Permeable Driveways

Researching permeable paving and wondering what the difference is between permeable driveways and porous driveways? Don’t despair!

Often used interchangeably, the technical difference can best be explained using familiar paving examples

Porosity – implies the material has small ‘pores’ in an otherwise solid surface. For example Sandstone is ‘porous’ as it lets water through what is actually classed as a rock.

Permeability – water is able to penetrate only via gaps between solid pavers. For example, If you tipped a bucket of water on a section of paved driveway next to a concrete footh path, water will penetrate through the gaps in the pavers.

The important factor here is the rate at which water can penetrate, to be of practical benefit returning to the ‘ground water’ table. Concrete has 96% of its pores connected, technically making it ‘porous’ but we know intuitively – concrete is not practically porous, rather it channels rain off in our stormwater system because its porosity flow rate is so exceedingly small!

Typically ‘Porous’ paving see a higher effective water penetration than Permeable paving, mainly because the entire surface is able to absorb water, not just the small percentage of surface that are gaps!

Porous paving also avoids the reality of ‘dirt compaction in the gaps’ on driveways – a result of daily vehicle compaction. Dirt eventually accumulates and is compacted over time, clogging the permeable sections and results in the familiar hardy-weeds growing.

Intuitively, its much harder for dirt to become compacted and clog pores of hard surfaces like sandstone. Just as a honeycomb provides strength its voids, Porous paving ensures any weight loading is distributed over the structure and not allowing dirt compaction that occurs between permeable paving gaps.

Porous paving therefor experiences a longer practical design life returning water to the ground water table. Which is why it is chosen not just to take 1Tonne or more vehicle weights daily, but to with stand hundreds of pedestrians daily.

Nearly 25% of StoneSet by volume is air! Meaning a quarter of the surface are voids that maintain their porosity and to allow water to flow through.

If StoneSet is applied as a 16mm layer on top of an existing rigid, non porous surface (such as an old concrete driveway) this is loosely termed semi-permeable paving. Water passes freely through the top layer but is unable to penetrate into the ground.

Fully permeable is when StoneSet is applied over the specified 150mm ‘compacted road base’ before applying the resin stone mix at 25mm layer. This achieves a porous base and overall permeability rate of 103L/sqm/min, essentially as porous as soil and grass.

StoneSet has a porosity rate high enough to satisfy councils and certifiers it can be classed as soft landscaping. Even with some of the most demanding councils hard to soft landscaping ratios in Australia.

Examples of bases that can support a fully permeable surface include;

• Deco Granite
• Crusher dust
• Road Base
• Blue Stone
• Crushed Rock

Typically councils class a 25mm application of StoneSet as fully permeable in the calculation of hard / soft landscaping ratios when considering development applications.

Indeed nearly all Tree Surrounds StoneSet install for councils involve this method of fully permeable paving.

Resurfacing an existing hard surfaces such as concrete driveways is possible using an ‘overlay‘ of 16mm StoneSet.

The finished stone driveway surface can still be called ‘permeable paving’ however the base will not allow water to penetrate into the soil below, so this can sometimes be termed ‘semi permeable’.

Therefore the 16mm application of StoneSet is mainly those looking at concrete resurfacing to achieve a stone driveway.

Typically this permeable paving cost per square metre is cheaper than alternative options of concrete driveway removal when weighing up options for concrete driveway alternatives.

The resulting stone surface can still be called a permeable and indeed StoneSet can put in place ways of redirecting water flow to the garden and reduce stormwater runoff.

Others of course are just happy to create a decorative stone ‘amazing driveway‘ which essentially receives no UV or Water erosion damage like some other common driveway materials Australia has available.

Permeable driveways offer an eco-friendly alternative to traditional concrete ones. The concept aims to curb surface runoff caused by rainfall, particularly in urban areas prone to flooding. By enabling rainwater to seep into the ground through a permeable driveway, you can decrease runoff, enhance the well-being of nearby trees, and comply with council regulations relating to hard-to-soft landscaping ratios, while ensuring your property retains the desired size and adequate driveway space.

Gravel driveways, while permeable, can be messy and high maintenance. They often require annual stone replacement or after rain. Opt for a resin bound gravel like StoneSet paving for a permeable driveway that combines the appearance of loose gravel without the hassle of loose stones.

When installed on a suitable permeable base, a resin-bound stone driveway offers a fully permeable solution that complies with council standards. This elegant and enduring option ensures both functionality and beauty for your driveway.