Material Change of Use

Section 55 of the Town and Country Planning Act 1990 defines 'development' to include, among other things, 'the making of any material change in the use of any buildings or other land'. Not every change of use is 'material' — the change must be significant enough in planning terms to require permission, and the Act sets out several categories of use or operation that are not to be treated as involving development at all.

The Act also gives concrete examples of what does count as a material change of use. It declares, 'for the avoidance of doubt', that 'the use as two or more separate dwellinghouses of any building previously used as a single dwellinghouse involves a material change in the use of the building and of each part of it which is so used'. Similarly, extending the area or height of a waste deposit on already-used land is treated as a material change of use, as is using an external part of a building not normally used for advertising to display advertisements.