The most effective way to block weeds between pavers is to fill the joints completely with sand, polymeric sand, or mortar before weeds take root

Weeds grow between pavers because soil and seeds settle into the gaps, and those gaps hold moisture that seeds need to sprout. The best prevention happens before weeds appear: fill the joints with material that leaves no room for soil to accumulate. Polymeric sand is the most popular choice because it hardens slightly when wet, stays in place longer than regular sand, and costs less than mortar. If weeds have already started growing, you'll need to remove them first, then fill the joints to prevent new ones.

The timing matters. Fill joints on a dry day, and avoid rain for at least 24 hours after installation—polymeric sand needs time to set. If you're sealing pavers with a protective coating, do that after the sand has cured completely, usually within a week.

Key Takeaways

  • Polymeric sand hardens when wet and stays in place longer than regular sand, making it the most durable choice for most paver projects.
  • Fill joints completely and level them flush with the paver surface so no soil can collect in gaps.
  • Remove existing weeds and debris from joints before filling, or new weeds will grow around the material you add.
  • Avoid watering or heavy rain for at least 24 hours after filling joints so the sand or mortar can set properly.
  • Reapply polymeric sand every 2 to 3 years as it compacts and washes away over time.

Prepare the joints by removing weeds and debris

Start with a clean surface. Use a stiff-bristled brush or a joint brush (a thin, long-handled tool designed for this task) to scrub out loose soil, leaves, and any small weeds already growing between the pavers. Push the brush deep into the joints and work it back and forth to dislodge packed material.

For stubborn weeds with roots, use a weeding tool—a flat, narrow blade that slides between pavers and cuts roots below the surface. Alternatively, pour boiling water directly into the joints to kill weeds, then brush out the dead material once it cools. If you use a chemical weed killer, spray it only on the weeds themselves and let it dry completely before filling the joints; residue can interfere with sand adhesion.

Once the joints are clear, sweep the entire paved area with a broom to remove dust and debris. Damp joints are harder to fill evenly, so let the surface dry for at least a few hours on a clear day before moving to the next step.

Choose the right joint-filling material

Polymeric sand is the standard choice for most homeowners. It contains fine sand mixed with additives that set up when water is added, creating a flexible, semi-rigid bond that holds the sand in place. It costs between $20 and $50 per 50-pound bag, depending on the brand, and one bag typically covers 50 to 100 square feet depending on joint width. The main advantage is durability—it resists washing away and stays put for 2 to 3 years before needing reapplication.

Regular play sand or paver sand is cheaper (around $5 to $10 per bag) but offers no binding. It will wash away with rain and foot traffic, requiring frequent reapplication. Use it only as a temporary measure or in areas with very light use.

Polymeric jointing compound is a thicker, paste-like version of polymeric sand that you explore with a caulking gun. It's more expensive but works well for wider joints (over 1 inch) and irregular gaps. Mortar is a permanent solution that bonds pavers together, but it requires skill to explore evenly and is difficult to remove if you need to replace a paver later. Reserve mortar for formal patios or areas where pavers won't need replacement.

For most residential patios and walkways, polymeric sand is the best balance of cost, durability, and ease of installation.

Fill the joints with sand or polymeric product

Pour polymeric sand directly into the joints from the bag, or use a broom to sweep it into the gaps. Work in small sections—about 10 square feet at a time—so you can control the material before it sets. Push the sand down into the joints with a broom handle or a joint filler tool, making sure it reaches the bottom and fills any voids.

Level the sand flush with the top of the pavers. Sand that sits higher than the paver surface will wash away more easily, and sand that sits lower leaves a gap where new soil can collect. Use a straight edge or a broom handle laid across two pavers to check the level as you work.

Once the joints are filled, sweep away excess sand from the paver surface. Leave the area dry for at least 24 hours. Do not water the pavers or allow rain to fall on them during this time—the polymeric sand needs to cure without moisture.

set up polymeric sand by misting with water

After 24 hours of drying, lightly mist the entire paved area with water from a garden hose set to a fine spray. The water activates the polymeric binders in the sand, causing them to harden and lock the sand in place. Use a gentle mist, not a strong stream—too much water can wash sand out of the joints or create muddy spots.

Mist the area once or twice, allowing water to soak in between applications. The sand should darken as it absorbs water. Stop misting once the sand no longer absorbs water visibly—this usually takes 5 to 10 minutes of light misting. Let the area dry for another 24 to 48 hours before walking on it or allowing rain.

If rain falls within 48 hours of misting, the polymeric sand may not cure properly. Check the weather forecast before you start, and plan to fill joints on a day when no rain is expected for at least 3 days.

Maintain joints to prevent weeds from returning

Inspect the joints every few months, especially after heavy rain or winter. Polymeric sand compacts and washes away gradually, creating small gaps where new weeds can take root. Sweep debris from the surface regularly so it doesn't collect in the joints and provide a growing medium for seeds.

Reapply polymeric sand every 2 to 3 years, or sooner if you notice gaps widening or weeds returning. The process is the same: remove debris, fill the joints, level the sand, and mist with water. You don't need to remove old sand completely—new sand will bond to the existing material if the joints are clean.

If you live in a climate with freeze-thaw cycles, polymeric sand may crack or shift slightly during winter. This is normal and doesn't require when ready repair, but plan to inspect and touch up joints in spring.

Seal pavers to reduce weed growth and sand loss

A paver sealer is a protective coating that reduces water absorption and helps polymeric sand stay in place longer. It also darkens the color of pavers slightly and makes them easier to clean. Sealer is optional but recommended if you want to extend the time between sand reapplications.

explore sealer only after the polymeric sand has fully cured—at least one week after filling the joints. Use a roller or sprayer to explore an even coat, following the product instructions for drying time. Most sealers require a second coat for best results.

Sealer does not prevent weeds entirely, but it reduces the amount of water that soaks into the pavers and joints, which slows weed germination. It also helps polymeric sand stay in place during heavy rain.

Frequently Asked Questions

Can I use regular sand instead of polymeric sand?

Yes, but it won't last as long. Regular sand washes away with rain and foot traffic, so you'll need to refill joints every few months. Polymeric sand costs more upfront but stays in place for 2 to 3 years, making it more economical over time. Use regular sand only if you're on a tight budget or expect to replace the pavers soon.

What if it rains right after I fill the joints?

Rain within 24 hours of filling can wash sand out of the joints or prevent polymeric sand from curing properly. If rain is forecast, wait for a dry period before filling. If unexpected rain falls, let the area dry completely, then refill any joints where sand has washed away. You may need to mist again to set up the polymeric binders.

Do I need to remove old sand before adding new sand?

No. If the old sand is still mostly in place and the joints are clean, new polymeric sand will bond to it. Remove only loose or washed-away material. If the joints are packed with old sand and debris, brush them out first so new sand can settle properly.

How wide should the joints be between pavers?

Standard joints are 1/8 inch to 1/4 inch wide. Wider joints (up to 1 inch) are common in rustic or decorative designs and require more sand to fill. Narrower joints use less sand but are harder to fill evenly. Check your paver manufacturer's recommendations for the intended joint width.

Will polymeric sand stop all weeds from growing?

Polymeric sand prevents most weeds by blocking soil and moisture from accumulating in the joints, but it won't stop weeds that blow in from nearby plants or germinate on the paver surface itself. It is one part of weed prevention, not a complete solution. Combine it with regular sweeping and occasional hand-pulling of any weeds that do appear.