Why is my concrete driveway sinking on one side in Fredericton and how much does it cost to repair?

Your driveway is likely sinking due to soil settlement, washout from poor drainage, or frost heave damage — all common issues in Fredericton's clay-heavy soils and freeze-thaw climate. The repair cost depends on the severity, but expect $3-$6 per square foot for mudjacking or $5-$10 per square foot for poly levelling.

Soil settlement is the most frequent cause of sinking driveways in the Fredericton area. The Saint John River valley has clay-rich soils that expand when wet and shrink when dry, creating unstable conditions under concrete slabs. If the gravel base wasn't properly compacted during installation, or if water has washed away the supporting material, sections of your driveway will gradually sink as the soil beneath compacts under the weight of vehicles.

Poor drainage accelerates the problem. Fredericton's spring snowmelt and heavy rains can saturate the soil around your driveway, especially if gutters overflow or the grading slopes toward the concrete instead of away from it. Water infiltration weakens the soil's bearing capacity and can wash away the gravel base through small gaps in the concrete joints. Check if water pools near the sinking area after rain — this usually confirms drainage as a contributing factor.

Frost heave damage from New Brunswick's 4-foot frost depth can also cause differential settling. When soil freezes and expands unevenly under your driveway — often due to varying moisture content or soil composition — it can lift sections during winter and leave voids when it thaws in spring. Over several freeze-thaw cycles, this creates permanent settlement in the affected areas.

Mudjacking is the most common repair method, costing $3-$6 per square foot in the Fredericton market. A contractor drills small holes through the sunken concrete and pumps a cement-based slurry underneath to lift the slab back to level. This works well for settlement up to 2-3 inches and typically costs $800-$1,500 for a typical residential driveway repair. The concrete can usually be driven on within 24 hours.

Poly levelling uses expanding polyurethane foam instead of cement slurry, costing $5-$10 per square foot. While more expensive, poly levelling is lighter weight (won't overload weak soil), cures faster (driveable in 15 minutes), and works better in Fredericton's clay soils that may not support the additional weight of cement slurry. Budget $1,200-$2,500 for a typical repair.

Complete replacement becomes necessary when the sinking exceeds 4 inches, when the concrete has cracked extensively, or when the underlying soil problems are too severe for lifting methods. A new driveway section costs $8-$15 per square foot, so replacing a 200-square-foot sunken area would run $1,600-$3,000 including proper excavation and base preparation.

Address the root cause or the problem will return. Improve drainage by extending downspouts away from the driveway, regrading soil to slope away from the concrete, and sealing any cracks where water can penetrate. In Fredericton's clay soils, proper drainage is essential for long-term concrete stability.

Hire a professional for this repair. Mudjacking and poly levelling require specialized equipment and experience to avoid over-lifting or creating new cracks. A contractor can also assess whether the soil conditions will support lifting or if replacement is the more cost-effective long-term solution.

Need help finding a professional concrete contractor? New Brunswick Concrete can match you with experienced contractors familiar with Fredericton's soil conditions for a free assessment of your driveway repair options.

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