A drainage layer is laid, the depth of which corresponds to the type of traffic which will access the surface. This is generally classed as type3 reduced fines. This means 20mm stone mixed with smaller stones to create a firm foundation but the difference between this and type 2 is that the ‘dust’ content is removed which makes the sub-base as permeable as possible. It is also possible to use clean 10-20mm stone. Often a plate test is carried out to ascertain the type of surface to be excavated. This means a plate which can be 250-500mm round or square is placed on the ground and a load is placed on the plate (often a simple tyre jack and a vehicle) The depth that the plate sinks will show the type of ground conditions and the corresponding depth of sub-base. This is often classed as the CBR (California bearing rate), in layman’s terms it means the firmness of the soil to be excavated.
Often we get scenarios where excavation is not possible or is minimal such as sites of archaeological value or in areas where tree roots need protecting. Here the issue is that the sub-base needs to be as thin as possible whilst still retaining surface loading. Often here, we advise laying of a geotextile layer first, then a layer of (for example) 100mm clean 20mm stone retained by our Ecogrid Cell Web, a secondary geotextile layer is then laid and then the Ecogrid standard grids or Ecogrid Bloxx is laid.
An Ecogrid approved geotextile layer follows to enhance surface support, provide a layer of filtration and to stop the drainage layer stone migrating up to the surface. A screed layer is laid, this can be a large granulate sharp sand or clean fine sharp angular stone, typically 20-30mm deep laid, levelled and compacted.
The grids are then laid as per our fitting advice or downloaded fitting sheets. Grid fill can be as aesthetics determine but should be:
- Sharp angular stone (river bed rounded stone is not as suitable as it does not lock in to the grid cells as well and there is a potential for a small amount of travelling)
- 15-30mm is best as the larger stones lock better and do not stick in to tyre treads
- Crushed slate is our own infill of choice, especially Crushed Welsh slate as this is an abundantly available option and blends nicely with the black grids.
We offer a complete turnkey solution to all clients:
- Initial consultation by telephone, email, video call
- Written, fixed term quotations and design advice
- Site visits, surveys and advice
- Sample supply
- CPD visits
- Efficient supply chain from extensive UK stock
- Swift, up to ‘same day’ additional product supply
- Consultations with installation teams throughout the installation
- Aftercare advice and on-going support