Design process

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.

Restricted Building Work (RBW) has information on 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 will need to provide 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.

You'll need to fill out the Certificate of Work or the Design Certificate of Work clarification letter.

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.

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

Every Design LBP (“Design LBP” includes a New Zealand Registered Architect and Chartered Professional Engineer) who carried out design RBW work must sign their own Certificate of Work for the work they did.

There may be a need for multiple Certificates of Work if the design work is carried out by multiple designers or there is specialist design work required, such as a project that involves both a structural Chartered Professional Engineer and a specialist fire designer. In providing the certificate of work in this example, the designers must:

• State the parts of the work they carried out, having applied the skill and care reasonably required of a competent design professional.
• State that all of the RBW design work in the Certificate of Work complies with the relevant parts of the Building Code (as per the wording on the Certificate).

Consenting

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
• The Certificate of Work from you as a Design LBP (or from a New Zealand Registered Architect or Chartered Professional Engineer). This should be given 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

For the avoidance of doubt, an LBP cannot supervise other LBPs undertaking work in the same licence class. LBPs are legally entitled to carry out RBW and are individually accountable for the work they themselves produce.

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 an 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. However, 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.

In some cases, a licensed designer may have a set of drawings reviewed by a colleague for quality assurance purposes (such as checking for any errors or omissions), after which the designer will be submitting the plans with their own Certificate of Work. This is not considered to be ‘supervision of restricted building work’, as the primary designer holds a licence.

For more information on supervision, please refer to the Supervision Practice Note

Producer statements

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 that as a result, 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 Chartered Professional Engineer, or the New Zealand Registered Architects Board if the designer is a Registered Architect).

Design of Trusses

It is common practice for a Design LBP to use a truss fabricator to create plans and specifications for the trusses in a building.

A  roof truss is a building element that performs a role in distributing the structural loads from the roof down to the frame below it. This contributes to the building’s ability to withstand vertical and horizontal loads. An excess load may cause a failure of the building.

The design of roof trusses is therefore restricted building work, and a certificate of work is required for their design. This needs to be from a licensed building practitioner with a design class licence that covers the design, or supervision of the design, of roof trusses.

As the building design LBP will be incorporating the trusses into their overall design, they would clearly indicate on their Certificate of Design Work (CoW) how they have incorporated the trusses into their own design

NOTE: Although the design of the roof trusses is RBW, the off-site manufacturing of them in a factory is not.

Design summary

You do not have to use or provide a design summary, but this would be very useful and is part of best practice for the industry. 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 very 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

Your clients will need to engage trade LBPs (carpenters, roofers, external plasterers, brick and blocklayers, foundations experts) to carry out or supervise the relevant 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. Your client will need to provide these forms to the council as part of a Code Compliance Certificate application.

It’s important that they understand it’s an offence to knowingly not use an LBP to carry out RBW.

MultiProof

A national multiple-use approval (known as a MultiProof) can be issued by the Ministry of Business, Innovation and Employment (MBIE), to 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.

A CoW must be included in an application for the MultiProof approval, and a separate CoW must be included in a building consent application covering any relevant site-specific issues, or customisation of the MultiProof design.