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Altering an existing building

When thinking about altering an existing building, there are a number of requirements you need to know about.

Requirements you need to know about

Buildings undergoing alterations have to meet regulations under building legislation. This means that, over time, they may have to be upgraded to fully comply, or in some cases more closely comply with the current Building Code.

When altering an existing building you need to make sure that the building:

  • continues to comply with the Building Code as it may have applied to the same extent as before the work
  • complies as near as reasonably practicable with requirements for:
    • means of escape from fire to the extent this applies to the use of the building
    • access and facilities for persons with disabilities.
  • is designed, constructed and used in a way that allows for sustainable development.

See the Ministry of Business, Innovation and Employment (MBIE) webpage requirements of section 112 and 133AT of the building act for a detailed breakdown.

You can find guidance on how to prepare your consent application, as far as upgrades are concerned, on the Altering an existing building page of the MBIE website.

Requirements for an earthquake-prone building

If your building is recorded as an earthquake-prone building and you have received an earthquake prone building notice, you may need to undertake seismic work so that the building is no longer earthquake prone.

For more information on what earthquake-prone means and what responsibilities you have as an owner of an earthquake-prone building, see Owners of potentially earthquake-prone buildings.

Requirements for fire safety

Users of your building must be able to:

  • escape in the event of fire
  • use it safely and without endangering their health.

Requirements for people with disabilities

Examples of users with disabilities include those who have long-term physical, mental, intellectual, or sensory impairments, as well as many others.

The Office for Disability Issues and NZS 4121:2001 have more information.

How we assess the requirements

We assess your upgrade requirements on the As Near As Reasonably Practicable (ANARP) basis.

This assessment takes into account the complexity and the cost of the proposed building work.

Adding a single toilet to your 10 level commercial building is a low cost and low complexity upgrade.

However, if you want to change the use of a building from offices into apartments, or the other way round, this may be seen as a complete upgrade.

Guidance documents

For guidance on how ANARP is applied see:

​For guidance on how we assess fire reinstatement see:

​For guidance on how we assess installation of domestic fire alarms see:

​For guidance on how you can get your building ready for a home based business see:

Our tip

If as part of the alteration you wanted to change the use of a building, this may require a substantial upgrade of the building to comply with the building code in all respects.

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