How do I level a settled Ottawa concrete slab driveway?

Leveling a settled concrete driveway requires professional slab jacking (mudjacking) or polyurethane foam injection — this is not a DIY project. Concrete slabs settle when the base beneath them compresses or washes out, and attempting to level them with surface patching compounds will fail within one Ottawa winter.

Slab jacking is the most common method for lifting settled concrete driveways in Ottawa. A contractor drills strategic holes through the concrete slab and pumps a cement-sand-water slurry (or modern polyurethane foam) beneath the slab under pressure. This fills voids in the base and gradually lifts the slab back to its original level. The holes are then patched with concrete. Polyurethane foam injection is newer technology that uses expanding foam instead of cement slurry — it's lighter, sets faster, and won't wash out, but costs more upfront.

Ottawa's clay soils and freeze-thaw cycles make concrete slab settling particularly common. Clay expands when wet and shrinks when dry, creating unstable subgrade conditions. Additionally, water infiltration through cracks or joints can wash out granular base material beneath the slab, creating voids that allow sections to drop. The 50+ freeze-thaw cycles Ottawa experiences each winter accelerate this process by driving water into any gaps between the slab and base.

Professional slab jacking in Ottawa typically costs $8 to $15 per square foot depending on the extent of settling and accessibility. This is significantly less expensive than tearing out and replacing the concrete driveway, which would run $10 to $16 per square foot for standard concrete. However, slab jacking only works if the concrete itself is structurally sound — extensively cracked or spalled concrete may need replacement regardless.

Surface leveling compounds and concrete resurfacing will not fix settled slabs. These products are designed for minor surface imperfections, not structural settling. Applying them over a settled slab creates a sloped surface that still pools water and looks uneven. The freeze-thaw action will crack and spall the thin overlay within one winter, leaving you with the original settling problem plus damaged surface material.

Signs your concrete driveway needs professional attention include sections that have dropped more than 25mm, water pooling in areas that previously drained properly, cracks that have widened significantly, or trip hazards where slabs meet. If the settling is minor (less than 12mm) and the concrete is otherwise sound, you might monitor it for one season to see if it stabilizes, but Ottawa's climate typically means settling will continue and worsen.

When to consider replacement instead of leveling: If your concrete driveway shows extensive cracking, surface scaling from salt damage, or has settled in multiple areas, full replacement may be more cost-effective long-term. A concrete contractor can assess whether the existing base is salvageable or if the settling indicates broader foundation problems that slab jacking won't permanently solve.

Need help finding a concrete contractor experienced with Ottawa settling issues? Ottawa Driveways can match you with local professionals who specialize in slab jacking and concrete repair for a free assessment of your specific situation.