Last Updated on June 16, 2026 by
Interlock driveways, walkways, and patios are one of the more popular exterior investments homeowners make in the GTA, and for good reason. A well-installed interlock surface looks clean, adds curb appeal, and when maintained properly, lasts for decades without the cracking problems that plague poured concrete. The catch is that interlock systems require more ongoing attention than most homeowners expect when they commission the installation, and the consequences of neglect tend to build quietly until they become expensive.
The two most common maintenance questions around interlock are whether it needs to be sealed and when repair is necessary versus when problems can be monitored. Both questions have answers that depend more on the specific condition of the installation than on any universal rule, and getting them right requires understanding how interlock systems actually work rather than relying on what a pressure washing company or a sealant product label says.
How Interlock Systems Work and Why They Fail
An interlock surface is not held together by mortar or adhesive. Individual pavers sit on a compacted base of granular material, typically a layer of crushed stone beneath a bedding layer of coarse sand, and they’re held in position laterally by edge restraints at the perimeter and by joint sand packed into the gaps between pavers. The system derives its strength from the interlocking geometry of the pavers and the confinement provided by the edge restraints. Remove the edge restraint or allow the joint sand to erode, and the pavers begin to migrate.
This is the fundamental vulnerability of any interlock installation: it’s a system, and the failure of any one component affects the whole. The base can settle unevenly if it wasn’t compacted adequately or if the soil beneath it shifts. The edge restraints can migrate outward if they weren’t properly pinned or if the soil behind them erodes. The joint sand can wash out if the surface drains poorly or if aggressive pressure washing removes it faster than rainfall would. Each of these failure modes produces different symptoms and requires a different repair approach.
Joint Sand Erosion: The Most Common Problem
Joint sand erosion is the most frequently encountered interlock maintenance issue in the GTA, and it’s also the most consistently mismanaged. When joint sand washes out, the gaps between pavers widen, individual units begin rocking underfoot, weeds establish themselves in the gaps, and the confinement that keeps the surface stable is gradually lost. The progression from minor sand loss to significant surface instability can happen over just a few seasons in installations with drainage issues or that have been pressure washed repeatedly without sand replacement.
The correct response to joint sand erosion is to sweep new polymeric sand into the joints and compact it properly. Polymeric sand contains binding agents that activate when wetted and then cure to form a semi-rigid joint that resists washing and discourages weed germination. It’s not permanent, but it significantly outlasts plain kiln-dried sand in resisting erosion. Standard maintenance on a well-installed interlock surface typically involves refreshing the joint sand every three to five years depending on conditions.
Where homeowners go wrong is in treating joint sand replacement as optional or deferring it until the surface is visibly unstable. By the time individual pavers are rocking or shifting, the sand has usually been depleted enough that some pavers have settled into slightly different positions, and a simple sand top-up won’t restore a uniform surface. At that point, the affected section needs to be lifted, the bedding layer re-screeded, and the pavers reset before new joint sand makes sense.
Edge Restraint Failure and Paver Migration
Edge restraints are the plastic or aluminum channels installed at the perimeter of an interlock surface that prevent the outer courses of pavers from spreading outward over time. When edge restraints are properly installed, they’re pinned to the base material with spikes at regular intervals and backfilled on the exterior side to resist outward movement. When they’re not, they migrate outward as the surface receives foot or vehicle traffic and the lateral pressure of the installation pushes against them.
The visible symptom of edge restraint failure is a gap opening between the last course of pavers and whatever the surface meets at its edge: the lawn, a garden bed, a concrete curb, or a garage apron. As the gap widens, the outer courses of pavers lose confinement and begin to spread further, which accelerates the process. In a driveway installation, vehicle tires crossing the edge repeatedly accelerate the failure significantly.
Early edge restraint migration, caught within one or two seasons, can usually be corrected by resetting the restraint and re-pinning it at closer intervals with longer spikes. Migration that has been ongoing for several years often means the pavers in the outer courses have spread enough that the base material beneath them has been exposed or disturbed, and the repair involves resetting the edge restraint, reinstating the outer courses of pavers, and repacking the base material to support them correctly.
Base Settlement: When the Problem Is Below the Surface
Uneven settling of an interlock surface, where sections of the surface have dropped relative to adjacent areas and water pools in low spots, is usually a base problem rather than a surface problem. The pavers themselves are fine; the granular material beneath them has compacted unevenly, either because the original base wasn’t compacted thoroughly enough during installation or because soil movement beneath the base has caused differential settlement.
In the GTA, clay-heavy subsoils are a significant contributor to base settlement. Clay expands when wet and contracts when dry, and those volumetric changes translate into surface movement over time. Installations over clay that don’t include adequate base depth or a separation layer between the subsoil and the granular base are more susceptible to this kind of settlement than those on sandier ground.
Addressing base settlement properly means lifting the affected pavers, removing and re-grading the bedding layer, and assessing whether the granular base beneath it needs to be added to or excavated and recompacted. Pavers that have settled significantly into a low spot can sometimes be reset by adding bedding sand beneath them rather than excavating the full base, but this only works if the base itself is stable. Adding sand on top of an unstable base produces a repair that settles again within a season or two.
The Sealing Question: What Sealers Actually Do
Interlock sealing is one of the more commercially pushed maintenance services in the GTA landscape industry, and the claims made for it are sometimes broader than the evidence supports. Understanding what sealers actually do, and what they don’t, makes it easier to evaluate whether sealing makes sense for a specific installation.
Concrete paver sealers fall into two broad categories: film-forming sealers that sit on the paver surface and create a visible coating, and penetrating sealers that absorb into the paver and work within the material. Film-forming sealers are the ones that produce the wet look or enhanced colour finish that’s commonly advertised. They protect the surface from staining and slow the weathering of the paver colour, but they also trap moisture if applied to pavers that aren’t fully dry and can make wet surfaces slippery. They need to be reapplied every two to four years as the film breaks down.
Penetrating sealers are less visible in their effect but generally more durable and more appropriate for surfaces in Ontario’s climate. They reduce water absorption by the paver material, which slows freeze-thaw damage from within the unit, and they provide some stain resistance without creating a surface film that can peel or become slippery.
What sealers don’t do is fix joint sand erosion, correct base settlement, address edge restraint failure, or compensate for poor drainage. Sealing a surface with significant joint sand depletion before addressing the sand locks in the existing condition makes subsequent joint sand application less effective because the sealer reduces the paver surface’s ability to hold the new sand in the joints. The correct sequence is always to repair any structural or joint issues first, then seal if sealing is desired.
When Sealing Is Worth Doing and When It Isn’t
Sealing is most beneficial for interlock surfaces in a few specific situations. New natural stone pavers that are more porous than concrete pavers benefit from sealing to reduce staining and moisture absorption from the outset. Concrete pavers in high-stain-risk locations, such as driveways where vehicle fluid drips are likely or patio areas near barbecues and outdoor kitchens, benefit from the stain resistance a sealer provides. Installations where maintaining the colour of recently installed pavers is a priority benefit from the UV protection that quality sealers offer.
Sealing is less clearly beneficial for concrete pavers on a standard residential walkway or driveway that’s in good condition and doesn’t have specific staining concerns. The cost of professional sealing every two to three years adds up over the life of the installation, and the structural performance of the interlock system is not improved by sealing. A homeowner who hasn’t sealed their interlock in five years and has a surface that’s performing well has not made a mistake.
The pressure to seal frequently often comes from service providers whose business model is based on recurring sealing contracts. That’s not a reason to dismiss sealing as useful, but it is a reason to evaluate it on its merits for the specific installation rather than treating it as a universal requirement.
Weed Control in Interlock Joints
Weeds growing through interlock joints are one of the most consistent complaints from GTA homeowners with older installations. They’re also one of the most frequently misunderstood problems. Weeds in interlock joints are almost never growing up from below; they’re established from seeds that land on the surface and germinate in whatever organic material has accumulated in the joint. The joint itself, particularly when the sand has depleted and gaps have widened, provides exactly the sheltered, moisture-retaining environment that weed seeds prefer.
The practical implication is that clearing existing weeds without refreshing the joint sand produces temporary improvement at best. New seeds will find the same gaps and establish again within a season. Refreshing with polymeric sand after thorough cleaning removes the welcoming environment for establishment and is the more durable approach. Chemical treatments applied without addressing the joint condition are similarly temporary.
Repair Timing and the Ontario Climate
Interlock repair, particularly work involving base excavation, bedding layer resetting, and edge restraint reinstallation, is best done when the ground is neither frozen nor waterlogged. In Ontario, that means the window runs from roughly late April through October, with mid-spring and early fall being the preferred times for significant work. Base material that’s excavated and recompacted when the ground is dry and stable settles more predictably than work done in wet spring conditions when soil moisture is high.
Joint sand application and sealing have somewhat different requirements. Polymeric sand needs dry weather for activation and curing, and most manufacturers specify a minimum temperature for application. Sealing also requires dry pavers and stable temperatures. Late summer, when consistent dry weather is more reliable and temperatures are warm enough for proper curing, is often the best practical window for sand and sealing work.
For homeowners in and across York Region, the spring assessment window after snowmelt is the right time to identify what the winter has done to an interlock surface. Freeze-thaw cycling through the base material and any joint sand remaining from the previous season can produce settling, edge migration, and joint gaps that weren’t present in fall. Catching these early gives the full warm season to address them before the next winter begins.
Choosing a Contractor for Interlock Repair
The interlock repair market in the GTA includes a wide range of operators, from dedicated hardscape specialists with significant experience to general landscapers who do interlock work seasonally without deep expertise in base construction and drainage. The quality difference between them is meaningful, particularly for work involving base excavation or significant resetting of an established surface.
For repair work that goes beyond joint sand refreshing and simple paver resetting, look for a contractor who can explain specifically what’s causing the problem before describing what they’ll do to fix it. A contractor who identifies surface settlement as a base compaction issue rather than just “the pavers sinking” is demonstrating that they understand the system rather than just the visible surface. done correctly addresses the underlying cause rather than presenting the surface. Work that treats only the symptoms produces repairs that recur within a few seasons and costs more in the long run than a properly diagnosed and executed repair would have at the outset.
For homeowners who are also dealing with masonry issues elsewhere on the property alongside interlock problems, finding a contractor who handles both means the diagnostic and scheduling conversation can happen in one assessment rather than two. A who offers hardscaping services can assess the full exterior maintenance picture and help prioritize work in a sequence that makes sense rather than treating each issue as an isolated job.
FAQ’s
How long should a properly installed interlock driveway last?
A well-installed interlock driveway with a proper base depth, adequate compaction, and consistent maintenance of joint sand and edge restraints should last 25 to 40 years before the pavers themselves reach the end of their service life. The base system, if constructed correctly, often outlasts that. Most interlock failures that appear within the first 10 years reflect installation issues rather than material limitations, and most surfaces that reach 20 years in good condition will continue performing well with routine maintenance.
Can individual pavers be replaced if they crack or stain severely?
Yes, and this is one of the practical advantages of interlock over poured concrete. Individual pavers can be lifted, replaced, and reset without disturbing the surrounding surface, provided a matching replacement paver is available. Colour matching becomes more challenging as the installation ages and the existing pavers weather, but a close match is usually achievable. Keeping a small supply of original pavers from the installation is worth doing when possible, precisely for this purpose.
Is it worth resealing an older interlock surface that has never been sealed?
It depends on the condition of the surface. If the pavers are structurally sound, the joints are in good condition, and the surface is performing well, sealing an older installation is primarily a cosmetic decision. If the pavers are showing significant weathering or colour fade and the homeowner wants to refresh the appearance, sealing with a colour-enhancing penetrating sealer can produce a meaningful improvement. Address any joint or structural issues first; sealing over depleted joints or settled sections doesn’t improve either condition.
Does interlock need to be redone completely if one section has settled significantly?
Not necessarily. Sectional repair, where only the affected area is lifted and the base beneath it is corrected, is often appropriate when the problem is localized rather than systemic. If the settlement is caused by a specific drainage issue or a soft spot in the subgrade beneath one area, that area can be excavated, the underlying issue addressed, and the pavers reset without disturbing the rest of the surface. If the settlement is widespread and reflects a base that was under-built throughout, a more comprehensive approach may be more cost-effective than repeated sectional repairs.
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