Certificates of work

, Build 180

Certificates of work can be relatively simple documents, but they can also lead to some confusion. Here we address what they are for, who should fill them out and what they should include.

A CERTIFICATE OF WORK (CoW) is required when submitting a building consent application to show that a suitably qualified design professional has designed or supervised the design of any restricted building work (RBW).

The CoW must be provided by one or more LBPs (or suitably registered design professional) that carried out or supervised that design work. The CoW states that the design work either complies with the Building Code or whether waivers or modification of the Building Code are required.

Design of restricted building work

A CoW is only required for the design of RBW. The design of RBW (or restricted design work) can be identified by the following features:

  • The building is a house or small-to-medium apartment building.
  • The work is certain design work relating to the primary structure, external moisture management system or fire-safety system – that is, the preparation of any drawing, specification or other document according to which the primary structure, external moisture management system or fire-safety system is proposed to be constructed or altered.
  • The work requires building consent.

A record of work is completed by the tradesperson who carries out or supervises the RBW, whereas the CoW is completed by the designer who designs or supervises the design of the RBW.

Purpose of certificates of work

The requirements for a CoW are laid out in section 45 of the Building Act 2004 – How to apply for building consent. In summary, the purpose of a CoW is to:

  • provide assurance for building consent authorities that the design has been carried out or supervised by a competent person
  • track professional accountability without giving rise to additional civil liability by recording who completed or supervised each part of the design
  • confirm that the design complies with the Building Code
  • detail any waivers or modifications of the Building Code that have been required.

Collaborative design

Where two or more LBPs are involved in carrying out or supervising the design work for a building consent application involving RBW, there may be a choice about who provides the CoW. If a particular design is carried out by an LBP under supervision of another LBP – that is, a senior designer – the CoW should be provided by the LBP that is taking responsibility for the design.

However, if two LBPs work on different aspects of the plans and specifications that are RBW, each LBP would be expected to provide a CoW for their respective parts. For example, one may design the foundation and another the elements of the superstructure.

The LBP who signs the CoW is the one who will be professionally accountable for the work. If you are completing the CoW as a supervisor for work designed by someone else, it is very important that you check the work meets an acceptable standard, is compliant with the Building Code and adequately describes any waivers or modifications of the Building Code.

Take accountability for your work

If there are issues with the work, the CoW also allows the BCA, consumer or regulator to track down who completed or supervised the work if further investigation is needed.

A common issue the Building Practitioners Board sees is an LBP completing a CoW for work carried out by other designers that has not been completed to an acceptable standard (negligence). Some designers will use their licence to rubber-stamp others’ work so it can be submitted in a building consent. However, this is not the purpose of a CoW.

If you sign a CoW with incorrect statements regarding compliance to the Building Code – or any waivers or modifications – you are showing poor professional judgement as either you did not check the design adequately or you were not able to identify the deviations from the Building Code. Either way, you could be found by the Building Practitioners Board to have acted negligently or incompetently.

LBPs are accountable to the Board for their professional conduct, and if they are negligent or incompetent or otherwise do not meet their obligations under the Building Act, they can be disciplined. Using your licence to rubber-stamp a CoW without adequately checking the design is an abuse of the licensing system and will not be accepted by the Board.

Further guidance

The document Guidance on the use of certificates of work, producer statements, and design features reports relates to RBW and can be found at www.building.govt.nz.

This guidance document was developed for practitioners working on the Canterbury rebuild. However, the principles apply for restricted design work anywhere in New Zealand.


1. Why do we use CoWs?
a. So BCAs can see if a competent person carried out the work.
b. So we can track down the correct designer if they need to be held professionally accountable for their work to the Building Practitioners Board.
c. To highlight any waivers or modifications of the Building Code in the design.
d. All of the above.

2. Can more than one LBP provide a CoW for a design?
a. Yes, if more than one LBP has contributed to a design, this should be recorded through the CoWs.
b. No, only one LBP should provide a CoW per building consent

3. Why is it a problem if you sign a CoW without supervising and adequately checking the design work?
a. It is not a problem – the BCA will pick up anything that is not Code compliant.
b. It is not a problem – signing a CoW will not increase your civil liability for the project.
c. The design could be substandard, which could lead to significant problems and harm to the client – for example, leaky buildings.
d. You could be disciplined by the Building Practitioner Board for working negligently.
e. c and d.


Answers: 1. d 2. a 3. e

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