Uses Excluded From Definition Of Development
Certain operations and uses of land are specifically excluded from the meaning of development and for the purposes of the Town and Country Planning Act, the following operations or uses of land do not constitute development of land, namely
(a) The carrying out in accordance with any regulations or orders made under this Act of works for the maintenance, improvement or other alteration of any building, being works which do not materially affect the external appearance of the building;
(b) The carrying out by a highway authority of any works required for the maintenance or improvement of a road (if the works are carried out on land within the boundaries of the road);
(c) The carrying out by statutory undertakers of any works any works for the purpose of inspecting, repairing or renewing any sewers, mains, pipes, cables or other apparatus, including the breaking open of any road or other land for that purpose;
(d) The use of any buildings or other land within the curtilage of a dwelling-house for any purpose incidental to the enjoyment of the dwelling-house as such;
(e) The use of any land for the purposes of agriculture or forestry, including afforestation, and the use for any agricultural purpose, other than for dairy farming and the breeding and keeping of livestock, including any creature kept for the production of food, wool, skin of fur or for the purpose of its use in farming the land, or of any building occupied together with the land so used;
(f) In the case of buildings or other land which are used for a purpose of any class specified in a development order made under section 15, the use thereof for any purpose of the same class.
Matters Declared to be a Material Change of Use
(a) The use as 2 or more dwelling-houses of any building previously used as a single dwelling-house involves a material change in the use of the building and of each part thereof which is so used;
(b) The deposit of refuse or waste materials on land involves a material change in the use thereof, notwithstanding that the land is comprised in a site already used for that purpose, if either the superficial area of the deposit is thereby extended or the height of the deposit is thereby extended and exceeds the level of the land adjoining the site.
(c) Without prejudice to any regulations relating to the control of advertisements, the use for the display of advertisements of any external part of a building which is not normally used for that purposes, for the purposes of this section, a material change in the use of that part of the building.
The above are specifically declared to involve a material change of use and the intention is to make it clear beyond doubt that these changes of use constitute development and so require planning permission.