A Guide to Permitted Development Rules

Whether you’re simply looking to improve your existing house or carry out major works to one you’re intending to buy, it pays to understand the scope of the available Permitted Development (PD) rights.

They are granted in the form of General Development Planning Orders (GDPOs) which apply separately to England, Wales, Scotland and Northern Ireland, and, in effect, they give implied planning consent to carry out certain classes of development.

In order to carry out work under PD the work must strictly conform to the current criteria, so it does make sense to either check with your local authority before carrying out the works or have a qualified surveyor confirm that they are in order.

An increasing number of local authorities offer a consultancy service for a small fee, and will confirm in writing whether or not a planning application is required. This can be very useful when it comes to reselling the property within the first four years of completion.

My home benefits from PD rights, how far can I extend?

Under the rules, the ‘original’ (as it stood in or prior to 1948) rear wall of a detached home can be extended by up to 4m in depth with a single storey extension; this is reduced to 3m if you live in a semi or terrace. If your proposed new extension will be within 2m of a boundary, then the eaves height is limited to 3m under PD.

If you hope to build a two storey extension (no higher than the house), this can project up to 3m from the original rear wall, so long as it is at least 7m from the rear boundary. It’s also important to note that no extension can project beyond or be added to what is deemed to be the front of the house or an elevation which affronts the highway. And a side extension can not make up more than half your house’s width.

Furthermore, with the exception of conservatories, new extensions must be built of materials ‘similar in appearance’ and with the same roof pitch as the main house. So while PD rights are beneficial, there’s a lot to consider before starting work.

Is there anything else I can do under my PD rights?

In the past volume limitations were applied to the entire house — so if you extended, you were unlikely to be able to convert your loft under PD rights as well. The good news is that the latter has now been separated out, allowing you to undertake both without one restricting the other. So, you can also convert your loft into a bedroom or extra living space by up to 50m³ in a detached house, or by 40m³ within any other home. Flush rooflights or those which do not project further than 150mm are permitted, but you will need permission to add a dormer window on any roof elevation which faces the highway.

Improvements: What you can do

• Build a porch.
• Carry out internal alterations.
• Convert and occupy the loft space.
• Install microgeneration equipment such as solar panels (apart from wind turbines).
• Install satellite dishes.
• Erect antenna.
• Put in rooflights or dormer windows.
• Put in new doors or windows.
• Extend the back of your home.
• All subject to design constraints; e.g. porch has to be less than 3m³, rooflights and dormers must not face the highway, etc.

Extensions: What You Can Do

• You can extend a dwelling by 4m to the rear if it’s single storey or 3m if it’s double.
• There are height restrictions but they boil down to a single storey extension not being higher than 4m in height to the ridge and the eaves, and ridge heights of any extension not being higher than the existing property.
• Two storey extensions must not be closer than 7m to the rear boundary.
• It must be built in the same or similar material to the existing dwelling.
• Extensions must not go forward of the building line of the original dwelling.
• Side extensions must be single storey, maximum height of 4m and a width no more than half of the original building.
• In Designated Areas side extensions require planning permission and all rear extensions must be single storey.
• An extension must not result in more than half the garden being covered.
• You can only do it once and the original building is either as it was on 1st July 1948 or when it was built. In Northern Ireland it is as it was built or as it was on 1st October 1973.
• In Wales and Northern Ireland an extension must not be bigger than 15% of the volume of the existing house or 70m³, whichever is the greater up to a maximum of 115m3. In Designated Areas this volume is reduced to 10% or 50m³, whichever is the greater.
• In Scotland the limit is 24m² or 20% of the floor area up to a maximum of 30m². In Designated Areas this comes down to 16m² or 10%.

Outbuildings: What you can do

• You can construct all sorts of outbuildings for the use and enjoyment of the home so long as they do not cover more than 50% of the garden space. In Scotland this is reduced to 30%.
• In Wales and Northern Ireland any outbuildings closer to the house than 5m count as extensions. In Scotland any outbuildings larger than 4m2 and closer to the dwelling than 5m count as extensions.
• Outbuildings must be single storey with a maximum ridge height of 4m for a pitched roof or 3m for any other kind of roof. The eaves height must be no more than 2.5 metres.
• If the outbuilding is closer to the boundary than 2m it shall be no higher than 2.5m.
• No outbuilding can be forward of the original dwelling. In Wales and Northern Ireland the same applies unless the resulting building would be more than 20m from the road.

Did you know...?

Balconies, verandas and raised platforms (above 300mm) do not fall under PD rights. You will also now need planning permission to construct a drive from non-porous materials such as tarmac. But you can construct a new drive of porous materials, or non-porous if provision for drainage is provided on the property, under PD.

Note: The government recently announced that it will relax permitted development rules relating to extensions for a three year trial period, starting from 30 May 2013 and ending on the 30 May 2016. The new rules will mean that for single storey rear extensions the limit will be 8m for a detached house and 6m for a semi or terraced house; in effect a 100% increase in the permitted amount. It is important to remember though that these changes have not yet come in to effect and hence current limits still apply. For more details on the new rules see the Planning Portal announcement.

Article updated May 10th 2013