FAQs

With a wealth of experience in grass paving we are uniquely placed to work closely with engineers and architects alike and, this we are happy to do. This experience has enabled us to produce a range of design guide booklets for traffic and water flow applications, please feel free to contact us for details. Our UK based activity also sees us providing a full supply and lay service to customers through our own contracts division.

BOMANITE are our licensees in the USA and elsewhere in locations where their own network have approved representation for the grasscrete system. In the USA mesh reinforcement differs in that it is manufactured to an imperial "x" grid rather than the 200 x 200mm metric format commonly found elsewhere. To overcome this problem they developed a hybrid withdraw able former that is used by their own approved contractors.

Convention tells us that if we want the best then we have to pay more for it; in some cases we often don't even consider the better option for those very reasons. Contrary to convention the structural advantages that grasscrete offers will help to make significant savings in both the "construction" and "whole life" costs of the project. Kerb edge restraints can be eliminated, sub-base depths can be reduced and generally the laying time is much quicker than for pre-cast. Another key feature is transportation, in a 12m container we can deliver upwards of 7200sq.m of formers (depending on type), or the equivalent of fifty truck loads of pre-cast. In fact a recent calculation proved that we were able to ship 15,000Km to a particular site and have grasscrete installed cheaper than a pre-cast block sourced from just 20Kms away.

We stand in the fortunate position of being able to supply all types of grass paving from our own wide range. This perhaps helps us to be more objective than many companies when it comes to settling on the best solution. When considering a design there are a few "golden rules" that can help the process if applied as a checklist.

"The paving will be rarely used" is a fairly common statement often used to drive down the specification to "affordable" levels…think however about furniture removal, dustcarts and those other "heavy" vehicles that turn up when not expected. For fire tracks think about the need to support fire appliances on what is likely to be saturated ground conditions. Many grass paving systems rely upon grass to anchor the units in place, however the combination of seasonal variation in growth and frequency of use can often over-stress the grass and result in units failing under load. The ability to self-drain and at the same time feed the grass cover, are key factors in sustaining growth. A preferred system should therefore provide for both, not drain so slowly that soil is washed out under heavy rain or have such a thin layer that moisture isn't held at the roots. The closer you get to 100% grass cover the closer you will get to natural grass conditions.

"Sustainable Urban Drainage System" is becoming an increasingly used term with planners and developers seeking to mitigate the implications of handling surface water run-off on the local storm water network. This often involves the use of self-draining paving layers together with the installation of pre-formed sub-ground retention tanks, to store surface water for a controlled release into the drainage network. Although the use of pre-formed tanks is a fairly recent innovation, we have for 30 years published the values of having an "on-site" solution to storm water management. Whether compartmenting high volumes of water in retention tanks is the best way forward, time will tell.

Our own experience tells us that a more uniform percolation process will create a more natural balance; in this way there is less risk of causing shrinkage in clay soils due to urbanised modification of water tables. With the notion that grasscrete can drain at up to 90% the rate of natural grass a safe lag time can be achieved, storing water within the system with low risk of ponding, until the ground can naturally re-charge. 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. Rather than being a costly, engineered structure the blanket is simply another layer below the sub-base consisting of single size stone or crushed concrete wrapped within a geo-textile layer. The required permeability of the base layer of geo-textile will be dictated by the nature of the sub-grade, in granular soils the water should be allowed to pass freely through, whereas for water-logged clay soils it will be better to hold drained water so that it can be released into a piped network. Consideration should also be given to whether the drainage blanket should be used to modify waterlogged sub soils allowing ground water to rise into the drainage blanket under hydrostatic pressure, so that it can be piped away.

Our brochure mixes indicate suitable cultivars for temperate European climates. We agree that these are often not suited to other climate zones, where consideration should there be given to the use of indigenous species. These can often be found in hybrid types that have been modified to enhance performance and in doing so are now ideally suited to use in grass pavers. We will always welcome information and advice from growers around the world on this very subject so that we can expand our own knowledge and level of service to customers.

For traffic applications we recommend a sub-base, this will enable load to be spread for both permanent and temporary construction traffic. The depth of the sub-base should be based upon the condition of the ground relative to the required bearing capability. grasscrete for instance is designed upon an allowable ground bearing of 45kN/sq. m. Most circumstances will see a sub-base depth of 150mm as being sufficient, this should however be proportionately increased where CBR values of 4% or less are encountered. We do not recommend the introduction of root zone mediums into the sub-base or sand-blinding layer. An organic content can vary the drainage and structural performance of the sub-base.

For non-traffic applications such as slope protection works, there is no requirement for a sub-base; on very steep slopes the placement and compaction of a sub-base could in any case be problematic. The key requirement on slopes is to prepare the sub-grade to a reasonable line and level, whether it's grasscrete or grassblock the finished level will tend to reflect that of the formation level. Excessive use of sand regulating layers should be avoided as this can lead to washout. For watercourses we recommend the installation of a geo-textile of appropriate flow rating below the paving layer. This prevents a loss of sub-grade should any soil pockets be washed out under water flow

The terms relate to the depth of the structure and to the extent of the vegetation. An Extensive roof features a thin depth structure with planting that is self sustaining on poor or low fertility soils. Plant types such as sedum are normally found here. This type of roof isn't normally accessed on a regular basis. A Simple intensive roof has a similar format but with a thin over-layer of soil.

This enables the introduction of grass types albeit again with access limitations. Intensive systems have a soil covering of significant depth and can generally sustain a normal garden function with the inclusion of shrubs and small trees.

No, grassroof is intended to be laid over a roof membrane, whether this is a new or existing installation. The system is installed via leg supports that bond to the roof via adhesive pads.

It's first of all important to remember that flat roofs tend to leak due to a combination of UV attack and continuous saturation and drying or freeze / thaw. grassroof will protect the roof from UV attack, will attenuate the drying process and help to protect against frost. The combination of these benefits should enable a longer serviceable life for the membrane to be achieved. If at any time a roof leak is encountered then the corresponding section of grassroof can be easily removed by a simple saw cut to gain access to the leak for a local repair.

grassroof can be installed on shallow pitched roofs that have a membrane over a board decking structure, rather than a tiled covering. For this type of specification an Extensive format should be used to avoid soil being washed down the roof.

Well they are concrete as indeed are many of the crib systems but that's pretty much where the similarity ends. A cribwall is a stem gravity structure with a network of interlacing components that form a structure into which no fines stone is in filled. Resistance to overturning is significantly achieved by the weight of its footprint through it's foundation. The wall has minimal interaction with any ground movement or settlement and provides little scope for articulation; therefore the "Limit State" is fairly short.

The BETOCONCEPT range by contrast involves the use of dry laid machine pressed concrete units in hollow core plant-able format or split stone faced solid units. As the height of the wall or its surcharge loads increases, the design then incorporates a granular backfill of design width linked to the wall by our BETONAP reinforcing geo-grids. In this way the block and foundation width remains the same only the backfill varies. Often the width of back fill is no greater than the working space/temporary works demand upon a traditional stem or crib structure. This enables savings to be made in overall project cost.

The relatively small size of each unit enables almost total flexibility in plan layout with curves being constructed without special blocks. Similarly the wall can be regularly changed in height to accommodate rolling contours. Walls can be constructed in single wall or terraced format and in the planted form provides not only a retaining wall but a vertical garden area an ideal solution to those confined sites.

With its dry build format the BETOCONCEPT range is ideally suited to those difficult to reach areas, requiring no mortar it's also the ideal project for the weekend builder.

First of all contact us, if you live in the UK, as we manufacture the system here under an exclusive agreement. Linked into the French licensor, we offer a free no commitment design service that comes with a 10 year warranty. We are also able to provide a supply and lay service through our own contracts division. We don't pressurise we let the system sell itself.

The inside rear cover of our brochure identifies a range of plants for different aspects of open sun or shade. In addition to this the horizontal planting aspect is ideal for strawberries that only the athletic slugs will reach.

A concrete base that should be level and able to take the load of the tipped materials as well as loading shovels/lorries etc. The construction of the wall can then take place straight from the delivery lorry, by using the crane-offloading grab. Removal is just as simple enabling it to be easily re-located.