be beyond DIY repair and require professional concrete restoration or partial replacement.