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Planning Permission Application

The Application Process

extensionIf you have decided that you wish to go ahead with your planned extension or modification to your property then you must decide whether you need to apply for planning permission. Check out the "Planning Permission" and "Listed Building" sections on the House Extension Online website for general guidelines.

If you believe you need planning permission, then contact you local council planning department for advice. They should be able to tell you whether or not you do need permission before progressing you building work. If they advise you that permission is required, ask then for a Planning Application form. Ask them how many copies of the application they wish to receive and also how much they charge. This will vary from council to council, but you should expect to pay at least £100 for a full application.

extensionYou will also need to submit plans of the proposed extension. Again, several copies may be required and they must be at a specified scale, often 1:50 or 1:100. Location maps are often required by the council to give them an accurate idea of where the property is situated. Boundaries of the property must be clearly marked on these maps. Some councils have arrangements with Ordnance Survey to provide these documents at a small charge, though you can contact Ordnance Survey directly to obtain these maps.

How the Council Processes Applications

extensionThe council should acknowledge receipt of you application within a couple of days of receiving them. They will then publish your application onto the Register of Planning Applications that the Council is legally required to maintain and make available for public inspection. These applications are then publicised to the relevant people and organisations. This will most likely include your neighbours, which is why it is a very good idea to inform you neighbours of your planned extension.

To ensure the application is thoroughly assessed a planning officer will visit your property to check out the proposed positioning of the extension and to ensure that the plans submitted match the current layout of the property.

At this stage representations made by interested parties will be considered. This is done by the planning officer who co-ordinates all relevant information and prepares a report on the application and how it should be determined. If the application is straight forward and not controversial the Chief Planning Officer may be able to determine the result of a planning application

Planning permission

extensionAs mentioned previously not all property developments require planning permission. However, it is important that you check with the local council planning department whether your planned extension requires permission, as it could be very costly if you carry out some building works which later have to be altered or even demolished because you failed to obtain the correct planning permissions. It is best to take the advice of an architect or planner.
The rules for when planning permission is required are complicated and therefore, a complete list of the specifications is not covered within this section. However, the following list can be used as a general guide.Full details for information on building regulations, planning guidance and policy documents, circulars, research and statistics can be found on the Communities and Local government website at

On 21 May 2007, the Government published the Planning White Paper, Planning for a Sustainable Future which aims to reform the planning system. These reforms will have an affect on the town and country planning system. There is a Consultation period from 21 May 2007 to 17 August 2007. A copy of the White Paper can be downloaded from the Communities and Local Goverment Webite on

Extension to a House

Planning Permission is required if any of the following applies:

  • If the proposed extension is closer to any highway than the original property unless it is at least 20 metres away from such highway. This includes any public right of way including bridle paths and footpaths.
  • If more than half the original amount of land surrounding the house is covered by additional buildings
  • If the extension is higher than the highest point of the original house
  • If the volume of the house is increased by more than 15% (10% for those properties within a conservation area)
  • If the volume of a house is increased by more than 115 cubic metres

extensionThis is a brief list of the regulations with regards when planning permission is required. For full details contact either your local council planning department, seek advice from an architect or planner, or look at the ODPM (Office of the Deputy Prime Minister) website at

Do I need permission to extend my house?

You will not require permission, provided that the proposed extension complies with Rules A - F below.

Rule A. The size of the extension must not be more than -
i. Terrace house
• 50 cubic metres or 10% of the original house volume, whichever is the greater.

ii. Any house in a Conservation Area
• 50 cubic metres or 10% of the original house volume, whichever is the greater.

iii. Any other house (detached or semi-detached)
• 70 cubic metres or 15% of the original house volume, whichever is the greater.

Note 1 - In all cases size is calculated from external measurement, and there
is an upper limit of 115 cubic metres.

Note 2 - Any extension built since 1 October 1973will not be treated as part
of the original house volume. It will therefore be necessary to subtract the
volume of any existing extension from the allowances specified above. The
amount left over (if any) is the amount which you can extend without planning
permission providing the proposed addition also complies with Rules B to F
(see Illustration 1).

Illustration 1
Building an Extension (Note 2 & Note 3)


extensionThree identical extensions but only the extension at house ‘A’ would not require planning permission. At house ‘C’, the existing garage was added after 1
October 1973 and is therefore treated as an extension. The volume of the garage (44m3) plus the proposed extension (30m3) would exceed the stated allowance
(70m3) and so planning permission would be required.

At house ‘B’, planning permission would be required because the extension would be within 5 metres of an existing building belonging to the house, causing that
building to be treated as if it were part of the extension. The combined volume again exceeds the stated allowance.

Finally, at house ‘A’, the existing garage would not be treated as an extension as it would remain beyond 5 metres from the house and the proposed extension.

Rule B. The design and materials to be used to build the proposed extension must be in keeping with the main house.

Rule C. No part of the extension should be nearer to any road than the part of the original house nearest to the road.

Rule D. No part of the extension should be higher than the highest part of the existing roof of the house.

Rule E. The extension should not be more than 4 metres high if it comes within 3 metres of the boundary of the property (see Illustration 2). Height is to be measured from ground level, measuring the level of the surface of the ground immediately adjacent to the building or, if it is not uniform, the level at its highest adjacent part.

Rule F. The ground area covered by the extension and any other buildings within the boundary of the property (excluding the original house) must not be more than half the total area (not counting the ground area of the original house).

Illustration 2
Building an Extension (Rule E)


Note 3 - In some cases other buildings on your property will be treated as extensions and will reduce the allowances for extending your house. If an extension to your home comes within 5 metres of another building belonging to the house (e.g., garage, shed or greenhouse, etc.) that building will be treated as if it were part of the extension (see Illustration 1).

Any building added to your property which is more than 10 cubic metres in volume and which is within 5 metres of your house is treated as an extension and so reduces the allowances for further additions to the house without planning permission
(see Illustration 3).

Small shed (less than 10 cubic metres) is not treated as an extension but will reduce the allowance for further extension to the house (see Note 3).

A large shed/summerhouse/garage (greater than 10 cubic metres) is treated as an extension if within 5 metres of the house. If you live in a house which is a listed
building or is in a Conservation Area, all additional buildings which are more than 10 cubic metres in volume, regardless of the distance from your house, are treated as extensions and reduce the allowance for extending without planning permission.

Note 4 - The figures given for maximum sizes in Rule A represent the total amounts which can be built without planning permission. If, for example, you are making an addition to the roof of your house and also extending the house, the volume of both structures added together must not exceed the relevant amount shown at Rule A.

Note 5 - If you live in a house which is a listed building, it is likely that you will need Listed Building Consent for the building operations covered in this booklet. Your local planning office will advise if such consent is required.