Table 7.5 of C/AS1 specifies the acceptable peak heat release rate and total heat release rate for external wall claddings and the limitation depends upon building height, distance to relevant boundary and purpose groups.

The smaller the heat release value, the more stringent the requirement is, and the smallest ‘Peak Heat Release Rate specified in the Table is 100kW/m2 and 'Total Heat Released' is 25MJ/m2 and the materials which meet this requirement are given a classification ‘A’.

Specify James Hardie cladding materials confidently in a fire rated wall application as all James Hardie cladding materials have an ‘A’ classification and make them suitable for use in this application. James Hardie cladding materials are also classified as non-combustible materials and tested to AS1530-Part 1 test method.

James Hardie has a range of fire rated wall systems tested at BRANZ varying between 30 to 90 minute fire rating. Refer to http://www.jameshardie.co.nz for more information regarding these systems or to download the Fire and Acoustic Design Manual.