In most circumstances you will not need to apply for planning permission, but if you intend to:
and if the area is:
then you need to apply for planning permission.
The intention of this is to control the amount of water run-off that reaches the drains, not to increase the number of planning applications. If your hard standing is made of a porous material or it drains into the garden or some form of soak-away on the property, it will not require planning permission.
The Department for Communities and Local Government has issued guidance on what counts as permeable and how to construct hard-standings that conform to the rules. A link to it can be found below.
Please note that if you need to undertake significant terracing, embanking or other earth works you will need to apply for planning permission regardless of the size of the hard standing or whether it is built of porous material.
Also please note that the principal elevation could be any side of the house. Kingston uses the following definition to decide which side of the house is the principal elevation:
"The elevation that is designed to be the main elevation of the property (which will generally front a highway) and includes the most architectural detail (for example gable or bay window details or decorative porches)."
This would normally be what everyone considers to be the front of a property, but if your house is at an angle to the road, on a corner, backs onto a road or if you are at all unsure you should check with the planning department which side of your house forms the principal elevation.
If your property is a flat or maisonette (including those converted from houses) or a commercial property, such as a shop or public house you will need to apply for planning permission.
If you live in a listed building, you will need planning permission for any outbuilding and may need listed building consent for any significant works in the grounds (curtilage).