FAQs - reaction to fire testing

Frequently asked questions about reaction to fire and fire behaviour.

1. What is reaction to fire testing?
Two key aspects to fire testing are Fire Resistance and Reaction to Fire and there is often confusion between the two. Fire resistance is the measurement of the ability of a material or system to resist, and ideally prevent, the passage of fire from one distinct area to another. Reaction to fire is the measurement of how a material or system will contribute to the fire development and spread, particularly in the very early stages of a fire when evacuation is crucial.

SBI, SFI, flammability, ignitability, surface spread of flame and classification are all terms people might use to describe reaction to fire testing.
2. Why is reaction to fire testing important?
The contribution of a product to a developing fire, in terms of ease of ignition, energy produced and flame spread will have an impact on how easy it is for people to escape from the area of the fire.
3. When is reaction to fire testing required?
Reaction to fire testing can be required in order to comply with the Building Regulations. In England and Wales this is covered by Approved Document B; in Scotland by Technical Handbooks Domestic and Non-Domestic; in Northern Ireland by Technical Booklet E; and in the Republic of Ireland by Technical Guidance Document B.

Reaction to fire testing is required for certain products destined for railway applications and produced in accordance with the standard DD CEN TS 45545.

Even when reaction to fire testing is not required under the building regulations, a relevant insurer or authority for a building may request an enhanced reaction to fire performance for which testing is required.

Some manufacturers carry out reaction to fire testing to find out more about their product, or to demonstrate the superiority of their product in the market place.
4. How are European classification and National classification for
reaction to fire testing related?
The national class cannot be assumed to equate to the new European class. While European classification is recognised in the UK, the converse is not true - national class is not accepted in Europe and hence European test evidence must be obtained if a product is to be used in mainland Europe.

The European tests and National tests are physically different, although they are all used to demonstrate reaction to fire performance.

Table 1: Example of requirements taken from Table 10 Classification of linings in Approved Document B for England Volume 2 – Buildings other than dwelling houses.
Location European class National class
Small rooms of area not more than:
a) 4m2 in residential accommodation
b) 30m2 in non-residential accommodation
D-s3, d2 3
Other rooms (including garages) C-s3, d2 1
Circulation spaces within dwellings C-s3, d2 1
Other circulation spaces, including the common areas of blocks of flats B-s3, d2 0

Table 2: Transposition table of reaction to fire classification showing European and British standards 
Euro-class EN 13501-1 England, Wales, Northern Ireland Scotland
A1 Non-combustible Non-combustible
A2 (or better) Limited combustibility Non-combustible
B-s3, d2 (or better) 0 Low risk (0)
C-s3, d2 (or better) 1 Medium risk (1)
D-s3, d2 (or better) 3 High risk (2 & 3)
E-s3, d2 (or better) 4 Very high risk
F-s3, d2 (or better) Unclassifiable Very high risk
5. What standards are used in European reaction to fire testing?
The four standards listed below are used for reaction to fire classification of a wall or ceiling lining product. Sometimes other standards are used for different products such as floorings.  This table shows how different classifications utilise testing to different standards.
Classification Relevant test standard
A1 BS EN ISO 1716
BS EN ISO 1182
A2 BS EN ISO 1716
BS EN ISO 1182
BS EN 13823
B, C, D BS EN ISO 11925-2
BS EN 13823
E BS EN ISO 11925-2
6. How are tests used to give a classification?
To achieve a classification, a product must be tested to the required standards, and the required performance achieved. The resulting reports are then used to create a classification document.
7. Why are different tests used depending on the level of classification aimed for?
Reaction to fire testing can be conducted on products with very different performance. Products that do not easily combust will not produce observable test results in a test designed to challenge a product that ignites and burns easily. For this reason there is a range of European tests used to cover the different classifications, just as there is a range of tests used for the British test standards.
8. What do SBI and SFI mean?
The main reaction to fire tests are commonly referred to by the title of the test in words, or a shortened version of this. The main tests used to establish European reaction to fire classifications are listed below, with the commonly used names for these tests highlighted in bold:
BS EN ISO 1182: 2010 Reaction to fire tests for building products - Non-combustibility test
BS EN ISO 1716: 2010 Reaction to fire tests for building products - Determination of the gross heat of combustion (Bomb calorimeter)
BS EN 13823: 2010 Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item (SBI)
BS EN ISO 11925-2: 2010 Reaction to fire tests - Ignitability of building products subjected to direct impingement of flame - Part 2: Single-flame source test (SFI)
9. What is an SFI or Small Flame Ignitability test?
The SFI test uses a single small flame source to assess the ignitability of the product. The product is mounted in the test apparatus in a vertical orientation and the flame is applied. Observations are made on whether the product has ignited, the flame propagation up the product, and any flaming particles that may fall from the product.
10. What size specimen is tested in a SFI test?
The specimen must be 250 (+0, -1) mm x 90 (+0, -1) mm. A minimum of 8 specimens are required, with more specimens required if the product is to be tested on its edge as well as its surface. Further specimens may be required for specimen analysis when writing the test report.
11. What is a SBI or Single Burning Item test?
The SBI test replicates a small fire in the corner of a room, with the room corner being constructed from the product to be tested. A flame from a burner with a known output is applied to the product. The products of any resulting combustion are measured, and these allow calculation of the energy that the product has contributed to the fire. Classification will be assessed on the rate of energy production, the total energy produced over a certain period of time, lateral spread of flame and the observation of any flaming particles that may fall from the product.
12. What size specimen is tested in a SBI test?
Each specimen is constructed from a “short wing” and a “long wing”. The long wing is 1500mm high by 1000mm wide. The short wing is 1500mm high by 495mm wide. All tolerances are ± 5mm.

A minimum of 3 specimens are required. Further specimens may be required if a product produces a result on the border line between two classification and the higher classification is sought. Further specimens may also be required for testing of variations in the product, or for specimen analysis when writing the test reports.
13. What variations in a product can influence its reaction to fire performance?
The following product variations and end use applications can all affect the performance of a product, and can be assessed using the SBI test:

Product variable:
  • Thickness
  • Colour
  • Density
End use application:
  • Mounting and fixing
  • Substrates used
  • Air gap
  • Exposed edges
  • Joints
14. What information is required to produce a full quotation for
reaction to fire testing?
A detailed discussion with the client is required before producing a full quotation for reaction to fire testing. There are possible variations in the approach to testing, and a full knowledge of the product is required in order to give advice on the best course of action for the client.

Questions may be asked about the product, its variations and its end use.

Questions about the product variables:
  • Material
  • Thickness
  • Colour
  • Density
Questions about the products end use application:
  • Mounting and fixing
  • Substrates used
  • Air gap
  • Exposed edges
  • Joints
15. What are the advantages of an indicative test?
Full testing to achieve a classification involves testing to one or more standards, conditioning of the specimen prior to testing and testing of multiple specimens. An indicative test involves a single test only, and can give an indication of the performance of a product at a lower cost and in a shorter timescale than full testing. This is useful where a product is still at the development stage.
16. Do any materials get a classification without testing?
Yes, some materials for which there is a lot of historic data, such as wood and metal can in some cases be classified without testing. The Building Regulations provide details for “typical performance ratings of some generic materials and products”.  European Commission decisions can also be used in some instances, see FAQ 19 for details on this.
17. What is a classification document?
A classification document is produced using the product's test reports. It is the classification, and not the test reports that demonstrate the classification of the product. It is the classification document that a manufacturer will show to customers and enforcers to demonstrate compliance with the regulations. If you want to check the product you are purchasing meets your requirements for reaction to fire, you must see a classification document to EN 13501-1.
18. How do I know if a classification document covers a certain product?
A classification document must contain the product name and product description including:
  • thickness
  • colour
  • mass per unit area or density of the product
  • application rate and application method for an applied chemical product
  • mounting and fixing
  • air gap
  • substrate
  • edge testing
  • joint testing
Some product description information may be contained in the test reports, and not the classification document. If this is the case you must ask to see all the relevant documentation to be sure that the classification document relates to the product you wish to purchase.
19. Does the wood product I want to install have a European Class D without further testing?
Wood and wood-based products achieve a classification without the need for further testing providing they meet certain criteria. These criteria are listed in the relevant European Commission Decision.

Copies of these Commission Decisions are available for free via the internet. To use a Commission Decision to find the performance of your product you will need to know the density, thickness and end use condition for your product. You may also need to know mounting or profile details, and be able to check if your product conforms to the relevant product standard. You should check your product against these criteria as listed in the table in each Commission Decision. This table will also tell you the relevant reaction to fire classification.

If your product does not meet the conditions listed in the table, you will need to determine the product’s reaction to fire performance through testing.
Commission Decision title Commission Decision number Link to the EUR-Lex website providing free access to European law
Solid wood panelling and cladding 2006/213/EC http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:079:0027:0031:EN:PDF
Wood-based panels 2007/348/EC http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:131:0021:0023:EN:PDF

Link to the EUR-Lex website page where you can search for commission decisions: http://eur-lex.europa.eu/en/index.htm.
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