Fibre Reinforced Facade Encyclopedia: Testing and standards
EN ISO 11925-2 is the European reaction to fire test that measures the ignitability of a product subjected to direct impingement of a small flame, equivalent to a match or a cigarette lighter held against the surface or the edge. It is the screening test that underpins Classes B, C, D and E in the EN 13501-1 classification system: no product can reach any of those classes without passing it, and Class E is awarded on this test alone.
A 20 mm gas flame held against a specimen for 15 or 30 seconds. It is the least dramatic of the European fire tests and the one that eliminates the most products, because a material that cannot survive a lighter flame has no route into the classification system at all.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Standard | EN ISO 11925-2 Reaction to fire tests: ignitability of products subjected to direct impingement of flame | Single-flame source test |
| Specimen | 250 mm long by 90 mm wide, mounted vertically | Tested in end use thickness |
| Flame | About 20 mm high, burner inclined at 45 degrees | |
| Exposure for Class E | 15 seconds | |
| Exposure for Classes B, C and D | 30 seconds | |
| Criterion | Flame tip must not reach 150 mm above the point of application | Within 20 s for the 15 s exposure, within 60 s for the 30 s exposure |
| Droplets | Filter paper below the specimen observed for ignition | Feeds the d classification for Class E |
| Application point | Surface exposure and edge exposure | Chosen to reflect the end use condition |
| Classes it does not serve | A1 and A2 | Those need EN ISO 1182 or EN ISO 1716 plus EN 13823 |
How the test runs
A specimen 250 mm long and 90 mm wide is clamped vertically in a frame inside a draught free enclosure. A small propane burner, producing a flame about 20 millimetres high and inclined at 45 degrees, is brought up so that the flame touches the specimen at a defined point 40 millimetres above its lower edge. The flame is applied for 15 seconds or 30 seconds depending on the class being sought, then withdrawn, and the specimen is observed.
The measured quantity is whether the tip of the flame on the specimen reaches a mark 150 millimetres above the point of flame application. For the 15 second exposure the observation window is 20 seconds from the start of application; for the 30 second exposure it is 60 seconds. A piece of filter paper is laid beneath the specimen and observed for ignition by any flaming droplets that fall.
Products are tested with the flame applied to the surface, to the edge, or to both, depending on how the product will be used in the building. An edge exposure is generally more severe, because the flame reaches the core of a layered product directly, and it is the condition that exposes a combustible core behind a protective facing.
How it feeds EN 13501-1
EN 13501-1 assembles a classification from several tests. Classes A1 and A2 rest on the EN ISO 1182 non-combustibility furnace test or the EN ISO 1716 gross calorific potential test, with EN 13823, the single burning item test, for A2. Classes B, C and D rest on the single burning item test together with EN ISO 11925-2 at the 30 second exposure. Class E rests on EN ISO 11925-2 at the 15 second exposure alone. Class F is assigned where a product does not achieve Class E or where no performance is determined.
The small flame test therefore sets the floor. A product that fails the 15 second exposure is Class F and has no usable European reaction to fire classification. A product that passes at 15 seconds but not at 30 seconds is capped at Class E no matter how it might perform in the single burning item test.
The droplet classification also draws on this test for Class E. Where flaming droplets from the specimen ignite the filter paper, the classification becomes E-d2. For Classes A2 to D the d0, d1 and d2 droplet classifications come from observations during the single burning item test instead.
Reading a European classification
A full EN 13501-1 classification is written as a main class, a smoke suffix and a droplets suffix, for example B-s2,d0. The main class comes from the test route described above, the s rating from smoke production in the single burning item test, and the d rating from flaming droplets. Each part carries its own evidence, and the classification report names the laboratory, the tests and the end use conditions covered, including substrate, fixing method and air gap.
ShapeShell-RT is classified B-s2,d0 under EN 13501-1 by Intertek Testing Services. Reaching Class B required a pass of the 30 second EN ISO 11925-2 exposure alongside the single burning item test result. ShapeShell-RT is a fibre reinforced polymer and is not non-combustible; Class A1 and A2 are furnace test classes that a polymer composite cannot reach.
Australian and North American comparisons
Australia has no direct equivalent. The nearest small scale ignition measure is the ignitability index from AS 1530.3, which uses a radiant panel with a pilot flame rather than a direct small flame, and which reports on a 0 to 20 scale rather than pass or fail. Internal linings in Australia are regulated on group number from AS 5637.1, a full room test lineage, and external walls on non-combustibility under AS 1530.1.
The United States uses ASTM E84 for surface burning characteristics and ASTM E136 for non-combustibility, with no small flame screening step of this kind in the main building code route. None of these results convert into an EN class, and a product sold into Europe, Australia and North America carries three separate sets of reports.
Standards and references
- EN ISO 11925-2 Reaction to fire tests: ignitability of products subjected to direct impingement of flame, single-flame source test
- EN 13501-1 Fire classification of construction products and building elements
- EN 13823 Single burning item test; EN ISO 1182 non-combustibility; EN ISO 1716 gross calorific potential
- AS 1530.3 for the Australian ignitability index; AS 5637.1 for group numbers
- ASTM E84 and ASTM E136 for the North American equivalents
Related terms
Questions specifiers ask
What does EN ISO 11925-2 measure?
Whether a small flame applied to the surface or edge of a specimen for 15 or 30 seconds causes flame to spread 150 mm above the point of application, and whether flaming droplets ignite filter paper below.
Which EN 13501-1 classes need it?
Classes B, C and D require the 30 second exposure alongside the single burning item test. Class E is awarded on the 15 second exposure alone. Classes A1 and A2 use furnace and calorimetric tests instead.
Is passing the small flame test a good fire result?
On its own, no. It is a screening threshold. A product can pass it and still be Class E, which is the lowest classified level in the European system.
What is the difference between surface and edge exposure?
The flame is applied either to the face of the specimen or to its bottom edge. Edge exposure is generally more severe because it reaches the core of a layered product directly.
What class is ShapeShell-RT?
B-s2,d0 under EN 13501-1, classified by Intertek Testing Services. It is a fibre reinforced polymer and is not non-combustible, so Classes A1 and A2 are not available to it.
ShapeShell-RT is classified B-s2,d0 under EN 13501-1 by Intertek Testing Services, alongside its Australian and UK test evidence. See ShapeShell-RT specifications
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.