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Appeal Decision 184 - Certificate of Lawful Development.

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


December 2010 - Code a00184


Summary of Case (appeal dismissed): 


The property is a two-storey detached house. The front elevation of the property is “T” shaped, with a large two-storey front projection in the centre . The application was for a proposed dormer on the side roof slope of the two-storey front projection. 


As I was unable to view the drawings for this application, please refer to the extract below from the appeal decision notice, along with the Aerial Photo. 


The key issue was whether the proposed dormer would be contrary to Class B, part B.1(b), which states that “development is not permitted by Class B if … any part of the dwellinghouse would, as a result of the works, extend beyond the plane of any existing roof slope which forms the principal elevation of the dwellinghouse and fronts a highway”.


The Inspector stated the following: 


“The Department of Communities and Local Government (DCLG) has issued technical guidance on the operation of the GPDO. This advises that in most cases, the principal elevation will be that part of the house which faces the main highway serving the house, and will usually contain the main architectural features such as main bay windows or a porch serving the main entrance to the house. It advises that the principal elevation could include more than one roof slope facing in the same direction, for example where there are large bay windows on the front elevation, or where there is an "L" shaped frontage. In such cases, the guidance advises, all such roof slopes will form the principal elevation and the line for determining what constitutes "extends beyond the plane of any existing roof slope" will follow these slopes. 


In the case of [the application site], the footprint of the building is roughly Lshaped at ground level, but more T-shaped at first floor. Its eastern elevation, which faces the road, has a front projection with a gable facing the road and this contains bay windows at ground and first floors. To the north of this projection, the roof slope of the gable continues down to form the roof of a garage to the side. Behind the front projection containing the bay windows is a further wall of the house, with a roof slope facing the road and extending the full width of the house behind the gable projection and the garage. This wall contains a living room to the south of the gable, which has a window facing the road, as does the bedroom above. It is set back some way from the front gable. The main entrance to the house is via a porch in the corner formed by the side wall of the gable element and the wall of the living room. 


The proposed dormer would be constructed above, and slightly behind the front wall of, the garage, coming off the side roof slope of the gable projection. It would be in front of the roof slope of the rear part of the building containing the living room (the roof slope which fronts the road), albeit on the other side of the gable from the living room. 


It is clear from the DCLG Technical Guidance that the “principal elevation” of a building could include more than one wall facing in the same direction, and is not always a flat plane. In this case, the principal elevation is not confined to the gable projection; the main entrance is set back from this, and the elevation behind the main entrance, containing the living room, is equally part of the principal elevation. This is agreed by the appellant. The roof slope above this part of the building, which continues for the whole width of the rear element of the house, is thus part of the principal elevation of the dwelling. The test in B.1(b) is whether the alteration to the roof extends beyond the plane of that roof slope. Clearly, the alteration proposed here does. It is not, therefore, permitted under Class B”. 


Main Conclusions: 


·       Where the front elevation of a property is staggered, then more than one wall facing the same direction can form “the principal elevation”.
[Note: This would appear to contradict at least one other appeal decision – for further information see the entry in the “Reference Section” on “Principal Elevation”].
[Relevant to: “Principal Elevation”, A.1(d), B.1(b), E.1(b), F.1, G.1(b)].


·       Where a front-facing roof slope is set back behind a forward projecting structure, then the former can still form part of “the principal elevation”.
[Relevant to: “Principal Elevation”, A.1(d), B.1(b), E.1(b), F.1, G.1(b)].


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


·       Appeal Decision Notice: 

·       Aerial Photo: 





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