Weeds commonly grow between pavers because seeds settle and germinate in loose joint sand. Sealing the paver surface offers a long-term solution by stabilizing the joint sand. The process creates a hardened barrier within the joints, blocking weed seeds and preventing moisture accumulation, which inhibits germination. This stabilization also protects the paver surface from erosion and staining.
Preparing the Paver Surface
The longevity and effectiveness of the paver sealant depend entirely on the preparation of the surface underneath. Any existing weeds must be thoroughly removed, either manually by pulling them out completely or chemically using a potent weed killer. It is important to address the root systems of weeds, as simply cutting them at the surface will allow them to regrow quickly.
Following weed removal, the old or loose joint sand must be removed from the gaps between the pavers. This is often best accomplished using a pressure washer, which can blast out the sand, dirt, and any remaining organic matter or rooting zones. The goal is to clean the joint down to a depth that allows for new, clean joint sand to be installed, ideally to the full depth of the paver.
After the deep cleaning, the entire paver surface requires a wash to remove any debris, efflorescence, or lingering residue from cleaners. A pressure washer is effective for this step as well, but care must be taken not to damage the pavers or the underlying bedding sand. Allowing the surface to dry completely before any new materials are introduced is critical.
Depending on the climate and humidity levels, this drying period can take anywhere from 24 to 48 hours. Sealer requires a dry, porous surface to penetrate properly, and applying it over a damp surface will result in a milky appearance, poor adhesion, and a shortened lifespan. Moisture trapped beneath the sealer can also lead to efflorescence, a white, powdery mineral deposit on the surface.
Selecting a Joint Stabilizing Sealer
The primary function of the chosen product must be to lock the sand within the paver joints to achieve the goal of weed prevention. This is known as joint sand stabilization, where the sealer permeates and hardens the sand, preventing its erosion and blocking seed penetration. Sealers designed for this specific purpose contain polymers that bind the sand particles together into a solid mass.
The two main categories of sealers are film-forming and penetrating. The best choice for weed prevention is typically a specialized joint stabilizing sealer, often an acrylic film-former. Film-forming sealers create a durable, visible layer on the surface and within the joints, physically locking the sand in place and often providing an aesthetic enhancement, such as a “wet look.”
Penetrating sealers, in contrast, soak into the paver material and offer a natural, invisible finish without a surface film. While they offer excellent water repellency and protection against staining, they are generally less effective at providing the robust joint stabilization needed to stop aggressive weed growth. Film-formers, however, can range from high-gloss to a matte or low-sheen appearance.
The durability of the sealer is an important factor, with many film-forming stabilizing sealers offering protection for two to five years before reapplication. Choosing a product specifically labeled as a “joint stabilizing sealer” or one formulated for use with polymeric sand ensures the necessary binding agents are present. This specialized formulation creates the solid barrier against weed seeds and moisture in the joint.
Step-by-Step Sealing Application
Before beginning the application, optimal weather conditions must be confirmed to ensure the material cures correctly. The temperature during application and for the subsequent 24 hours should typically be above 50°F (10°C), and rain must not be forecast for at least 24 hours. The surface must be bone-dry, and avoid applying the sealer in direct, intense sunlight, as this can cause the material to flash-cure too quickly and result in streaking.
Once the surface is dry, the joints must be topped up with clean, dry sand, ideally polymeric sand, and compacted to ensure a stable fill. This full filling prevents future shifting and movement of the pavers. Any excess sand or dust must be meticulously swept and blown off the paver surface using a leaf blower, because the sealer will bind any remaining residue to the paver face, creating a permanent haze.
The sealer is typically applied using a pump-up sprayer, which allows for an even, controlled distribution, or a roller for smaller areas. The first coat should be applied liberally to ensure the material flows deeply into the sand joints, fully saturating the sand and utilizing the joint stabilization properties. It is important to work in small, manageable sections, ensuring the material remains wet long enough to penetrate the joints effectively.
Immediately after application, use a squeegee or foam roller to pull excess material across the surface and into the joints, preventing pooling that could dry into a thick, slick patch. This action is crucial for avoiding uneven curing and potential surface defects. Any areas where the sealer is sitting on the surface rather than soaking in must be promptly addressed to maintain a uniform finish and prevent a non-slip hazard.
A second, lighter coat is often recommended to maximize durability and finish. This coat should be applied perpendicular to the direction of the first coat after the manufacturer’s specified inter-coat drying time, typically a few hours. This cross-hatch technique ensures complete and uniform coverage. The finished area must be protected from foot traffic for at least 12 hours and vehicle traffic for 24 to 48 hours to allow the sealer to fully cure and the sand to harden.