Permeable driveways, surfaces that allow water to drain through rather than run off, are increasingly relevant on the Central Coast as urban stormwater management tightens, flood-prone areas expand due to climate change, and council policies evolve to require higher lot-level stormwater retention. Understanding whether permeable concrete suits your site, your council’s requirements, and your budget is the starting point.
The short answer: pervious concrete is an excellent solution for the right site but has significant maintenance requirements and is not the default best choice for all Central Coast properties.
What Is Pervious Concrete?
Pervious concrete (also called porous concrete or no-fines concrete) is a specialised concrete mix with little to no fine aggregate (sand). The absence of fine aggregate creates a system of interconnected voids, typically 15-35% by volume, through which water drains rapidly. A well-designed pervious concrete surface can pass 200-800 litres per m² per minute, easily handling the heaviest rainfall events on the Central Coast.
Pervious concrete differs from permeable pavers (brick or concrete blocks with gaps) in that it is a continuous concrete surface without joints or gaps, but water flows through the concrete matrix itself.
How Pervious Concrete Driveways Work
A pervious concrete driveway system consists of three layers:
- Pervious concrete surface: 100-125 mm of no-fines concrete with 15-25% void content
- Reservoir aggregate layer: 200-400 mm of clean crushed aggregate (no fines) that acts as a temporary storage reservoir for water that has passed through the surface
- Prepared subbase: Depending on the design intent, this may be:
- A geotextile membrane over native soil (allowing water to infiltrate into the ground)
- An impermeable liner with slotted pipe drainage (capturing water and directing it to a detention tank or infiltration pit)
The design of the subbase determines whether the system infiltrates water into the ground (infiltration design) or captures and reuses it (detention design). In flood-prone areas, detention with controlled release is often the required approach.
Central Coast Council Requirements
Central Coast Council’s Development Control Plan (DCP) and various Local Environmental Plans (LEP) require on-site stormwater detention (OSD) for new development and significant alterations above certain impervious area thresholds. Key points:
When permeable driveways may be required:
- New subdivision lots in some zones require a minimum percentage of permeable paving
- Development on flood-affected land (which includes parts of Woy Woy, Toukley, The Entrance, and the western shores of Lake Munmorah) may have specific stormwater management requirements
When permeable driveways may be incentivised:
- Some DCP provisions allow larger impervious area calculations if permeable surfaces are used, effectively giving you more area to work with for the same stormwater impact
Check before you build: Contact Central Coast Council’s development enquiry team or check the Planning Portal for your specific lot. Flood planning levels and stormwater management requirements vary significantly across the region.
Is My Site Suitable for Pervious Concrete?
Not all sites are suitable for infiltration-type pervious concrete:
| Site Condition | Suitability | Notes |
|---|---|---|
| Sandy or well-drained soil | Excellent | Rapid natural infiltration |
| Clay-heavy soil | Poor for infiltration | Water won’t soak away, detention design needed |
| High water table (Woy Woy, The Entrance) | Poor for infiltration | Groundwater concerns |
| Contaminated land | Not suitable | No infiltration on potentially contaminated sites |
| Near septic system | Caution | Infiltration can affect septic drainage |
| Sloping site | Moderate | Need careful design to prevent lateral flow |
| Flood-affected land | Detention design only | Infiltration may conflict with flood management |
For clay-heavy soils, common across much of inland Gosford and Wyong, a detention-type system (capturing and slowly releasing water) rather than an infiltration system is the practical approach.
Advantages of Pervious Concrete for Central Coast Properties
Stormwater management: The Central Coast’s high-intensity summer rainfall (often 30-50 mm in a single storm event) can overwhelm conventional drainage. Pervious driveways reduce peak runoff significantly.
Reduced urban heat: Pervious concrete surfaces are cooler than impervious surfaces because water evaporating from the aggregate below cools the surface. This can be meaningful on north-facing driveways in summer.
Acoustic benefits: The rough, voided surface of pervious concrete has some sound absorption properties compared to dense concrete, useful for driveways adjacent to living areas.
Groundwater recharge: On suitable sites, pervious concrete contributes to groundwater recharge, beneficial in water-stressed periods.
Council credits: In some planning scenarios, permeable surfaces are credited toward your allowable impervious area, enabling larger structures or paved areas than would otherwise be permitted.
Disadvantages of Pervious Concrete
Maintenance requirement: The voids that make pervious concrete permeable also trap debris, leaf litter, and fine sediment. This progressively reduces the permeability. Without maintenance, typically vacuuming or pressure washing 1-2 times per year, pervious concrete can clog and lose its permeability within 3-8 years.
Cost: Pervious concrete typically costs 20-40% more than standard dense concrete to install, due to the specialised mix and the aggregate reservoir below the surface.
Strength: Pervious concrete is typically lower compressive strength (15-20 MPa vs 25-32 MPa for standard concrete) due to its reduced aggregate content. Heavy vehicles, frequent heavy truck access, or point loads from jacks or supports may not be appropriate on pervious surfaces.
Resurfacing limitations: Standard concrete resurfacing overlays cannot be applied over pervious concrete, the overlay would fill the voids and eliminate the permeability. If the surface is damaged and resurfacing is desired, the pervious concrete must be replaced, not resurfaced.
Freeze-thaw vulnerability: Less relevant for the Central Coast, but worth noting: the water in pervious concrete voids can freeze and expand in very cold conditions, not an issue at sea level on the Central Coast but potentially relevant at higher elevation properties.
Pervious Concrete vs Alternative Permeable Surfaces
| Surface Type | Permeability | Lifespan | Maintenance | Cost |
|---|---|---|---|---|
| Pervious concrete | High | 20-30 yr | Annual vacuum/wash | $130 to $180/m² |
| Permeable interlocking pavers | High (at joints) | 25+ yr | Joint refilling, annual wash | $120 to $200/m² |
| Gravel driveway | Very high | N/A (ongoing) | Regular regrading | $20 to $40/m² |
| Standard concrete + slotted drain | Low (surface), captured | 30+ yr | Drain cleaning only | $140 to $200/m² |
| Permeable asphalt | Moderate | 10-15 yr | Annual maintenance | $90 to $140/m² |
For most residential applications on the Central Coast where permeable surface is desired, permeable interlocking pavers or gravel are lower-maintenance alternatives to pervious concrete. Pervious concrete’s advantage is its single-surface appearance without gaps or joints.
Cost Guide
| Component | Cost Range |
|---|---|
| Pervious concrete surface (m²) | $130 to $180/m² |
| Standard dense concrete (for comparison) | $100 to $150/m² |
| Aggregate reservoir layer installation | Included in above or $20 to $40/m² additional |
| Detention tank (if required) | $2,000 to $8,000 depending on size |
| Council application (if required) | $400 to $1,500 |
| Annual maintenance (vacuuming/washing) | $150 to $400 per visit |
Frequently Asked Questions
Does Central Coast Council require permeable driveways in new estates? It depends on the specific development control conditions for your lot. In some new estate releases in the Wyong area, permeable paving is specified in the subdivision conditions. Check your lot’s title conditions and the relevant DCP. See our council requirements guide for general approval information.
Can I get my existing driveway made permeable? Converting an existing dense concrete driveway to a permeable surface requires full removal and reconstruction, you can’t drill holes in existing concrete to make it pervious. The exception is breaking out sections and installing permeable paver strips or gravel channels within an existing concrete driveway.
Will a pervious driveway help with flooding at my property? Depends on the flood type. Overland flow flooding (where water runs across your property from a road or neighbour’s land) isn’t significantly reduced by a pervious driveway, the water arrives faster than the ground can absorb it. For nuisance ponding from your own property’s rainfall runoff, pervious concrete does help significantly.
How do I know if my soil will drain water away? A simple percolation test (dig a hole 300 mm deep, fill with water, and measure how long it takes to drain) gives an indication. If the hole drains completely within 30 minutes, your soil has adequate permeability for an infiltration-type system. If it takes hours, a detention-type design is needed.
Is pervious concrete available from local suppliers on the Central Coast? Yes. Several concrete batch plants in the Gosford/Wyong area produce no-fines concrete mixes. Pre-bagged pervious concrete products are available from trade suppliers for small areas. For large installations, a specialist installer familiar with pervious concrete placement is recommended, the timing of placement and compaction is critical to achieving the design void content.
Not sure if a permeable driveway is right for your property? Get a free site consultation, an independent contractor assesses your soil, drainage, and council requirements and gives you honest advice on whether pervious concrete or another permeable solution is appropriate.