Weeds sprouting between pavers or through cracks in a concrete driveway are one of the most frustrating maintenance issues for NZ homeowners. Our warm, wet climate — especially in the North Island — creates ideal conditions for weeds to take hold in even the smallest gap. The good news is that with the right approach, you can clear existing weeds and stop them coming back.
Why Weeds Grow Through Paved Driveways
Weeds don't actually grow up from deep underground through solid pavers — they mostly germinate from seeds that blow in and settle into joints, cracks, and gaps where dust and organic matter accumulate. Once a tiny root system establishes, it can widen existing gaps and make the problem worse over time. Poor installation, eroded jointing sand, and lack of a proper weed membrane beneath the pavers are the most common root causes.
Step 1 — Remove Existing Weeds Thoroughly
Before you can prevent weeds, you need to clear what's already there:
- Pull by hand or use a weeding tool — a narrow hoe or paving weeder gets into tight joints. Always try to remove the root, not just the top growth.
- Pressure washing — a good blast with a pressure washer dislodges weeds, moss, and old jointing sand at the same time. Work at an angle to avoid blasting sand too deep.
- Boiling water — a simple, chemical-free option for small areas. Pour directly onto weeds in joints.
- Spot herbicide — a glyphosate-based spray (available at Bunnings or Mitre 10) kills weeds to the root. Follow label directions carefully, keep it off garden beds, and allow adequate drying time before rain. Always read the safety data sheet.
Safety note: When using any herbicide, wear gloves, eye protection, and avoid spraying on windy days. Keep children and pets off the area until fully dry.
Step 2 — Re-Sand Joints with Polymeric Sand
This is the single most effective long-term fix for paver driveways. Once weeds are cleared and the surface is dry:
- Sweep polymeric jointing sand (sometimes called paving sand or stabilising sand) into all the joints.
- Compact it with a plate compactor or tamp it down firmly.
- Sweep off excess from the paver surface.
- Lightly mist with water to activate the binding agent — this causes the sand to harden and lock together.
Polymeric sand creates a semi-rigid joint that is far harder for weed seeds to penetrate and much more resistant to washout than standard bedding sand. It's widely available at PlaceMakers and most paving suppliers.
Step 3 — Apply a Paving Sealer
Sealing your pavers after re-sanding adds another layer of protection:
- A penetrating sealer soaks into the paver surface and joints, binding the sand further and making it harder for seeds to germinate.
- It also protects against oil stains and makes future cleaning easier.
- Reapply every few years depending on traffic and UV exposure.
Check with your paver supplier for a sealer compatible with your specific paver type (concrete, clay brick, or natural stone).
Step 4 — Use a Weed Membrane (For New or Relaid Driveways)
If you're installing a new driveway or relaying an existing one, geotextile weed matting laid beneath the bedding layer is essential. A quality non-woven geotextile:
- Blocks weed growth from below
- Still allows water drainage (important for stormwater compliance under the NZ Building Code)
- Extends the life of the sub-base
This is standard best practice and BRANZ guidance supports proper sub-base preparation for long-lasting paved surfaces.
Ongoing Prevention — Comparison of Methods
| Method | Effectiveness | Cost (approx. guide) | DIY Friendly? |
|---|---|---|---|
| Hand weeding | Low–Medium | Minimal | Yes |
| Boiling water | Low–Medium | Minimal | Yes |
| Glyphosate spray | Medium | Low | Yes |
| Polymeric sand | High | Moderate | Yes |
| Paving sealer | High | Moderate | Yes |
| Weed membrane (sub-base) | Very High | Moderate–High | Partial |
| Full relay by professional | Very High | Higher | No |
Concrete Driveways — Crack Control
For concrete driveways, weeds grow in cracks rather than joints. The fix is slightly different:
- Clear weeds and treat with herbicide.
- Once dead and dry, use a flexible polyurethane or silicone crack filler (available at Bunnings or Mitre 10) to seal the crack.
- For larger cracks or structural movement, a concrete repair mortar may be needed.
- Sealing the whole concrete surface with a concrete sealer reduces future cracking and weed ingress.
Note that significant cracking in a concrete driveway can indicate sub-base failure or tree root damage — worth investigating before just filling cracks.
When to Call a Professional
If your driveway has widespread weed problems, significant cracking, sunken pavers, or drainage issues, it's worth getting a professional driveway layer to assess the situation. A full relay with proper sub-base preparation and weed membrane is often more cost-effective in the long run than repeated patch repairs. You can find qualified local driveway layers on tradedirectory.co.nz to get a few quotes and compare.
For driveways near property boundaries or with stormwater implications, check with your local council — some work may require a building consent under the NZ Building Code.