Planning Permission for Extension Projects

Planning Permission for Extension Projects

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Planning Permission for Extension Projects


Does your extension need Planning Permission?

This will be determined by factors like the size of your build, the Permitted Development rights which apply to your property, and whether you live in a conservation area. Whilst the application process can be daunting, this guide will give you information for a single storey extension, and we can help with your house extension plans and whether you need conservatory planning permission (or loft conversion planning permission).


Planning Permission and the Law

It is lawful for planning applications to be decided according to development policy, unless there are contra-indications with material considerations. Application decisions are therefore policy-led, as opposed to influence-led. Near neighbours and the public will be consulted in most cases, but the result of the application will not be decided via popularity or grievance. Planning policies prevent results being decided by arbitrary, perverse or improper factors.


Your Local Planning Authority

If you are in doubt about your exact local planning department, consult the Directgov website and enter your postcode to give you your LPA.


How Material Considerations affect applications

Local Authority Planning Departments base their decisions on material considerations. This can be complex since what defines a material consideration is not specified in law. Moreover, not every material consideration applies to each project. The most common material considerations which might impact applications are:


Appearance, materials & design

Design covers things like dimensions, shape, proportions, materials, style and finish of a building. Acceptable design is subjective and variable. With respect to material considerations, the design should fit its surroundings by following, reflecting or tastefully contrasting the design of adjoining buildings.



If an area contains an archaeological site, it may be protected. It may not result in a refusal, but the site will normally require excavation before work starts. The developer should also take extra care with the work site.


Density of the building & layout

The proposed scale and design of a new build should match the existing site with respect to the nearby buildings, retaining the character of the area. The amount of space round a build is also important, as well as where it sits within the plot. Following the pattern of the area in this respect also defines the character of an area.


Development benefits

Sometimes the benefits of a proposal outweigh local or policy objections. This clearly is a positive material consideration.



The planning authority will consider the impact of new proposals on trees and plant life, and wildlife, especially with any protected species (such as otters.)


Green Belt

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In green belts, most new builds will be viewed as inappropriate, so material considerations will be very restrictive. However, there is a limited set of acceptable development criteria in the NPPF (National Planning Policy Framework). Here are the criteria:


  1. 1 Agricultural and forestry buildings
  2. 2 Outdoor sports facilities and, providing that open spaces and green belt purposes remain unaffected, outdoor recreation and cemeteries.
  3. 3 Extensions and alterations to existing buildings, provided they do not result in disproportionate additions to the scale of the original property.
  4. 4 You can replace existing buildings, provided the new building does not mean a change of use, and is not larger than the previous building
  5. 5 Limited housing for the local community and limited infilling of properties in villages so long as they follow the policies in the Local Plan
  6. 6 Limited infilling or partial or complex redevelopment of brownfield sites which are either redundant or in continuing use (not including temporary buildings), so long as open space and green belt purposes remain unaffected.

At Extension Architecture, we have good experience of working on several interesting Green Belt projects.


Parking & access

The noise of cars in parking places and access drives can constitute a material consideration, especially if the development is adjacent to existing residential properties with gardens. Highway safety will be considered, adequate physical access parking provision and turning space. Councils vary re parking requirements, for example the amount of off-street parking required is reduced if there are good public transport links, adequate road parking or public car parks.


Permitted Development

Another Material Consideration that will also be weighed by the local Planning Department is the level of permitted development rights in the area. For further reading on Permitted Development, see our article on Permitted Development, or call us if you would like a Permitted Development extension.


Physical factors

What this means is which buildings or obstacles are currently present. It is also the underlying ground conditions, and mapping & charting of the site as per existing topography. These can influence or constrain the preferred position of a proposal within a site. In addition, access to local services and amenities are common material considerations.


Planning history

This Material Consideration is a search of past approved permissions, refusals and appeals in the immediate area.



Even though planning history is considered, each case has to be looked at on its individual merits. Planners should be fair and consistent when applying their policies.


Residential amenities

Even though planning history is considered, each case has to be looked at on its individual merits. Planners should be fair and consistent when applying their policies.


Risk of flooding

Applications for new builds in vulnerable areas are likely to be unsuccessful, unless there are no other options outside the risk zone.


Special designations

The new build may possibly impact on areas of outstanding natural beauty, conservation areas or listed buildings. Buildings, views and open spaces contribute to an area’s character, which is quite a big material consideration. Planners try to protect listed buildings, whilst the law protects conservation areas.


Support / opposition level

If public opinion lends weight to a subjective judgment, such as on its design merits, then this will be a material consideration.


Things that won’t affect applications


These are not material considerations and won’t affect planning:

  1. 1 The loss of any private views
  2. 2 Legal matters which are personal and private, like right of way, boundary disputes or contracts
  3. 3 Whether if will raise or lower a property’s value
  4. 4 The possibility of any future development
  5. 5 An agenda from the applicant, such as profit
  6. 6 An applicant’s personal behaviour, or business operations
  7. 7 Inconvenience caused during the building process
  8. 8 Competitive issues with similar business within mutual proximity
  9. 9 Morals or religion
  10. 10 Aspects covered by other legislation, such as environmental health, party walls or building regulations
  11. 11 Additional legislative details like Party Wall protocols, Building Regulations and environmental health


The Pre-app. Route

We can arrange a pre-planning application meeting for you to get an indication of the planning officer’s view and of the possible material considerations. This is better than going to full planning and risking a refusal, in the case of any contention.



We know what kind of proposals are most likely to be accepted, as we know the LPA planning policies. Call us and we can help. We can also tell you about any supporting statements you may need such as Design & Access Statements, Planning Statements, Heritage Reports , Transport or Noise Impact Assessments, or Flood Risk Assessments.

   photo of drawings for article on Planning Permission for Extension        

We prepare professional architectural drawings for your extension plans, then submit your fee and application to the council.


Examples of our submissions:

  1. 1 All elevations are at a 1:100 or 1:50 scale
  2. 2 Context drawings and other representations
  3. 3 Floor plans for each level at a 1:100 or 1:50 scale
  4. 4 Ordinance survey-based location plan at a 1:1250 scale
  5. 5 Roof plan at a 1:100 or 1:50 scale
  6. 6 Site plan at a 1:500 scale

(We label any revisions for clarity to the planners.)


Your neighbours

Do have a talk with the neighbours about your proposal. They will be consulted by the LPA, but only material considerations will be used. If there are no objections, it won’t go to a Planning Committee but will be approved using delegated powers. We recommend that you contact them early so that planning applications can be submitted along with a letter of support from them.

Draft a letter of support for them to sign or rewrite. Include details about your meetings with them and how you have included their views. The letter stops the application getting into politics so the officer can focus on the technical side of the proposed development.


What happens next?

After your application has been submitted, LPA procedure is quite simple, as you can see in the following chart. Also shown are details of how to proceed, should the application be refused.

chart for article on Planning Permission for Extension  

After your planning submission has been validated, the LPA posts all the documents and drawings on its website for the public to view. They also begin consulting re your case to inform parties with interest of your intended development. They talk to:

  • Neighbouring residents
  • The Parish Council
  • Stakeholders
  • In-house professionals
  • External Professionals

In this way they gather technical expertise and advice for them and for you. The application must run for eight weeks so that all parties have an opportunity to respond.

After six weeks, when all the feedback is in and after their site visit, the officer puts all their findings together with the relative planning policies and any relevant material considerations. After internal discussions they will write a recommendation for either approval or refusal. This will include conditions like working hours for the build or pre-build approval of materials. These will need to be agreed formally before building can start.

Deciding your application can be done by officers or the Planning Committee which is a small body of councillors. Simple cases are taken by officers but any controversial ones go to the committee. You can request that your application goes before the committee if you are not happy with the usual route. You may be able to lobby councillors ahead of the Planning Committee meeting and even participate as a speaker. This is quite a good idea because they are not bound by the recommendations of planning officers.


Planning FAQs


Q: What are planning decisions based on?


  • Local Planning Authority development policy and material considerations
  • Many factors relate to land development, although private matters do not
  • See your local neighbourhood plans for relevant development policies


Q: What is the neighbourhood plan?

A: This is the plan intended to give best policy to the local community via consulting the people who use the area, from its residents to businesses, stakeholders and local MPs. These plans are the first policy documents a Local Planning Authority will consult. They are made up of written policies, explanations and proposal maps covering issues such as:

  1. 1 Area-specific issues
  2. 2 Community
  3. 3 Countryside
  4. 4 Design
  5. 5 Development Control Criteria
  6. 6 Employment
  7. 7 General Strategy
  8. 8 Green Belt
  9. 9 Heritage
  10. 10 Housing
  11. 11 Sustainability
  12. 12 Tourism & Leisure
  13. 13 Transport


Q: Can my time limit be extended?

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A: It is lawful for your permission to run out after three years, except where you have made a substantial start such as completing your foundations. However if you have not begun the build and the three years is nearly up, you will usually have to make a new application.


Q: Could i change my design a little after getting approval?

A: Minor alterations are permissible if you apply for a non-material amendment, but larger alterations might need a further application. Your local planners decide whether the amendment is large or small.


Q: I was refused. Help!

A: 75% of householder applications are granted in England, although this varies a lot from council to council. If you are refused, we can address the reasons with an amended re-submission, or you can appeal to the Planning Inspectorate. About 35% of appeals are granted. Listed building or conservation area decisions, attached conditions, enforcement notices or non-determination can be challenged (when it was not decided within the required limit.) The appeal can be in writing, hearing or public enquiry. Call us for guidance.


We can help

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We are an independent company with planning consultants, architects and interior designers under one roof. We can guide you through the process with our advice and selection of services. Our success rate is very high.

You can call or email us to discuss your extension proposal. 0203 409 4215