On the 1st October 2008 new planning regulations came into force. You can no longer pave over your front garden without considering where the surface water may drain to. Below is the current information from the Planning Portal:
You will not need planning permission if a new or replacement driveway of any size uses permeable (or porous) surfacing which allows water to drain through, such as gravel, permeable concrete block paving or porous asphalt, or if the rainwater is directed to a lawn or border to drain naturally.
If the surface to be covered is more than five square metres planning permission will be needed for laying traditional, impermeable driveways that do not provide for the water to run to a permeable area.
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 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 which 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.
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.
Rain gardens are widely used in the USA and elsewhere but are a relatively new concept in the UK.
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.
Serious flooding in 2007 caused loss of life, disruption of peoples' lives and damage estimated at about 3bn GBP. 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.
Building Regulations do not generally apply. However, you will need to make sure that any alterations do not make access to the dwelling any less satisfactory than it was before.
So, for example, changing levels to introduce steps where none existed before would be a contravention of the regulations.
If you are making a new access into the garden across the footpath you will need to obtain permission from the local council to drop the kerbs and the pavement may need strengthening. This is to protect any services buried in the ground such as water pipes.