Polymeric sand that is disappearing from paver joints is not automatically a “buy another bag and sweep some on top” problem. The right repair depends on how much joint material remains, whether the pavers move, whether water is concentrating in the area, and whether the existing material is still sound enough to remain.
The short answer
A thin topping over shallow, dirty or loose old joint material is usually a poor repair. For one current polymeric-sand system, Alliance Gator instructs installers repairing an existing paver surface to remove old joint material at least 1½ inches deep, keep the pavers dry, refill the joint with the compatible product, compact it into the joint and activate it exactly as directed. Other products can specify different joint dimensions and watering procedures, so the bag and technical sheet for the actual product control.
First ask why the sand is failing
- Normal erosion or age: joints have gradually become low after years of rain, cleaning and traffic.
- Pressure-washing damage: a concentrated jet has excavated the joints.
- Incorrect installation: joints were not filled deeply enough, were not compacted, or were activated incorrectly.
- Paver movement: rocking or shifting pavers can crack joint material. Polymeric sand is not a structural substitute for a stable base and edge restraint.
- Drainage: concentrated runoff can repeatedly erode one path or keep joints wetter than the product was designed to tolerate.
- Wrong product/system: joint width, overlay construction, natural stone, or a non-draining base can require a different product.
Can you just add more polymeric sand on top?
Sometimes a manufacturer allows localized replacement where pressure washing has removed loose or damaged material, but “topping” an old joint with a thin new crust is not the same thing as rebuilding the joint. Alliance Gator specifically warns against filling part of the joint with ordinary sand and placing polymeric material only on top; its guidance says the jointing product should occupy the required depth so it has a dense, consistent body beneath the exposed surface.
If the existing joint is only slightly low but still hard and sound, do not assume it is defective. Many polymeric-sand systems are intentionally finished below the top or chamfer of the paver so tires and feet do not directly abrade the joint.
What a proper repair actually involves
- Inspect the pavement first. Mark loose, rocking or sunken pavers and areas where water concentrates.
- Remove failed joint material to the depth required by the replacement system. Work carefully enough that bedding material beneath the pavers is not excavated.
- Let the pavement dry as required. Polymeric products commonly require dry pavers before installation; trapped moisture can interfere with activation and cure.
- Sweep the new material fully into the joints. Do not leave bridges over voids.
- Compact/consolidate where the manufacturer requires it. Alliance Gator, for example, specifies vibration with a plate or roller compactor and repeated filling so the material drops into voids rather than remaining fluffy at the top.
- Set the finished joint height correctly. Many systems call for the sand to finish below the top/chamfer of the paver.
- Clean the paver face thoroughly. Residual polymeric dust can harden or haze when activated.
- Activate with water exactly as directed. Too little, too much, uneven watering or runoff through the joint can all cause trouble.
When a sand repair is really a paver repair
If the same joints repeatedly open, if pavers rock underfoot or tires, if borders are spreading, or if low spots hold water, replacing the joint material alone may only hide the symptom. Fix support, edge restraint, drainage or settlement first. A polymeric joint is designed to work with a stable interlocking pavement; it does not hold an unstable pavement together like mortar.
DIY decision: what equipment and disruption are involved?
A localized patio repair can be a reasonable homeowner project. A large driveway is different. Removing old joint material can be slow and messy, pressure washing can excavate bedding if the nozzle is handled badly, and proper consolidation may require a plate compactor with a protective pad. The pavement then has to be dry enough for the product, cleaned of residue and watered within the product’s specified window.
- Can you remove the old material without washing out the bedding layer?
- Do you have a way to compact the new material into deep joints?
- Can you keep sprinklers and rain out of the cure window?
- Can vehicles stay off the area long enough?
- If the pavers move, are you prepared to lift and reset them rather than simply re-sand?
What to ask a contractor
- How much of the old joint material will be removed?
- What exact jointing product will be installed?
- What joint depth and width does that product require?
- Will the pavers be compacted after filling?
- How will bedding sand be protected during removal?
- Are any loose or sunken pavers being reset first?
- How will rain and irrigation be controlled during installation and cure?