Fire classification

Fire safety requirements in the national building regulations are often based on fire development (standard fire curve). The requirements for the materials used and the structures are determined by the building use, size, fire load and operation.

Fire classification

a) Fire classification of materials: Reaction to fire (fire growth)

If a fire should occur, it is important that the building can be evacuated as quickly as possible in order to save lives. The time available for evacuation depends on the building materials and their fire properties.

The fire safety in construction products is determined through Euroclasses. The Euroclasses were introduced following a resolution by the Commission (2000/147/EEC) from February 8, 2000 to create a common platform for the comparison of the fire properties of construction materials.
Fire testing of the products is conducted in accordance with harmonised testing methods. 

Fire resistance tests for Euroclasses:

  • Fire resistance tests for building products – Non-combustibility, EN ISO 1182. 
  • Fire resistance tests for building products – Determination of calorific potential, EN ISO 1716. 
  • Fire resistance tests for building products – Building products, except for flooring materials exposed to thermal heat from a gas burner (SBI), SS-EN 13823. 
  • Fire resistance tests for building products – Ignitability of products subjected to direct impingement of flame – Part 2: Single-flame source test, EN ISO 11925-2. 
  • Fire resistance tests of floorings – Part 1: Determination of the burning behaviour using a radiant heat source, EN ISO 9239-1

Read more >>
VTT: EUROCLASS System

Note: The purpose of the SBI test method (Single Burning Item test) is to use a larger sample model compared to the standard test methods in order for the test results to better correspond to a full-scale reference fire development phase. Experience shows that the SBI method works less well for products that consist of multiple layers, such as lightweight sandwich panels of polystyrene with a surface layer of metal. The results from the SBI method tend to depend on the location of the test object, and a standard with detailed instructions for mounting and fixing for reaction to fire testing of the test object (EN 15715) has therefore been developed.

 

The main properties to determine the Euroclass for a specific product is its non-combustibility, ignitability, flame spread, calorific value as well as the development of smoke and burning droplets. Depending on the outcome of the various properties, the product is assigned a fire classification as shown below.  

 

Fire classification

 

Euro class Example 
A1, A2  Stone wool, gypsum board
B Painted gypsum board
C Gypsum board with paper-based wallpaper
D Wood
E Fire-retardant EPS
F Non-tested materials, EPS


Additional classes for smoke development  Additional classes for burning droplets
 s1 the structural element may emit a very limited amount of combustion gases  d0 burning droplets or particles must not be emitted from the structural element
 s2 the structural element may emit a limited amount of combustion gases  d1 burning droplets or particles may be released in limited quantities
 s3 no requirement for restricted production of combustion gases  d2 no requirement for restriction of burning droplets and particles

  • Class A1 is non-combustible and the requirement level and cannot be combined with any additional class. 
  • Class A2 is also classified as non-combustible as no flashover occurs for the application of the products in these classes. 
  • For classes A2 to D there are additional classes for smoke development s1, s2 or s3, and the amount of burning droplets emitted d0, d1 or d3 (e.g. A2-s1, d0). 
  • Class E only has additional class d2. 
  • Class F means that the product is not documented, the product does not meet the criteria for any class, or the manufacturer has not provided the fire properties for the product. Class F cannot be combined with any additional class either. 
  • When establishing the Euroclass for pipe insulation, the sub-index “L” is used (e.g., A2L – s1, d0).

The building regulations of the Swedish National Board of Housing, Building and Planning (BBR) [Boverket] require that building materials and structural elements are designed to ensure persons who occupy a building must be able to move to a position of safety so that the emergency services are able to carry out rescue and fire-fighting activities. The inner and outer surfaces must be designed in such a way that they do not contribute to the development of fire and smoke.

 

Continuous glowing combustion and smouldering

Continuous glowing combustion and smouldering fire are not yet included in the European classification system, although some member states already have requirements for them.

Continuous glowing combustion is a property which means a product can continue to glow after the fire exposure factor has been removed. A European harmonised test method for continuous glowing combustion is under development. This property not only affects the thermal insulation but essentially all building products.

Glowing combustion means fire development of a product that has resulted from prolonged, low-intensity heat exposure. By way of example, glowing combustion can occur in thermal insulation in a ceiling above a recessed lighting fixture. As yet there is no harmonised European testing method for smouldering fire.

 

Toxic gases

As previously stated, the toxic gases produced by a fire are lethal at an early stage of the fire development phase and therefore call for special attention. There is currently no harmonised European methodology for testing and evaluating the toxicity of building products in a fire. However, work is in progress in this area.

  • PAROC stone wool belongs to the highest requirement level in the European classification system for materials, Euroclass A1. 
  • PAROC stone wool is made of natural stone and only a small amount of organic binder agent is added in the manufacturing process. 
  • PAROC stone wool is a non-combustible material.

 

b) Fire classification of structures: Fire resistance (fire compartmentation)

While the products are classified according to how they react to fire, roofs, walls, floors, ceilings and even construction systems, including ventilation ducts and pipes are classified based on their fire resistance. The fire classification system has been formulated based on functional requirements. Fire properties are tested in a full-scale furnace using a standard fire curve for temperature/chronological development. Here the following properties are tested and classified.

  • I = Insulation. The time it takes to produce an increase in temperature on the cold side of the structural element, usually 140 ⁰C.
  • E = Integrity. The length of time that the structural element retains its integrity against flames or hot gases in a standard fire.
  • R = Load carrying capacity. The length of time that the relevant structural element is able to carry the current load in a normal fire development phase.
  • M = Mechanical effect. The ability of the structural element to cope with the mechanical impact in a standard fire.

The test results are obtained in the form of a time stamp which shows how many minutes the structural element resists the fire before the threshold for each criterion is exceeded. If the product meets the requirements for class REI 60, the result means that the structural element can resist fire for one hour with respect to load bearing capacity, integrity and insulation. Insulation capacity is determined by the temperature on the opposite side if the temperature of the fire is not allowed to rise more than 140 degrees. In certain cases, additional criteria can be included in the classification. M stands for resistance to shock loads and is usually required for firewalls.

Fire requirements for a building are set in the building regulations of the Swedish National Board of Housing, Building and Planning [Boverket].  

  • PAROC stone wool is an excellent choice for fireproof structures due to its high melting point. 
  • PAROC stone wool retains its properties even at 1,000 ⁰C 
  • PAROC sandwich panels are an excellent choice for interior walls. Depending on the thickness and type you choose, the products are classified from EI 15 up to EI 240. We can also provide double-wall structures that can be used as firewalls with classifications EI-M 60, 90 and 120.

 

c) Fire classification of construction systems

one fire cell, ventilation ducts and pipes must meet the set fire requirements. Penetrations in interior walls to another fire cell must be designed to ensure that flame propagation is prevented.

HVAC products are covered by a harmonised standard, EN 14303, which means that all technical insulation must be CE marked.

There are also harmonised testing standards for fire testing of building installations, such as ventilation ducts, piping and cable trays. There are a number of EN testing standards but no harmonised product standards for all systems. Please consult our country-specific pages for information about local regulations and requirements.

  • Stone wool insulation is an excellent solution for fire insulation of ducts, pipes and other installations. 

 

d) Fire classification of buildings

At the beginning of a construction project, during the planning phase, the designer must determine the operational and building technical class that the building must comply with. In many cases there is no alternative, but sometimes you can choose from multiple classes.

Read more at Boverket's website >>