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Appeal Decision 226 - Certificate of Lawful Development.

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March 2011 - Code a00226


Summary of Case (appeal allowed): 


The property is a two-storey mid-terrace house. The application was for a proposed rear dormer and a proposed single storey rear extension. The proposed rear dormer would be set back by more than 20cm from the outer edge of the section of the roof overhanging the rear wall of the house, but less than 20cm from the point where the vertical plane of this wall meets the slope of the roof. The outer wall of the proposed single storey rear extension would project 3m from the rear wall of the main house, but its roof would have an overhang that would project slightly past this line.  


The first key issue was whether the proposed dormer would be contrary to Class B, part B.2(b), which states that “Development is permitted by Class B subject to the following conditions … (b) other than in the case of a hip-to-gable enlargement, the edge of the enlargement closest to the eaves of the original roof shall, so far as practicable, be not less than 20 centimetres from the eaves of the original roof”. 


The Inspector stated the following: 


“The dispute between the parties is as to where the 20cm should be measured from. The condition requires that it should be from the eaves but there is no definition of “eaves” either in relation to Class B or in Article 1(2) of the GPDO itself. The Council relies on a previous appeal decision [February 2010 - Code a00092] in which the then Inspector went into this matter in some detail. Since both parties are aware of it, I shall not repeat the reasoning in full. With the aid of a sketch diagram, the Inspector portrays “eaves” as typically comprising a three-dimensional overhanging projection from the outside wall of a building, with a number of component parts. He goes on to run through possible definitions of the term before drawing what he considers to be a crucial difference between “eaves” and “outer edge of the eaves” in determining the point from which the 20 cm should be measured, in the context of the wording of the condition. 


That decision is dated 1 February 2010 and pre-dates the technical guidance. The guidance, aided by a simple diagram, plainly says (p35) that the 20cm should be measured along the roof slope from the edge of the enlargement to the outer edge of the eaves. The Inspector in his decision reasoned that, had the legislators intended “eaves” to mean “outer edge of the eaves” for purposes of the condition, they would surely have said so. To that extent, the guidance is responding in a purposive way to that very question, by clarifying the position. In nevertheless preferring to side with my colleague’s earlier interpretation rather than the technical guidance, the Council, in correspondence with the appellant, points to legal advice on which it relies and to what it considers to be anomalies in the guidance, on the basis of which it considers the guidance on this point to be in error. 


The Council does not disclose its legal advice but in so far as it contrasts the guidance on p35 with guidance on determining eaves height on p11, I must assume that that contrast is what underpins its view as to its unreliability. I can, up to a point, appreciate why it might take such a view. On p11, the guidance defines eaves’ height in terms of the point at which an outside wall would meet the upper surface of the roof slope. Moreover, I noted on p42 of the guidance the statement that “…The eaves of a building will be the point where the lowest point of a roof slope, or a flat roof, meets the outside wall of the building.” Taken out of context, these references, in so far as they might be taken for authoritative definitions, appear to conflict with how eaves are determined for purposes of the condition. 


However, my colleague had, correctly in my view, described eaves as being something more than simply a line on a building in two dimensions i.e. where the plane of the outside wall meets the roof slope or, for that matter, the edge of the roof slope. Both of the definitions of eaves to which I have referred are given in the guidance for purposes of dealing with eaves’ height. However, the eaves also include those parts of the roof which might project beyond the plane of the outside wall and indeed the appeal dwelling has boxed eaves below the roof slope. I therefore see no inconsistency in taking a different part of the eaves as the point from which to measure the extent to which an enlargement of a roof should be set back in the roof slope. I do not therefore accept that there are anomalies in the guidance with regard to how the term “eaves” is used for purposes of interpreting the provisions of the revised GPDO. 


My colleague also raises concerns that measuring the 20cm from the outside edge of the eaves could lead to dormers which might appear out of proportion with the roof slope or whose front face could overhang the outside wall of the dwelling. On the former, the 20cm nevertheless provides for a degree of set back within the roof slope, so a dormer could not cover its full extent nor, given the limitation set out in B.1(a), could its height exceed that of the highest part of the roof. With regard to the latter, it is true that, in theory, a dormer could, under the guidance, be built so as to overhang a main rear wall. However, no-one would sensibly build a dormer in that way, for obvious structural reasons. 


Plan ref. SK009A shows that the front face of the proposed dormer is overhung by a fascia which contains guttering from which the rainwater goods descend. Given that the technical guidance shows the measurement as being taken to the front face, I consider it reasonable to exclude those elements. The plan shows the 20cm set back being taken from the edge of the roof slope, excluding guttering at the base of that slope, to the front face of the dormer, following the diagram on p35 of the guidance. On that basis, I conclude that the requirements of condition B.2(b) would be met and that the loft conversion would, if built as proposed, be permitted development.” 


The second key issue was whether the projection of the roof overhang of the proposed single storey rear extension by more than 3m beyond the rear wall of the original house would be contrary to Class A, part A.1(e), which states that “development is not permitted by Class A if … the enlarged part of the dwellinghouse would … extend beyond the rear wall of the original dwellinghouse by more than … 3 metres”. 


The Inspector stated the following: 


“The dwelling forms part of a terrace and the existing rear wall is as originally built. I have no evidence to suggest otherwise. Plan ref. SK009A shows the extension in section and identifies what might appear at first sight to be an overhanging roof, or part of the rear wall, as a fascia. A parapet is shown above the level of the roof of the extension. While the line of the rear wall is partly obscured by a fence, it is possible to scale it from the plan and I measure it at just below 3m. The technical guidance, at p16, makes clear how the depth of any extension should be measured and it has been followed in the submitted plans. While plan ref. SK009A leaves a little room for doubt in the way the fascia has been drawn, it is clearly enough labelled. On this basis, I conclude that the rear extension would be permitted development.” 


Main Conclusions: 


·       For the purposes of the 20cm set back, the term “eaves” applies just to the outer edge of the section of the roof overhanging the wall. As such, the 20cm set back should be measured 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)].


·       Where the rear wall of an extension would comply with the 3m/4m rear projection limit of Class A, part A.1(e), but the eaves / guttering / soffit / fascia of the extension would project slightly past this line, then this would still be permitted development.
[Relevant to: A.1(e)].


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


·       Appeal Decision Notice: 

·       OS Map: 

·       Existing Front and Rear Elevations: 

·       Proposed Front and Rear Elevations: 

·       Proposed Side Elevations: 

·       Proposed Floor Plans: 




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