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How to Get Planning Permission for a House Extension: Quick and Easy Guide

Planning permission is often seen as the major milestone when it comes to making your project a reality. But how can you gain planning permission for your house extension? We'll share how here.

What is planning permission?

In simple terms, planning permission is permission from your local council to build something.

Most small projects will be covered by what's called permitted development and can include some types of extension work, namely small single storey rear extensions, outhouses and dormer roofs to typical UK houses.

The local council decide on building proposals so that they can maintain a general plan for the urban growth their constituency. This stops people building huge structure where they would be very out of place!

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Why Do I Need Planning Permission?

Most house extensions require planning permission, although there are a few exceptions. The most common reasons for needing planning permission are:

- The extension will exceed the permitted development rights.

- The extension is in a conservation area or has listed building status.

- The proposed extension will result in increased noise or pollution levels.

- The new structure will cast shadows on neighbouring properties. 

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What planning rules are important to a house extension?

Each local council will have slightly different rules when it comes to what is considered 'acceptable' and ' unacceptable' development. In addition - this will also be dependant on your local area, the materials on the outside of buildings and the shape of those buildings. 

For a house extension, the most common terms and policy you need to be aware of are:

- Policies describing the local character.
- Policies about overdevelopment
- Overlooking, overshadowing and overbearing rules.
- Garden amenity requirements.

Special planning rules for houses in the UK

Some area have tighter rules on building a house extension, you should also check whether your house is located in any of the following:

- Green belt or metropolitan green belt land - These areas will have strict rules regarding the additional size of extension you can create and where, for more information, see our guide on gaining planning permission on green belt land.

- A conservation area - these areas will be more strict on maintaining the visual character of the buildings, this normally means using certain materials as seen from the street and decorative items on the windows.

- Listed or historical building - These projects will need special attention and care to show the listed building is being protected and retained as part of the project.

- AONB Area of Outstanding Natural Beauty - these areas, much like with green belt land, will be stricter on maintaining natural landscapes and views, this normally means any building work must be subtle when viewed from the outside.

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How will I know if my planning application will be accepted?

While there is no 100% confirmation of acceptance, gaining planning permission for your house extension will be much more likely if your architect has done the following. 

1. Check the local precedent to give you a likely indication of what has already been accepted in your area.

2. Cross check that the design complies with all of the relevant policy for the local council receiving the planning application. 

3. Produce the drawings and design statement documents in order to make the best case possible for your project. 

Where there is no precedent or there are multiple uncertainties regarding your project, your Architect should suggest whether it is worth applying for pre-application advice.

The pre-application advice service allows you to make a speculative application in order to get advice on your plans from the council, this allows you to gain more information without risking a public refusal of your planning application. 

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How Do I Know If My House Extension Needs Planning Permission?

Your house extension will likely need planning permission as soon as you go beyond the criteria shown in the permitted development rules. 

A handful of these reasons would include. 

- Your house is in a conservation area, the greenbelt or it is listed.

- The extension footprint is larger than 3 metres in depth and higher than 4 metres high.

- The extension is unconventional in nature e.g. different types of materials. 

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How Do I Go About Getting A Planning Permission? 

Getting planning permission can be straightforward if you follow these steps below. 

Step 1

Speak to an expert

Many professionals will be able to tell you immediately whether your project is likely or unlikely to get planning permission.

We offer free consultations where we have helped hundreds of people reach this answer quickly and free of charge. Get this answered today. 

Step 2

Have your project drawn up correctly

Once you know your plans are likely to work. Have your project drawn up to the correct format for a planning application. 

It is possible to draw you own plans for a planning application, however it is very important to make sure the drawings are correct, namely:

1. drawings should show the existing and proposed building.
2. They should include a site location plan at 1:1250 scale and existing and proposed site plans at 1:250 or 1:200 scale.
3. It is recommended to submit floor plans at either 1:00 or 1:50 scale. 

Drawings should also follow the line weight, hatched and colour formats, these can be found on each local council's website.

Step 3

Submit your planning application on the planning portal

Once you have you house extension drawings and any relevant statements completed, you can send the application via. the UK planning portal website. 

This website will allow you to upload your drawings, and fill in the forms detailing the address, the applicant and important information regarding the site and the proposal.

Following this, you will need to pay the application fee to have the application processed and decided on. For a householder planning application this fee is normally £236 +VAT.

Step 4

Monitor and communicate prior to a decision

As Architects, it is really important that we reach out and communicate with the planning officer deciding on your project. 

The reason for this is to allow for problems to be addressed early and before they issue their decision. About 75% of applications we submit will have concerns from the council that were later rectified and accepted.

Step 5

Gain your planning decision

After 6 weeks - or longer if an extension of time has been requested - you should receive a decision letter telling you whether your project has been approved or refused. 

When approved, it is likely that your project will be subject to conditions, these commonly include 3 year time limit to start construction and that the project follow the planning drawings in size and design. 

Additional conditions are common however, be sure to check these and address them at the stage requested.

My planning application was refused, what can I do?

If your planning application has been refused, don't worry! There are multiple options available depending on the reasons for refusal and the conduct of the local council. 

1. Appeal the decision - You can appeal the decision if you think the local planning authority has made a mistake in their assessment. This is normally free but will require a statement of case to be drafted and can take a lengthy amount of time.

2. Submit a new application. If you think that your original application may not have been assessed fairly, you can submit a new application with amended plans. Many councils offer a free resubmission when the resubmitted project is similar in scope. 

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I have built my extension and now I need planning permission, what do I do?

If you have built your project and you've been told you need to submit or resubmit a planning application, this is possible and is known as a retrospective planning application. 

It goes without saying that it is not recommended that you try to apply for planning permission retrospectively if you know you require it. Retrospective planning permission does hold a very real risk that your project will need to be knocked down entirely and this does happen. 

Making a retrospective planning application is the same as making a regular planning application as seen above. It is important that - where possible - you contain evidence or information which shows why it was built without planning permission in the first place.

Retrospective planning permission

Planning permission - it's all about planning 

With the guide above, you should have all the necessary information for gaining planning permission on your next house extension. 

Planning policy is a dense subject, therefore if you do have any further questions please do reach out to us. You can book in a free consultation below where you can get professional advice on the likelihood of your project when it comes to planning permission.

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We're here to answer your planning questions. Our free consultations have allowed many homeowners to get the answers they need free of charge.

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