Appeal Decision 233 - Certificate of Lawful
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April 2011 - Code a00233
Summary of Case (appeal
The property is a two-storey
end-of-terrace house with a gable-end main roof. The property has previously been extended with a two-storey
side extension, which is significantly set-back from the main front building line. The gable-end roof of the
two-storey side extension joins onto the main gable-end roof, with the eaves and ridge-line of the former at a
similar level to the eaves and ridge-line of the latter. The application was for a proposed rear dormer on the
main rear roof (i.e. the rear roof of the original part of the house).
The key issue was whether the
proposed enlargement of the roof would be contrary to Class B, part B.1(c), which states that “Development is
not permitted by Class B if … the cubic content of the resulting roof space would exceed the cubic content of
the original roof space by more than— (i) 40 cubic metres in the case of a terrace house, or (ii) 50 cubic
metres in any other case”.
The Inspector stated the
“The Council calculate
that the proposal would increase the volume of the original roof at No. 54 by about 28 cubic metres. However,
there has previously been a side extension to No. 54 the roof of which had a volume of about 73 cubic metres.
Therefore, the combined volume of the proposal and the roof of the existing extension would be about 101 cubic
metres. The appellant does not take issue with the calculations.
Class B of Part 1 of the
Town and Country Planning (General Permitted Development) Order 1995 (the Order) permits the enlargement of a
dwellinghouse consisting of an addition or alteration to its roof. However, that development is not allowed if
the cubic content of the resulting roof space would exceed the cubic content of the original roof space by more
than 40 cubic metres in the case of a terrace house such as No. 54.
The Order provides
interpretation as to what the term “resulting roof space” means. It means the roof space as enlarged, taking
into account any enlargement to the original roof space.
The issue of whether the
proposal is permitted development depends on whether the roof of the side extension is an enlargement to the
original roof space.
The roof of the side
extension abuts part of the gable end of the original dwelling and in part overlaps part of the original rear
roof slope. Having regard to the original roof of No 54 and the roof of the side extension I am of the view that
the original roof space has been enlarged by the roof of the side extension.
I therefore conclude that
the proposal would not be permitted development because the volume of the proposed enlargement of the
roof space combined with the volume of the roof space as enlarged by the side extension exceeds the 40
cubic metre limit.”
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).
[Relevant to: “Interaction between Class A, Class B, and
Class C”, Class A, A.1(i), Class B, B.1(c)].
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