Designing primary structure, the weathertight elements, or fire safety systems on residential buildings may be classified as “Restricted Building Work” (RBW). You must be a Licensed Building Practitioner in the design class or a New Zealand Registered Architect or Chartered Professional Engineer to do or supervise this type of work.
Read more about the types of buildings that are RBW.
You still have to comply with the requirements of the Building Code and apply for a building consent. You will also have to state the RBW you design complies with the Building Code.
Certificate of work (or RBW Design Memorandum)
The person applying for building consent is responsible for submitting the certificate of work with their application. As the designer, you must provide a certificate of work (otherwise known as a RBW Design Memorandum) to the building owner. This certificate of work needs to be given to the local council when applying for building consent.
You'll need to fill out either the certificate of work or the design certificate of work clarification letter:
Please make sure you include the following information:
- What the Design RBW is, and whether you carried out or supervised this work
- Acknowledgment that the Design RBW complies with the Building Code, or, if waivers or modifications of the Building Code are needed, what they are
- Your LBP number – or your registration number if you are a New Zealand Registered Architect or Chartered Professional Engineer.
As a result of issues raised over the wording of the certificate of work, a guidance document has been produced. The document relates primarily to Canterbury earthquake work, but the examples within are applicable to general design work.
The certificate of work form set out above reflects the suggested approach outlined in these letters, as well as discussions with IPENZ, ACENZ, NZIA and various Councils.
The main changes to the certificate of work are:
- A new section ('Basis For Providing This Memorandum') which enables the provider to outline the basis on which they are providing the Certificate. This will assist both providers and BCAs in identifying whether there will be any additional Certificates for the project.
- the new wording of the declaration (in line with the two clarification letters sent out earlier in the year)
- the ability for the provider of the Certificate to state that they did all of the RBW design for primary structure (B1) and/or external moisture management (E2) rather than filling out the sections for each of the specific elements. This can be achieved by only having to select the first tick box under primary structure (B1) and/or external moisture management (E2).
It is important to note the following:
Signing of the Declaration
The statement of building code compliance on the certificate of work must be made by an individual. You cannot sign the declaration on behalf of a company. For example, using the words “Bill Bloggs on behalf of Bill Bloggs Design Limited” in the declaration (or anywhere else on the Certificate) does not meet the requirements of the Building Act 2004.
The certificate of work does however have an optional section elsewhere in which you can simply record the name of your company.
Who must provide a certificate of work
Not every Design LBP (“Design LBP” includes a New Zealand Registered Architect and Chartered Professional Engineer) who works on a project needs to provide a Certificate of Design Work. While all RBW design work for a project must be covered by one or more Certificates of Work, a certificate of work is not required from every Design LBP.
A lead designer who is a Design LBP can provide a certificate of work covering all of the RBW design work, even if some of that design work has been done by another person, for example a structural CPEng, and a specialist fire designer. In providing the certificate of work in this example, the lead designer must say that they supervised the work of the others and, having applied the skill and care reasonably required of a competent design professional, state that all of the RBW design work complies with the relevant parts of the Building Code (as per the wording on the certificate of work).
Alternatively, each LBP who carried out design RBW work can sign their own certificate of work for the work they did.
If the project involves RBW Design work, the building consent application must include:
- If known at the time of the building consent application, the name of each LBP who is engaged to carry out or supervise the construction of the RBW; and a
- Certificate of Work from you as a Design LBP (or from a New Zealand Registered Architect or Chartered Professional Engineer). Please give this to the owner to include in their building consent application.
The RBW parts of the application that the council will check are:
- Whether the design work is RBW
- If it is RBW, whether the plans and specifications were prepared by, or supervised by one or more Design LBPs
- Whether a certificate of work (or Certificates of Work, if more than one) covers all of the RBW Design work for the project
- Whether the RBW Certificates of Work identify the RBW with reference to the included plans and specifications
- Whether the application has all the names of the LBPs who will be involved in carrying out or supervising RBW (if known at this time)
- Whether the RBW Certificate of Work states that RBW complies with the Building Code
- Whether waivers or modifications are required, and if so what those are.
If you need to apply for a waiver or modification to the Building Code, you can do so in the building consent application. If the waiver or modification relates to RBW, then the details of the waiver or modification you’re applying for must also be on the certificate of work.
Supervision of Design RBW
If you are supervising RBW, you provide direction and oversight of the design work to make sure it is done properly and complies with the Building Code. To do this, you must be a LBP in the design class (or a New Zealand Registered Architect or Chartered Professional Engineer). You will also need to sign a form stating you supervised RBW design and the design complies with the Building Code.
You can only supervise RBW if you are licensed to do so. As a designer, architect or engineer you may observe construction on-site, and check that the work is being done in accordance with the building contract, but if you are not licensed to do that type of physical construction or alteration RBW, then you are not able to supervise and provide a Record of Work for that RBW construction work.
The certificate of work is not a producer statement. It is simply a means of recording who carried out or supervised the RBW design work for a project. It includes a statement from the Design LBP that they have applied the skill and care reasonably required of a competent design professional, and based on this they state that the design work complies with the relevant parts of the Building Code.
Before issuing a building consent, a Building Consent Authority (BCA) must still be satisfied (on reasonable grounds) that the provisions of the Building Code would be met if the building work were properly completed in accordance with the plans and specifications (which cover both RBW and non-RBW elements) that accompanied the building consent application. In determining this, the BCA may seek further information, which may include a producer statement.
Area of Practice and certificate of work
A Design LBP is able to design any category of building that is within their individual competence. For example, a Design LBP with an Area of Practice 1 can submit a certificate of work covering design work covered by Area of Practice 2 – as long as they are competent to do so (it is a ground for disciplinary action before the Building Practitioners Board to carry out or supervise work outside of your own competence). The Area of Practice is for initial licensing assessment purposes only.
If, having accepted the certificate of work as part of an application, the BCA considers the accompanying plans and specifications to have been done negligently or incompetently, the BCA can make a complaint about the LBP designer to the Building Practitioners Board (or to IPENZ if the designer is a CPEng, or the New Zealand Registered Architects Board if a registered architect).
Design of Trusses
The Ministry of Business, Innovation and Employment (MBIE) is aware that in many instances, a Design LBP will use a truss fabricator to create plans and specifications for the trusses in a building. In these instances, MBIE's view is that the plans and specifications should be incorporated into the design for the rest of the building to be covered by a single certificate of work. In signing the certificate of work, the Design LBP, having applied the skill and care reasonably required of a design professional, is stating that all restricted building work in the plans and specifications complies with the relevant provisions of the Building Code.
In order to make this statement, the Design LBP would need to make sure they have provided the correct information to the truss fabricator and would need to check that the information used by the detailer is correct and matches what was supplied. The Design LBP needs to ensure that the truss will fit in with the rest of the building’s design to meet the requirements of the Building Code.
You do not have to use or provide a design summary but it is very useful and is becoming industry best practice. As a designer, you will have to make decisions for any building project about how compliance with the Building Code will be achieved. A design summary is a list of how the design complies with the relevant Building Code clauses. Design summaries are really helpful in showing the council the choices that were made to gain compliance and the reasons why.
A design summary can:
- provide a checklist on Building Code compliance
- show which parts of the project relate to compliance (or to construction, or to contract)
- provide references to design documents and details
- act as a checklist during construction, showing where design plans will need a variation, amendment or a new building consent
- help reduce the consent processing time and avoid costly delays.
Things to tell your client about RBW
Your clients will need to engage trade LBPs (carpenters, roofers, external plasterers, brick and blocklayers, foundations experts) to carry out or supervise the RBW construction.
They will need to supply the council with the names of these trade LBPs (ideally at the same time as they apply for a building consent, but if not then definitely before RBW construction starts).
They will need to let the council know if any trade LBP leaves the project and is replaced.
When RBW construction is finished, the trade LBP(s) who carried out or supervised the RBW must provide their clients with a Record of Work form [203 KB PDF]. Your client will need to provide these forms to the council as part of the CCC application.
It’s important that they understand that it’s an offence knowingly not to use an LBP to carry out RBW.
Contact us to find out more.
MultiProof Designs (National multiple use approvals)
MultiProof approvals are issued by the Ministry of Business, Innovation and Employment (MBIE) and state that a specific set of building plans and specifications complies with the Building Code. MultiProof approval can be obtained for standardised building designs intended to be replicated 10 or more times in a two year period.
Councils must accept a MultiProof as evidence of Building Code compliance – but a building consent is still needed even with a MultiProof.
From 1 March 2012:
- An application for a MultiProof must include a Certificate of Work which states that any RBW in the MultiProof design complies with the Building Code
- An application for a building consent using a MultiProof design will still need to have a separate Certificate of Work included for any relevant site-specific parts of the design, and any customisations made to the MultiProof design, if restricted building work is involved.