Non ignitable board Kronopol OSB SF-B

The fire is a thermal decomposition of flammable materials in uncontrolled time. As opposed to the combustion processes in a furnace or fireplace, the fire is an unrestrained phenomenon. An uncontrolled fire starts when its source, i.e. a cigarette end or electric arc delivers the energy sufficient for inflammation of other flammable material.

Three factors shall occur to cause fire:

  • ammable material,
  • oxygen,
  • source of heat.

In case one of the aforementioned factors is absent, the risk of fire drops. Two of the factors, i.e. oxygen and source of heat are beyond any control. Thus, only one of the factors, i.e. the flammable material, may be controlled. That is why the selection of the appropriate building materials is so important while designing public utility facilities.

How can we then assess the probable reaction of building materials to fire? Doe they combust easily? Do they facilitate spreading of fire? Do they produce significant amounts of smoke while burning? It is enough to check the Euro Class, i.e. the fire classification of the material within the scope of its reaction to fire. The classification is identical in the entire European Union, and it includes all the important information about the reaction of materials to fire.

It classifies each building material to one of the seven basic fire Euro Classes:

Euro Class


Description of performance in case of fire



Absolutely non-flammable products of the highest class; no contribution to fire; no flame attack



Non-flammable products of the highest class; no contribution to fire; no flame attack



Very limited contribution to fire; no flame attack



Limited but noticeable contribution to fire



Significant contribution to fire



Crucial contribution to fire – fire hazard



Products not tested or negative results of all the fire tests

Euro Class

Smoke production (rate and volume)


Practically no smoke


Average amount and density of smoke


High volume of dense smoke

Euro Class

Intensity of production of flaming droplets / particles


No flaming droplets


Few flaming droplets (similar to sparks from burning wood)


High number of flaming droplets and particles

Such a ranking arrangement is remarkably clear and understandable. The best, the safest products are classified in Classes A1, A2 and B. The further classes include gradually products with worse and worse fire characteristics (more and more flammable). Class F includes the products with no requirements set.

In order to meet the highest European requirements, the technologists of SWISS KRONO have designed and implemented into production non-ignitable OSB SF-B boards which have been classified as - B, s2, d0.

For the purpose of specification of the resistance of the non-ignitable OSB boards manufactured by Swiss Krono Group to fire, fire tests have been performed with the use of the non-ignitable OSB boards. For the test purposes, an office room was arranged where a sample fire was started. A timer was activated at the moment when the fire was started. After twenty minutes, when the burner which was feeding the fire, the flame went out immediately and only the external layer of the OSB SF-B was charred which provided a safe layer to protect against fire. The fire did not spread. No other objects in the room were damaged by fire.

The chemicals used during the production cycle provide technological water in the course of chemical reactions. The water absorbs the energy produced in the burning process and it prevents the pyrolysis reaction. Furthermore, a graphite layer is formed to prevent the access of oxygen to the burning material, which decreases subsequently the combustibility of the board and inhibits the process of fire spreading.

Every minute matters in case of fire. The more slowly the fire spreads, the better chances the fire brigades will have to evacuate people from the hazardous place. 

The boards have been manufactured to be applied in such public utility facilities as schools, kindergartens, sports halls or hospitals.