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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. 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 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.









SS-ISO 1182

DIN 4102



NFPA 701, NP92-503

CSE RF 1/75/A



A1-A2 (obrännbar)


M0 (obrännbar)


Klass 0



B1 (svårantändlig)


M1 (oantändligt)


Klass 1


Svårantändligt enligt Boverket

B2 (normalantändlighet; något tuffare än kraven för svenska ”svårantändligt”)

BS5867-2:1980 typ C

M2 (lågantändlig)


Klass 2


Lättantändligt enligt Boverket

B3 (lättantändlig)


M3 (måttligt antändlig)


Klass 3





M4 (högantändlig)


Klass 4-5


The National Board of Housing, Building and Planning in Sweden
DIN - German standardization authority
ISO - International standardization body
SIS - Standardization in Sweden
Arkitektkopia / Örjan Westerlund