The "GPDO Part 1 (All Classes) - LDC Appeal Decisions" document has been updated to include 4 additional appeal decisions relating to householder permitted development legislation, for which the conclusions are as follows:

October 2021 - Code a01341 (appeal allowed):

• This appeal decision provides an example of where it was concluded that particular works do fall within the scope of Class B, on the basis that the works do not exceed what constitutes “the enlargement of a dwellinghouse consisting of an addition or alteration to its roof”. (*)
  [Note: The works include an “L”-shaped roof extension (or similar) that covers approx half of the roof of the rear projection].
  [Quote: “The appeal property is a 2 storey house with an ‘outrigger’ to the rear. The development would see the construction of a large box dormer on the main rear roof slope. This would link into a smaller addition above the outrigger. There is agreement that, on its own, the larger dormer to the main roof would be development permitted by Class B. Thus, the focus of the dispute is the proposed element above the outrigger. The outrigger has a mono-pitched roof, much lower in height than the roof of the main dwelling. The addition to the top of this would form a bathroom. It would not extend above the whole of the outrigger, but only about half of it. Thus, it is not the case that an entire new storey would be added to the outrigger. The development would involve the construction of sections of wall to raise the height of part of the outrigger (by up to 2.7m) but that does not, in itself, mean that the development cannot be regarded as an addition to the roof; other developments accepted as being roof alterations/additions (such as hip-to-gable conversions) also involve walls being raised in height significantly. In my view, the additions to the walls in this case are not so substantial as to place the development outside the category of an addition or alteration to the roof of the property. Moreover, despite its lower height, the element above the outrigger would link physically and functionally with the new dormer on the main roof slope, with stairs allowing it to be accessed from the converted loft space. Indeed, the new bathroom appears primarily intended to serve the bedroom that would be created there. Thus, while the Council characterises the element above the outrigger as an extension, I regard it as an integral part of an addition to the roof of the property and part and parcel of the loft conversion. For these reasons, I regard the development proposed as an addition/alteration to the roof of the property, falling wholly within classes B and C.”].
• Where a property has a secondary roof that’s slightly lower than the main roof, then an extension on top of this secondary roof should be assessed against Class B (i.e. rather than Class A). (*)
  [Note: The secondary roof is the roof of an original two-storey rear projection on a two-storey house].
• For the purposes of the post-06/04/2014 version(s) of Part 1 of the GPDO, where a property has an original rear projection with a side-facing pitched roof, all of which is lower than the main rear roof, then an “L”-shaped roof extension (or similar) that extends from the main rear roof onto the side roof of the original rear projection is permitted development. [Note: The roof extension, for all of its (rearmost) width, extends across the original rear eaves]. (*)
  [Conclusion: The works comply with Class B].
• The phrase “the highest part of the ... roof” relates to the property as a whole (i.e. not only to the part of the property that’s being altered or enlarged). (*)
• For example, where a property has a secondary roof that’s lower than the main roof, then an extension on top of this secondary roof can be higher than the highest part of this secondary roof (i.e. so long as the extension is not higher than the highest part of the main roof). (*)
  [Note: The extension is higher than the ridge-line of the original two-storey rear projection].

October 2021 - Code a01340 (appeal dismissed):

• The height of a structure should be measured from the highest part of the adjacent ground level (i.e. rather than from each part of the adjacent ground level). (*)
  [Note: The structure is an outbuilding].
• When measuring the height of a structure, “ground level” means the ground level as it exists (immediately) prior-to-works. [Note: In other words, “ground level” means “existing” ground level]. (*)
  [Quote: “Class E.1 (e) (ii) requires that the building should not exceed 2.5m in height where it is within 2 metres of the boundary of the curtilage of the dwellinghouse. Technical Guidance states that the height of the building should be measured from the highest ground level immediately adjacent to the building. Considering recent case law [McGaw v Welsh Ministers and the Council for the City and County of Swansea [2020] EWHC 2588 (Admin)], it is therefore necessary to establish the highest pre-existing ground level adjacent to any part of the external walls of the proposed building.”].
• This appeal decision provides an example of where it was concluded that, when measuring the height of a structure, “ground level” is the level that existed before the ground was raised or lowered.
  [Note: The ground was lowered at a similar time to (the start of) the erection of the outbuilding].
• This appeal decision provides an example of where it was concluded that a structure is not “immediately adjacent” to a particular piece of ground.
  [Conclusion: The outbuilding is not immediately adjacent to the earth mound (on the basis that the distance between the wall of the outbuilding and the earth mound is approx 0.5m)].
  [Quote: “The Appellant’s photograph, taken in March 2019, does not show the pre-existing land levels that would have been adjacent to the proposed outbuilding (i.e.500mm from the flank wall of the neighbouring garage). Instead, it shows the level of an earth mound on land at [the neighbouring property to the south-west] which abutted the site boundary.”].

October 2021 - Code a01339 (appeal allowed):

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October 2021 - Code a01338 (appeal allowed):

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Notes:

• To view the conclusions, summaries, and decision notices for any of the above appeals, please view the "GPDO Part 1 (All Classes) - LDC Appeal Decisions" document. As a member of the Planning Jungle website, you can view the decision notices for all of the appeals on the website for no extra cost.
• Any of the above conclusions marked with a "(*)" contradict other appeal decisions. The "Reference Section" within the above document indicates how many appeals have supported and contradicted each particular conclusion.