Permeable solutions for driveways. Your questions answered.
Download our driveway legislation guide
What are the changes to planning laws?
From 1 October 2008 new rules apply for householders wanting to hard surface over their front gardens. If the surface to be covered is more than five square metres, you will need planning permission for laying traditional, impermeable driveways that do not control rainwater running off onto roads. This will apply to new driveways, drive extensions or drive replacements. You will NOT need planning permission if the surface to be covered is less than five square metres or if the new surface is permeable or porous or if a traditional surface is laid and the rainwater is directed to a lawn or border to drain naturally or if it is directed to a soakaway via a drainage channel. An estimated 70% of existing driveways already drain in a sustainable way.
What about existing drives and products?
No retrospective planning consent is needed for existing driveways and hard surfaces.
What solutions are there which avoid the need for planning permission?
A wide range of solutions is available, in five main groups:
- Permeable paving
- Sustainable drainage systems (SUDS) or rainwater harvesting systems (RWH)
- Porous asphalt
- Gravel or a mainly green, vegetated area, such as wheel tracks in traditional materials with a surrounding permeable area
- Traditional hard surfaces with controlled run-off to your garden or lawn or to a purpose-built rain garden or soakaway
Tell me more about permeable or porous surfaces.
The simplest solution is a surface layer of loose gravel over a driveway sub-base.
Hard surfacing which allows water to soak into it can be laid with concrete permeable paving or porous asphalt.The material allows water to soak through. They must be laid on top of a sub-base which allows water to be stored and pass through and unlike traditional hardcore. You can use Bradstone Drainage, Bedding and Jointing Aggregates as a sub base for permeable paving. Full laying instructions are available now from Bradstone.
What about natural drainage solutions?
Where appropriate it may be possible simply to allow run-off into lawns and flower beds. Alternatively, you can direct run-off from your driveway to a depression in your garden to collect, store and slowly allow rainwater to soak into the ground or to flow to the drains.
Soakaways are a similar idea except that water is piped into a gravel-filled trench or special container and allowed to soak into the ground. They are more suitable for houses with larger front gardens as they require space and need to be located a suitable distance from buildings.
And how about rainwater harvesting?
One way of reducing the risk of flooding, overcoming the need for planning consent, reducing water demand by about a third and saving money on metered water supplies is to collect and reuse rainwater, a technique known as rainwater harvesting, to provide non-drinkable water for garden irrigation, car washing and toilet flushing. Bradstone’s system uses hard and soft surfaces to collect rainwater from your driveway - and your roof or patio too - filters out leaves and debris, then stores it in a holding tank beneath the drive or patio. Water can then be drawn off via a pump as needed.
What other factors need to be considered?
Slopes. The driveway should be sloped away from the house wherever possible towards the road. Do not direct water into rain gardens or soakaways close to buildings. If the driveway slopes towards the house use a drainage channel to collect any excess water and connect it to the drains that take the roof water.
Underground services. Make sure there are no underground services close to the ground surface where you are paving (eg water pipes, cable TV, electricity cables, etc).
Contaminated sites. If you live on a site that was contaminated by previous uses the shallow soils may have been specifically designed to prevent water soaking into the ground. If this is the case you will have to connect the paved area to the drains.
Soil type. The soil below the driveway must be sandy or gravelly (not clay) otherwise a connection to the drains may be required. This can be checked by a simple test.
Connection to drains. The new regulations acknowledge circumstances and houses where it may be necessary to allow run-off to drains, but this should be the last option considered, may need planning consent and therefore might not be allowed.
Where can I get more advice?
For further advice, call the Bradstone helpline on: 01335 372289.