Specialty Timbers New ZealandVerification Method B2/VM1
From NZ Building Code Clause B2 Durability, Amendment 12, effective 28 November 2019:
1.0 Durability Evaluation
1.0.1 Verification that the durability of a building element complies with the NZBC B2.3.1 PERFORMANCE
B2.3.1 Building elements must, with only normal maintenance, continue to satisfy the performance requirements of this code for the lesser of the specified intended life of the building, if stated, or:
(a) The life of the building, being not less than 50 years, if:
(i) Those building elements (including floors, walls, and fixings) provide structural stability to the building, or
(ii) Those building elements are difficult to access or replace, or
(iii) Failure of those building elements to comply with the building code would go undetected during both normal use and maintenance of the building.
(b) 15 years if:
(i)Those building elements (including the building envelope, exposed plumbing in the subfloor space, and in-built chimneys and flues) are moderately difficult to access or replace, or
(ii)Failure of those building elements to comply with the building code would go undetected during normal use of the building, but would be easily detected during normal maintenance.
(c) 5 years if:
(i)The building elements (including services, linings, renewable protective coatings, and fixtures) are easy to access and replace, and
(ii)Failure of those building elements to comply with the building code would be easily detected during normal use of the building.
and B2.3.2 PERFORMANCE
B2.3.2 Individual building elements which are components of a building system and are difficult to access or replace must either:
(a) All have the same durability, or
(b) Be installed in a manner that permits the replacement of building elements of lesser durability without removing building elements that have greater durability and are not specifically designed for removal and replacement. will be by proof of performance and shall take into account the expected in-service exposure conditions by one or more of the following:
- In-service history,
- Laboratory testing,
- Comparable performance of similar building elements.
1.1 In-service history
1.1.1 Verification of durability based on inservice history of a building element, including materials, components and systems shall take into account but not be limited to:
- Length of service,
- Environment of use,
- Intensity of use,
- Any reaction with adjacent materials,
- Limitations in performance,
- Degree of degradation, and
- Changes in formulation.
1.2 Laboratory testing
1.2.1 Verification of durability based on successful performance in a laboratory test shall be accompanied by an assessment of the tests performed, their relevance to field and service conditions, and in particular:
- Types of degradation mechanisms likely to be induced by testing,
- The degradation mechanisms likely in service,
- Details of methods of assessment,
- Variability of results, and
- The relevance of the test to the building element under study.
1.3 Similar materials
1.3.1 For the purposes of evaluation, a building element may be considered as similar to another building element with proven performance, if both are subject to the same controls for composition and overall performance. Examples of such controls are Approved Documents or Standards. Where such a direct comparison is not possible, the building element shall be independently assessed to determine the degree of similarity.
1.3.2 Assessment shall take into account but not be limited to:
- Product composition,
- Method and quality assurance of manufacture,
- Degradation mechanisms,
- Local environment,
- Conditions of use,
- Required maintenance, and
- Performance in use.
COMMENT:
Environment
- To be acceptable, any opinion in support of the assessed durability for a building element shall clearly identify the conditions of use and the environment under which that durability will be achieved. If the building element can be reasonably expected to be used in circumstances which will reduce the durability, any limitations in use shall be clearly identified and evaluated.
- Circumstances which need to be considered include, but are not limited to:
- Maintenance required to achieve the required durability (e.g. painting, cleaning, replacing high wear items such as washers),
- Installation details of the total system (e.g. fixings, flashings, jointing materials),
- Compatibility with other materials (e.g. galvanic corrosion, plasticiser migration),
- Locality or macroclimatic effects (e.g. coastal or thermal areas, wet or damp ground conditions),
- Microclimatic effects (e.g. sheltered areas on buildings such as eaves),
- External environment influences (e.g. local industrial operations such as fertiliser works), and
- Internal environment (e.g. swimming pools, chemical processing areas, sauna rooms).
Definitions
Building has the meaning given to it by sections 8 and 9 of the Building Act 2004.
Building Code means the regulations made under section 400 of the Building Act 2004.
Building element Any structural and non-structural component or assembly incorporated into or associated with a building. Included are fixtures, services, drains, permanent mechanical installations for access, glazing, partitions, ceilings and temporary supports.
Durable Resistant to wear and decay.
Specified intended life has the meaning given to it by section 113(3) of the Building Act 2004.
Section 113(3) states:
“(3) In subsection (2), specified intended life, in relation to a building, means the period of time, as stated in an application for a building consent or in the consent itself, for which the building is proposed to be used for its intended use.”
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