The effect of post-treatment machining and accelerated weathering on the fire test performance of Chemco FRXtreated western red cedar
Opportunities for using western red cedar on the exterior of buildings in bushfire-prone areas are limited by the requirements of Australian Standard (AS) 3959 Construction of buildings in bushfire-prone areas. There are allowances for the use of fire retardant-treated timber and data have been developed that demonstrate that western red cedar treated in final shape and form with Chemco FRX (FRX) satisfies the AS 3959 requirements.
The ability to treat finished products was of limited interest to the western red cedar processing industry because of the large range of profiles that would need to be FRX-treated and the potential for drying degrade following treatment. Western red cedar importers and processors stated that being able to machine western red cedar after fire retardant treatment would provide a significant benefit. The preferred machining options ranged from a) fire retardant treating slightly oversize products and then remachining to final profile to b) fire retardant treating 50 mm thick rough sawn boards and then machining to any profile.