13.3 Retaining walls up to 3 metres depth of ground

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Legally required professional: Chartered Professional Engineer.

The distance between the wall and any boundary or existing building must be at least the height of the wall.

What the law says

Schedule 1 of the Building Act 2004

Exemption 41. Retaining walls

1. Building work in connection with a retaining wall in a rural zone, if:

(a) the wall retains not more than 3 metres depth of ground; and

(b) the distance between the wall and any legal boundary or existing building is at least the height of the wall.

2. In subclause (1), rural zone means any zone or area (other than a rural residential area) that, in the district plan of the territorial authority in whose district the building work is to be undertaken, is described as a rural zone, rural resource area, or rural environment, or by words of similar meaning.

How it works

This exempts retaining walls designed or reviewed by a Chartered Professional Engineer not exceeding three metres and in a rural zone as long as they are not too close from the boundary or existing buildings (refer to subclause (1)(b)).

Find a Chartered Professional Engineer - engineeringnz.org

This exemption recognises that in low density rural zones such as farms, the consequences of failure of any retaining wall are less likely to cause injury than they would be in higher density urban environments. The additional requirement for a Chartered Professional Engineer to be involved also helps to make sure that retaining walls covered under this exemption are less likely to fail.

For removal of retaining walls, please refer to exemption 31 in section 1.4 Removal of building element. 

Note: If there is a fall of at least one metre, a safety barrier may be required under Building Code clause F4 – Safety from falling.

What is exempt

1. A homeowner wants to construct a retaining wall on a rural property that is 2.5 metres high, three metres away from an existing dwelling, and is designed by a Chartered Professional Engineer.
2. A farmer decides to rebuild an earthquake-damaged retaining wall on their rural property that is three metres high and located six metres away from a legal boundary. The wall design has been reviewed by a Chartered Professional Engineer.

What needs consent

1. A homeowner wants to construct a retaining wall on a rural property with a height of three metres, one metre away from an existing dwelling and designed by a Chartered Professional Engineer. A building consent is required because the wall is closer to the dwelling than its own height.
2. A homeowner wants to construct a retaining wall on a rural property that is three metres high and five metres away from the property boundary which has been designed by an engineer, but not a Chartered Professional Engineer. Though the retaining wall is not located closer to a legal boundary than its own height, a building consent is required as the wall has not been designed or reviewed by a Chartered Professional Engineer.