How do I maintain the expansion joints in my concrete driveway myself, and how much would the materials cost in Ottawa?

Expansion joints are one of the most overlooked maintenance items on concrete driveways, and in Ottawa's climate they take a serious beating. These joints — the grooved or filled lines between concrete slabs — exist to absorb movement as concrete expands and contracts with temperature changes. When Ottawa temperatures swing 60+ degrees between summer highs and winter lows, those joints are constantly working. Maintaining them yourself is entirely doable and well worth the effort.

Why Expansion Joints Fail in Ottawa

The original joint filler (usually a flexible caulk or foam backer rod) degrades over time from UV exposure, salt, snowplow scraping, and the constant freeze-thaw cycling. Once the filler cracks or pulls away, water enters the joint, freezes, and begins undermining the concrete slabs from below. In neighbourhoods across Barrhaven, Kanata, and Orleans, you'll see concrete driveways with perfectly fine slabs but completely failed joints — which leads to slab rocking, corner cracking, and eventually full panel replacement costing $1,500 to $3,000 per slab.

Materials You'll Need

Everything is available at Home Depot, Lowe's, or local Ottawa building supply stores:

• Foam backer rod (closed-cell polyethylene): $8 to $15 for a 20-foot roll. Buy a diameter slightly wider than your joint so it compresses snugly when pushed in. Most residential driveway joints are 10mm to 15mm wide
• Self-levelling polyurethane sealant (e.g., Sikaflex 1a or Loctite PL Concrete Crack Sealant): $12 to $18 per tube. You'll need 2-4 tubes for a typical two-car driveway. Polyurethane stays flexible in Ottawa's -30°C winters, unlike silicone which can harden and crack
• Caulk gun: $8 to $15 if you don't already have one
• Concrete joint cleaner or wire brush: $5 to $10
• Compressed air can or leaf blower: For clearing debris from joints

Total materials cost: $45 to $75 for a standard driveway with 20-30 linear feet of joints. Compare that to hiring a contractor at $300 to $600 for the same job.

Step-by-Step Process

Clean the joints thoroughly. Use a flat-head screwdriver or putty knife to scrape out old, crumbling filler. Then use a wire brush to clean the joint walls. Blow out all dust and debris with compressed air. The sealant needs clean, dry concrete to bond properly

Install backer rod. Push foam backer rod into the joint so it sits about 10mm below the concrete surface. This controls the depth of sealant (you want a 10mm depth, not a joint filled to the bottom) and prevents the sealant from bonding to the bottom of the joint, which would restrict its ability to flex

Apply sealant. Cut the caulk tube nozzle at an angle matching your joint width. Apply self-levelling sealant in a steady bead, slightly overfilling the joint. Self-levelling formula will settle to a smooth, flat surface on its own. For joints on a slope, use a non-sag formula instead and tool it smooth with a wet finger or popsicle stick

Cure time. Keep traffic off the sealed joints for 24-48 hours. Check the weather forecast — you need temperatures above 5°C and no rain during curing. In Ottawa, the best window is July through September

When to Do This

Inspect and maintain joints every 2-3 years in Ottawa, or whenever you notice gaps, crumbling, or separation. The ideal time is late summer or early fall before the ground freezes. Doing this in early October gives the sealant time to cure fully before Ottawa's first hard frost.

If your inspection reveals that concrete slabs have shifted significantly or joints are wider than 20mm, that's beyond DIY territory. Connect with a concrete contractor through Ottawa Driveways for a professional assessment and repair plan.