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Planning application drawings for a residential extension

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Planning Permission for House Extensions

Some extensions can be built under permitted development rights, while others require a formal planning application. Understanding the correct route at the beginning can help avoid delays, unnecessary costs and problems later.

Planning permission is one of the first issues to consider when extending a home.

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Some extensions can be built without a full planning application because they fall within permitted development rights. Other proposals will need to be submitted to the local planning authority for approval before building work begins.

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The correct route will depend on the type of property, the size and position of the extension and any restrictions affecting the site.

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A modest rear extension to a house may be relatively straightforward.

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A large wraparound extension, double-storey addition or extension to a flat, listed building or home in a conservation area may require a more careful planning strategy.

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What Is Planning Permission?

 

Planning permission is the formal approval required for certain types of development.

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For a house extension, the local planning authority will consider whether the proposed work is acceptable in principle.

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The council may look at:

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  • The size and position of the extension

  • The height and overall scale

  • The relationship with the original house

  • The design and materials

  • The effect on neighbouring properties

  • Loss of daylight or outlook

  • Privacy and overlooking

  • The effect on the street scene

  • The character of the surrounding area

  • Trees, landscaping and local constraints

  • Any relevant local planning policies

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Planning permission does not deal with every technical detail of the construction.

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Structural calculations, insulation, foundations, drainage and other technical matters are generally addressed separately through the Building Regulations process.

Do All House Extensions Need Planning Permission?

 

No.

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Some house extensions can be built under permitted development rights without making a standard householder planning application.

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However, permitted development rights are subject to limits and conditions.

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They do not apply equally to every property.

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You should not assume that an extension is automatically permitted simply because a neighbour has built something similar.

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The neighbouring property may have a different planning history, a different relationship with the boundary or a different type of approval.

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What Is Permitted Development?

 

Permitted development rights allow certain types of home improvement to proceed without a full planning application, provided that the work remains within the relevant limits and conditions.

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Depending on the circumstances, permitted development may allow:

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  • A modest single-storey rear extension

  • Some larger single-storey rear extensions using the prior-approval process

  • Certain side extensions

  • Some double-storey rear extensions

  • Loft conversions within the relevant limits

  • Rooflights

  • Porches

  • Outbuildings

  • Other limited alterations

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The permitted development rules can be useful, but they are not always simple.

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The position should be checked carefully before building work begins.

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Where appropriate, it is often sensible to apply for a Lawful Development Certificate so that there is formal evidence that the proposed work is lawful.

When Is a Planning Application More Likely to Be Required?

 

A formal planning application is more likely to be needed where the proposal includes:

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  • A large rear extension

  • A wraparound extension

  • A double-storey side extension

  • A double-storey rear extension outside the permitted development limits

  • A side extension on designated land

  • An extension that projects beyond the relevant height or depth limits

  • A design that would dominate the original house

  • A significant impact on a neighbouring property

  • A balcony, raised terrace or platform

  • Major alterations to the front of the property

  • An extension to a flat or maisonette

  • Work to a listed building

  • Work to a property with restricted permitted development rights

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A planning application may also be the best route where the homeowner wants greater flexibility than permitted development allows.

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Rear Extensions

 

Rear extensions are among the most common home-improvement projects.

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A rear extension may create:

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  • A larger kitchen and dining room

  • An open-plan family space

  • Better garden access

  • A utility room

  • A downstairs WC

  • A home office

  • Additional living space

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Some smaller single-storey rear extensions may fall within permitted development rights.

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Larger extensions, double-storey extensions and more ambitious designs may require a planning application or another form of approval.

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The effect on neighbouring properties is important.

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The council may consider the depth, height and position of the extension and whether it would appear overbearing or reduce a neighbour’s daylight and outlook.

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Side-Return Extensions

 

A side-return extension uses the narrow strip of land alongside the rear addition of a traditional terraced or semi-detached house.

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This is particularly common with Victorian and Edwardian properties.

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A side-return extension can create a wider kitchen and dining space without using too much of the garden.

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However, it may raise planning issues because it is close to the boundary and can affect the neighbouring property.

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The height of the roof, the treatment of the boundary wall and the impact on neighbouring windows should be considered carefully.

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A glazed roof, rooflights or a roof lantern can help introduce daylight into the enlarged internal space.

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Wraparound Extensions

 

A wraparound extension combines a rear extension with a side-return extension.

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It can provide a major transformation of the ground floor and create space for a large kitchen, dining and family room.

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However, wraparound extensions frequently require a planning application.

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They use more of the available footprint and can have a greater effect on the neighbouring properties.

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The design should aim to create a balanced addition rather than simply use every available square metre.

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Double-Storey Extensions

 

A double-storey extension can add valuable space on both floors.

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It may provide an enlarged kitchen or living area at ground-floor level and an additional bedroom, bathroom or home office upstairs.

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However, the planning considerations are more significant.

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The council may look carefully at:

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  • The scale and massing

  • The effect on neighbouring properties

  • The position of upper-floor windows

  • Privacy and overlooking

  • The roof design

  • The relationship with the original house

  • The effect on the street scene

  • Whether the extension appears subordinate to the main building

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A well-designed double-storey extension should normally feel like a considered addition rather than an oversized structure attached to the house.

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Extensions to Flats and Maisonettes

 

Permitted development rights for householders generally relate to houses rather than flats and maisonettes.

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An extension to a ground-floor flat is therefore likely to require a planning application.

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You may also need:

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  • Freeholder consent

  • Leaseholder consent

  • Approval under the terms of the lease

  • Building Regulations approval

  • Party Wall advice

  • Structural design

  • Separate consent for work to a listed building where relevant

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Flats can present additional complications because the external walls, garden areas and structure may not be owned solely by the individual leaseholder.

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The legal position should be checked before work begins.

Conservation Areas


A conservation area is an area recognised for its special architectural or historic interest.
 

Extensions are still possible, but the design may need to respond more carefully to the character of the property and the surrounding area.
 

The council may pay particular attention to:
 

  • The size and position of the extension

  • The visibility from the street

  • The roof design

  • The choice of bricks, render, tiles and windows

  • The treatment of original features

  • Trees

  • The effect on neighbouring buildings

  • Whether permitted development rights are restricted
     

A contemporary extension may still be acceptable in some circumstances, but the design should be carefully considered.

 

Listed Buildings


If the property is listed, the process is more demanding.
 

Listed-building consent may be required for alterations that affect the special architectural or historic interest of the building.
 

This can apply to internal as well as external work.
 

An extension to a listed building may require careful design, appropriate materials and a heritage-focused approach.
 

Do not assume that ordinary permitted development rules will apply.

 

Article 4 Directions and Planning Restrictions


Some properties are affected by restrictions that remove or limit permitted development rights.
 

These may include:
 

  • Article 4 directions

  • Conditions attached to an earlier planning permission

  • Restrictions affecting newer developments

  • Conservation-area controls

  • Listed-building requirements

  • Restrictions resulting from a previous change of use

  • Leasehold or freehold limitations
     

A property may appear similar to its neighbours but have a different planning history.
 

It is sensible to review the position before relying on permitted development rights.

 

Larger Home Extensions and Prior Approval


Some larger single-storey rear extensions may be possible through the prior-approval route.
 

This is sometimes referred to as the larger-home-extension scheme or neighbour-consultation scheme.
 

The process is not the same as a normal householder planning application.
 

The local authority will notify adjoining neighbours and consider whether the proposal may affect their amenity.
 

The route applies only in specific circumstances and remains subject to the relevant limits and conditions.
 

It should not be treated as an automatic approval.

 

What Drawings Are Needed for a Planning Application?


A planning application will normally need a clear set of drawings showing the existing property and the proposed extension.
 

Depending on the project, the submission may include:
 

  • A location plan

  • A block or site plan

  • Existing floor plans

  • Proposed floor plans

  • Existing elevations

  • Proposed elevations

  • Existing and proposed roof plans

  • Sections where helpful

  • Dimensions

  • Materials

  • A written description of the proposal

  • Additional supporting information where required
     

The drawings should explain the project clearly enough for the planning officer, neighbours and other consultees to understand what is proposed.
 

Poorly prepared drawings can create confusion and delay the application.

 

How Long Does a Planning Application Take?


A householder planning application should normally be decided within eight weeks after it has been validated by the local planning authority.
 

Validation matters.
 

If documents or drawings are missing, the application may not be registered immediately and the eight-week period may not begin.
 

Some applications take longer because the council requests amendments, the proposal is sensitive or the planning department is dealing with a heavy workload.
 

It is sensible to allow additional time within the overall project programme rather than assume that approval will arrive exactly eight weeks after submission.

 

Will My Neighbours Be Consulted?


Where a formal planning application is submitted, the council will normally publicise the proposal and give relevant neighbours an opportunity to comment.
 

A neighbour does not have an automatic right to prevent an extension simply because they dislike it.
 

However, the council may consider relevant planning concerns such as:
 

  • Loss of daylight

  • Loss of outlook

  • Overlooking

  • Privacy

  • The scale of the extension

  • An overbearing effect

  • The appearance of the development

  • The effect on the character of the area
     

Personal disagreements, loss of a private view and the effect on property value are not normally the main planning considerations.

 

What Happens If Planning Permission Is Refused?


A refusal does not always mean that the extension is impossible.
 

The decision notice should explain why the application was refused.
 

Depending on the circumstances, it may be possible to:
 

  • Revise the design

  • Reduce the size

  • Adjust the roof

  • Change the position of windows

  • Improve the relationship with the neighbouring property

  • Submit a revised application

  • Explore a permitted development alternative

  • Seek further planning advice

  • Appeal where appropriate
     

In many cases, a carefully amended design can address the council’s concerns.

 

What Is a Lawful Development Certificate?


A Lawful Development Certificate can provide formal confirmation that proposed work falls within permitted development rights and does not require a standard planning application.
 

The certificate can be valuable because it creates a clear planning record.
 

This may be useful:
 

  • Before construction begins

  • When selling the property

  • When remortgaging

  • When answering questions from solicitors

  • Where the permitted development rules are complex

  • Where neighbours may raise concerns

  • Where a builder wants confirmation before starting work
     

A Lawful Development Certificate is not always compulsory, but it is often sensible.

 

Planning Permission and Building Regulations Are Different


Planning permission considers whether an extension is acceptable in principle.
 

Building Regulations deal with how the extension is designed and constructed, including foundations, structure, insulation, drainage, ventilation and fire safety.
 

Most extensions need Building Regulations approval even where planning permission is not required.
 

You may also need structural calculations, Party Wall advice and other specialist input depending on the project.

 

Think About the Whole Project


The planning application is only one stage of an extension project.
 

Before construction begins, you may also need:
 

  • Building Regulations drawings

  • Structural calculations

  • Building Control approval

  • Party Wall notices

  • A Party Wall Award

  • Drainage investigations

  • A build-over agreement

  • Freeholder or leaseholder consent

  • Builder quotations

  • A written specification

  • A realistic project budget
     

A good design should take these issues into account from the beginning.

 

Planning Your House Extension


A carefully designed extension can transform the way a home works.
 

The right planning route will depend on the property, the size of the proposal and the restrictions affecting the site.
 

It is worth exploring the options properly before committing to a particular design or asking builders to provide detailed quotations.

 

Find Suitable Extension Professionals


Depending on your project, you may need architectural design support, planning advice, Building Regulations drawings, structural calculations, Building Control input, Party Wall advice and an experienced extension builder.
 

Tell us a little about your home, the extension you are considering and the stage you have reached. We can help connect you with suitable professionals for the next steps.

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