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45 degree code

To safeguard the amenity of occupiers of neighbouring dwellings and to promote the provision of a satisfactory level of habitable accommodation within the existing house, the council will operate a 45 degree code.

What does this mean?

This relates to the impact of an extension on windows to habitable rooms in adjoining dwellings. Habitable rooms include:

  • living room
  • lounge
  • sitting room
  • playroom
  • bedroom
  • study
  • dining room
  • conservatory
  • kitchens

Extensions, which would breach the 45 degree code, will not normally be allowed.

The exception is a single-storey extension where the length of the extension would not exceed 3.5 metres in length as measured from the nearest window in the adjoining dwelling.

Application of the 45 degree code

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The measurement is taken from the centre of the windowsill level on the ground floor for single storey extensions and the quarter point of the windowsill for two or more storey extensions.

On the drawings adjacent, 'X' marks the mid-point and quarter-point at windowsill level of the nearest habitable room window in the adjoining house.

'C' is the point of the extension, which is closest to the common boundary with the adjoining property.

A marks the position where a horizontal line drawn across the base of the nearest habitable room window in the adjoining house would meet the side of the proposed extension.

The angle between 'X-C' and 'X-A' should be at most 45 degrees, as measured on the plan, within the bay or bow, window in line with the plane of the rear extension.

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