# The Town and Country Planning General Development Order 1988, Paragraph B.1: Development not permitted


Development is not permitted by Class B if—
(a) any part of the dwellinghouse would as a result of the works, exceed the height of the highest part of the existing roof;
(b) any part of the dwellinghouse would, as a result of the works, extend beyond the plane of any existing roof slope which fronts any highway;
(c) it would increase the cubic content of the dwellinghouse by more than 40 cubic metres, in the case of a terrace house, or 50 cubic metres in any other case;
(d) the cubic content of the resulting building would exceed the cubic content of the original dwellinghouse—
(i) in the case of a terrace house by more than 50 cubic metres or 10%, whichever is the greater,
(ii) in any other case, by more than 70 metres or 15%, whichever is the greater, or
(iii) in any case, by more than 115 cubic metres; or
(e) the dwellinghouse is on article 1(5) land.

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Source: https://www.legislation.gov.uk/uksi/1988/1813/schedule/2/part/1/chapter/2/paragraph/B.1 (the official version)
Page: https://openlegislation.uk/town-and-country-planning-general-development-order-1988/schedule-2/part-1/chapter-2/paragraph-B.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.