How to Clean Interlock Joints Without Damage

Interlock can look excellent for years, but the joints tell the real maintenance story. Learning how to clean interlock joints properly helps stop weeds, ant activity, loose pavers, and water from working their way beneath the surface. The goal is not to blast every joint clean. It is to remove buildup while keeping the pavers stable and replacing the jointing material that cleaning removes.

For homeowners across the GTA, this work is especially worthwhile after a long winter. Freeze-thaw cycles, road salt, shade, leaves, and windblown soil can all leave joints looking tired well before the pavers themselves have worn out.

Start by Checking What Is in the Joints

Before reaching for a pressure washer or weed killer, inspect the joints closely. Most interlock installations use either regular joint sand or polymeric sand. Regular sand is loose and can wash out easily. Polymeric sand contains a binding agent that firms up after activation with water, helping resist weeds and erosion.

If the joints are deep, empty, or uneven, cleaning alone will not solve the problem. Pavers that rock when stepped on, low areas that hold water, or joints wider than they used to be can point to base movement below the surface. Those areas may need repair before new sand or sealer is applied.

Also look for the type of growth you are dealing with. Small weeds in a few joints are usually a routine maintenance issue. Thick moss, repeated ant nests, or broad areas of weeds often mean the joints have lost too much sand or the surface is staying damp for too long.

Clear Weeds, Moss, and Loose Debris First

Start dry whenever possible. Sweep the entire patio, walkway, or driveway with a stiff outdoor broom to remove leaves, gravel, soil, and loose joint sand. A narrow joint brush, hand weeder, or flat scraper works well for weeds that have taken root between pavers.

Pull weeds out as completely as you can, including the roots. Simply cutting them at the surface makes the area look better for a short time, but the roots remain and new growth returns quickly. For stubborn growth, use a paver-safe weed treatment according to the product directions. Avoid pouring salt, bleach, or harsh household chemicals into joints. They can discolor pavers, harm nearby grass and planting beds, and leave residue that affects new joint sand.

Moss should be loosened with a stiff brush and treated with a cleaner made for masonry or pavers if needed. Work in small sections and rinse thoroughly. A mild cleaner is usually enough when moss is caught early. Heavy black staining, rust marks, or oil stains may require a product designed for that specific stain rather than stronger pressure washing.

How to Clean Interlock Joints With a Pressure Washer

A pressure washer can make interlock look dramatically cleaner, but it is also the easiest way to damage the joints. Used too closely or at too high a setting, it can strip out sand, chip the paver surface, scar softer stone, and force water into the bedding layer below.

Use a fan-tip nozzle rather than a pinpoint tip. Keep the wand moving and hold it at a shallow angle to the surface, not straight down into the joints. Start with the lowest effective pressure and test an inconspicuous spot first. The right setting depends on the age and condition of the pavers, the joint material, and how much staining has built up.

Clean the paver faces first, then make controlled passes along the joints only where necessary. Do not linger over one area. Some sand loss is normal, especially with old regular sand, so plan to refill the joints after washing.

For a small, lightly soiled walkway, a garden hose, brush, and paver cleaner may be the better choice. Pressure washing is most useful when surface grime, moss, or old sealer residue has built up. It is not automatically the best answer for every interlock surface.

Keep Water Away From Weak Areas

Take extra care near pavers that are already loose, edges that have shifted, or areas with visible settlement. High-pressure water can worsen a weak installation by carrying out bedding sand from below the pavers. If water pools after washing or a paver moves underfoot, stop cleaning that area and address the repair first.

This is also a good time to check drainage. Interlock should direct water away from the home and should not hold standing water after a normal rainfall. Cleaning can reveal low spots that dirt and moss had been hiding.

Let the Surface Dry Before Adding New Sand

Once cleaning is finished, give the interlock time to dry fully. On a warm, dry day, the surface may look dry within hours, but moisture can remain deeper in the joints. For polymeric sand, follow the manufacturer's conditions carefully. Most products require dry pavers and dry joints before installation.

Do not rush this stage. Adding polymeric sand to damp joints can cause the binder to activate unevenly, clump on the surface, or fail to harden as intended. If rain is expected, wait for a clearer weather window.

Refill the Joints the Right Way

Clean joints need to be refilled to protect the installation. Joint sand locks the pavers together, supports their edges, discourages weeds, and limits water from washing material out of the base.

For standard joint sand, sweep clean, dry sand across the surface until the joints are filled. A plate compactor with a protective pad can help settle sand deeper into the joints on larger areas, but it should be used carefully on older or uneven pavers. Sweep again after compacting and top up joints as needed.

Polymeric sand is often a good choice for driveways, patios, and walkways that have recurring weed growth or washout. Sweep it into the joints exactly as directed, making sure the joints are filled evenly but the paver faces are thoroughly cleared. Any dust left on the surface before activation can leave a stubborn haze.

Activation is the step that causes the most trouble. Use a gentle shower setting, not a hard stream, and apply water in controlled passes. Too little water may leave the sand soft. Too much water can wash the binder away or carry it onto the paver surface. Follow the product instructions for watering and curing time, and keep foot traffic off the area until it has set.

Consider Sealing After the Joints Are Stable

Interlock sealer can improve color, help resist stains, and make seasonal cleaning easier, but it should be applied only after the surface is clean, dry, and properly sanded. Sealer is not a repair for loose pavers, failed joints, or poor drainage.

The right sealer depends on the paver type and the look you want. Some leave a natural finish, while others deepen the color or add a slight sheen. A breathable sealer is generally preferred because trapped moisture can cause whitening, hazing, or peeling. Older interlock may also need old failing sealer removed before a new coat can perform properly.

If you are unsure whether a surface was sealed before, test a small inconspicuous area first. Water that beads strongly on the paver may indicate an existing sealer. Water that darkens and absorbs quickly usually suggests the surface is unsealed or the previous sealer has worn away.

Keep Joints Cleaner Between Major Cleanings

A few simple habits reduce the amount of deep cleaning your interlock needs. Sweep leaves and soil away before they break down into the joints. Trim back plants that keep the surface shaded and damp. Address small weed growth before roots become established, and rinse spills such as oil, fertilizer, or barbecue grease as soon as possible.

A spring inspection and a fall cleanup are usually enough for well-maintained residential interlock. High-traffic entrances, rental properties, and commercial walkways may need more frequent attention. The exact schedule depends on drainage, shade, tree cover, and how much traffic the surface sees.

Well-kept joints do more than improve curb appeal. They help protect the structure of the entire interlock surface. If repeated washout, weeds, or sinking pavers are becoming a pattern, professional cleaning and joint restoration can be a sensible way to protect the investment before minor maintenance turns into a larger repair.