What are the alternatives to impermeable surfacing?

What are the alternatives to impermeable surfacing?

Angus Crichton, House & Garden Marketing Manager at ACO Water Management, looks at alternatives to impermeable surfacing that can be environmentally friendly and aesthetically pleasing. 

Both grass and gravel have their distinct advantages as landscaping materials. The attractiveness of a traditional grass swathe is pleasing to many; the growing popularity of modern, lower maintenance gravel, complete with a satisfying crunch underfoot, is proving a worthy challenger to traditional lawns.

What is common to both surfaces is that, when walked upon or driven over regularly, they can become marked or rutted. Shoes and tyres can soon damage grass – the shortcut across the lawn soon becomes an ugly, muddy footway. Gravel is notorious for scattering or migrating beyond where it is laid, drifting into dips and rises that make the surface uneven. While gravel looks, feels and sounds good, it can be hard work pushing a pram, wheelbarrow or wheelchair over it. This has led some homeowners to opt for paving, which comes with its own concerns.

With the rise in electric vehicles that need access to a charging point, paving over urban front gardens is increasingly popular . However, paving lawns or flowerbeds creates an impermeable seal over the rainwater-absorbing soil, increasing runoff into stormwater drains. When it comes to runoff, sustainable drainage systems (SuDS) are preferred as they allow rainwater to be dispersed on site, more closely mimicking nature, and lightening the load on the UK’s strained sewerage system.

Therefore, regulations state that rainwater from a new or renovated driveway must be dispersed on site and not allowed to drain into the road or pavement. In England and Wales, this applies to surfaces over 5m2; in Scotland, the rule applies to all developments whatever the area. Grass and gravel surfaces are permeable so fulfil this requirement, but how can they be trafficked regularly by pedestrians and cars without rutting, gravel scatter and creating access problems?

The remedy is reinforcement

Ground reinforcement tiles consist of a network of plastic cells that are a convenient size to handle and install. The tiles often interlock for greater stability and have fixing points to anchor into sub-base beneath. The cells are then filled with either gravel or soil – ideal for planting grass.

The rigid interlocking cells of ground reinforcement tiles transfer the weight of traffic and pedestrians directly to the sub-base, protecting grass from damage. They also lock gravel in situ, preventing scattering and allowing easier access across gravel surfaces. The size and supportive structure of the cell ensures the gravel remains smooth and undisturbed when an individual with a walking stick or in a wheelchair moves across it. The tiles can be easily cut to meet the edges of an adjoining surface, ensuring smooth transition from one surface to another for those with walking aids. In this way, ground reinforcement tiles can help landscapers to fulfil building regulations for people to gain access to buildings.

Layers of good drainage

Careful attention must be given to the layers below the grass or gravel surface to ensure they can take the weight of traffic across it and remain free draining. 

  • Sub-layer: The existing base is dug out to create a smooth and level sub-layer which is then compacted. A stabilisation fabric can then be laid between the sub-layer and the sub-base. 
  • Sub-base: Fill the excavated area with free-draining MOT Type 3 aggregate. A free-draining sub-base such as MOT Type 3 is essential if a higher level of drainage is required through the product, particularly if grass is sown. 
  • Laying Course: The area is levelled with a layer of sharp sand and or soil, depending on whether grass is to be sown. A second stabilisation fabric can be installed between the sub-base and laying course to prevent the latter settling into the former. 
  • Ground Reinforcement Grids: These are then fitted on top of the laying course following the staggered pattern in the installation instructions and pegged if installed on a slope. The grids are then filled with the chosen grass or gravel finish.

Attractive, compliant and sustainable

Ground reinforcement tiles such as ACO’s GroundGuard and GravelGuard offerings ensure that grass or gravel driveways and pathways are practical, attractive and compliant with regulations. GravelGuard is ideal for gravel surfaces traversed on foot, by bike or by wheelchair. GroundGuard can withstand the weight of domestic vehicles and can be planted with grass as well as filled with gravel. Both provide sustainable drainage that eases the pressure on the country’s storm drains and waterways.

For more on ACO drainage solutions for the home and garden visit Ground Reinforcement with ACO.

Related posts