Should I tear out old concrete or overlay it in Ottawa?

In Ottawa's climate, tearing out old concrete and starting fresh is almost always the better long-term investment — but overlaying can work in specific, limited situations. The decision comes down to the condition of your existing concrete, the integrity of the base beneath it, and whether the surface has experienced freeze-thaw spalling or structural cracking.

When Tearing Out Is the Right Call

If your concrete driveway shows any of the following, tear-out and full replacement is the only durable solution in Ottawa:

Structural cracking — cracks that run through the full depth of the slab, or cracks wider than 6mm, indicate base movement or failure beneath the surface. Overlaying over structural cracks guarantees those cracks will reflect through any new surface within one to two Ottawa winters. The freeze-thaw cycle is relentless — water finds every crack, freezes, expands 9 percent, and widens the damage with every cycle.

Frost heaving or settled sections — if slabs have shifted vertically relative to each other, the granular base has either failed or was never adequate. Ottawa's frost line sits at 1.2 to 1.5 metres, and any base that doesn't account for that depth will move. No overlay fixes a heaved base. You're building on an unstable foundation.

Widespread surface spalling — concrete that has scaled and spalled across more than 30 to 40 percent of its surface has compromised structural integrity. Spalling in Ottawa is usually caused by freeze-thaw cycling combined with salt exposure, and it typically means the concrete mix lacked adequate air entrainment (the critical 5 to 8 percent air void content that allows concrete to survive Ottawa winters). Overlaying over heavily spalled concrete produces poor bond adhesion and the new layer delaminates quickly.

Base drainage problems — if water pools on your driveway or drains toward your foundation, the grading is wrong. An overlay maintains the same grade. Only a tear-out allows you to regrade the base properly.

When an Overlay Can Work

A concrete overlay or resurfacing product can be a reasonable option if your existing slab is structurally sound — meaning the base is stable, slabs haven't shifted, cracking is hairline or cosmetic only, and the surface is flat and draining correctly. The existing concrete must be thoroughly cleaned, any cracks repaired with appropriate filler, and the surface mechanically prepared (shot-blasted or ground) to ensure proper bond. A properly applied overlay on a sound slab can last 8 to 15 years in Ottawa with good maintenance and resealing every 2 to 3 years.

The honest reality is that most Ottawa concrete driveways being considered for overlay are 25 to 40 years old, sitting on base layers that were never deep enough for Ottawa's frost conditions, and showing a combination of structural cracking, heaving, and spalling. In that scenario, an overlay is money spent delaying the inevitable.

Ottawa-Specific Cost Reality

Full concrete tear-out and replacement for an average Ottawa driveway (40 to 60 square metres) runs $6,000 to $14,000, including demolition, disposal, new granular base (minimum 300mm Granular B plus 150mm Granular A), and fresh 30 MPa air-entrained concrete. A concrete overlay on a sound existing slab runs $3,000 to $7,000 — meaningful savings if the conditions genuinely support it, but a poor investment if the base is compromised.

When getting quotes, ask every contractor to assess the base condition before recommending an overlay. A contractor who recommends overlaying without inspecting the base or probing for soft spots is cutting corners. Have them core-drill or excavate a small test area if base integrity is uncertain — it's worth the extra step before committing thousands of dollars.

Need help finding a concrete driveway contractor in Ottawa? Ottawa Driveways can match you with local professionals for a free estimate — or browse the Ottawa Construction Network directory at justynrookcontracting.com.