The Town and Country Planning (General Permitted Development) (England) Order 2015

Class F – extensions etc of office buildings

Permitted development

F.  The extension or alteration of an office building.

Development not permitted

F.1  Development is not permitted by Class F if—

(a) the gross floor space of the original building would be exceeded by more than—

(i) in respect of an original building or a development on—

(aa) article 2(3) land, or

(bb) on a site of special scientific interest,

25% or 50 square metres (whichever is the lesser);

(ii) in any other case, 50% or 100 square metres (whichever is the lesser);

(b) the height of the building as extended would exceed—

(i) if within 10 metres of a boundary of the curtilage of the premises, 5 metres; or

(ii) in all other cases, the height of the building being extended;

(c) any part of the development, other than an alteration, would be within 5 metres of any boundary of the curtilage of the premises;

(d) any alteration would be on article 2(3) land; or

(e) the development would be within the curtilage of a listed building.

Conditions

F.2  Development is permitted by Class F subject to the following conditions—

(a) any office building as extended or altered is only used as part of, or for a purpose incidental to, the use of that office building;

(b) any extension is, in the case of article 2(3) land, constructed using materials which have a similar external appearance to those used for the building being extended; and

(c) any alteration is at ground floor level only.

Interpretation of Class F

F.3  For the purposes of Class F, where 2 or more original buildings are within the same curtilage and are used for the same undertaking, they are to be treated as a single original building in making any measurement.