Planning Act 1999

The consent authority may, in writing, issue an alteration permit if in the opinion of the consent authority:

the proposed alteration will not materially affect the amenity of adjoining or nearby land or premises; and

the alteration does not authorise a substantive change to the existing building or existing works.

Despite subsection (1), an alteration permit must not be issued if it will allow an increase in the number of dwellings capable of separate occupancy.

If the consent authority refuses to issue an alteration permit, the consent authority must give the applicant a statement of the reasons for the refusal.

For subsection (1)(b), a substantive change is:

a change that increases non-compliance with a measurable aspect of the development by more than 5%; or

if the change is not conveniently measurable – an alteration that materially changes the character of the existing building or existing works.