The Fire Resistance classification is based on the time during which construction elements accomplish their function in case of an unstoppable, fully developed fire.
The functions are separation (separating a fire from other rooms), load bearing, and separation and load bearing. They are expressed as R (load bearing capacity), E (Integrity, i.e. flames don’t come through it) and I (Insulation).
Load bearing elements are characterized by the classification REI (T). Non-load bearing elements are characterized by EI (T). (T) stands for the time the element meets the requirements for R, E and I: 30, 60, 90, and 120 minutes up to 6 hours.
The European Standard 13501-Part 2 defines which test has to be carried out to get a Fire Resistance classification for construction elements:
- EN 1364 for non-load bearing elements
- EN 1365 for load bearing elements
- EN 1366 for service installations
- EN 1634 for fire doors and shutters
- EN 81-58 for lift landing doors
- ENV 13381 for contribution to fire resistance
A FR coating will be evaluated according to ENV 13381-part 4:2002. Testing according to EN 13381 can be carried out on short beams. To get the full ENV13381 certificate, 10 short (1 meter) beams of different thicknesses and profiles have to be tested, with loaded and non-loaded references.
The different steel thicknesses and profiles allow calculation of the massivity. Also, different coating thicknesses can be inputted. All data are then plotted into a graph as shown in Figure 2. This graph shows which coating thickness is required for a specific steel massivity to reach a certain fire resistance. The comparative results are especially valuable for construction engineers.
Very important to know is that a material which performs excellent in the Reaction-to-Fire tests does not necessarily perform well in the Fire Resistance tests. A typical example is steel. It performs brilliantly in the Reaction-to-Fire (Class A1) tests, but fails miserably in the Fire Resistance tests—if it’s not protected.
