Report: Pathways to Building Code compliance for farm-totara timber
Sustainable Forest Solutions
The author wishes to acknowledge the support from the organisations and individuals that have enabled this project to be undertaken. These include; the Ministry for Primary Industries (through the Sustainable Farming Fund), Tane’s Tree Trust and the New Zealand Farm-Forestry Association, (including the Indigenous Forestry Section), the Northland Totara Working Group members Paul Quinlan and David Bergin for assistance in finalising this report, Michael Hayes & Geoff Cookson, for their time and donated sample boards of timber for testing, and saw-miller, Shane Hyde, for his time and the use of his band-saw in re-sizing some of the timber samples. The time and input from Robin Curtis, CEO of NZ Sustainable Forest Products, is also acknowledged and much appreciated.
In producing this report, reasonable care has been taken regarding the accuracy of the information presented. However, no guarantee as to the truth, accuracy or validity of any of the comments, implications, recommendations, findings or conclusions are made by the author, the Northland Totara Working Group, Tane’s Tree Trust, or any other party. Therefore, neither the authors, nor any of the supporting organisations, shall not be liable for, or accept any responsibility for, any loss, damage or liability incurred as a result of direct or indirect result of any reliance by any person upon information or opinions or recommendations expressed in this work. Users of any of this information, whether contained or inferred, in or arising from this report do so at their own risk.
Compliance with the Building Code can be demonstrated using various pathways. Some pathways must be accepted by the building consent authority as meeting the performance requirements of the Building Code1. Such compliance paths as Acceptable Solutions are desirable because designers are likely to specify such materials and ready markets exist due to the ease with which consent is granted.
Compliance Paths that must be accepted by building consent authorities as meeting the performance requirements of the Building Code
Acceptable Solutions and Verification Methods
Acceptable Solutions are simple step-by-step instructions that offer one way to comply with the Building Code1.
Verification Methods are prescriptive tests or calculation methods that offer another way to comply with the Building Code1.
Verification Methods and Acceptable Solutions are prepared by the Ministry of Business, Innovation and Employment in accordance with section 22 of the Building Act 2004. Verification Methods and Acceptable Solutions are for use in establishing compliance with the New Zealand Building Code2.
Acceptable Solutions and Verification Methods provide details for construction that, if followed, result in compliance with the Building Code. A design that complies with an Acceptable Solution or Verification Method must be accepted by a building consent authority as complying with the Building Code1.
There is at least one Acceptable Solution or Verification Method for compliance with each of the Building Code clauses. For example, for Clause B1 of the Building Code there are two Verification Methods and three Acceptable Solutions, referred to by their Building Code clauses and unique identification numbers. That is, B2/AS1 is Clause B2 of the Building Code, Acceptable Solution 11.
Verification method 1 of Clause B2 (B2VM1) Durability evaluation take into account the expected in-service exposure conditions of a building component and offers three methods to prove durability performance (1.0.1):
- In-service history
- Laboratory testing
- Comparable performance of similar building elements.
Two NZ Standards, NZS 3640 and NZS 3602 offer Acceptable Solutions for timber durability.
Verification Methods for structural integrity are provided in NZS 3603, while Acceptable Solutions are provided in NZS 3604.
Timber components need to meet both structural and durability requirements to comply with the Building Code.
The Building Act contains provisions for a voluntary product certification scheme that enables product manufacturers to have their products certified as meeting nominated performance requirements of the Building Code1.
Building products or methods that are used in accordance with a product certificate must be accepted as complying with the Building Code1.
Codemark product certification provides a way for a product to meet the requirements of the building code. CodeMark is an unchallengeable form of product assurance. Building consent authorities (BCAs, usually councils) must accept a product certificate as evidence of compliance with the Building Code, provided the product is used in accordance with the use and limitations defined on the certificate6.
Only accredited product certification bodies can evaluate products for CodeMark and issue CodeMark certificates. They must follow the CodeMark Scheme Rules when doing so. The Joint Accreditation System of Australia and New Zealand (JAS-ANZ) is the body responsible for assessing and accrediting product certification bodies6.
The Building (Product Certification) Regulations 2008 prescribe the6:
- criteria and standards for accreditation as a product certification body, including the fees payable to the accreditation body
- criteria and standards for certification of products
- minimum content for product certificates
CodeMark certificate holders have ongoing responsibilities to ensure their certified product continues to be manufactured to the same standards, levels and quality as those against which it was evaluated and certified. To keep certificates valid, the requirements of the Codemark Scheme Rules need to be followed and annual auditing undertaken by the product certification body7.
A determination is a binding decision made by the Ministry of Business, Innovation and Employment. It provides a way of solving disputes or answering questions relating to the Building Code and territorial authority/building consent authority/regional authority decisions under the Building Act1. A determination meets the performance requirements of the Building Code that is covered.
Although a determination must be accepted by the building consent authority as meeting the performance requirements of the Building Code, the issue under question is specific to that building consent authority and might only be seen as a guide by other BCA's.
Compliance Paths that do not need to be accepted by building consent authorities as meeting the performance requirements of the Building Code
The Building Code describes how completed building work must perform rather than how a building must be built. Any product or system can be used in a building provided it meets the relevant performance requirements of the Building Code9.
An alternative solution is a building design or proposed construction that differs, in part or wholly, from the solutions offered by the Acceptable Solution or Verification Method. This must demonstrate compliance with the performance requirements of the Building Code to the satisfaction of the building consent authority.1 An alternative solution must provide evidence that it meets performance criteria of the building code and allows for innovation and uniqueness. Compliance needs to be clearly established for the Building Consent Authority to be satisfied "on reasonable grounds" and issue a building consent8.
An alternative solution can include a construction material that differs completely or partially from those described in the Acceptable Solutions or Verification Methods. Where an alternative solution is for a product, sufficient evidence that it complies with the requirements of the Building Code might include8:
- Comparison with Acceptable Solutions or Verification Methods.
- Comparison with a product previously accepted by a BCA.
- Comparison with a determination issued by MBIE.
- Manufacturers literature on a proprietary product
- In-service history
- Expert evidence
This approach is very much in line with product assurance (see below).
For a product to comply fully with an Acceptable Solution or Verification Method, evidence must show that it meets the requirements of these. An alternative solution offers another way for products to meet the relevant performance requirements of the Building Code9 and involves evaluating the product against criteria that, if met, will demonstrate compliance with a particular Building Code clause. This might involve9:
- comparing the product against a relevant product standard referenced in an Acceptable Solution or Verification Method
- comparing the product to another document (eg a New Zealand or overseas standard, other technical information, test
results or research)
- look at in-service history and performance of a similar product within New Zealand or in similar conditions
- identify any relevant determinations issued by the Ministry. Is there a determination on a situation where a similar product is specified? As determinations relate to a particular case, their application may be limited. However, they do provide sound guidance on the application of the Building Act and Building Code at a particular time.
Evidence should therefore be established to demonstrate where the product complies with clauses of the Building Code. Evidence includes product assurance claims (technical information, independent assessments, industry-based schemes, appraisals) and/or product certification (CodeMark).
The product assurance approach developed in 2010, is about providing evidence and information that the product complies with the Building Code. Product assurance offers manufacturers and product suppliers cost-effective ways to show Building Code compliance and therefore market acceptance3. Manufacturers and suppliers may choose less stringent levels of assurance than Codemark certification, such as product technical statements (PTS's) or independent testing for products that are already well used and accepted in the New Zealand building industry6, or where the Building Consent Authority is easily satisfied that their product is Building Code compliant.
Demonstrating that a product meets the requirements of the relevant Building Code clauses requires reliable evidence (such as technical information, independent assessments, appraisals, product certification or industry-based schemes)4. Claims made by the manufacturer or supplier must be backed up by technical information that5:
- meets Building Act obligations under section 14G (manufacturers' and suppliers' responsibilities)
- shows compliance with the Building Code
- assures users the product is made to the same specification and quality as specified.
Claims can be supported with technical opinions, independent assessments/appraisals, laboratory testing or proof of in-service history5.
At a minimum, such evidence must include5:
- relevant technical information
- a purpose and use statement that includes any limitations relating to the product’s use
- clear design, construction and installation information and support for designers and builders
- clear maintenance information for the product including what is required and what the impact would be on ongoing performance, especially durability (if maintenance is not done to the required level).
- comprehensive (showing how the products performance complies with Acceptable solutions, Verification methods or standards cited in these).
- credible (an appropriately qualified organisation carrying out product assessments and making claims only where competent to do so)
- relevant (testing and evidence that relates to the product)
- controlled (where, when and how the product can be used so that it is fit for purpose, including limitations).
Information can also be provided about design instructions, links to installation manuals or similar.
Fact-based performance claims such as statistical data about the product's past performance should be provided rather than anecdotal evidence. Factual claims demonstrating a history of successful manufacture, sale and use in relevant situations or markets might show how the product performs in different local conditions in New Zealand such as in high wind zones, corrosion zones, seismic zones, or zones with high levels of UV exposure, and would include the effect these conditions have on product life5.
Where the level of risk of not complying with the relevant requirements of the Building Code is high, more comprehensive evidence would need to be provided.
Product technical statement (PTS)
Product technical statements were developed by MBIE as a tool for products or systems to meet Building Code obligations. Key details are summarised to provide reliable technical information and help for10:
- designers and specifiers to assess and specify building products
- Building Consent Authorities to consent building work
- Product support to enable builders and homeowners to receive clearer information about installation and maintenance
- meeting Building Act responsibilities
A PTS should include the following information10:
- a description of the product and its intended use
- details of the manufacturer (if issued by a supplier)
- date of issue (or revision) and relevant links so users can confirm they have the latest version
- purpose and use (how the product can be used and any limitations on that use)
- any conditions on the use of the PTS
- a statement of the Building Code clauses relevant to the product and clear links to evidence to support compliance claims (such as relevant test reports, technical opinions, product certification details or other supporting information)
- links to design, construction and installation instructions
- links to maintenance requirements so the building owner can maintain the product effectively and a description of potential consequences of not carrying out specified maintenance
- contact details for technical support; ideally for New Zealand organisations that can provide product advice and assistance.
Appraisals are independent technical opinions of a building product or system's fitness for purpose. They have no legal standing but can be used as evidence of Building Code compliance through a process of testing and verification.
A producer statement is a statement supplied by or on behalf of an applicant for a building consent, or by or on behalf of a person who has been granted a building consent. It is a statement that certain work will be, or has been, carried out in accordance with certain technical specifications.1
Producer statements were introduced by the former Act and are no longer expressly referred to in the Building Act. A building consent authority may, at their discretion, accept and consider a producer statement as part of the plans or specifications for a building consent. This will assist the building consent authority in deciding whether it is satisfied on reasonable grounds the provisions of the Building Code will be met if the building work is completed in accordance with the plans and specifications. A building consent authority should have a formal procedure or policy in place for the use and consideration of producer statements, especially if a producer statement(s) will be required to prove building work complies with a building consent.1
- New Zealand Building Code Handbook (2014)
- Timber treatment has just got simpler (Build 124)
- Product assurance in the New Zealand building market
- Showing your products comply with the Building Code
- Establishing and providing information and evidence about your product
- CodeMark as a product certification scheme
- How CodeMark works
- Alternative solutions for compliance with the Building Code
- Product Assurance Decision Tool (pdf)
- Creating and providing a product technical statement
See also: New Zealand Building Code Handbook. The preface describes the status of Verification Methods and Acceptable Solutions and explains alternative methods of achieving compliance.