Resin Bound Knowledge Base
Resin Bound Knowledge Base
Product Suitability - Substrate
There are two basic types of installation and these are commonly referred to as a ‘Full Install’ (Dig-out) or Overlay:
● Full Installation (Dig-Out)
The ‘Full Installation’ involves the current surface being removed along with its sub-base if this fails to meet a minimum specification. The excavated surface is then replaced by the specified sub-base and overlaid with a porous tarmacadam or concrete base course. Finally, the resin bound surface is installed over the new base to a depth defined by the intended end use of the installation. There are significant benefits to a full installation and whilst all installations come with a StarScape ULTRA product guarantee, only a full installation by a skilled installer can have a meaningful system guarantee.
An ‘Overlay’ installation simply covers the existing surface with a resin bound surface. Whilst this is significantly cheaper than a full installation (dig out), it sacrifices many of the key benefits associated with a resin bound surface. As shown in the table below; the depth, permeability and quality of an overlaid surface are typically unknown and as such the majority of overlay installations should not be guaranteed as SuDS compliant or receive a performance guarantee.
There are three common types of base on which a resin bound surface should be installed:
1) New open-graded tarmacadam/bitmac
2) New permeable concrete
3) New compacted DTp3/MOT Type 3 (Foot traffic only)
4) Existing asphalt, tarmacadam/bitmac (overlay)
5) Existing concrete (overlay)
6) Existing compacted DTp/MOT (Foot traffic only)
In basic terms, a ‘Full Install’ requires excavation and removal of the existing surface whilst an ‘Overlay’ simply applies a resin bound system over the existing surface. If practical reasons or cost dictate that an overlay is the best choice then serious consideration should be given to the use of a resin bonded ‘coat & scatter’ system such as StarScape PRO for an overlay on concrete or StarScape FLEXIBLE on a tarmacadam overlay.
The ideal base course for a resin bound surface is 10-day-old, open graded tarmacadam with a PEN value between 70 & 100 or a 14-day-old, porous concrete surface which meets BS-5328 specification. In many circumstances a resin bound surface can be laid directly over the existing surface which can greatly reduce both the time taken and the overall cost of the installation however, it should be noted that this is not always the case and a resin bound surface should only be applied to an existing tarmac/concrete surface that meets the required quality. A resin bound surface should never be viewed as a restorative solution to an already damaged surface.
You may be able to overlay an existing surface with a resin bound surface if:
● The current surface is undamaged (shows no signs of cracking) concrete or asphalt.
●The current surface has no drainage or flooding issues
●Tree roots do not run directly under the current surface.
●The completed surface will not be used by heavy goods vehicles (such as refuge collection).
You should not overlay an existing surface with a resin bound surface if:
● The current surface is damaged (cracking or movement) concrete or asphalt.
● The current surface does not allow water to freely drain or escape.
● The current surface is paved, loose gravel or non-solid (such as soil or compacted stone).
An overlaid surface can be significantly cheaper than a full installation however it is unlikely to be porous (SuDS compliant), achieve its maximum tensile strength or come with a guarantee. Any problems with the base on which a resin bonded surface is installed are likely to result in problems (such as reflective cracking) and as the quality of an overlaid base is unknown, reputable manufacturers, suppliers and installers will not typically offer any guarantees.
We strongly advise that the use of StarScape PRO resin bonded surfacing is given consideration if the existing surface is to be overlaid.