Joint sand that locks the pavers and stops the weeds.

The sand between interlock pavers is not filler. It holds the pavers together and locks the surface. When it erodes out over years, the joints open up, soil blows in, weeds root, ants nest, and the pavers start to shift underfoot. Re-sanding with polymeric sand is the least expensive intervention and the one that makes the biggest difference to a tired surface.

Why regular sand keeps failing

Plain mason sand or coarse bedding sand washes straight back out in the first heavy rain. It also provides no resistance to weed germination. The result is an annual cycle: sand washes out, weeds come up, homeowner pulls weeds, sand goes back in, repeat. Polymeric sand is different. It contains a binder that activates when misted with water. Once cured, the sand sets up into a firm but slightly flexible joint that resists washout, flexes with the freeze-thaw cycle instead of cracking out, and leaves no hospitable gap for weed seeds.

How polymeric binder mechanics work

The binder in polymeric sand is a polymer compound mixed through the sand particles. It stays inert until water is applied at the right stage. When misted after the sand is swept in and seated, the polymer activates and begins to cure. Done correctly, the joint hardens into something between a compacted sand joint and a thin mortar joint: firm enough to resist washout and weed penetration, but flexible enough to move slightly with the seasonal expansion and contraction of the pavers and base without cracking or popping out.

The right re-sanding sequence

• Clear the old joints first. The eroded sand, weeds, and debris have to come out so the new sand has clean depth to bond into. Sweeping new polymeric sand over old, half-filled joints reduces the bond and shortens the lifespan of the repair.
• Sweep polymeric sand in stages. Dry sand worked down into joints from multiple directions, then compacted lightly with a plate compactor, then swept again to fill any voids that appeared during compaction.
• Mist to activate. A careful, controlled misting, enough to wet the joints without flushing the sand out. This is the step most DIY attempts get wrong: too much water washes the binder out of the joint before it can cure.
• Cure time before traffic. Most polymeric sands need 24 hours dry time before foot traffic and a few days before vehicle traffic. A clear forecast window matters.

Illustrative cost ranges

Re-sanding typically runs roughly $3.50 to $6 per square foot in the Niagara market, depending on joint width, how much old material has to come out, and whether the surface needs pre-cleaning. Bundled with cleaning and sealing the total cost per square foot is lower than the two jobs done separately. Full illustrative ranges are on the cost guide.