For everyone else there is greater freedom thanks to the system of permitted development, which allows homeowners to build without planning permission in certain specific circumstances. Here, Telegraph Money outlines the rules.
Building a rear extension
Building out into your back garden is a popular way to gain extra space. You can build an extension up to 3m deep behind a semi-detached, terraced, or link detached home. If the property is detached, you can go back 4m.
You can’t tack your new extension on to an existing one, though. You must base your measurements on where the back wall was in the original plans for the house, or the footprint of the house as it stood in 1948.
Extensions can be up to 4m high (around 13ft). If part of the roof is within 2m (circa 6.5ft) of your boundaries, that section will need to drop to 3m (around 10ft) high.
The extension must not protrude beyond the side of the house, cover more than half of your outside space, or come within 7m of your rear boundary.
If you want to go bigger you will need to apply for either “prior approval”, to extend up to 6m (8m for detached houses), or obtain planning permission.
If you want to build an extension using different materials from the rest of the property, you’ll also need planning permission – permitted development will only cover you if the materials match with the rest of the house.
And owners of flats and maisonettes planning to go into the garden will need planning permission.
It is important to remember that local councils can limit permitted development rights by using an “Article 4 direction”, so it’s always worth double checking whether these rules apply in your area.
Even if they do, you won’t get off scot-free in the admin department, because you will need to comply with building regulations, and get a certificate to prove it. You may also need to get party wall agreements from your neighbours, unless your home is detached.
Getting a ‘double decker’ extension
Under permitted development you could opt for a two-storey extension with the same depth restrictions as for single story projects.
Two-storey extensions must be behind the main house and the roof can’t be higher than the existing ridge and eaves. Any part of the roof which is within 2m of your neighbours’ property must be no higher than 3m.
