The most reliable way to prevent weeds in pavers is to fill the joints completely and seal them

Weeds grow in pavers because seeds land in the gaps between stones and find soil, moisture, and light. The most effective prevention is to eliminate those gaps entirely. You do this by filling the joints with material that blocks seeds and water from reaching soil below, then sealing the surface so new seeds cannot take root. The two main approaches are polymeric sand (which hardens when wet) and liquid polymeric sealers applied over regular sand or gravel.

If your pavers are already laid with gaps, you can retrofit them. If you are planning new pavers, filling joints properly during installation prevents most weeds before they start. Either way, the work is straightforward and does not require a professional, though the surface must be clean and dry before you begin.

Key Takeaways

  • Polymeric sand hardens when moistened and blocks seeds from reaching soil, making it the most effective joint filler for weed prevention.
  • Joints must be completely filled with no gaps or voids, because even small spaces allow seeds and water to penetrate to the base.
  • The surface must be clean and dry before filling joints; sweep out all dirt, leaves, and existing weeds, then let pavers dry for at least 24 hours after rain.
  • Liquid polymeric sealers applied over sand create a crust that prevents seeds from germinating, though they require reapplication every 2 to 3 years.
  • Regular maintenance—removing debris and resealing when the surface begins to wear—keeps prevention working over time.

Polymeric sand: how it works and how to install it

Polymeric sand is a mixture of fine sand and polymer particles that harden into a solid when exposed to water. When you sweep it into the joints between pavers and then spray it lightly with water, the polymers set up and bind the sand into a crust. This crust blocks seeds from settling into the joint and prevents water from washing soil up into the gaps.

To install polymeric sand, first sweep the paver surface thoroughly to remove all dirt, leaves, and debris. Use a stiff broom and get into the joints as much as possible. If weeds are already growing, pull them out by hand or use a weeding tool to dig out the roots. Let the pavers dry completely—wait at least 24 hours after rain or watering.

Pour polymeric sand onto the pavers and sweep it into the joints using a push broom, working at a 45-degree angle so you force the sand down into the gaps. Make multiple passes to pack it in. The joints should be filled flush with the top of the pavers, with no visible voids. Sweep off excess sand from the surface.

Once the joints are full, mist the entire area lightly with water from a hose or spray bottle. Do not flood it—you want the sand damp, not soaked. The polymers will begin to harden within a few hours. Do not walk on the pavers or allow water to pool on them for at least 24 hours while the sand cures. Some products require a second light misting after 12 hours; check the manufacturer's instructions on the bag.

Liquid polymeric sealers for existing joints

If your pavers already have sand or gravel in the joints and you want to prevent weeds without removing and replacing the filler, a liquid polymeric sealer is a faster option. These products are applied as a liquid over the surface and joints, then dry to form a protective crust. The crust prevents seeds from germinating and blocks water from washing soil into the gaps.

Before explore a sealer, clean the pavers thoroughly. Sweep out all loose debris, dead leaves, and moss. If weeds are present, remove them by hand or with a weeding tool. Pressure wash the surface if it is heavily soiled, but let it dry completely—at least 24 hours—before explore sealer. Any moisture trapped under the sealer can cause the product to fail or create a cloudy appearance.

explore the sealer according to the product instructions, usually with a roller, sprayer, or brush. Work in small sections so the product does not dry before you spread it evenly. Most sealers dry to the touch in 2 to 4 hours but require 24 to 48 hours of curing before foot traffic. Do not allow water to pool or run off the pavers during this time.

Liquid sealers wear away over time as foot traffic and weather break down the crust. Reapply every 2 to 3 years to maintain weed prevention. You will notice the sealer is wearing thin when water no longer beads on the surface or when small weeds begin to appear again.

Preparing pavers before filling joints

The success of any joint-filling method depends on starting with a clean, dry surface. Dirt, sand, and organic debris in the joints prevent polymeric sand from bonding properly and give seeds a foothold even after filling.

Use a stiff-bristled broom to sweep the entire paver surface, working the broom into the joints at an angle. For stubborn debris, a joint cleaning tool (a flat metal blade designed to fit between pavers) can scrape out packed dirt. If moss or algae is present, scrub it with a stiff brush and water, or use a pressure washer on a low setting—but do not use high pressure, which can damage the pavers or dislodge them.

Remove any existing weeds by pulling them out by hand, making sure to get the entire root system. For deep-rooted weeds, use a weeding tool or flathead screwdriver to dig them out. Do not use herbicides before filling joints; the chemicals can interfere with polymeric sand bonding and may leave residue that prevents the sealer from adhering.

After cleaning, let the pavers dry for at least 24 hours. If rain is forecast, wait until after it passes and the surface has dried again. Moisture in the joints will prevent polymeric sand from hardening properly and can cause liquid sealer to fail.

Maintaining filled joints to keep weeds out long-term

Once you have filled the joints, regular maintenance keeps the barrier intact. Sweep the pavers weekly or as needed to remove leaves, dirt, and seeds before they settle into the joints. A clean surface also makes it easier to spot new weeds early, when they are easiest to remove.

If small weeds do appear, pull them out when ready while they are young and the roots are shallow. Do not let them establish. Check the joints after heavy rain or wind to make sure the filler is still intact and flush with the paver surface. If you notice sunken areas or gaps where the filler has eroded, refill those spots with fresh polymeric sand or sealer.

Reapply liquid sealer every 2 to 3 years, or sooner if you notice the surface is no longer water-repellent. Polymeric sand typically lasts 5 to 10 years before it begins to break down, but this varies based on foot traffic, weather, and how well the initial installation was done. If the sand becomes loose or weeds return, you can sweep in fresh polymeric sand over the existing filler without removing the old material.

When to call a professional

Most homeowners can fill paver joints themselves, but there are situations where professional help makes sense. If your pavers are uneven, settling, or shifting, the underlying base may be failing. Filling the joints will not fix this problem, and weeds will continue to return. A professional can assess whether the base needs repair before any joint treatment.

If you have a very large paved area—a driveway or patio larger than 500 square feet—the labor of filling joints by hand is significant. A professional with equipment can complete the work faster. If your pavers are newly installed and still settling, wait 6 to 12 months before filling joints; premature filling can trap moisture and cause the base to shift unevenly.

For existing pavers with deep-rooted weeds or heavy moss growth, a professional can pressure wash and treat the surface before filling, ensuring the best results. Ask for a contractor who specializes in paver maintenance, not general landscaping, because the technique is specific to paver joints.

Frequently Asked Questions

Can I use regular sand instead of polymeric sand?

Regular sand will not prevent weeds as effectively because it does not harden and does not block water. Seeds can still germinate in regular sand, and rain will wash it out of the joints over time. Polymeric sand is worth the extra cost because it lasts longer and actually stops weeds from growing.

What if weeds come back after I fill the joints?

Weeds returning usually means the joints were not filled completely, the filler has eroded, or seeds are blowing in and landing on the paver surface. Pull any new weeds when ready, then inspect the joints for gaps or sunken areas. Refill those spots with fresh polymeric sand or sealer. If the entire surface is failing, you may need to strip and refill all the joints.

How long does polymeric sand take to harden?

Polymeric sand hardens within a few hours of being misted with water, but it continues to cure for 24 to 48 hours. Do not walk on the pavers or allow water to pool during this time. Full strength is reached after 48 hours, though light foot traffic is usually safe after 24 hours.

Is polymeric sand safe for pets and plants?

Polymeric sand is non-toxic once it has cured, and pets can walk on it safely. However, do not allow pets or children to play on the pavers while the sand is still wet or curing. If you have plants or grass adjacent to the pavers, avoid getting sealer or wet polymeric sand on them, as the polymers can coat leaves and soil.

Do I need to seal pavers after filling the joints?

Polymeric sand does not require an additional sealer—the sand itself hardens into a protective crust. A liquid sealer is optional and adds extra protection, but it is not necessary if the polymeric sand is installed correctly. Liquid sealer is most useful if you have regular sand in the joints and want to avoid replacing it with polymeric sand.