difference between reaction and resistance to fire

The Difference Between Reaction And Resistance to Fire: “Euroclass” And “REI / EI”


For safety reasons, it is crucial to understand the difference between reaction and resistance to fire. Therefore, we will stress the importance of prevention and protection of fire systems.


Systems of protection have the purpose of preventing fires. There are Active or Passive systems.

Active systems are associated with containment and extinguishment, and require human or automatic activation; these are the active protection systems. For example, fire extinguishers, smoke detectors, an alert system for occupants and fire department, etc.

Passive protection systems are all building construction and design measures that take into consideration the type of material to obstruct and therefore limit the amount of damage of an eventual fire. Examples of passive protection are:

  • Compartments analysis
  • Security distances
  • Fire-rated walls, doors, and smoke barriers
  • Safe escape routes
  • Structures resistance to fire
  • Reaction to fire of building material.

Individual European State Members establish technical norms and state laws that dramatically regulate and determine the levels of performance and security of building construction products. Moreover, they recognize the subject of fire protection in buildings requirement among the seven essential European regulations for building construction products. As for the external “wrapping” components of a building, the RESISTANCE TO FIRE of the structure and the individual material’s REACTION TO FIRE behavior is evaluated.



The resistance to fire is the ability of a structure or an individual compartment (external wall, beams, doors, and fire barriers, etc..) to resist a determined amount of time to its’: stability, integrity, and isolation capability. Expression in minutes (15, 20, 30, 40, 60, 90, 120, 180, 240, and 360) about the nominal fire curve.

The REI marking identifies the fire-resistance rating of a structure. The REI marking consists of the following elements:

  • R = Load-bearing. The ability of a construction element to preserve its’ mechanical characteristics and the relevant load capacity during a normal fire.
  • E = Integrity. In other words, the structure’s ability to NOT allow the passage or production of gas or vapor to the area NOT exposed to the fire.
  • I = Thermal Insulation. To clarify, the ability of a structure to reduce within a temperature limit the transfer of heat to the unexposed (cold) side. The temperature limit is usually 140°C.



  • REI (followed by the number n, which indicates the classification). The constructive element must preserve for a determined amount of time n its mechanical resistance, the integrity of flames and gases, and the thermal insulation.
  • RE (followed by the number n, which indicates the classification). The constructive element must preserve for a determined amount of time n its’ mechanical resistance, the integrity of flames, and gases.
  • R (followed by the number n, which indicates the classification). The constructive element must preserve for a determined amount of time n its’ mechanical resistance.

For the classification of the elements not meeting the criteria R, it is automatically sufficient as long as E and I are met. For each element that meets the criteria, tests are made, and results are obtained. Classification is then assigned by verifying the time value obtained for mechanical fire resistance with the nominal fire curve reference.

In addition, test results, analytical calculations, or verification tables determine the performance rating of fire resistance.

Fire reaction of material


The reaction to the fire test must show the insulation material’s behavior when exposed to a direct flame of ignition. After that, the norm subdivides insulation materials into reference classes based on the method of test. Since the level of contribution of the material in a fire is strongly dependent on the type and conditions of the test, it is necessary to distinguish between insulation material with a CE marking by the European series norms EN13xxx and 14xxx, and those without a CE marking.


For material with a CE marking, the EUROCLASS (EN 13501-01) system defines the fire reaction rating. Commonly, it combines various harmonized tests (EN11925-2 and EN 13823). The system divides insulation products into seven classes (A1, A2, B-F):

  • Firstly, tests assign class F to products without a determined reaction to fire rating. Products that have a good reaction to fire rating, paired (jointed), or coated (with a facer) with combustible material, may also belong to this class.
  • Secondly, tests assign classes E-B to products of organic or inorganic nature with high contents of organic. It is necessary to make a small flame test to obtain a Class E. The harmonized European norm EN 13823 (SBI) defines an additional test to obtain the Class D-B, as well as it is also necessary to make a small flame test lasting 30 seconds.
  • Finally, tests assign class A (A1-A2) to products of inorganic nature. In this case, the SBI test is combined with the measurement of the power (heat) meter (EN 1716) and the analysis of incombustibility (EN 1182).

For the Classes A2-D, the test evaluates the quantity of smoke produced. While for Classes A2-E, the test evaluates the droplets (dripping) and burning particles. The harmonized norms of the series EN 13xxx and 14xxx take into consideration the reaction to fire of buildings containing thermal insulation in real life or end-use conditions.
In the case of applications where the structure is externally insulated, as in the external thermal insulation system, it considers, for example, the entire test to one sample wall.


To sum up the article we have prepared a detailed video where we explain the difference between reaction and resistance to fire.


To learn more about the difference between reaction and resistance to fire you can get in touch at +44 7887 884768. You can also contact us via sales@globepanels.com or by completing the contact form below. Once you reach out to us we can provide you with a free quote and can also discuss our products and services further.


Alberto Adriano

✓ Entrepreneur in the field of International Commerce of Industrial Thermal Insulation ✓ Sales Director at Globe Panels Ltd ✓ 12 years of experience in Sandwich Panels ✓ Exporting to Latin America since 2009.

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