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International classifications for fire resistance

Below we try to explain different international classifications for fire resistance.
This summary of fire classification is based on trying to give a picture of all the different national standards that exist. Only an interpretation of different standards. We take no responsibility for the accuracy of the data in the text and tables below. They are based on collected information and experience and should be used only for comparison and understanding. Fire classification of materials is based on the construction and textile industry, where there has been a desire to be able to choose as fireproof materials as possible for buildings and interior design.


Structure, test and classification criteria

As a rule, the countries' national standards are built on two foundations. One standard describes how the test is done and another describes the rules for how the classification is done.

In the description of the test, you specify how large the test strip should be, how the flame you are firing with should be, the angle of the flame towards the material, and so on. On the one hand, criteria are described for how long the material may burn after the flame is removed, how long the annealing time may be, etc. The criteria are then grouped so that a certain burning time gives a certain class, eg that a product is determined to be classified as "Flammable".


National standards only

The standard that in Sweden describes how the test is to be performed is called SS 65 00 82. It is originally based on the now replaced British test standard BS3119: 1959. These roughly correspond to the American NFPA 701 and the German DIN 4102.


All of these are based on a test with a gas burner where the damage is measured on a vertically hanging test strip that is allowed to burn for a certain time, after which the flame spread is measured. For all, the criteria are also based on how long the burning time is after the flame has been removed. The idea behind the test is that they should mimic the case if a candle is tilted against a curtain. In Sweden, the requirements are set by the National Board of Housing, Building and Planning.


Internationalization is under development but only concerns solid building materials for walls, ceilings and floors.


The national standards

The table below shows the test method and classification criteria for the countries we usually trade from. The table could not be made complete so that a total comparison can be made. For the criteria, however, it can be said that each row corresponds approximately to the same level of flame safety and is for information only. The comparison can not be made exactly as the standard and test methods is very different between the standards.

The German box B1 applies in our industry as the acceptable level of low flammability. Materials that without specified details are said to be "fire rated" usually have the same or better class than German B1. "Fire retardant" is usually class B2 according to German standards.






Euro class




SS-ISO 1182

DIN 4102

BS 476 pts 6 & 7

NFP 92501 

EN 13501-1

NFPA 701, NP92-503

CSE RF 1/75/A



A1-A2 (Fireproof materials)

Class 0

M0 (non-combustible)

A1-A2 (Non combustible)


Klass 0



B1 (Not easily flammable)

Class 0 and 1

M1 (Non flammable)

B (Hard to burn)

C (normally burning)


Klass 1


Svårantändligt enligt Boverket

B2 (flammable)

Class 1 and 2

M2 (Low flammability)

D (normally burning)


Klass 2


Lättantändligt enligt Boverket

B3 (Easily flammable)

Class 2 and 3

M3 (Moderately flammable)

E-F (Easilly burning)


Klass 3





M4 (flammable)



Klass 4-5


For DIN 4102 B1 and M1 certificates, new certification process needs to be performed every other 5 years


The newer EN-13501 certificates (EN = Euro-Norm) however are in general much more expensive to obtain compared to the ‘old’ (DIN 4102) FR certificates. But the big advantage is, that the Euro-Norm certificates don’t lose the validity, unless the producer change anything to the product or the formulation or as long as the EU-norm doesn’t change. 

EN-13501 is also more comprehensive containing information about burning behavior, smoke emissions and droplets.


An EN certificate according to 13501-1 has no "expiry date”.


This is defined in the relevant regulation according to European law. FR certificates according to EN 13501-1 are therefore initially valid indefinitely. Therefore there is no indication of a fixed period of validity (only a date on which the product was first tested), the information about the validity without a given end date is even written on each certificate. The exact text depends on the laboratory, for example:

When the criteria of EN 13501-1 are not changed (by European Union) and when the technical composition / the production process are not changed, the certificate is still valid.

The EN-standard is based on a test for the actual materials response to fire, smoke development and droplets while burning.
The EN‐classification have the three following standard groups:

Fire behavior:

Class A1             (highest level)
Class A2             (not burnable materials)

Class B               (inflammable materials)

Class C               (normal flammable materials)

Class D               (normal flammable materials)

Class E                (normal flammable materials)

Class F                (not classified materials)


Smoke development:

Class S1             (Very limited smoke development)

Class S2             (Limited smoke development)

Class S3             (no demands on smoke development)


Burning droplets:

Class d0             (No burning droplets or particles)

Class d1             (limited burning droplets)

Class d2             (no demands on burning droplets)



The National Board of Housing, Building and Planning in Sweden
DIN - German standardization authority

CEN - The European Committee for Standardization
ISO - International standardization body
SIS - Standardization in Sweden
Arkitektkopia / Örjan Westerlund