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Appeal Decision 237 - Certificate of Lawful Development.

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April 2011 - Code a00237


Summary of Case (appeal allowed): 


The property is a two-storey detached house set within very considerable grounds, and situated within a conservation area. The south (south-east) elevation is the principal elevation, and does not front a highway (it faces a highway at a significant angle and at a significant distance). The application included a proposed two-storey front extension, which would more than triple the volume of the house, and with a roof that would join onto the roof of the main house. 


The Council refused the application with the following reason for refusal: 


“The proposed two storey front extension would enlarge the dwelling through an addition to the existing roof and the site lies with article 1(5) land. Therefore the development would fail to accord with B.1 (e) as set out in Schedule 2, Part 1, Class B of the Town and Country Planning (General Permitted Development) Order 1995 (amended 1 October 2008).” 


The key issue was whether the proposed extension would be contrary to Class A, part A.1(i), which states that “Development is not permitted by Class A if … it would consist of or include … an alteration to any part of the roof of the dwellinghouse”. 


“Based on the Block Plan the existing dwelling is typically 5 m deep but the front extension would project up to 14 m forward of the original wall and a modest rear extension is also proposed. The net result would be a massive extension that more than triples the footprint of the original dwelling, but the Council has agreed the broad scale of the extensions under its application No 10/P/02249. That scheme was under construction at the time of my inspection and the main difference with this scheme relates to the design of the roof. Accordingly, by reference to the reason for refusal, the issue to be determined is whether the proposed alterations to the roof of [the application site] should be assessed against Class B or Class C of the amended 1995 Order. 


The Department for Communities and Local Government’s [DCLG’s] Technical Guidance “Permitted development for householders” says on page 7: “changes to the roof of a house are not permitted development under Class A, but may be permitted development under Class B or C. For example, where a proposed two storey extension at the rear of a house has a roof that joins onto the main roof of the original house, the works will need to meet the requirements of both Class A (which covers the enlargement of the house) and Class C (which covers any alterations to the roof) in order to be permitted development. If the works also include the creation of a dormer window to enlarge the roof space, either in the extension or the original roof space, then they would also need to meet the requirements of Class B” (my emphasis). Although the example refers to a rear extension, the substance of this advice does apply to the circumstances pertaining in this appeal, i.e. where an extension butts into an existing roof. 


It is clear from the submitted plans [notably drawing No 992/P-02] that the proposed extension does not include the addition of dormer windows to either the extension or the original roof space and hence Class B does not apply. The Appellants’ have explained why the criteria in C.1 are not breached and I have no reason to dispute this, particularly as the Council has not challenged these observations at final comments stage. However to elaborate on this further, paragraph C.1 (a) says development is not permitted by Class C if: “the alteration would protrude more than 150 millimetres beyond the plane of the slope of the original roof when measured from the perpendicular with the external surface of the original roof.” The ridges of the extension would be perpendicular to that of the roof of the original house. The points at which the roofs of the extension would join or attach to the existing roof of the dwelling would give rise to alterations to the original roof of the dwelling. The proposed roof structure would be permitted under Class A up to the point at which it attached to the existing roof of the dwelling, and it would not amount to a protrusion for the purpose of Class C. As such the limitation to no more than 150 millimetres would not apply. 


This approach to the construction of Part 1 arises from the advice on page 37 of the Technical Guidance, which says: 


“This limitation to projection from the roof plane should not be applied in cases where the roof of an extension to a house that is permitted development under Class A is joined to the roof of the original house. In such cases, the roof of the extension should not be considered as protruding from the original roof.” 


This is notwithstanding my colleague’s observations on A.1 (i) (iv), which led her [January 2010 - Code a00081] to assert that an extension with a pitched roof would not be permitted by Class A. In her defence this view was expressed prior to publication of the Technical Guidance which, in the absence of judicial authority, should be taken to be the definitive guide to the interpretation of the amended 1995 Order. 


It might be said such an approach is unsatisfactory because it would appear to allow someone to circumvent the volume threshold in Class B by implementing a Class A extension with a roof that does not contain a habitable room, which could thereafter be retrofitted. However it seems to me that is a consequence of the particular drafting of the SI and it is not for me to comment on the wisdom or otherwise of such wording. DCLG have advised on the approach to be adopted and it is incumbent on the decision maker to adopt that approach. 


I am satisfied the conditions in C.2 are met because no windows are proposed to be included in the roof slope forming a side elevation of the extension. On this basis the works as proposed to alter the existing roof are permitted development by virtue of Article 3 and Class C of Part 1 to Schedule 2 of the amended 1995 Order.” 


[Note: In my opinion, the interpretation that the roof of this type of extension should be assessed against Class C (and not Class B), as per the advice in the “DCLG - Permitted development for householders - Technical guidance” (August 2010) document, is very contrived and questionable – please see my notes on this issue in the entry for March 2011 - Code a00224


In addition, in my opinion, the above appeal decision provides a particularly strong example of how the current version of Part 1 of the GPDO is simply not fit-for-purpose. The current version of this legislation clearly attempts to protect conservation areas by ruling out two-storey rear extensions, by ruling out all side extensions, and by ruling out all roof extensions. And yet, even in a conservation area, the same legislation then allows a two-storey (!) front (!) extension, with no real restriction on the depth (!) of the extension, and for this extension to involve an extension to the main front (!) roof (!), with no real restriction on the volume (!) by which the main roof is extended. It’s very frustrating that the government does not currently appear to have any plans to amend Part 1 of the GPDO, despite the many significant flaws with the legislation]. 


Although it does not appear to be an issue raised by the Council, the Inspector also looked at the issue of whether the front elevation of the property can be said to “front” the highway: 


“Drawing No 992/P-03 shows that at its nearest point the south-east elevation is approximately 170 m away. However at that point the angle between the south-east elevation and the highway is more than 45° and so applying the Technical Guidance this is not an appropriate point at which to measure. The nearest point within 45° of the south-east elevation where all the land between the elevation and the highway is within the control of the Appellants measures approximately 180 m. There does not appear to be any definition of substantial but the Oxford English Dictionary refers to it as of considerable size. On this criterion I consider [the application site] might be said to front a highway. 


Nevertheless the Technical Guidance continues: “The same may be true where there is a significant intervening area of land in different…use between the boundary of the curtilage of the house concerned and the highway”. The Council’s delegated report says: “Old Portsmouth Road is located immediately to the south of the land in the wider ownership of the applicant. However, the majority of this land is under a different usage (equestrian purposes) and therefore taking into account the advice set out in the DCLG Technical Guidance Note it is unlikely that this could be considered to front a highway”. 


My site visit revealed that there is a riding arena in this area and that there are a number of paddocks. I have no reason to doubt that these are consistent with the equestrian use referred to by the Council and whilst there were no horses on site at the time of my inspection I understand why that would be with the building works ongoing at the present time. In the circumstances I agree with the Council’s assessment. Hence it is because the land edged blue on the submitted plan is in a different use, rather than the distance per se, that leads me to conclude that the south-east elevation does not front a highway.” 


The Inspector rejected an application by the appellant for costs against the Council. 


Main Conclusions: 


·       Class A does permit an extension with a roof that would join onto the roof of the main house.
[Note: This would appear to contradict at least one other appeal decision – for further information see the entry in the “Reference Section” on “Interaction between Class A, Class B, and Class C”].
[Relevant to: “Interaction between Class A, Class B, and Class C”, Class A, A.1(i), Class B, B.1(c)].


·       Where a Class A extension would have a roof that would join onto the roof of the main house, but the roof of the extension would not contain any dormers / rooflights / habitable rooms / etc, then the extension should also be assessed against Class C (and not Class B), ignoring the 150mm projection limit.
[Note: This would appear to contradict at least one other appeal decision – for further information see the entry in the “Reference Section” on “Interaction between Class A, Class B, and Class C”].
[Note: In my opinion, this interpretation is very contrived and questionable].
[Relevant to: “Interaction between Class A, Class B, and Class C”, Class A, A.1(i), Class B, B.1(c)].

·       Where the principal elevation does not front a highway, an extension can extend in front of the principal elevation.
[Relevant to: “Principal Elevation”, A.1(d)].


·       Furthermore, in such cases, the amount by which the extension can extend beyond the principal elevation does not appear to be directly* restricted by any limitation.
(*i.e. other than the general requirement to remain within the “curtilage”, and the general restriction of A.1(a) that prevents more than 50% of the original garden being covered by buildings).
[Relevant to: “Principal Elevation”, A.1(d)].


·       This appeal decision provides an example of where it was considered that a particular elevation does not front a highway, even though the elevation faces in the direction towards a highway.
[Relevant to: “Fronts a highway”, A.1(d), B.1(b), G.1(b)].


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


·       Appeal Decision Notice: 

·       Drawings: 

·       Costs Decision Notice: 





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