Demonstrating and assessing compliance for buildings undergoing alterations

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A building undergoing an alteration may be granted a building consent by demonstrating:

• that the proposed alterations (ie the new building work) will comply fully with applicable clauses of the Building Code, and
• that the building as a whole will continue to comply with all other relevant Building Code clauses (eg structure) to at least the same extent as before the alteration,
• that the building as a whole will comply ‘as nearly as is reasonably practicable’ (ANARP) with applicable Building Code clauses for fire and accessibility after the alteration takes place, and
• if the building is earthquake prone and the alteration is a substantial alteration, that the proposed alteration includes the necessary seismic work so that the building is no longer earthquake prone.

Building Code compliance can be demonstrated using Acceptable Solutions, Verification Methods, or NZS 4121:2001 (as an Acceptable Solution under section 119 of the Building Act). Other methods of compliance may also be accepted by the BCA, such as an alternative solution.

Alternative solutions for complying with the Building Code has further information.

Meeting the requirements

The following steps set out a process to ensure the requirements for alterations to existing buildings, whether they are earthquake prone or not, are thoroughly considered in the building consent process. It is helpful for:

• applicants putting together building consent applications
• BCAs or territorial authorities considering building consent applications.

This advice does not apply to establishing compliance of new building work with the Building Code. 

Read the following pages for further information:

• How to support your building consent application
• Different ways to comply with the Building Code. 

In practice, the steps set out below are unlikely to be a linear process. A pre-application meeting between the applicant, their designer(s) and the BCA and/or territorial authority is recommended, and ongoing dialogue is likely to be necessary.

Step 1: Applicants check what is required for the proposed alteration

Building consent applicants should work through the diagram in Step 1 to see which requirements apply:

• section 112 applies to buildings that are not earthquake prone
• section 133AT applies to buildings that are earthquake prone.

If the alterations requirements apply, go to step 2.

View the full details for Step 1

Step 2: Applicants consider current and proposed Building Code compliance for the whole building

Building consent applicants need to consider the whole building (not only the part being altered) and:

• provide evidence that the building will continue to comply with all clauses of the Building Code to the same extent as before the alteration, and
• identify the Building Code clauses relating to fire and accessibility that the building will not fully comply with after the proposed alteration. These are the outstanding clauses an ANARP assessment will apply to for fire and accessibility.

Buildings subject to section 133AT will also need to consider the requirements of 'substantial alterations' if this requirement is triggered.

View the full details for Step 2

Step 3: Applicants assess ANARP for the outstanding fire and accessibility Building Code clauses

To assess ANARP, MBIE recommends that building consent applicants complete, and BCAs consider:

• a gap analysis between the building’s current and full compliance with the fire and accessibility provisions, and
• a weighting exercise to consider the sacrifices and benefits of full compliance.

View the full details for Step 3

Step 4: BCAs determine whether the proposed alteration complies with the requirements

BCAs consider the full building consent application to determine whether or not the proposed alteration complies with the requirements of section 112 or section 133AT of the Building Act. Subject to other building consent requirements also being met, they approve or decline the application.

View the full details for Step 4

Step 5: If required, territorial authorities consider if discretion applies to the application

If required, territorial authorities may consider applying discretion to approve a building consent in certain circumstances when the requirements aren't met.

View the full details for Step 5

Additional resources

MBIE has previously issued advice on requesting information about means of escape from fire for existing buildings. This guide sets out different levels of information that building consent applicants should provide, and BCAs or territorial authorities should look for when considering a building consent application for an existing building undergoing an alteration, change of use or subdivision. It is relevant for understanding the level of information needed to assess compliance with the alterations requirements.

MBIE recommends using this advice in conjunction with this guide for establishing an appropriate ANARP threshold for fire and accessibility by broadening the applicable Building Code clauses to include those for accessibility. Important links are identified in each step of the process.

Requesting information about means of escape from fire for existing buildings.