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) 

Interaction of Class A, Class B and Class C extensions

  (i.e. interaction between general extensions and roof extensions)

·       Class A does permit an extension with a roof that would join onto the roof of the main house.
[Note: This contradicts the entry four below].
[Source: November 2009 - Code a00047].
[Source: January 2010 - Code a00085].
[Source: March 2010 - Code a00107].
[Source: March 2010 - Code a00111].
[Source: “DCLG - Permitted development for householders - Technical guidance” (August 2010)].
[Source: December 2010 - Code a00167].
[Source: February 2011 - Code a00206].
[Source: January 2011 - Code a00200].
[Source: March 2011 - Code a00224].
[Source: April 2011 - Code a00237].
[Source: April 2011 - Code a00238].
[Source: May 2011 - Code a00245].
[Source: July 2011 - Code a00259]. 

·       Where a Class A extension would have a roof that would join onto the roof of the main house, then the extension should also be assessed against Class B and Class C as follows:
a) The works would need to comply with both Class A and Class C (although the 150mm projection limit of Class C would not apply), and,
b) If the extension contains a dormer window, then the works would also need to comply with Class B.
[Note: This contradicts the entry three below and the entry four below].
[Note: In my opinion, this interpretation is very contrived and questionable].
[Source: “DCLG - Permitted development for householders - Technical guidance” (August 2010)]. 

·       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 contradicts the entry two below].
[Note: In my opinion, this interpretation is very contrived and questionable].
[Source: March 2011 - Code a00224].
[Source: April 2011 - Code a00237].
[Source: April 2011 - Code a00238].
[Source: May 2011 - Code a00245]. 

·       Where a Class A extension would have a roof that would join onto the roof of the main house, then the extension should also be assessed against Class B (note: in this particular case, the roof of the extension would contain dormers / rooflights / habitable rooms / etc).
[Note: This contradicts the entry below and the entry two below].
[Source: December 2010 - Code a00167].
[Source: January 2011 - Code a00200]. 

·       Class A does not permit an extension with a roof that would join onto the roof of the main house.
[Note: This contradicts the entry above, the entry two above, the entry three above, and the entry four above].
[Source: January 2010 - Code a00081].
[Source: April 2010 - Code a00115].
[Source: January 2011 - Code a00188]. 

·       Class A does not permit an extension with a roof that would join onto the roof of the main house in the case where the roof of the extension would contain dormers / rooflights / habitable rooms / etc.
[Note: This contradicts the entry two above and the entry three above].
[Source: April 2010 - Code a00113]. 

·       Where there is an existing extension with a roof that joins onto the roof of the main house, then this will reduce the volume allowance that remains for roof extensions under Class B, part B.1(c).
[Source: November 2010 - Code a00149].
[Source: November 2010 - Code a00161].
[Source: December 2010 - Code a00172].
[Source: January 2011 - Code a00198].
[Source: January 2011 - Code a00200].
[Source: January 2011 - Code a00205].
[Source: March 2011 - Code a00218].
[Source: April 2011 - Code a00233].
[Source: July 2011 - Code a00258]. 

·       Furthermore, even if the roof of the existing extension doesn’t contain any dormers / rooflights / habitable rooms / etc, this will still reduce the volume allowance that remains for roof extensions under Class B, part B.1(c).
[Source: November 2010 - Code a00149].
[Source: November 2010 - Code a00161].
[Source: December 2010 - Code a00172].
[Source: January 2011 - Code a00198].
[Source: July 2011 - Code a00258]. 

·       Where there is an existing extension, then even if its roof is at a lower level and doesn’t join onto the roof of the main house, this will still reduce the volume allowance that remains for roof extensions under Class B, part B.1(c).
[Source: November 2010 - Code a00161]. 

·       Class A does not permit an extension that would alter the roof of an original single storey projection (in the case where the roof of the latter is at a lower level and separate from the main roof of the house).
[Source: February 2010 - Code a00094]. 

·       The erection of a first floor rear extension on top of an existing single storey rear extension would not fall within the scope of Class B.
[Note: This contradicts the entry below].
[Source: June 2009 - Code a00007]. 

·       The erection of a first floor rear extension on top of an original single storey rear projection would fall within the scope of Class B.
[Note: This contradicts the entry above].
[Source: February 2010 - Code a00098]. 

·       Where a property has an original rear projection (with a roof at a similar level to the main roof) then an extension (e.g. a dormer) on the roof of the original rear projection would fall within the scope of Class B (i.e. rather than Class A).
[Note: This contradicts the entry two below].
[Source: December 2009 - Code a00068].
[Source: February 2010 - Code a00091].
[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]. 

·       Where a property has an existing rear extension (with a roof at a similar level to the main roof) then an extension (e.g. a dormer) on the roof of the existing rear extension would fall within the scope of Class B (i.e. rather than Class A).
[Source: June 2011 - Code a00255]. 

·       Where a property has an original rear projection (with a roof at a similar level to the main roof) then an extension (e.g. a dormer) on the roof of the original rear projection would need to be assessed against Class A and Class B.
[Note: This contradicts the entry two above].
[Source: October 2010 - Code a00143]. 

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