How to Stop Weeds Coming Through Block Paving Without Chemicals

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Natural Ways to Stop Weeds Coming Through Block Paving

  • ✔ Use geotextile fabric under the paving base

    Installing a geotextile membrane beneath your sub-base helps stop weeds from pushing up through the ground. It acts as a barrier between the soil and the hardcore, preventing roots from penetrating while still allowing water to drain through. It’s especially useful on soft or previously overgrown ground, and works best when laid flat with overlaps and pinned edges before adding your sub-base layer.
  • ✔ Properly compact sub-base and jointing sand

    Weeds thrive in loose, poorly compacted areas. Make sure your MOT Type 1 sub-base is compacted in layers using a plate compactor, and do the same with the bedding layer. After the blocks are laid, sweep in jointing sand and compact again to minimise gaps. Tight joints and a solid foundation leave no space for weeds to grow.
  • ✔ Refill joints with polymeric or kiln-dried sand

    Over time, jointing sand wears away or gets washed out, leaving space for weed seeds to settle. Refill the joints every year or so using kiln-dried sand for a quick fix, or polymeric sand if you want a longer-lasting, hardened finish. Polymeric sand contains binders that set when wet, helping to lock the blocks together and resist plant growth.
  • ✔ Regular brushing to prevent seed settling

    A simple yet often overlooked step — sweeping your paving regularly stops seeds, moss, and dirt from building up in the joints. By keeping the surface clean, you make it harder for anything to take root. It’s quick, easy, and one of the most effective preventative measures you can take without using any chemicals at all.
  • ✔ Use boiling water or vinegar as spot treatments

    For the occasional weed that does sneak through, boiling water or white vinegar can be effective spot treatments. Pouring boiling water directly onto weeds damages the plant and its roots without harming surrounding paving. Vinegar (especially with 5%+ acetic acid) can also kill top growth but may require repeated application and won’t affect roots as deeply. Both are pet-safe and eco-friendly alternatives to chemical weed killers.

Comparison of Natural Weed Control Methods

Method Best For Cost Effectiveness
Geotextile Fabric Under Base Best for: New installs or full relays ££ (moderate) Prevents weed growth from below
Proper Sub-base & Sand Compaction Best for: All paving types, especially new installs £ (low if DIY) Removes voids where weeds grow
Polymeric Jointing Sand Best for: Long-term weed prevention £££ (higher upfront) Hardens and locks out weeds
Kiln-Dried Sand Best for: Regular maintenance or top-ups £ (low) Easy to apply, but needs upkeep
Regular Brushing Best for: Ongoing maintenance Free Effective for prevention, not removal
Boiling Water / Vinegar Best for: Spot-treating visible weeds Free / £ (very low) Quick fix, not permanent
🔹 Why do weeds keep growing through my block paving?
Weeds can grow through block paving if the joints aren't properly filled or the base isn’t well compacted. Seeds settle in gaps, especially when jointing sand is worn away or the paving hasn’t been maintained. In some cases, weeds push up from underneath if there’s no weed barrier like geotextile fabric in place.
🔹 Can I stop weeds without using weed killer?
Yes, absolutely. Using a solid sub-base, compacting properly, brushing regularly, and keeping joints filled with kiln-dried or polymeric sand can all stop weeds naturally. Spot treatments like boiling water or vinegar are also effective without relying on harsh chemicals.
🔹 Is polymeric sand really worth it?
If you want long-term weed resistance and low maintenance, polymeric sand is worth considering. It hardens once wet, locking in place and making it much harder for weeds to take hold. It costs more upfront but can save time and hassle down the line — especially in high-traffic or exposed areas.
🔹 How often should I top up the sand in my paving joints?
Topping up kiln-dried sand once a year is usually enough for most patios or driveways. Heavy rain, foot traffic, or pressure washing can speed up sand loss, so check your joints regularly and refill as needed to block weed growth before it starts.
🔹 Does pressure washing block paving encourage weed growth?
It can if you’re not careful. High-pressure cleaning often blasts out jointing sand, leaving gaps for seeds to settle. If you do pressure wash, always follow up by re-sanding the joints to keep them tightly sealed and resistant to weed growth.