Guidance for small scale applications

Information, considerations and design advice on small scale development.

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All applications are considered with regard to national and local planning policy.

The main areas of consideration for smaller applications are:
Generally, householder development that is ancillary to and in keeping with a dwelling within a domestic setting is reasonable. However, site constraints, street scene, impact on neighbouring properties and previous development can prevent the principle of a proposal from being acceptable. In Green Belt, the principle of extending a house is acceptable providing it does not result in ‘disproportionate additions over and above the size of the original dwelling’.
The visual impact that a proposal would have on a property and the wider streetscene. When assessing applications, the council must ensure that development does not have an adverse visual impact on the built and natural environment.
The resulting impact of the proposal on nearby neighbours/occupants the council must ensure that the amenity of neighbouring residents and the public is not significantly affected by new development.
To ensure that highway safety is not compromised by securing in-curtilage parking where possible, relative to the size of dwelling, the council must ensure that suitable safe access points are available and that sufficient parking is provided to meet the demands of a property.
In addition to the main considerations, when assessing a planning application there are a number of environmental constraints that may affect your proposal.

You can check if a property falls within any constraints mentioned by clicking here.
An AONB is a statutory designation, whose distinctive character and natural beauty are so important that it is in the nation's interest to safeguard them. There are two AONBs in Northumberland.
An Article 4 Direction is a statement made under the Town & Country Planning (General Permitted Development) (England) Order 2015 which removes some or all permitted development rights from a property to protect the character of an area.

To find out more about Article 4 Directions in Northumberland click here.
Conservation Areas are designated by local authorities for their special architectural or historic interest. This means the planning authority has extra powers to control works to and demolition of buildings to protect or improve the character or appearance of the area.

For maps showing Conservation Areas click here.

To find out more about Conservation Areas in Northumberland click here.
A designation for land around certain built-up areas; the fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open and prevent the encroachment or loss of the countryside. The essential characteristics of the Green Belt are their openness and their permanence with local policy to support this found in relevant local plans and core strategies.
The Local Planning Authority has a duty to assess flood risk and water management implications of all new development however it is recognised that minor developments like householder extensions are unlikely to raise significant flood risk issues.

For further information from Environment Agency for planning applications click here.
There are approximately 5,500 listed buildings in Northumberland for which permission is required to carry out both internal and external works other than essential like-for-like repairs. A listed building is a building, object or structure which is of “special architectural or historic interest” and is graded I, II* or II depending on its importance, with grade I being the highest.

Listing protects buildings from unauthorised demolition or unsympathetic change, and aims to ensure that future changes do not cause harm. Permission may also be required to carry out works to any buildings or permanent structures within the curtilage of a listed building.

To access further information from Historic England click here.

To find out more about Listed Buildings in Northumberland click here.
If your site is located within or near to a designated wildlife area such as a Site of Special Scientific Interest (SSSI) or an area of bat activity additional restrictions may apply and further information may be required with your application such as a protected species survey.

To access further information from Natural England click here.

To find out more about ecology in Northumberland click here.
Find information on design principles below.

As a general rule, extensions should not appear to dominate the original house or neighbouring properties. They should complement the design of the original property and the wider area, in terms of scale and design.

Subordinate extensions
Under this approach, the original house should be dominant and all extensions should appear as sympathetic additions. A well-designed subordinate extension will help to maintain the original appearance of a house and the wider area, and are a good option in most instances.

Dwelling with a subordinate extension

Integrated extensions
Extensions can be designed to appear as part of the original house. If the design and building materials match in with the existing, the approach can work well for extensions to detached houses and extensions to the end of uniform terraces. However, this approach is not always appropriate for extensions to semi-detached properties.

Dwelling with an integrated extension
Roof and wall materials of extensions should match or complement those of the existing building. This will help to ensure that extensions and alterations sit well against the original property and the wider area. Poorly matching or uncommon materials can damage the character of a building. New wall or roofing materials should match the existing unit sizes, coursing, texture, pointing and colour (where applicable). In some cases, reclaimed materials may need to be used typically within a Conservation Area.

Proposed materials matching the existing dwelling

The use of non-matching materials can appear complementary to the existing materials (often on modern extensions to older properties). This will depend upon the overall quality of the design and how it looks in context. Material samples may be requested in this instance prior to approval being given.

Proposed materials complementary to that of the existing dwelling

Buildings often have architectural features and details which contribute to their character and appearance. When designing an extension, it is often desirable to replicate features such as opening pattern, window lintels/sills, eaves detailing, gutters and rainwater pipes.

Proposed extension matching the features of the main dwelling.


It is not necessary to incorporate grand or intricate detailing for the design of small extensions. Where buildings have ornate features and details; simpler extensions can be preferable so as not compete with the main building.  Generally, unless a high quality contemporary design is proposed, it will normally be appropriate to replicate basic features and details.

Proposed simple extension against an ornate building
Extensions should respect and integrate with the street scene. Proposed openings and its overall form should reflect proportions, design and layout of the properties around it. If a building has a well-balanced pattern of openings, the addition of too many windows, which are not aligned and of various sizes, will cause disruption and harm the look of a building and street scene. This would also apply to the addition of dormer windows.

A porch extension that matches the window pattern and form of the street scene
Overlooking and loss of privacy

Overlooking occurs where there is insufficient distance and unrestricted views between an opening or platform and a neighbour’s existing window or private garden. Direct views into habitable rooms such as reception rooms, kitchens and bedrooms are particularly sensitive. Bathrooms, store rooms, hallways, landings and garages are not as sensitive.

An extension that impacts privacy

Overbearing impact and outlook

Extensions or outbuildings can sometimes have an over dominating physical presence that damages the outlook of neighbours. Whether or not an extension or outbuilding has an over-dominating impact will depend on its overall size, the distance between neighbouring properties, and the position of habitable room windows or well used parts of the garden beyond boundaries.

An extension that has an overbearing impact

Loss of light

In many cases, extensions and outbuildings that have an overbearing impact upon their neighbours, will also cause an unacceptable loss of light to neighbouring properties and their gardens dependant on the orientation of the property.

An extension that causes loss of light
Where there is an increase in habitable accommodation, it will be expected that the in-curtilage parking provision should be addressed to cater for any increased demand or loss of spaces to prevent adverse effects on highway safety and street scene.

A proposal that increases parking provision along with habitable accommodation
View our design guidance below.


The construction of a basement does not present too many design concerns provided there are no adverse alterations to the external appearance of the property that would impact the street scene.
  • Consider the existing building line and limit the projection of front extensions.
  • The design should not cause imbalance when viewed against neighbouring properties.
  • Subordinate extensions sit more favourably in the street scene.
  • Should respect attached neighbours to minimise loss of light and overlooking.
  • Footprint of front extensions should not compromise in-curtilage parking.
  • Two storey front extension should ensure that they sit well within the street scene and do not adversely affect residential amenity.
  • Consider the existing street scene, including past extensions;
  • Retain a reasonable relationship between existing buildings and extensions;
  • Avoid an overbearing visual impact with regard to bulk and proximity to boundaries, both from inside; adjacent properties and from neighbouring gardens;
  • Prevent excessive daylight loss or overshadowing to habitable rooms of neighbouring properties;
  • Where a conservatory is to be located close to the boundary of a neighbouring property consider the installation of obscure/opaque glazing on that boundary elevation or retention of existing boundary screening to prevent loss of privacy to both you and your neighbour.
  • Side extensions should usually incorporate a roof design to match that of the existing building. Alternatives may be appropriate however on a contemporary dwelling or on a contemporary extension to a traditional building.
  • Subordinate two storey side extensions should have a ridge line that is set down from that of the existing building and set back from the front elevation.
  • Windows with an outlook toward a main living area will not normally be permitted in the side elevation, however small windows to bathrooms, hallways, stairs or landings may be acceptable.
  • Two storey and first floor side extensions can have a significant impact upon the visual amenity of the street scene. Terracing effects can be created where adjacent semi-detached properties build side extensions that both meet the party boundary. This leads to a loss of openness between the properties and a loss of uniformity in the character of the street scene and should be avoided.
  • In designing two storey side extensions, consideration needs to be given to the need to maintain access to the rear of the property and to the need for maintenance to be carried out to the property.
  • End of terrace extensions can adopt an integrated approach (see considerations) to become part of the terrace. Extensions which result in the take up of amenity or public open space will generally be resisted.
  • Corner plots provide important space between adjoining streets and add character to an area. Consideration needs to be given to the siting and design of side extensions such that it does not appear more dominant in the street scene than neighbouring properties. Proposed extensions on corner plots should respect the building lines of both streets in order to maintain the openness of the area along with good visibility for motorists and pedestrians.
  • The addition of dormer windows can have significant impact upon the property and street scene, dormers should therefore be positioned and designed to minimise the character of the area.
  • Dormers should be set into the roof slope and avoid appearing overly large as extensions by setting them in from external walls.
  • Dormers should not exceed the height of the existing roof.
  • In some cases smaller dormers appear less intrusive than a single large extension.
  • The proposed materials should match the existing although contemporary solutions that are complementary are also acceptable.
  • Dormers to front elevations should be in keeping with the character of the street, flat roof or box dormers to front elevations will generally be resisted.  
  • Consider the location of the outbuilding in relation to the existing property and the street scene and surroundings.
  • Consider the siting and scale of the outbuilding with regards to loss of light, overbearing and privacy issues to neighbouring properties.
  • Subordinate outbuildings are considered favourable.
  • Consideration should be given to the materials and finishing details; these should complement its surroundings.
  • Proposals for annexes should be subordinate in scale, ancillary and tied to the main dwelling to be considered under householder development. Larger annexes may be subject to full planning permission.
  • Ensure that the proposal does not conflict with the form of boundary treatment within the surrounding area (scale and materials);
  • Consider breaking long runs of boundary treatments that are adjacent to the public realm by inserting brick or stone piers at an appropriate height, especially those that are adjacent to a public footpath;
  • Consider highway safety where on corner sites so as to ensure that they do not detract from the character of the area or are prejudicial to highway safety;
  • Make sure that the proposals for high boundary walls are not detrimental to visual amenity, and the need for natural surveillance of the public realm to help prevent anti-social behaviour.
doors & windows.jpg
  • New openings should follow the fenestration pattern of existing where possible and be materially in keeping.
  • Upper floor side windows must respect the amenity of neighbouring properties and be reduced in size/obscure glazed where necessary.
  • Materials and subsequent appearance matching that on existing house and reflect the local architectural style and character.
  • If the building is a Listed/subject to an Article 4 Direction, like-for-like repairs and sympathetic alterations are encouraged.