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Fire classification verifies the fire safety of buildings - standard EN 13501-1


Why is fire classification necessary?

Unified European fire classifications are necessary primarily to verify the fire safety of buildings. Unified classification also facilitates the free movement of construction products in Europe since testing according to country-specific requirements is no longer required.

While harmonised fire classification systems of reaction to fire of building products are in place in Europe, the member countries decide which fire classes apply in their national building regulations.

Structural fire safety in buildings is regulated by E1 The National Building Code of Finland.

The classification of construction products using test data from reaction to fires (classification standard EN 13501-1) is one of such classification systems. Others include fire classification of building elements (classification standards EN 13501-2, 3 and 4) and the classification using data from external fire exposure to roofs tests (classification standard EN 13501-5).

Basic information on construction product fire classification

A class specified according to the classification standard EN 13501-1 indicates the reaction of the construction product to a fire in a room. Fire classes include A1, A2, B, C, D, E and F.

Class A1 product

No contribution to fire at any stage (non-combustible). Products such as mineral wool and fibre-reinforced concrete contain very little organic (combustible) compounds and can be classified as class A1 products. If they contain only a maximum of 1.0 per cent of organic compounds, they do not require testing to be classified as such.

Class A2 product

Does not contribute to the fire load, no flash-over takes place during fully developed fire in a room (very limited contribution to fire). Products such as coated mineral wool, sheets of fibre-reinforced concrete and painted sheets of metal can be classified as class A2 products.

Class B product

Slow and limited release of heat when the product reacts to a burning item in a room (e.g. burning furniture, curtain or waste paper basket). Some fire retardant wood products are classified as class B products.

Class C product

Reacts as a class B product, but can release more heat faster. For example, wooden floor surfaces without fire protection (Cfl) attached to a class A2 product.

Class D product

Reacts as a class C product, but can release more heat faster. Examples include chipboard and plywood without fire protection depending on product thickness and application.

Class E product

Can sustain a small flame attack without essentially spreading the fire. Examples include chipboard and plywood without fire protection.

Class F product

Does not meet any of the above requirements or has no classification.

Additional classification is given for smoke production and the occurrence of flaming droplets

Classes s1, s2 and s3 indicate the smoke production level and classes d0, d1 and d2 the occurrence of flaming droplets in burning construction products. In case of a fire, flaming droplets or particles can spread the fire from the initial point of ignition.

Practical description of the smoke development classification:

  • class s3: no requirement for restricted production of combustible gases
  • class s2: the product may emit a limited amount of combustion gases
  • class s1: stricter restrictions than for class s2


Practical description of the occurrence of flaming droplets classification:

  • class d2: no requirement for restricted production of flaming droplets
  • class d1: restricted burning time of flaming droplets
  • class d0: no flaming droplets


Professional, standard-compliant testing services

The classification standard EN 13501-1 lists all the testing standards and class requirements.

We use standard-compliant testing equipment to specify the fire class of construction products. We can also help with the test planning of fire classification.

Read more about our type approval services for construction products and materials.

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Contact us

Tel. +358 20 722 7070
Fax +358 20 722 7001
Opening hours 9:00 - 11:00 and
12:00 - 15:00,
GMT +2 time zone