Fire Performance

Fire Performance of Laminated Timber Beams

Laminated Timber is noted for its inherent ability to withstand the effect of fire. It has a superior fire resistance rating when compared to steel. This makes Glulam structures a safe choice for large public buildings.  Safe evacuation of people is the most important aspect of fire safety.  Because Glulam structures do not collapse under fire, safe evacuation is possible and fire fighters are able to gain access to the seat of fires preventing further damage.  Rebuilding after fire has often been achieved by removing the charcoal layer from the Glulam beams while they are still in position and replacing the burnt out roof. (Refer Case Study Morrison's Fire).

• Timber has the unique property of forming a charcoal layer on the surface which slows down the rate of burning. In this way timber retains it strength and shape for some considerable time in a fire.  Large section Glulam members will not burn out by themselves but need an external flame source to continue burning. Unprotected metals, while rated non combustible, lose their strength quickly under fire and collapse suddenly.
• The rate of charring for Glulam beams has been established by controlled testing and can be calculated at .66 mm per minute.  Thus, in half an hour a large section Glulam beam will sustain 20mm of char on surfaces exposed to flame.
• The fire resistance of timber increases as the structural size increases and the exposed area ratio decreases.
• When a fire is brought under control; before major damage occurs, Glulam members will frequently still be usable, subject to cosmetic repairs.
• Even though timber does burn, any contribution from a burning structure to the fire is insignificant compared with the contribution of the building’s contents which constitute the main fire load.