Permitted Development: What Can I build?

In 2015, the government introduced new legislation covering planning permission rules. Consolidating a variety of amendments made in the 20 years since the legislation was last updated, the focus was on relaxing the conditions to make it easier to carry out certain types of building work.

Central to this was an extension of so-called Permitted Development Rights, which waive the need to seek planning permission for specified developments. Permitted Development effectively allows work to be carried out under general planning consent authorised by Parliament, removing the need to go through the local authority planning process.

So, what is now covered by Permitted Development Rights, and what does it mean in practice?

Home Improvements and Building Extensions

You do not need to seek planning permission to build a single storey extension on a home of up to 8m in depth, or 6m for a terrace or semi-detached. The maximum height of a single storey extension is 4m, reduced to 3m if the extension comes within 2m of the property boundary.

A two storey extension can extend up to 3m from the original rear wall, as long as it is within 7m of the boundary edge. It must not exceed the original height of the property.

Extensions to the front are not covered by Permitted heights. Side extensions are restricted to a maximum of half the width of the original property.

Loft Conversions

In the past, homes were limited to the total living space they could add under permitted development, meaning you normally would not be able to build an extension and then add a loft conversion without planning permission. This has now been relaxed, covering all loft conversions up to 50m3 in detached homes, or 40m3 in all other dwellings.

Outbuildings and Internal Improvements

Single storey outbuildings can be built under permitted development rights as long as they do not take up more than 50 per cent of the garden space. The maximum height is 4m for pitched roofs, or 3m for any other type. In Wales, Scotland and Northern Ireland, outbuildings closer to a house than 5m may be counted as extensions.

Most simple internal improvements are covered by permitted development, including adding a porch to the front of a property. Exceptions include balconies and verandas, which require planning permission.

How It Works

Permitted Development Rights do not completely cut local authorities out of the process of extending or improving existing properties. Parties seeking to carry out work must first seek prior approval from their local planning department, to check that their plans conform to permitted regulations.

Although this process is much quicker than the formal procedures for seeking planning permission, local authorities are still able to withdraw the assumed consent under what are known as Article 4 orders. An example would be if a neighbour objected to the height of a proposed extension. Local planners would have the powers to remove statutory permission and force you to go through the planning process.

The guidelines for permitted developments are very precise and equally strictly enforced. For example, when adding an extension, you cannot cover more than 50 per cent of the garden, and this takes into account previous additions and outbuildings. Also, unless you are building a conservatory, you are expected to use materials in an extension to conform to the appearance of the original building.

Rules on permitted developments are even tighter in certain areas such as National Parks, Areas of Outstanding Natural Beauty and Heritage Sites. They also vary between the four Home Nations, so it is always worth making enquiries with your local authority, or employing a surveyor, before you begin.