Growing Concerns
February 2019

With increasing demand to green-up hard landscaped areas, Grass Paving has fast become a design option of choice for urban planners, architects and specifiers.

The benefits can be significant and it’s important to consider the fit for purpose choices for different applications.
A reinforced grass system can help permeate heavy rainfall and help address SUDs issues with obvious advantages over traditional hard paved landscapes with their increased runoff into the storm water channels.

Some grass paving systems help store rainfall within the system with low risk of ponding, until the ground can naturally re-charge is a significant benefit. This lag time is beneficial in the prevention of flooding and can be extended by introducing an underlying drainage blanket across the full extent of the paved area. The drainage blanket can be used to either attenuate permeation to the water table or be a vehicle for rainwater harvesting.

Today’s wide choice of grass paving systems means that Specifiers now have a wide choice of products. Without the clear guidelines of an industry standard it could be possible to end up with a product that might be fine in the short term, but will not stand the test of time, and in turn, not achieve any degree of sustainability. Future proofing is essential for grass paving.
Take for example a car park in daily use; “will the grass cover and then the structure stand-up to regular traffic”. These are the sort of challenging questions that that should be asked to ensure a correct specification.

For building developments emergency access roads must support the weight of the latest fire and access vehicles, with weight capacity up to 18 tonnes. In other areas think however about the potential for unplanned heavy use such as from refuse and skip vehicles.
Consider the strength of the under structures to the grass paving. Cast on-site concrete or pre-cast concrete provide the heavy-weight system as compared to plastic systems, specifiers must consider what is fit-for-purpose.
Careful consideration of grass paving types, particularly when likely to be subjected to frequent traffic. A relatively thin layer plastic paver might suffice for light traffic or secondary parking but will not stand the test of time of structural design of reinforced concrete.
This problem becomes more likely where plastic pavers are gravel infill for traffic use - with no grass to provide tensile anchorage, vibration across the surface will naturally cause a sieving effect that can lead to loss of gravel through into the base below or the gravel can also rotate with an abrasive effect on the side walls of the plastic grids, in each case the likely outcome is a break-up of the structure.

Good grass coverage will be essential to achieving the green vista many clients desire. Many grass paving systems rely upon grass to anchor the system in place, the depth and shape of the soil pockets therefore has a critical part to play if grass cover is to be sustained.

Adopting grass paving on driveways and car parks is a growing trend to address issues of greener external works. Specifiers can turn those large parking areas into sustainable green vistas with sustainability built in.
Grass paving systems can have an increasing role in sustainable harmonised urban landscapes. They provide fantastic green areas where once just asphalt was considered.

Grass Concrete Limited
Tel: + 44 (0) 1924 379443