Restricted Building Work (RBW)

If you’re doing or supervising building or design work as part of the construction or alteration of residential buildings, this work may be classified as ‘restricted building work’ (RBW). You must be a licensed building practitioner in the appropriate class to do or supervise this type of work.

A lot of residential building work will include RBW.

RBW is not limited to work that requires a building consent and may include work that is exempt from building consents. 

What falls under Restricted Building Work?

Generally, something is RBW if all of the following apply:

  • it involves the design, construction or alteration of a building
  • the building is a residential house of any height, or a small to medium apartment building of less than 10 metres in total height
  • the building is purely residential (such as an apartment building with no shops)
  • the work relates to the primary structure, the external moisture management in any building, and/or the design of fire safety systems in a multi-unit building.

Building categories 

RBW relates to residential construction and design, for certain houses and small to medium apartment buildings. It can be new construction, or alterations to an existing building. 

Definition of a house 

For the purposes of RBW, a house is a free-standing, fully detached building consisting of a single residential unit. It can also have a number of residential facilities such as a foyer, laundry, garage, and so forth. 

Definition of a small to medium apartment building 

For the purposes of RBW, a small to medium apartment building:  

  • contains 2 or more residential units (apartments) or residential facilities (foyer, laundry, garage, etc)  
  • does not contain commercial units or facilities (it has no shops) 
  • has a maximum height of less than 10m (the vertical distance between the highest point of its roof – excluding aerials, chimneys, flagpoles and vents – and the lowest point of the ground).  

Types of work 

RBW involves building or design work that is critical to the integrity of a building. In particular, it ensures the building is structurally sound and weathertight. 

This work includes:

  • the primary structure (construction or alteration) – all the structural elements of the building that contribute to resisting vertical and horizontal loads 
  • external moisture management systems (construction or alteration) – the building elements and systems which prevent the ingress of external moisture and help control moisture within the building fabric 
  • fire safety systems (design) – the building elements intended to protect people and property from fire. 

Building consents and exemptions 

From 15 January 2026, new legislation allows you to build small standalone dwellings up to 70 square metres without a building consent. These dwellings are often called granny flats. 

This exemption only applies to new builds, not alterations to existing buildings. 

Even without a building consent, some work on these granny flats will still be RBW. 

More information about what the granny flats exemption means for LBPs:

Building requirements and conditions for granny flats – What LBPs need to know

Upcoming changes: granny flats building consent exemption

More detailed guidance is on the Building performance website: 

Granny flats exemption: Guidance and resources(external link) — Building performance 

In this section

  • Design process

    Designing primary structure, the weathertight elements, or fire safety systems on residential buildings may be classified as Restricted Building Work (RBW).

  • Construction process

    Before restricted building work commences under a building consent, the owner must give the council written notice of the name of every licensed building practitioner (LBP) who is engaged to carry out or supervise the restricted building work (RBW).