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Question

I would like to know if engineered timber products (e.g., glulam) would have the same group number (e.g., Group 3) as their solid counterpart for the same timber species or if the group number for glulam would have to be determined in accordance with AS 5637.1.

Woodsolutions Answer +

For information about the fire performance of timber, including LVL and glulam, click on this link https://www.woodsolutions.com.au/articles/design-fire. Note particularly the advice that Fire tests have shown that glulam or LVL members can be regarded as solid timber for the application of AS 1720.4. The glue is not considered to affect the fire performance of these engineered products. Therefore the same Group Number will apply for glulam as for solid timber of the same species (Group 3 for all species tested so far).

Glulam in fire

Answered on 22-07-2021
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

Question

We have a modified wood product which is Fire Resistant in behaviour. How do we need to test/verify performance to allow use as cladding for Class 2/3 building? We are undertaking BAL testing now and expect BAL 40 minimum. I assume there is different testing required for Class 2/3 use?

Woodsolutions Answer +

The requirements for Class 2 and Class 3 buildings vary according to whether Type A, Type B or Type C construction is called for (refer Table C1.1 NCC 2019 vol. 1). Buildings of Type A or Type B construction are required to have non-combustible cladding. For an explanation of the requirements for external walls in Type A and Type B construction, including attachments, we refer you to the ABCB Advisory Note available here: https://www.abcb.gov.au/Resources/Publications/Education-Training/Fire-performance-of-external-walls-and-cladding. Combustibility is determined by testing in accordance with Australian Standard 1530.1: Combustibility test for materials. This involves placing specimens in a furnace at approximately 750°C, at which temperature they must produce only a limited amount of heat and flame, so it is quite severe. If you feel your cladding could pass this test we suggest you pursue it with the organisation that is conducting your BAL tests.

Cladding combustibility

Answered on 21-07-2021
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

Question

In Wood Solutions document "Design_Guide_04_Building_Timber_Bushfire_Areas_3-9_MB_0.pdf" page 41 and 42 (covering BAL 12.5 NSW Appendix A variations), is a table listing Stairs/decks/ramps – open sub-structure. In this table floor bearers and joist are listed as requiring Bushfire-resistant timber. Can you please advise on what document and section this variation from AS 3959 Sect 5.7.3 is based as we have been unable to find such relevant document?

Woodsolutions Answer +

The NSW variations to AS 3959 are set out on page 70 of a NSW Rural Fire Service document titled Planning for Bushfire Protection, available for download via this link https://www.rfs.nsw.gov.au/__data/assets/pdf_file/0005/174272/Planning-for-Bush-Fire-Protection-2019.pdf. By replacing clause 5.7 of AS 3959 with clause 7.7 of AS 3959, it 'upgrades' the requirements for verandahs, decks, steps and landings in BAL-12.5 to those of BAL-29, where the supports and framing of unenclosed subfloor spaces must be bushfire-resisting timber, if timber is to be allowed.

NSW variations AS 3959

Answered on 21-07-2021
Please note that our answer is based on the best advice available at the time. If the National Construction Code, Australian Standards or local requirements have been subsequently amended, our answer may no longer be correct in all details. For more information, please read our disclaimer.

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