With the surge in building construction over the last couple of years, and the resulting high demand for building materials, the MGA TMA Technical Advisory Support service has received requests for information on, ‘How do I know that the imported structural timber product being offered is compliant for use in Australia?”. Structural timber product compliance has received much attention due to the increased offering of imported timber products; however, the answer to this question is the same whether it is an imported timber product or a locally manufactured/produced timber product.
One of the keynote speakers at the recent MGA TMA Industry Breakfast held on the 22 June 2022, Craig Kay – Engineering Manager at Tilling Timber, spoke about “LVL! Australian standards and NCC Conformance” to address this issue; and the following provides a brief overview of the key points in relation to all structural timber products.
The National Construction Code (NCC – also referred to as the Building Code of Australia) sets the technical design and construction requirements for all buildings. The NCC references standards that are “deemed” to meet these requirements. For structural timber products, conformance can be demonstrated via a number of pathways but the most common is complying with the relevant Australian Standard.
Australian Standards require structural timber products to be identified/branded/marked if they are claiming compliance with the standard. These structural timber products include solid framing, LVL, glue-laminated timber, plywood, as well as preservative treated timber. If they are not identified, building surveyors/certifiers and builders can reject them as being non-conforming. Think of it this way, the product branding/marking indicates that the structural product manufacturer/supplier has complied with the requirements of the relevant standard and “stands by” the product! Would you buy a car that was unbranded?
Structural Timber Products
The vast majority of structural timber products are used in the construction of residential housing. The NCC references AS 1684 Residential timber-framed construction as a deemed-to-satisfy means of demonstrating compliance with the “technical design and construction requirements” for residential housing. Specifically, AS 1684 specifies the building construction practices as well as the design and selection of structural timber elements (e.g. stress-graded timber) and provides the link to the stress-grade properties given in AS 1720.1 Timber structures – Design methods.
Australian structural timber product standards have specific requirements in relation to branding/labelling/marking, which must be legible on the product, if claiming compliance with the Standard. The information required will include:
The number of the Australian/New Zealand Standard (AS or AS/NZS) to which compliance is being claimed. These include:
AS 2082 for visually stress-graded hardwood,
AS 2858 for visually stress-graded softwood,
AS/NZS 1328 for glue-laminated timber,
AS/NZS 1748 for MGP/machine graded pine,
AS/NZS 2269 for structural plywood including bracing, and
AS/NZS 4357 for structural Laminated Veneer Lumber (LVL).
Identification of who has stress-graded the timber or product or is making the engineering property determination (source of grading).
For stress-graded timber, if graded as seasoned, the word ‘SEASONED’ or the abbreviation ‘S’ (e.g., F17S).
For LVL, stress grades are not applicable but must carry a ‘registered product name/ trademark’ or manufacturer’s name (e.g., ABCD14). Note: Manufacturers of LVL will provide the design properties as well as span tables or direct the user to the appropriate span tables where applicable, for product use.
In addition, if the structural timber has been preservative treated, branding requirements in accordance with AS/NZS 1604 are also required. These include:
A unique identifier for the treatment plant (i.e., a plant number, a company name or a company logo).
A unique identifier for the preservative (i.e., product name or a preservative identification number).
Envelope treated timber products - Where timber products are envelope treated in accordance with AS/NZS 1604 they shall carry a warning label.
Note that for all treatment hazard classes (e.g., H2F, H3), each piece of structural treated timber must be legibly marked with this information.
As can be seen, there is a reasonable amount of information that is required in order to identify that the structural timber product is fit for purpose and compliant. This article provides a quick overview of the compliance requirements, but further information can be found in the following industry documents: