It sets the procedure for classifying the fire resistance of construction products and building elements from fire-resistance test data. It uses the performance criteria R (loadbearing capacity), E (integrity) and I (thermal insulation) and their combinations (R, RE, REI, EI), with performance expressed as a time in minutes. It is the counterpart, on the resistance side, of UNI EN 13501-1, which classifies products' reaction to fire. The current European edition is EN 13501-2:2023, which superseded EN 13501-2:2016.
Applies to construction products and building elements with a load-bearing and/or separating function (for example walls, floors, beams, columns, doors and closing elements) whose fire-resistance performance must be classified on the basis of test data. Ventilation services are excluded and are covered by other parts of the same series. It provides the classification language referenced by national fire-safety rules (for example the Italian Fire Prevention Code) to set compartmentation and structural-integrity requirements.
The standard turns the results of fire-resistance tests into a compact symbol. Each performance to be certified corresponds to a letter - R for load-bearing capacity, E for integrity against flames and hot gases, I for thermal insulation - and the letters combine (R, RE, REI, EI and others) according to the functions the element must guarantee. The symbol is followed by a number stating for how many minutes that performance is maintained. We describe this logic here - without reproducing the time tables or the test criteria, which remain protected content of the standard.
If reaction to fire describes how much a material feeds a fire, fire resistance answers a different question: for how long a building element keeps performing its function while the fire is under way. UNI EN 13501-2 brings order to that answer, turning test data into a readable, comparable classification.
At the core of the standard are three criteria, each with its own letter. They are certified singly or together, depending on what the element must guarantee.
| Symbol | What it guarantees | Logic |
|---|---|---|
| R | Load-bearing capacity | the element keeps carrying its loads without collapsing |
| E | Integrity | prevents the passage of flames and hot gases to the unexposed side |
| I | Insulation | limits the temperature rise on the unexposed face |
The letters are placed together according to the element's function: a beam or column, which only has to bear loads, is classified with R alone; a wall that separates two compartments without a structural role may be EI; a load-bearing, separating wall is REI. A number always follows the letters: it states the minutes for which those performances are guaranteed, chosen from a set of standardised values (for example 30, 60, 90, 120 minutes).
For particular elements and performances the standard provides further symbols that accompany the class - among others W (radiation), M (resistance to mechanical action), C (self-closing device) and S (smoke leakage). They remain a complement: the backbone of the language is the R, E, I criteria and the time in minutes.
Reaction to fire (UNI EN 13501-1) measures how much a material contributes to a fire and is a property of the product. Fire resistance (this standard) measures for how long an element keeps its function - load-bearing, integrity, insulation - during a fire, and is expressed with the R, E, I criteria.
It indicates an element that for 120 minutes keeps load-bearing capacity (R), integrity against flames and hot gases (E) and thermal insulation (I) together. Changing the letters changes the set of guaranteed performances: for example EI without R, or R alone for purely load-bearing elements.
Not this standard: the required class is set by fire-safety rules (for example the Italian Fire Prevention Code) according to the fire load, the compartmentation and the use of the building. UNI EN 13501-2 only provides the classification language; it does not impose the values.
Because not every element has to provide thermal insulation. A structure that only has to bear loads is classified R; an element that only has to stop the passage of flames and smoke without limiting the temperature on the unexposed side is E or RE. Only the performances relevant to the element's function are declared.