How do I fix sunken or uneven pavers on my Ottawa patio?

Sunken or uneven pavers are one of the most common patio issues in Ottawa, and our freeze-thaw cycle — over 50 transitions per winter between roughly -30°C and above zero — is almost always the root cause. Water infiltrates beneath the pavers, freezes, expands the base material, then thaws and leaves voids. Over a few seasons, individual pavers or entire sections can drop 1-3 cm, creating trip hazards and pooling water that accelerates the problem.

The repair process starts by carefully removing the affected pavers and any immediately surrounding them. Use two flat-head screwdrivers or paver pullers to lift them out without chipping the edges. Once removed, examine the bedding sand layer underneath. In most Ottawa repairs, you will find the bedding sand has either washed out or compacted unevenly. Scrape out the remaining bedding material down to the gravel base and check whether the base itself has settled. If the granular A base has dropped, you will need to add fresh material and compact it with a hand tamper or small plate compactor before rebuilding the bedding layer.

For the bedding layer, use coarse concrete sand (not play sand or limestone screenings, which hold moisture and are more susceptible to frost heave). Spread it to a consistent 25 mm depth using screed rails for accuracy. This uniform depth is critical — inconsistent bedding thickness is what causes pavers to settle unevenly in the first place.

Before resetting the pavers, check each one for cracks or surface damage from freeze-thaw. Ottawa winters are brutal on lower-quality pavers, so replace any that have delaminated or cracked through. Reset the pavers, confirm they are level with the surrounding surface using a straight edge, and then sweep polymeric sand into the joints. Activate the polymeric sand with a fine mist — not a heavy spray, which can wash it out before it sets.

If you are dealing with widespread settling across a large area rather than a few isolated pavers, the underlying issue may be inadequate base depth. Ottawa patios need a minimum 200 mm compacted granular base to handle our frost conditions, and high-traffic areas or those on clay-heavy Leda clay soils may need 250-300 mm. A section-by-section repair might be warranted, or in some cases, a full base rebuild is more cost-effective than repeated spot fixes.

Proper drainage also prevents recurrence. Make sure the patio surface still slopes away from your home at roughly 2% grade. If settling has reversed the grade direction, water will pool against your foundation and the settling will only get worse. Ottawa contractors experienced with our soil conditions can assess whether your base needs reinforcement or if a simpler bedding sand replacement will hold up through the next several winters.

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