Permeable or noN-permeable?
The answer to this is simple…It Is Permeable!
The reason Resin Bound paving is so popular is because it offers complete permeability as well as a smooth, decorative finish. It’s permeability is by design. The process starts by mixing a polyurethane resin and a chosen combination of aggregates within a forced action mixer until evenly coated. The material is then spread and trowelled to a smooth finish. This leaves small gaps which allow water to pass through.
It is important to understand that although Resin Bound is permeable, drainage issues can still occur if the base is not suitable.
Is The Base Suitable For Resin Bound?
Paying for a permeable paving solution is slightly more expensive so it needs to be done correctly. Any Resin Bound expert should be able to provide a step by step breakdown of their installation process and give sound advice as to whether a new base is needed to comply with SUDS legislation. (This also means avoiding the need for planning permission!)
Unfortunately, there are a few roque traders out there offering Resin Bound, trying to con people and cut corners to save money rather than doing a solid job. With this in mind, we have broken down what you can and can not use for a permeable base.
What Is SuDS and Why Is It Important?
SuDS is the Sustainable Urban Drainage System.
Natural ground is usually permeable therefore water drains through the surface providing natural drainage. This, however is not the case in urban areas. Built up areas largely consist of asphalt and concrete which are not permeable and do not allow drainage to occur naturally, leading to flooding. Resin Bound paving offers a solution to this growing issue. In fact, the environmental agency encourages the use of Resin Bound surfacing on large driveways and patios.
Resin Bound Paving Can Handle
- Open Graded Tarmac
- Permeable Concrete
- Eco Grid System
The two most popular bases for Resin Bound driveways are Open Grade Tarmac and Permeable Concrete due to their strength, permeability and durability factors. Both options are structurally sound if installed correctly and do not allow much movement.
Whilst permeable concrete is often a preferred base, it can cause a number of issues if not prepared correctly. The concrete should be cleaned properly and any damp/wet areas should be completely dried before laying Resin Bound over it. These precautions are suggested to ensure the resin adheres to the concrete.
Ideally tarmac will be laid on an appropriate sub base (MOT type 3), with enough depth to support the expected levels of traffic.
Eco grid systems offer great permeability, however, it’s fairly new to the resin bound industry so the long term structural qualities are yet to be proven. This is becoming a more widely used base for Resin Bound paving due to ease of installation, cost of materials and permeability.
ImPermeable Bases can be suitable
- Closed Grade Tarmac
- Impermeable Concrete
Resin Bound can be laid onto impermeable concrete or tarmac so long as precautionary steps are taken to allow for falls and drainage where needed. This reduces the risk of flooding. Aco drains are often installed as a way of collecting surface water and directing it to an area of drainage. This being said, the longevity of a resin driveway comes down to the quality of the base it is installed on. Experts know what to look for in an existing base, however these are a few of the red flags to look out for:
- crumbling in the tarmac
- cracks in the concrete
- weeds growing
unsuitable bases For Resin Bound
- Paving Slabs
- Block Paving
- Brick Paving
If the existing base is any of the above then it is NOT okay to overlay with Resin Bound. None of the options are solid enough to give the strength needed to ensure the resin won’t crack. Some companies will try to offer a cheaper solution by overlaying these existing bases but there is plenty of evidence out there proving that these will not work.