Interlock repair and re-levelling

A dip in front of the garage door, a front walk that catches a toe, a section by the downspout that has sunk since the house was built. Barrhaven driveways do this, and the pavers themselves are usually fine. The problem is under them, which is good news, because relaying costs a fraction of replacing.

Work out what moved and why, before lifting anything. Settlement is the base compacting or washing out beneath the pavers, and it shows up as a dish that gets deeper each year, usually near a downspout, a trench where a service was run, or the edge of the driveway. Heave is the opposite: frost lifting a section each winter that mostly drops back each spring, until one year it does not. Edge failure is the restraint giving way so pavers creep outward, opening joints across the field. Each has a different fix, and relaying a heaved section without addressing drainage buys a year.

Step one: lift and stack. The affected pavers are lifted carefully, keeping them in order where the pattern is complex, and stacked clear. Broken units are set aside. This is the point at which you find out whether the base is a proper compacted granular layer or 50 mm of sand over clay, which is what a fast builder-grade install often turns out to be.

Step two: fix the base. Washed-out or contaminated material is removed. New granular base is added in lifts and compacted with a plate compactor, each lift no thicker than the compactor can actually consolidate. Where water caused the problem, this is when it gets dealt with: extending a downspout, adding a drain, correcting the fall so surface water runs away from the house rather than pooling at the low point.

Step three: rebed and relay. Bedding sand is screeded to a consistent uncompacted thickness, and the industry guidance for that layer is 25 to 40 mm (CMHA, Application Guide for Interlocking Concrete Pavements). More sand is not better: a thick bedding layer consolidates unevenly and you get a new dip within two seasons. The pavers go back in the original pattern, and cut pieces are remade where they were damaged.

Step four: edges and joints. A failed edge restraint gets replaced, because everything else is temporary without it. Joints are filled with jointing sand, often a polymeric sand that binds when wetted, and the field is compacted with a protective pad so the pavers settle into the bedding evenly. A final sweep of sand tops up joints that drop.

How long it takes. A small settled area, a few square metres, is typically half a day. A driveway apron or a full front walk is one to two days. A whole driveway lift and relay usually runs two to four days. Polymeric sand needs dry weather and a dry surface to set, so rain moves the schedule.

What it costs in Ottawa in 2026. Indicative ranges, matching this site's price guide. A spot repair of a small sunken or heaved area commonly runs $200 to $600. A lift and relay of a larger section or a whole driveway generally falls between $1,500 and $5,000, which is usually a fraction of the cost of tearing out and starting again. A new edge restraint, often needed at the same time, runs about $15 to $25 per linear foot. The drivers: area, how deep the base failure goes, how much new granular is needed, whether the existing pavers can be reused, access for a machine and a compactor, and whether drainage work is part of the scope.

What makes a Barrhaven house different. Most of Barrhaven sits on Champlain Sea clay, the sensitive marine clay that swells when wet, shrinks in a dry August and loses strength when it is disturbed (NRC, Geotechnical properties of Leda clay in the Ottawa area). Clay holds water rather than draining it, so a base that is too thin or contaminated with clay fines has nowhere to send water and heaves. The Ontario Building Code puts foundations in clay soils as deep as 1.2 m for frost protection, which tells you how deep the freezing goes here (OBC 9.12.2.2). Driveways cannot be built to frost depth, so the defence is drainage and a properly thick, clean, well-compacted base. Add the age profile: Longfields and Chapman Mills driveways from the late 1990s and early 2000s are now at the age where an original thin base shows itself, while Stonebridge and Half Moon Bay installs from the last fifteen years more often fail at the edges.

Who should do the work. Hardscaping is not a licensed trade in Ontario and there is no provincial certificate to check. What you can check is liability insurance and WSIB coverage, and you should ask for both. A contractor may hold manufacturer or CMHA installer training, which is genuinely useful but is a credential from a trade body rather than a government licence. If any excavation is involved beyond lifting pavers, a locate request to Ontario One Call is legally required, free, and should be submitted at least five business days ahead (Ontario One Call).

What to ask before you hire. What caused this, specifically. How deep is the existing base and how will you check. How much new base are you adding and in what lifts. What bedding thickness. Are you replacing the edge restraint. Which jointing sand. Are you fixing the drainage that caused it, and what does that involve. Can you reuse my pavers and what happens if some break. What is the warranty on settlement, how long, and what voids it.

One caution. A contractor who proposes to lift a sunken area and add sand underneath to bring it up to level, without touching the base, is selling a cosmetic fix. It will look excellent for a year.