Hardstanding planning advice for householders
You will almost certainly require planning permission to create hard surfacing of more than five square metres to the front of your property, unless you can satisfy us that it is permeable and rainwater drains away naturally into the ground rather than into the public drains.
Here is some informal advice for householders. If you are unsure please check whether you will need planning permission here.
The problem with paving over gardens
Serious flooding in 2007 caused loss of life, disruption of peoples' lives and damage estimated at about £3bn. In many cases flooding happened because drains could not cope with the amount of rain water flowing to them.
The effects of climate change mean that this kind of heavy rainfall event and flooding may occur more often in the future. The drains in most urban areas were built many years ago and were not designed to cope with increased rainfall. More water is entering the drains from new developments and paving front gardens adds to the problem. Although paving over one or two gardens may not seem to make a difference, the combined effect of lots of people in a street or area doing this can increase the risk of flooding.
The harm caused by paving gardens is not limited to just flooding. Hard surfaces such as concrete and asphalt collect pollution (oil, petrol, brake dust etc) that is washed off into the drains. Many drains carry rainwater directly to streams or rivers where the pollution damages wildlife and the wider environment. In older areas the rainwater may go into the foul water sewer which normally takes household waste from bathrooms and kitchens to the sewage treatment works. These overflow into streams and rivers in heavy rainfall. As more water runs into foul sewers from paved areas there are more frequent overflows, passing untreated sewage into watercourses.
What is a “permeable surface”
This is the simplest type of construction. The driveway sub-base is covered by a surface layer of gravel or shingle. Gravel with different shapes and colours is available to make the surface more decorative. A strip of block paving or asphalt at the entrance can limit the loss and spread of gravel from the drive.
Hard permeable and porous surfaces
Hard surfacing which allows water to soak into it can be built with porous asphalt, porous concrete blocks, concrete or clay block permeable paving. The material has open voids across the surface of the material or around the edges of blocks that allow water to soak through.
To work effectively permeable surfaces should be laid over a sub-base which differs from traditional hardcore that has a lot of fine material in it (sand and silt) that stops water passing through it easily. For permeable and porous driveways different sub-base materials are required that allow water to pass through and also store the water for a while if it cannot soak into the ground as fast as the rain falls. Various materials are available, and two examples are known as 4/20 and Type 3 sub-base.
Materials for permeable sub-base are described as open graded and consist only of larger pieces of stone that have spaces between to store water.
Rain gardens and soakaways
An area of garden can be formed into a rain garden - a depression to collect and store rainwater running from conventional impermeable surfaces (asphalt, concrete and block paving), before slowly allowing it to soak into the ground or to flow to the drains.
The depressions can be located along the edge of the drive or as a larger area in the garden at a low point. The depression can be planted with suitable plants to help slow run-off, or gravel or cobbles can be used as decorative features. There may be a gravel-filled trench below it to increase the storage capacity and allow water to soak into the ground more easily. 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. In some areas many houses have the roof downpipes connected to soakaways. They are more suitable for houses with larger front gardens as they require space and need to be located a suitable distance from buildings.
To keep hard surfaces to a minimum a driveway can be created that has just two paved tracks where the wheels go.
These can be surfaced with blocks, asphalt or concrete, but to provide a durable construction they should have sub-base below. The area between and around the tracks can be surfaced in gravel or planted with grass or suitable low growing plants. Water must drain from the tracks into the surrounding permeable area. Typical width is between 300mm and 600mm for each track.