Resource Management Act and Building Act
Buildings may be controlled under both the Resource Management Act (RMA) and the Building Act. The RMA addresses the environmental effects of buildings, such as height or impact on amenities in the neighbourhood, and determines whether a structure may be built on a site. The Building Act addresses construction standards and determines how the structure may be built on the site.
The controls for the two acts may overlap. For example, you cannot start building work under a building consent until you have the required resource consents. You cannot subdivide a title until the territorial authority (city or district council) is satisfied that existing buildings comply with the building code.
However, the application process for RMA and Building Acts consents are separate processes.

The Resource Management Act 1991 (RMA) provides a framework for councils to manage sustainable use of the land and environment.
Regional councils prepare regional plans for management of air, water, land and soil. City or district councils prepare district plans for managing aspects of subdivision and land use that affect the environment such as height, appearance and location of buildings, or noise, glare and odour associated with the activities that take place in buildings.
The RMA empowers local authorities to choose which activities to undertake according to their community's needs, so plans and resource consent requirements differ between regions. Local authorities process resource consents and monitor and manage consented activities.
Amendments to the RMA came into force in July 2020 to accelerate the consenting process to fast track eligible development and infrastructure projects. The RMA is to be repealed and replaced with three new laws: the Natural and Built Environments Act, Strategic Planning Act and Climate Adaptation Act.
A resource consent is written approval from your local authority to carry out building work that may impact the environment or other people, by altering the overall form or character of an existing dwelling. The resource consent must be applied for before the building consent, as it must be included in the building consent application.

The Building Act 2004 sets out the law for the construction, alteration, demolition and maintenance of new and existing buildings. It requires local authorities to issue building consents and undertake building inspections to ensure compliance with the Building Code.
The Building Code establishes the minimum standard that must be achieved in any building work: you must meet the standard and you can exceed the standard.
Local authorities have no role in setting building standards and cannot set higher or lower building standards than the Building Code.
Amendments to the Building Act, that apply from 31 August 2020, remove the need for building consents for some low-risk building projects. The structures must still comply with the Building Code and relevant legislation, including resource and planing regulations, and you may still require a resource consent.
A building consent is written approval from the local authority to carry out specific building work in accordance with the current building code and regulations. Internal or external renovations may require a building consent, including structural work, altering existing plumbing or drainage and connecting into public drains. The local authority may grant an exemption to a building consent for low risk work.