Meeting the requirements for altering existing buildings

Building consent applicants, design professionals, building consent authorities and territorial authorities all have specific requirements for altering existing buildings.

Building consent applicants

Building consent applicants need to ensure their building consent application includes all the required information to demonstrate:

  • that compliance with other Building Code clauses is no less than what it was prior to the alteration
  • compliance 'as nearly as is reasonably practicable' with the Building Code for fire and accessibility (if applicable), including evidence of weighing up the sacrifices and benefits of achieving full compliance. This evidence is best provided in a thorough report
  • that in the case of a substantial alteration to an earthquake-prone building, the alteration includes the necessary seismic work so the building is no longer earthquake prone
  • that the proposed alteration (ie new building work) complies with the Building Code.

Building design professionals

Building design professionals (including designers, architects, engineers or other professionals, such as builders): 

  • may advise building consent applicants, or act as the applicant on behalf of clients
  • need to take into account the alterations requirements when preparing the building consent application documentation or advising on design.

Building consent authorities (BCAs)


  • determine which aspects of the Building Act and Building Code need to be assessed when considering a building consent application for an existing building undergoing an alteration, and whether or not these requirements are met
  • determine whether or not to grant a building consent under section 49 of the Building Act.

Territorial authorities

Territorial authorities step in where:

  • a BCA has determined that a building consent application does not comply with the requirements for alterations, and the applicant wishes to proceed with the proposed alteration without complying with some of the required provisions
  • the building is subject to a waiver or modification of the Building Code under section 67 of the Building Act (unless it relates to accessibility, in which case a determination is required under section 69 of the Building Act).
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This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: