Does anyone have any advice on whether the height of a proposed chimney is taken into account when assessing the height of a proposed single storey extension to the rear? I understand that in cases where development includes the provision of a chimney or soil/vent pipe you would assess the chimney under the provisions of Class G and therefore whilst it may not be permitted under Class A it may be permitted under Class G. However, does this still count where the chimney would be part of the extension and would result in the height of the extension exceeding 4 metres in height? The only reference to calculation of height I can see is under Class A.1 (b) where the guidance states that the height of all protrusions above the roof must be taken into account when assessing total height, but this relates to where development may exceed the height of the original roof. Does this way of measuring height apply in all circumstances or is there effectively no limit on the height of a chimney on a proposed extension as long as it doesn't breach Class G?
