When calculating the fire resistance rating of glue laminated timber elements, it assumed that charring of exposed surfaces of the Glulam member occurs at a uniform rate, in the case of NZ Radiata Pine, it is taken as 0.65mm per minute. When exposed to heat of a fire, timber undergoes a thermal breakdown (pyrolysis) into combustible gases, and a layer of charcoal forms on the burning surface.

The Thermal Resistance of softwood laminated flooring is rated at Rt = 0.81 m2°C/W (for 65mm thickness). Insulation coverings will make a difference to the thermal rating of the final product application. The New Zealand Standard 4214:1977 will assist further with calculations to include insulation coverings.