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.