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Appeal Decision 92 - Certificate of Lawful Development.

This appeal decision summary and assessment has been produced by Planning Jungle Limited.  For more information, please go to

February 2010 - Code a00092  


Summary of Case (appeal dismissed): 


The property is a two-storey semi-detached house, with a hipped roof.  An unlawful side dormer has previously been erected, and the corner of the flat roof of the dormer projects beyond the front elevation.  The application was for a proposed alterations to this dormer, including narrowing its width, reducing its height, and replacing its flat roof with a hipped roof. 


The appeal decision notice for this case is very lengthy, and only parts of it have been summarised below. 


In his conclusions, the Inspector stated the following: 


“In summary, the proposal would not be lawful for at least four reasons. First, the permitted development rights granted by Class B of Part 1 of Schedule 2 of the GPDO do not apply, because this part of the GPDO only permits the enlargement of a dwellinghouse consisting of an addition or alteration to its roof, not for altering or rebuilding an existing structure in the way proposed (including its walls). Secondly, in any case the relevant GPDO rights do not apply to an unauthorised, unlawful structure


Thirdly, Class B rights cannot be used to carry out the proposal because the eaves of the original roof no longer exist below the disputed enlargement to provide a measuring line from which to take the 20 centimetre measurement specified in Condition B.2(b), so it is not possible to comply with this condition; and in circumstances where the original eaves have been removed, an exception to the 20 centimetre criterion is not justified on the grounds that its application would be impracticable. 


Fourthly, even if a different view were to be taken on all the preceding points, and even assuming Class B rights apply and that a measurement can be taken between the proposed structure and the eaves of the original roof, Condition B.2(b) would not be met because, when this dimension is applied to the eaves rather than the outer edge of the eaves, the proposal would not comply with the 20 centimetre set-back criterion.” 


Further to the last point, the Inspector had earlier stated the following: 


“The appellant and the Borough Council interpret Condition B.2(b) differently. The appellant contends that the 20 centimetre measurement should be taken from the outer edge of the sloping roof. The Borough Council argue that the measurement should be taken from the point or line where the vertical plane of the side wall of the house meets the slope of the roof.  


One of the difficulties in this case is that the recently amended GPDO is open to alternative interpretations. The term "eaves" is not defined in the legislation, but usually refers to the overhanging or projecting part of a roof,  where a roof is designed with its outer edge projecting beyond the wall below. I do not see anything wrong with the Borough's interpretation of the GPDO. On the basis that the eaves are the part of a roof which projects beyond the house wall, the eaves include all of the overhanging volume. On the appellant's interpretation, the term "eaves" would have to be interpreted as meaning "outer edge of the eaves" – but that is not what the legislation states.  


As has been pointed out for the appellant, various consultation and guidance documents have been published suggesting that the 20 centimetre measurement should be taken from the outer edge of the eaves (excluding any guttering). Those documents do not have legal force. If Parliament had wanted the measurement to be taken from the outer edge of the eaves it would have been a simple matter to specify this.” 


The Inspector then included a diagram in his appeal decision notice to illustrate the above point. 


Main Conclusions: 


·       Permitted development rights do not apply to an unauthorised, unlawful structure.
[Relevant to: “General”]. 


·       For the purposes of the 20cm set back, the term “eaves” applies to all of the section of the roof overhanging the wall, and not just to the outer edge of this section.  As such, the 20cm set back should be measured from the point where the vertical plane of the wall meets the slope of the roof, rather than from the outer edge of the sloping roof.
[Note: This would appear to contradict at least one other appeal decision – for further information see the entry in the “Reference Section” on “B.2(b)”].
[Relevant to: B.2(b)]. 


Links to the “Appeal Decision Notice” and other associated documents (e.g. drawings, etc): 


·       Appeal Decision Notice: 

·       OS Map: 

·       Drawings: 

·       Costs Decision Notice: 






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