Class B – extension or alteration of an operational Crown buildingE+W
Permitted developmentE+W
B. The extension or alteration by or on behalf of the Crown of an operational Crown building.
Development not permittedE+W
B.1 Development is not permitted by Class B if—
(a)the building as extended or altered is to be used for purposes other than those of—
(i)the Crown; or
(ii)the provision of employee facilities;
(b)the height of the building as extended or altered would exceed the height of the original building;
(c)the cubic content of the original building would be exceeded by more than—
(i)10%, in respect of development on any article 2(3) land; or
(ii)25%, in any other case;
(d)the floor space of the original building would be exceeded by more than—
(i)500 square metres in respect of development on any article 2(3) land; or
(ii)1,000 square metres in any other case;
(e)the external appearance of the original building would be materially affected;
(f)any part of the building as extended or altered would be within 5 metres of any boundary of the curtilage of the original building; or
(g)the development would lead to a reduction in the space available for the parking or turning of vehicles.
Interpretation of Class BE+W
B.2 For the purposes of Class B—
(a)the erection of any additional building within the curtilage of another building (whether by virtue of Class B or otherwise) and used in connection with it is to be treated as the extension of that building, and the additional building is not to be treated as an original building;
(b)where 2 or more original buildings are within the same curtilage and are used for the same operational purposes, they are to be treated as a single original building in making any measurement; and
(c)“employee facilities” means social, care or recreational facilities provided for employees or servants of the Crown, including crèche facilities provided for the children of such employees or servants.