As per the Sustainable Planning Act 2009:
Development is any of the following -
(a) carrying out building work;
(b) carrying out plumbing or drainage work;
(c) carrying out operational work;
(d) reconfiguring a lot;
(e) making a material change of use of premises.
As per the Building Act 1975:
Building work is -
(1) (a) building, repairing, altering, underpinning (whether by vertical or lateral support), moving or demolishing a building or other structure; or
(b) excavating or filling -
(i) for, or incidental to, the activities mentioned in paragraph (a); or
(ii) that may adversely affect the stability of a building or other structure, whether on the land on which the building or other structure is situated or on adjoining land; or
(c) supporting, whether vertically or laterally, land for activities mentioned in paragraph (a); or
(d) other work regulated under the building assessment provisions, other than IDAS.
(2) For subsection (1)(d), work includes a management procedure or other activity relating to a building or structure even though the activity does not involve a structural change to the building or structure.