Policy information sourced from Lewisham Development Management Local Plan

DM Policy 31 Alterations and extensions to existing buildings including residential extensions

Development proposals for alterations and extensions, including roof extensions will be required to be of a high, site specific, and sensitive design quality, and respect and/or complement the form, setting, period, architectural characteristics, and detailing of the original buildings, including external features such as chimneys, and porches. High quality matching or complementary materials should be used, appropriately and sensitively in relation to the context. New rooms provided by extensions to residential buildings will be required to meet the space standards in DM Policy 32 Housing design, layout and space standards.

In addition, where it is necessary:

  • side extensions should normally be set back and down from the main building line to allow for a clear break between existing buildings and the new work in order to maintain architectural subordination to the original building
  • rear extensions will generally not be permitted where any part is higher than the height of the ridge of the main roof, or where the extension is not set back into the roof slope. Roof extensions on the street frontage of a building, particularly in a residential street will be resisted in favour of extensions to the rear of the building. Rooflights on the front roof slope of buildings should be considered in relation to the design of the dwelling and harmonise with the street-scene
  • residential extensions, roof terraces and balconies and non-residential extensions adjacent to dwellings should result in no significant loss of privacy and amenity (including sunlight and daylight) to adjoining houses and their back gardens. The requirements of DM Policy 32 should be referred to as appropriate. Residential extensions should retain an accessible and usable private garden that is appropriate in size in relation to the size of the property, and retain 50% of the garden area
  • additional or enlarged windows, doors and other openings, should be in keeping with the original pattern, and in the case of a roof extension should reflect the existing alignment of the windows. Replacement windows where controllable by the Council should closely match the pattern of the original windows. The repair of original windows will be encouraged
  • details of plant, pipework, fire escapes, lifts and other mechanical equipment including ducts and flues should be included within the initial planning application and be enclosed within the envelope of the building or, where that is impracticable, sited where they will have the least visual impact
  • the Council will consider proposals for building extensions that are innovative and have exceptional design quality where these are fully justified in the design and access statement.

Extensions will not be permitted where they would adversely affect the architectural integrity of a group of buildings as a whole or cause an incongruous element in terms of the important features of a character area.

Where the roofline or party walls of buildings or terraces are exposed to long views from public spaces, a roof extension in any form that would have an obtrusive impact on that view will not be permitted.

For more information please see the Local Plan