Resistance
to Fire
The old Italian Circular MI.SA. no. 91 of 14/09/61 has already been replaced by DM 16/02/2007 “Classification of Resistance to Fire of building products and elements for building works” and by DM 09/03/2007 “Performances of Resistance to Fire of constructions in activities, which are under the control of the National Corps of Firefighters”. The reference standard is EN 13501-2 “Fire classification of building products and elements – Part 2: Classification using data from fire resistance tests, excluding ventilation services”. This standard analyses all the structural elements, load-bearing and non-load-bearing, such as walls, beams, slabs, pillars, false ceilings, coatings, plasters, overhead floors, fire doors, exterior facades, etc. The standard of Eurocodes is EN 199x-1-7 “How to plan structures made of steel, concrete, wood, brickwork and aluminium according to proof procedures, specified in standards EN 13381-1-7”. DM 16/02/2007 provides the following classes of Resistance to Fire: 15, 20, 30, 45, 60, 90, 120, 180, 240, 360 (expressed in minutes). They represent the time, under which the structural element can maintain and ensure its function under the heating action, in a specific area of use.
Meaning
of REI acronym
R = Stability
Aptitude of a building element to preserve its mechanical resistance under the fire action
E = Resistance
Aptitude of a building element neither to let pass nor to produce flames, hot steams or gases on the unexposed side
I = Insulation
Aptitude of a building element to contain, within a certain limit, the heat transfer from the opposite side to the exposed one
Load-bearing brickworks and beams (structures planned to support an applied load): requisite REI.
Non-load-bearing brickworks or fire doors (elements and structures, not subject to any load, except for their own weight): requisite EI.
The substrates can be numerous, from steel to wood, obviously the wood is the best material in the structural field. In addition to an incomparable aesthetic result, it is extremely flexible, light and is a bad heat conductor.
Even if flammable, the wood organic composition remains the best guarantee during a fire. As a matter of fact, the superficial carbonization is a barrier against flames and high temperatures.
