Fibre Reinforced Facade Encyclopedia: Testing and standards
A group number is the National Construction Code’s classification of wall and ceiling lining materials by their contribution to fire growth in a room. Group 1 is the best and Group 4 the worst. It is determined under AS 5637.1 either by a full room fire test to AS ISO 9705 or by prediction from cone calorimeter data to AS/NZS 3837, and it applies to internal linings, not to external walls.
Group 1 means the lining did not cause flashover within 20 minutes of a room test, with the burner at 100 kW for the first ten minutes and 300 kW for the next ten. It is a fire growth classification, not a fire resistance rating and not a statement of non-combustibility.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Standard | AS 5637.1 Determination of fire hazard properties, Part 1: Wall and ceiling linings | |
| Reference test | AS ISO 9705 room corner test | Full-size room, 100 kW then 300 kW burner |
| Predictive test | AS/NZS 3837 cone calorimeter | Small specimen at 50 kW/m²; result predicted |
| Group 1 | No flashover within 20 minutes | Best performance |
| Group 2 | Flashover between 10 and 20 minutes | |
| Group 3 | Flashover between 2 and 10 minutes | |
| Group 4 | Flashover within 2 minutes | Worst performance |
| Smoke criterion | Smoke growth rate index or specific extinction area limit | Applies in unsprinklered buildings |
| Where required | NCC Volume One Specification 7 (fire hazard properties) | Internal linings by building class and location |
What the room test does
A room 3.6 by 2.4 by 2.4 metres is lined with the material on the walls and ceiling. A propane burner in one corner runs at 100 kW for ten minutes, then 300 kW for a further ten. Instruments record the heat released through the doorway. Flashover is taken as 1 MW total heat release. The time to reach it, if it is reached at all, sets the group number. Because the full test is expensive, AS 5637.1 also allows the group number to be predicted from cone calorimeter results, which is the usual route for cladding and lining products.
What the NCC requires
Specification 7 sets the minimum group number for internal wall and ceiling linings by building class, by location within the building and by whether sprinklers are installed. Fire-isolated exits and public corridors in some classes require Group 1; many other spaces accept Group 2, and Group 3 is permitted in limited locations. Unsprinklered buildings also have to meet a smoke criterion. The requirement is for the lining as installed, so substrate and fixing method are part of the tested system.
What Group 1 does and does not mean
Group 1 is the best result an internal lining can achieve under AS 5637.1 and is a strong reaction-to-fire credential. It does not mean the material is non-combustible; many Group 1 materials are combustible products with fire retardant treatment. It does not give the material a fire resistance level, which is a property of assemblies tested to AS 1530.4. And it does not on its own qualify a product for the external wall of a Type A or B building, where the NCC requires non-combustibility or a Performance Solution supported by AS 5113.
FRP and GRC in lining applications
Polymer composites can reach Group 1 with the right resin system and fire retardant additions; ShapeShell-RT holds a Group 1 classification from AWTA Product Testing. GRC and GRG, as cementitious and gypsum materials, are normally Group 1 by nature and are also candidates for non-combustible classification, which covers every lining requirement in the Code.
Standards and references
- AS 5637.1:2015 Determination of fire hazard properties, Wall and ceiling linings
- AS ISO 9705 Fire tests: full-scale room test for surface products
- AS/NZS 3837 Method of test for heat and smoke release rates for materials and products using an oxygen consumption calorimeter
- NCC 2022 Volume One, C2D11 and Specification 7 (fire hazard properties) (check the edition adopted in your jurisdiction)
- AS 1530.3 (early fire hazard indices, referenced for some applications)
Related terms
Questions specifiers ask
Is Group 1 the same as non-combustible?
No. Group 1 is a lining classification based on fire growth in a room test. Non-combustibility is a material classification from a furnace test under AS 1530.1. A Group 1 material may be combustible.
Is Group 1 a fire rating?
No. A fire rating in Australia is a fire resistance level in minutes, tested under AS 1530.4 for walls, floors and other elements. Group number is a reaction-to-fire property of a lining.
Does Group 1 allow a material on the external wall of a high-rise?
Not by itself. External walls of Type A and B buildings must be non-combustible under Deemed-to-Satisfy, or justified by a Performance Solution using AS 5113 and fire engineering. Group number is an internal lining classification.
What group number does ShapeShell-RT hold?
Group 1, classified by AWTA Product Testing under AS 5637. The full test table is on the ShapeShift fire rating page.
Can group number be predicted without a room test?
Yes. AS 5637.1 allows prediction from AS/NZS 3837 cone calorimeter data, which is the common route for products.
ShapeShell-RT holds an AS 5637 Group 1 classification and a full-scale AS 5113 facade test pass. See how each result maps to the NCC. See ShapeShell fire test data
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.