Guide · Interlocking
Interlocking repair starts with the cause
Pavers move only when something beneath or beside them has changed. Each symptom points to the base, the drainage or the edges, and a repair holds only when it fixes the right one.
What each symptom points to
Interlocking repair is diagnosis first and stonework second. How the surface should have been built in the first place is set out on the interlocking page; this guide reads what has gone wrong.
A localised dip
One defined depression in an otherwise true surface. The usual cause is local: an uncompacted service trench, decayed organic material or a soft pocket never dug out. The fix is to lift the area, dig to sound ground, rebuild the base in compacted lifts and reset the units.
Ruts in the wheel tracks
Two parallel hollows along the wheel paths mean the base is too thin or too loose for the load. Relaying the surface without correcting depth brings the ruts straight back. When they run the full length, most of the driveway is the realistic scope. Driveway repair covers vehicle-load failures in more depth.
Water standing after rain
The surface lacked fall from the start, has settled into a hollow, or now drains toward ground that no longer accepts water. Ponding soaks the base, and a soaked base deteriorates quickly through an Ontario winter. Act on this symptom first.
Joints opening up
Gaps widening, often in one direction, mean the field is spreading. The edge restraint has failed, was never installed, or was pinned into bedding sand rather than compacted base. The repair belongs at the perimeter, even though the damage shows mid-field.
Lifted or rocking units near the edge
Often frost, often fed by water collecting along the perimeter and freezing beneath the units. Check where roof water lands, whether a downspout empties onto the paving, and whether bed soil has risen above the stone.
Efflorescence and staining
A white bloom on newer concrete pavers is efflorescence, mineral salts surfacing from the concrete. It is cosmetic and fades. Dark patches tracing the joint pattern more likely signal moisture held in the base, which deserves a closer look.
How a reset is done properly
A sound repair is a small rebuild, not a cosmetic patch:
- Lift the affected units and stack them in order for reuse.
- Strip the bedding layer and dig into the base until firm, compacted material appears.
- Identify and correct the cause: the trench, the soft pocket, the missing restraint or the stray water.
- Rebuild the base in compacted lifts and restore the correct fall.
- Screed new bedding, reset the units flush with their surroundings and reinstate the edge restraint.
- Refill joints with polymeric sand over a slightly wider area, so no ring of fresh joints outlines the patch.
When replacement makes more sense
Repair stops paying when failure is widespread. Look for movement in several unrelated spots, water across the field, joints open to the bedding, and units spalling or cracking. By then the base is spent, and patching it buys the same lift-and-reset work over and over.
That is a harder conclusion to deliver than a quick fix. It also spares you paying for the same repair again a few seasons later.
Where interlocking sealing fits
Interlocking sealing treats the surface and the joints; it repairs nothing structural. It helps lock polymeric joints against washout, deepens unit colour and slows staining. The base below is untouched by any of it.
Sealing a surface that is still settling, spreading or holding water hides the symptom under a fresh finish. Fix the movement first, reset whatever needs it, then seal once the surface has proven stable. How often to reseal depends on traffic and exposure.
Prevention
What shortens an interlocking surface's life
Downspouts onto paving
A whole roof's runoff landing at one point erodes the base. Extend the outlet past the paving or pipe it underground.
Beds raised above the stone
Soil and mulch topped up every year end up higher than the paving, pushing water onto it and against its edge.
Steel plough blades
A steel edge dragged over pavers chips corners and scours faces. Fit a poly edge or rubber shoes.
Heavy salting
Chloride will not break pavers structurally, but it speeds surface scaling on concrete. Apply less, and only where needed.
Neglected joints
Without joint material, units stop bracing one another and debris moves in. Topping up joints costs little next to resetting a spread field.
Ignoring the first low spot
A hollow that holds water deepens with each freeze. It is the defect most certain to accelerate.
Questions
Repair questions, answered
Can you just re-level the sunken part?
Yes, when the cause is truly local. The area is lifted, the base corrected and the same units reset. Packing extra bedding sand under sunken pavers is not a repair, because the dip returns once the untreated base moves again.
Will the replacement pavers match?
Seldom exactly. Concrete units shift shade between production runs, and the existing surface carries years of weathering. Borrowing units from a hidden spot for the visible patch helps, and new units blend noticeably after a season outdoors.
Why are weeds growing in the joints?
Because the joint sand has washed out and windblown organic debris has taken its place. Weeds root in that debris, not in the base. Clearing the joints fully and refilling with polymeric sand works far better than pulling weeds.
Is it worth repairing or should I replace it?
Repair when the units are sound and the trouble is confined to one or two areas. Replace when movement appears in several unrelated places, water stands across the field and joints have opened to the bedding layer. At that stage the base is failing throughout, and patches turn into repeat spending.
Does sealing fix loose or sunken pavers?
No. Sealing protects the surface and joints and does nothing for a slumped base or a spreading edge. Correct the movement first and seal afterward.