Certificate of Lawful Development Appeal Decisions by category of development.

The Town and Country Planning (General Permitted Development) Order 1995
Part 1 (as amended on 1 October 2008) 

Highest part of the roof

·       For a property with a pitched or hipped roof, “the highest part of the existing roof” is the main ridge-line, and does not include raised parapet walls or chimneys.
[Source: September 2009 - Code a00025].
[Source: July 2010 - Code a00129].
[Source: “DCLG - Permitted development for householders - Technical guidance” (August 2010)].

·       For a property with a butterfly roof, “the highest part of the existing roof” is the line where the tiles meet the bottom of the parapet walls, and does not include raised parapet walls or chimneys.
[Source: July 2010 - Code a00129].

·       For a property with flat roofs, “the highest part of the existing roof” is the highest flat roof, and does not include raised parapet walls or chimneys.
[Source: “DCLG - Permitted development for householders - Technical guidance” (August 2010)].

·       The phrase “the highest part of the existing roof” refers to the house as a whole (i.e. the main ridge-line), and not just the part of the house where the works would be carried out.
[Note: This contradicts the entry three below].
[Source: December 2009 - Code a00068].
[Source: February 2010 - Code a00091].
[Source: February 2010 - Code a00103].
[Source: “DCLG - Permitted development for householders - Technical guidance” (August 2010)].
[Source: August 2010 - Code a00130].
[Source: December 2010 - Code a00179].
[Source: January 2011 - Code a00193].
[Source: January 2011 - Code a00194].
[Source: March 2011 - Code a00225].
[Source: April 2011 - Code a00230].
[Source: April 2011 - Code a00231].
[Source: June 2011 - Code a00255].

·       For example, where a property has an original rear projection, a dormer on the roof of the latter structure is limited by the height of the main ridge-line of the house, and not by the height of the ridge-line of the original rear projection.
[Note: This contradicts the entry two below].
[Source: December 2009 - Code a00068].
[Source: February 2010 - Code a00091].
[Source: February 2010 - Code a00103].
[Source: August 2010 - Code a00130].
[Source: December 2010 - Code a00179].
[Source: January 2011 - Code a00193].
[Source: January 2011 - Code a00194].
[Source: March 2011 - Code a00225].
[Source: April 2011 - Code a00230].
[Source: April 2011 - Code a00231].

·       For example, where a property has an existing rear extension, a dormer on the roof of the latter structure is limited by the height of the main ridge-line of the house, and not by the height of the ridge-line of the existing rear extension.
[Note: This contradicts the entry below].
[Source: June 2011 - Code a00255].

·       The phrase “the highest part of the existing roof” refers to the part of the house where the works would be carried out.
[Note: This contradicts the entry three above, the entry two above, and the entry above].
[Note: In my opinion, the above conclusion is questionable, because it contradicts caselaw].
[Source: February 2010 - Code a00098]. 

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