Protection from Fire: NZ Building Code Clause C

What is the NZ fire code?

The Department of Building and Housing released a new fire code on the 10 April 2012 (effective date 9 April 2013).  Further modifications were made to the Acceptable Solutions ( C/AS1 - 7) in late 2016, with an effective date of 1st January 2017.  For surface finishes these modifications only affected wall coverings, not floor coverings, by adding an alternative European test to the list of acceptable verification methods.


What is the fire test for floor coverings?

Section C is the part of the Building Code relating to fire, and within this are six Clauses ( C1-C6).  Supporting the clauses are two Verification Methods and seven Acceptable Solutions outlining requirements for different building types.

The new code in 2012 introduced a different fire test method for floor coverings: Critical Radiant Flux tested to ISO 9239-1. The fire test ISO 9239-1 is only for floor coverings, not wall coverings.

To comply with the code, a building needs to be matched to a Risk Group, which is paired with an Acceptable Solution.  Risk Groups are assigned depending on the buildings use; multiple use buildings should follow the requirements of the most onerous relevant Acceptable Solution.

-       C/AS1 is the Acceptable Solution for Buildings with Sleeping (residential) and Outbuildings, Risk Group SH

-       C/AS2 is the Acceptable Solution for Buildings with Sleeping (non-institutional), Risk Group SM

-       C/AS3 is the Acceptable Solution for Buildings where Care or Detention is provided, Risk Group SI

-       C/AS4 is the Acceptable Solution for Buildings with Public Access and Educational Facilities, Risk Group CA

-       C/AS5 is the Acceptable Solution for Buildings used for Business, Commercial and Low Level Storage, Risk Group WB

-       C/AS6 is the Acceptable Solution for Buildings used for High Level Storage and other High Risk Purposes, Risk Group WS

-       C/AS7 is the Acceptable Solution for Buildings used for Vehicle Storage and Parking, Risk Group VP

The code calls for flooring to comply with a MINIMUM critical radiant flux when tested to ISO 9239-1 of between 1.2 and 4.5 kW/m² depending on the area within the building and the building's Risk Group. 

fire floors

Table from NZ Building Code clauses C1-C6

This change in building code requirements won't affect your ability to specify the two most used floor coverings in our range - Tarkett Commercial Vinyl and Shaw Contract Carpet Tiles.  Both achieve critical radiant flux values of between 6 and 8, far exceeding the minimum set out in the new code. For a quick overview of which products comply to different CRF values check out our Product Guide.

Note also that ceramic and porcelain tiles are specifically assigned a nominal CRF of 4.5 kW/m² and do not require testing (see Appendix B of the C/VM2 document).

Appendix B Tiles


What is the fire test for wall coverings?

The Building Code uses a different fire test method for wall coverings: ISO 9705.  Tests performed under ISO 5660 and EN13501 are correlated to ISO 9705 so may be used as well. The results from the ISO tests provides a Material Group number: Group 1 is the most fire-resistant, through to Group 4.  The results from the EN test provide a Class number, with Class A as the most resistant, through to Class F.  All test methodologies allow for the provision of a smoke index rating (-S), which may or may not be required depending on the building's Risk Group.

Appendix C wall tests

Table from Appendix C, C/AS3

fire walls

 Table from NZ Building Code clauses C1-C6

Critical Radiant Flux Test

The inquisitive and technically minded amongst you may be wondering how the test works.  The test is designed to evaluate the tendency of a floor covering to spread flame when exposed to radiant heat.  It's quite straightforward - a radiant panel is set at a constant temperature, generating heat exposure along the length of the test sample material, ranging from 11kW/m² at one end to approx. 1kW/m² at the far end (see diagram below).  This is then left for 30 minutes, and the length of material burnt during this time is measured.  This measurement becomes the sample material's critical radiant flux value, a higher value is better as it means more energy is required to sustain the travel of flame across the material.


> If you'd like more information, don't hesitate to get in touch with one of our flooring experts.

> For a quick overview of which floor and wall products comply with particular CRF and Material Group values, check out our Product Guide.