Planning requirements for building an additional small residential unit on your residential zoned property.

Minor residential units

A minor residential unit is a small self-contained, detached building on a property that already contains an existing residential house. These units are intended to contribute to a range of housing choices without affecting the character of the area. 

There are no restrictions on who can live in a minor residential unit, i.e. it does not have to be a relative or dependent person.

Minor residential units are permitted in the residential zones below if they meet the following requirements:

  • The gross floor area of the minor unit is between 35mand 80m2 
  • There is only one other residential unit on the site and the minor unit is detached from it
  • The minor unit must have one parking space and the existing residential unit either one or two spaces, depending on the size of the unit. The parking areas of both units must be accessed from the same access.
  • The minor unit is single-storey with a maximum height of 5.5m
  • The unit must comply with the usual District Plan built form rules for residential units, with the exception of  site density and outdoor living space
  • The overall site must meet the minimum site area and outdoor living space  requirements below:
Zone Minimum size of existing site (outside Character Area overlays) Outdoor living space requirement

Residential Suburban

Residential Suburban Density Transition

Residential Banks Peninsula


90mtotal area with a minimum dimension of 5m

This can either be a single continuous area or divided into two separate spaces, as long as the main residential unit and the minor unit each have an area of at least 30m2 which is directly accessible from the unit

Residential New Neighbourhood 450m2 As above, except that the minimum dimension is 6m
Residential Hills 650m2 Not required
Residential Large Lot 1,500 - 5,000m depending on the location of the site Not required
Residential Small Settlement 1,000m2 Not required

If the above criteria can’t be met a resource consent will be needed.

Minor residential units on sites within a Character Area overlay will generally require resource consent due to the minimum net site requirements for residential units in Character Areas. In addition, consent will be required if the minor residential unit is: 

  • visible from the street; or
  • located between the road boundary and the main residential unit on the site.

Subdividing minor residential units

There is no specific provision in the District Plan for subdividing minor residential units from the primary residential unit.  This means that resource consent would be required to do this, usually as a non-complying activity due to the inability to meet the minimum net site area requirements for standalone residential units. 

Family flats

Family flats are different from minor residential units as they must only be occupied by family member/s who are dependent in some way on the household living within the main residential unit.  A legal instrument must be registered on the certificate of title for the property, to ensure that the use of the flat is restricted in this way. 

Family flats can be attached or detached and are considered to be part of the residential unit on the site.  They must comply with all the District Plan rules for residential units in the zone in which they are located.  If the family flat is no longer required by the dependent relative, it must either be removed from the site, have its kitchen removed or comply with the requirements for a minor residential unit if it is located in a zone where minor residential units are permitted.

Converting a family flat into a residential unit

In the Residential Suburban, Residential Suburban Density Transition and Residential Hills zones, a family flat that was existing on 6 December 2013 can be converted into a residential unit able to be occupied by anyone if certain criteria are met.

Development contributions

A minor residential unit is considered to be a development under the Council's Development Contribution Policy and is therefore subject to a development contributions (DC) assessment. A minor residential unit is however entitled to have the benefit of the Small Residential Unit adjustment which can reduce the DC requirement by up to 40%. A further 10% reduction can be applied to developments that meet the Council's Small Residential Unit Rebate Criteria.

Applications to develop a new family flat, or convert a family flat that did not exist prior to 6 December 2013 into a residential unit, will be assessed for development contributions, but will be eligible for a Small Residential Unit adjustment.

For more information please visit Development Contributions or contact a Development Contributions Assessor at


The addition of a family flat or minor unit will likely increase your rates for the property – due to both an increase in the rateable value and the addition of a second inhabitable unit.

Any change to your rates as a result of development will apply from the next rating year, beginning 1 July. 

The amount of any increase will largely depend on the increase to your rateable value, so we cannot estimate what the increase will be before that valuation has been set. 

Find more information on how rates are assessed.

Contact us

For more information or enquiries please contact the Duty Planner