Policy DH3
Alterations and extensions (including outbuildings)
The council will require a high standard of design and materials in all alterations and extensions to existing buildings. These should be:
- compatible with the scale and character of existing development, neighbouring properties and their setting;
- successfully integrated into the architectural design of the existing building;
- subservient to the original parent building and rear and side extensions should generally not rise higher than one storey below the original eaves or parapet line of the main part of the building; and
- the cumulative extent of extensions should never dominate the original parent building in bulk, scale, materials or design and extensions and roof terraces on top of back additions should generally not comprise more than half the length of the original back addition.
In considering applications for alterations and extensions the council will take into account the following:
a) scale, form, height and mass;
b) proportion;
c) vertical and horizontal emphasis;
d) relationship of solid to void;
e) materials;
f) impact on skyline silhouette (for roof top additions and plant);
g) relationship to existing building, spaces between buildings and gardens;
h) the impact on any heritage assets, including their setting and interpretation;
i) good neighbourliness in particular the amenities of the neighbouring properties, and other properties most directly affected by the proposal;
j) the principles of accessible and inclusive design; and
k) the principles of Secure by Design.
8.24 The design of extensions or alterations to buildings is of considerable importance, because they can change the character of individual buildings and that of an area as a whole. This is of particular concern in terraces of uniform appearance. The council recognises that there will be changing needs and requirements of occupiers, but seeks to ensure that extensions and alterations, even the most minor ones, do not affect the inherent qualities of existing properties.
Additions to buildings
8.25 To avoid an incongruous and cluttered townscape appearance, additions to buildings such as roof and rear extensions and outbuildings, should be designed in keeping with the character of the building or complement its architecture without being unduly dominant. Roof level alterations and extensions, including front mansards will need to integrate successfully with the building concerned, using matching and high quality materials and execution. Where there are existing extensions on a street these will be taken into account in determining the appropriateness of new proposals.
8.26 Other proposed installations to existing buildings such as external lighting, CCTV cameras, antennae and solar panels should also be designed and positioned to minimise their impact.
8.27 Plant and other building services should also be integrated into the design of the building. Where additions cannot be incorporated into the volume of the building, building services located at roof level should be positioned and adequately screened to minimise noise and visual intrusion .Planted front and rear gardens form an important part of the townscape character of many of the borough's streets. Where a proposed alteration or extension will result in an impact on a heritage asset the council will consider whether the level of harm that will arise from the proposal is acceptable. Applicants should consider the asset's significance and its relationship to its setting when deciding the forms of extension or alteration that might be appropriate.
8.28 Where extensions or alterations are proposed to a heritage asset, the council will seek the retention of as much historic fabric as possible, together with the use of appropriate materials and methods of repair in a manner appropriate to their significance. Extensions should not dominate the original asset or its setting in either scale, material or as a result of its siting.
8.29 The principles of Secured by Design should be considered early in the design process in order to ensure secure and inclusive development. The council will make use of Article 4 Directions to restrict forms of development which could have an unsympathetic impact on the character and appearance of individual buildings and terraces.