Fibre Reinforced Facade Encyclopedia: Testing and standards
The ignitability index is the first of the four indices produced by AS 1530.3, the Australian early fire hazard test, and it describes how readily a material ignites when exposed to increasing radiant heat with a pilot flame present. It runs from 0 to 20, where 0 means the specimen did not sustain flaming within the test and 20 means it ignited almost immediately. Lower is better, and the index is reported alongside spread of flame, heat evolved and smoke developed indices from the same apparatus.
An ignitability index of 0 is a genuinely useful result and a widely abused one. It says the surface did not sustain flaming under a rising radiant flux with a pilot flame. It does not say the material is non-combustible, and it says nothing at all about what happens on a ventilated facade cavity in a real fire.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Source test | AS 1530.3 early fire hazard test | Method covered in the AS 1530.3 entry |
| Scale | 0 to 20, lower is better | Derived from time to sustained flaming |
| Index 0 | No sustained flaming within the test period | Typical of cementitious and mineral surfaces |
| Companion indices | Spread of flame 0 to 10; heat evolved 0 to 10; smoke developed 0 to 10 | All four reported together |
| NCC use | Fire hazard properties of specified materials and assemblies | NCC 2022 Specification 7; check the edition adopted in your jurisdiction |
| Wall and ceiling linings | Regulated on group number, not on these indices | AS 5637.1 replaced the early fire hazard route for linings |
| Other Australian indices | Flammability index from AS 1530.2 | Different test, used for sarking and similar membranes |
| International equivalent | None; not convertible to ASTM E84 or EN 13501-1 | Different apparatus and different reporting |
What the index measures
In the AS 1530.3 apparatus a specimen is mounted in front of a gas fired radiator and exposed to a radiant heat flux that increases through the test, with a small pilot flame positioned to ignite any flammable gases that the specimen gives off. The operator records the time at which sustained flaming first occurs. That time is converted through a table in the standard into the ignitability index, on a scale where a shorter time to flaming produces a higher index.
The index therefore answers a narrow question: at what point does this surface start to burn when heat is applied to it and an ignition source is already present. It does not ask how much energy the material then releases, how far flame travels, or how much smoke is produced. Those are the other three indices, and all four are needed to read an AS 1530.3 report sensibly.
Where the NCC uses it
The early fire hazard indices are the older Australian system, and their role narrowed considerably when the group number system for wall and ceiling linings was introduced. Group numbers, determined under AS 5637.1 from the AS ISO 9705 room corner test or from cone calorimeter data, now govern internal linings in most Class 2 to 9 buildings.
AS 1530.3 indices remain in NCC Specification 7 for materials and assemblies outside the lining provisions, where the Code sets limits on the spread of flame index and the smoke developed index rather than on ignitability. The ignitability index is still produced by the test and still reported, and it appears in specifications, in state authority requirements and in older documents that have not been rewritten around group numbers.
How it is misquoted
- Quoted alone. A data sheet showing ignitability index 0 with no other index and no report number is marketing, not evidence. Ask for all four indices, the report number and the laboratory.
- Confused with non-combustibility. AS 1530.1 is a furnace test that returns Combustible or Not Deemed Combustible. AS 1530.3 is a radiant panel test that returns four numbers. A material can score well on the second and fail the first.
- Confused with the flammability index. AS 1530.2 produces a flammability index on a separate scale, used for sarking, membranes and insulation facings. It is a different test and a different number.
- Confused with group number. Group numbers run 1 to 4 and come from AS 5637.1. Group 1 is the best; the group system is what the NCC applies to wall linings.
- Treated as international. There is no conversion from an AS 1530.3 index to an ASTM E84 flame spread index or an EN 13501-1 class. Each market requires its own test.
- Applied beyond the tested build-up. The indices belong to the specimen as tested, including its coating, substrate and thickness.
Reading it as a specifier
Treat the four indices as a screening set that tells you how a surface behaves early in a fire, and then ask what the Code actually requires for the element in question. For an external wall on a Type A or Type B building the requirement is non-combustibility, evidenced by AS 1530.1. ShapeShell-RC, the GRC system, carries an AS/NZS 1530.1 result of Not Deemed Combustible from Ignis Labs. For an internal wall or ceiling lining the requirement is a group number; ShapeShell-RT, the FRP system, holds an AS 5637 Group 1 classification from AWTA Product Testing, and it is a polymer composite that is not non-combustible.
Where an AS 1530.3 result is genuinely called for, obtain the full report from an accredited testing body, confirm the specimen description matches the proposed build-up, and record all four indices in the specification rather than the one that flatters the product.
Standards and references
- AS 1530.3 Methods for fire tests on building materials, components and structures, Part 3: Simultaneous determination of ignitability, flame propagation, heat release and smoke release
- NCC 2022 Volume One Specification 7 Fire hazard properties (check the edition adopted in your jurisdiction)
- AS 5637.1 Determination of fire hazard properties: wall and ceiling linings
- AS 1530.1 Combustibility test for materials; AS 1530.2 Test for flammability of materials
- AS 5113 Classification of external walls of buildings based on reaction to fire performance
Related terms
Questions specifiers ask
What does an ignitability index of 0 mean?
That the specimen did not sustain flaming during the AS 1530.3 test under a rising radiant heat flux with a pilot flame present. It is the best result on the 0 to 20 scale.
Is a low ignitability index the same as non-combustible?
No. Non-combustibility in Australia is decided by the AS 1530.1 furnace test, which reports Combustible or Not Deemed Combustible. The two tests ask different questions.
Does the NCC still use ignitability index?
AS 1530.3 indices remain in Specification 7 for certain materials and assemblies, but wall and ceiling linings in most Class 2 to 9 buildings are now regulated on group number under AS 5637.1 instead.
What are the other AS 1530.3 indices?
Spread of flame index, heat evolved index and smoke developed index, each on a 0 to 10 scale, reported from the same test as the ignitability index.
Can an ignitability index be used for a facade on a high rise?
No. Type A and Type B construction require non-combustible external walls, and a combustible cladding needs a performance solution supported by full-scale testing such as AS 5113.
ShapeShift publishes the standard, the result and the testing body for each ShapeShell system so the right evidence reaches the certifier. See ShapeShell fire test data
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.