When timber is exposed to the heat of a fire, it goes through a thermal breakdown process and a layer of charcoal forms on its surface. This charred layer is the key to timber’s fire resistance, acting as an insulator that protects the inner core. Although the temperature at the char layer may be 300°C, the temperature of the inner core is considerably lower.

Large timber members (sawn timber or glulam), can be naturally fire resistant thanks to the unique charring properties of the wood. The self protecting nature of the charring layer increases the likelihood of a timber structure surviving fire as the uncharred inner core remains unaffected, maintaining its structural strength and stability. Therefore, glue laminated timber will not twist or spall in a fire event.

Hyne Timber uses both sustainably grown hardwood and softwood to engineer beautiful glue laminated (Glulam) timber beams.

LGL and Beam 17 come from Australian plantation pine. The fire properties of this species are listed in Material Group Number 3, which indicates that the material can reach flashover in more than 120 seconds but less than 600 seconds after exposure to 100kW. Pine wood is resistant for areas where Bushfire Attack Levels* are considered BAL-12.5 and 19.

Beam 18 is made of Victorian Ash. This hardwood is listed in the Fire Properties Group Number 3 and its bushfire resistance makes it suitable for BAL-12.5 and 19 (door and window joinery only).

Beam 21 is available in both Forest Reds and Spotted Gum. Spotted Gum is considered a bushfire resistant timber up to and including BAL-29 while Forest Red Gum is rated for BAL categories of 12.5 and 19. Based on the Building Code of Australia’s Early Fire Hazard indices, its spread of flame and smoke develop indexes sit low at 3 in a scale of 10.

* In the Australian Standards AS 3959, a home may experience different bushfire intensity levels. These are referred to as Bushfire Attack Levels (BAL). There are six levels in total: BAL Low, BAL-12.5, BAL-19, BAL-29, BAL-40 and BAL Flame Zone.

Many Australian standard tests exist to cover fire concerns. A summary of these can be found below:

Timber can be treated with chemicals that can modify its performance in fire. A number of treatments are commercially available in Australia. Hyne Timber does not offer fire retardant treated timber and advice should be sought directly from the companies offering these treatments.