How do I check my Ottawa concrete driveway joints before winter?

Checking your concrete driveway control joints before winter is one of the most important maintenance tasks you can do in Ottawa — a few hours of inspection and simple repairs in September or October can prevent thousands of dollars in freeze-thaw damage over the coming winter.

Concrete driveways rely on control joints (the intentional saw-cut or tooled grooves spaced every 3 metres or so across the slab) to control where cracking occurs as the concrete expands and contracts. In Ottawa's climate, where temperatures swing 60+ degrees Celsius between summer and winter, these joints do enormous work. When they fail — when the joint sealant cracks, shrinks, or falls out — water gets in, freezes, expands by 9 percent, and begins prying the concrete apart from the inside. After 50 or more freeze-thaw cycles in a single Ottawa winter, that damage compounds fast.

What to Look For

Walk your entire driveway on a dry day and inspect every joint closely. You are looking for four things. First, missing or crumbling joint sealant — the flexible sealant that fills the joint should be continuous, slightly recessed below the surface, and still bonded to both sides of the groove. If it is cracked, pulling away from the edges, dried out and brittle, or missing entirely, water is getting in. Second, joint width changes — if a joint has widened beyond 10mm or shows uneven edges, the slab sections may have shifted, which points to base movement beneath. Third, cracks running out of joints — control joints are supposed to be where cracks happen in a controlled way. If you see cracks running diagonally or transversely away from joints, the joint is no longer doing its job. Fourth, spalling or scaling at joint edges — salt and freeze-thaw damage often concentrates right at joint edges first. Pitting, flaking, or crumbling concrete within 50mm of a joint means water has already been working its way in.

Also check the perimeter expansion joints where your driveway meets the garage slab, the sidewalk, or the house foundation. These are wider than control joints and filled with a compressible backer material plus sealant. They are often the first to fail and the most damaging when they do, because water infiltrating next to the foundation is a serious problem.

How to Repair Before Winter

For joints with failed sealant, the repair process is straightforward. Clean the joint thoroughly — remove all old sealant, debris, and vegetation with a cold chisel, oscillating tool, or joint saw. Blow out dust and loose material with compressed air or a leaf blower. For joints deeper than 12mm, install closed-cell backer rod (a foam rope slightly wider than the joint) to give the sealant a backing surface and control the depth of the sealant to roughly half the joint width.

Apply a polyurethane or silicone concrete joint sealant rated for exterior use and freeze-thaw conditions. Polyurethane (such as Sikaflex or Tremco THC-900) is the preferred choice for Ottawa driveways — it remains flexible through extreme temperature swings, bonds well to concrete, and resists salt and UV degradation. Do not use standard caulking — it will fail within one winter. Tool the sealant slightly concave (below the surface) so snowplow blades and snow shovels do not catch and tear it out.

Timing matters significantly in Ottawa. Aim to complete joint sealing by mid-October at the latest. The sealant needs ambient temperatures above 5 degrees Celsius to cure properly, and you want it fully cured before the first freeze. September is ideal — warm temperatures, dry conditions, and the sealant has time to fully bond before freeze-thaw cycling begins.

When to Call a Professional

DIY joint sealing is entirely reasonable for a homeowner comfortable with basic caulking work. However, if you find wide joint separation (over 15mm), significant slab edge spalling, cracks running across the slab surface, or any vertical displacement between slab sections (where one side is higher than the other), those are signs of base movement or structural issues that need a professional assessment. Slab lifting (mudjacking or polyurethane foam injection) can sometimes correct settled sections without full replacement, but only if the base conditions are suitable.

If your driveway is showing widespread joint failure and surface scaling across multiple sections, it may be approaching the end of its serviceable life. A concrete driveway in Ottawa typically lasts 25 to 30 years with proper maintenance — if yours is approaching that age and showing significant joint and surface deterioration, it is worth getting a professional opinion on whether repair or replacement makes more sense before investing in another season of patching.

Need help finding a concrete driveway contractor for a professional assessment? Ottawa Driveways can match you with local professionals through the Ottawa Construction Network — browse the directory at justynrookcontracting.com/directory?trade=paving.