Fire resistance is one of the fundamental parameters to ensure the safety of buildings , limiting damage during a fire and protecting people. In Italy, fire regulations have undergone a profound evolution, with a growing focus on innovative approaches that balance safety, sustainability and costs. The definition of the fire resistance of structures is regulated by a series of regulations and decrees that establish the technical and procedural requirements to ensure the fire safety of buildings .
The fire performance classification system of construction products includes different general EUROCLASSES with regard to reaction to fire and fire resistance , based on the functional considerations mentioned below.
Fire safety: construction products and reference standards
Construction product regulations in the European Union have followed an evolutionary path to ensure safety, sustainability and innovation in the sector.
It all started with the EEC Directive 89/106 , known as the "Construction Products Directive" (CPD), which was the first step towards harmonising regulations in Europe. This directive placed emphasis on the essential requirements that construction products had to meet, including fire safety . The main objective was to ensure that construction works were safe and fit for their intended use, while promoting the free movement of such products on the European market.
In 2013, the Directive was replaced by Regulation CPR 305/2011 , which consolidated and expanded the principles of the previous Directive. The Regulation introduced more detailed rules for CE marking , simplifying regulatory compliance for manufacturers and improving transparency for users. This legislation ensured that construction products met uniform quality and safety standards across the European Union, thereby providing greater confidence in the sector.
Subsequently, in December 2024, Regulation (EU) 2024/3110 was published , which is intended to replace CPR 305/2011. This regulation represents a significant turning point, as it introduces several innovations aimed at making the sector more sustainable and technologically advanced. Among the most important innovations is the introduction of the digital passport for construction products , a tool designed to ensure traceability and access to key product information, integrating with BIM (Building Information Modeling) systems. Furthermore, the regulation places a strong emphasis on environmental sustainability , requiring manufacturers to declare the environmental performance of their products throughout their life cycle.
Another key innovation is the addition of new basic requirements for construction works, such as the impact of emissions on the external environment, along with the sustainable use of natural resources. The regulation also promotes the digitalisation of information flows through a harmonised data dictionary and introduces simplified procedures for SMEs, making the system more inclusive and accessible.
Finally, the regulation establishes compliance guidelines for 3D printed products , a rapidly growing sector, and regulates green public procurement (GPP), strengthening the link between construction and sustainability.
In short, the regulatory path has moved from an approach focused on safety to a broader and more modern vision, which includes sustainability, innovation and digitalization, to respond to the needs of a constantly evolving sector.
Reaction to fire
The reaction to fire of a material is the fire behavior of the material itself which, due to its decomposition, can feed or not the fire to which it is exposed, thus participating in the fire. It is a parameter specifically referred to materials as such, which assumes particular relevance in construction , for the characterization of finishing and covering materials, paneling, false ceilings, decorations and the like, and also extends to furnishing items, curtains and fabrics in general.
To determine the reaction to fire of a material , it is necessary to carry out experimental tests in the laboratory on specific samples. Based on the results of these tests, the materials are classified according to a scale from 0 to 5. Class 0 identifies non-combustible materials, while classes from 1 to 5 indicate an increasing participation in combustion, with higher values representing more flammable materials.
Fire resistance
Fire resistance is a parameter typically referred to structures and buildings and indicates the ability of a system composed of a material or multiple materials to resist sealing and insulation during a fire for a given time.
The acronyms that define the fire resistance characteristics are of the type “..,REI60, REI120,..” where the acronym REI indicates and certifies the possession of the following requirements:
R [Resistance] : maintenance of the mechanical resistance of the element following exposure to fire for a time defined by the acronym.
E [Emission] : ability to prevent the passage or production of fire or smoke on the side opposite to that in which the fire is developing;
I [Insulation] : thermal insulation designed to reduce the transmission of heat from one side of the element to the other side not exposed to the fire.
The number following the acronym REI indicates the time for which the above conditions must be maintained.
Fire resistance R of structures
On the basis of the information that is defined by the fire safety technician in charge of preparing the fire prevention project for the Fire Brigade, as well as defining the fire load, the R requirements to be guaranteed “…, R30, R60,...” are also defined for each compartment of interest and it is therefore necessary to carry out the fire resistance check of the structure.
To evaluate the fire resistance of structural elements, three technically different methods can be adopted, each characterized by specific peculiarities, advantages and disadvantages.
▪ Tabular method
This is the simplest and most immediate method , based on the use of standardized tables. The assessment is carried out by consulting the tables contained in the annex to the Ministerial Decree of 16/02/2007 , or, in the case where the Ministerial Decree of 03/08/2015 “Fire Prevention Code” is applied , those reported in paragraph S.2.15 . The strong point of this method is its ease of application, which makes it suitable for standard configurations. However, it is limited in applications to more complex contexts or those that do not fall within the limitations of applicability of the method.
▪ Experimental method
This approach is based on practical tests carried out in authorised laboratories , at the end of which a certification is issued which documents the fire resistance characteristics of the analysed sample. These certifications can take the form of a test report or a classification report , depending on the methodology adopted.
In the context of the Ministerial Decree 03/08/2015 , the reference criteria are found in paragraph S.2.13 . This method is distinguished by its reliability, but has high costs , both for the experimental tests and for any structural adjustments. Furthermore, the outcome of the verification depends entirely on the manufacturer or the certifier. This method is usually used by producers of standardized prefabricated elements for the certification of the products themselves.
▪ Analytical method
This is a more complex method than the previous ones, which requires the intervention of a professional registered in the list of the Ministry of the Interior . The assessment is conducted according to the indications provided by the Eurocodes and, in the case of the Ministerial Decree 03/08/2015 , according to the criteria indicated in paragraph S.2.14 , which are divided into simplified and advanced .
This approach allows to optimize the resistances, reducing the costs of structural adaptation, and is applicable to configurations of any complexity. However, to be applied correctly, it requires a thorough knowledge of the stresses characterizing the structure , as defined in the NTC 2018 (Technical Standards for Construction), and a detailed study of the entire structure.
In addition to the analytical method described above, there is also the more advanced and complex method that uses FSE (Fire Safety Engineering) , characterized by a high engineering and performance content. Also in this case, the assessment requires the intervention of a qualified professional, who must perform an analysis based on advanced CFD (Computational Fluid Dynamics) modeling. Unlike traditional methods, a natural fire curve is used , obtained through customized simulations, instead of the usual ISO 834 Curve (usually used in the standard analytical method).
The main advantage of this method lies in its ability to maximize fire resistance and, in some cases, completely eliminate the need for structural interventions . However, it is highly complex and requires a detailed study of the structure and its stresses, always in accordance with NTC 2018 .
In order to issue the CERT.REI certificates for the type of structural element, the experimental REI certificates provided by the manufacturer can therefore be used if the characteristics of the structure coincide with those certified, assessments with the tabular method which allows rapid checks thanks to the simplicity and availability of the data, finally if the two methods previously mentioned do not lead to positive results, we proceed with the analytical method which offers specific calculations to solve problems without expensive structural interventions.
However, in the case of complex cases, in order to issue CERT.REI certificates for the type of structural element, advanced FSE modelling may be necessary , which is most commonly used in the design phase of interventions on existing structures/new works.
The final choice must consider design needs, cost limits and maximum safety.
Fire resistance: FSE (Fire Safety Engineering) method
The fire resistance of structures as described above is relative and defined to ensure safety only for the time necessary for the evacuation of the occupants, accepting that they may collapse subsequently, provided that they do not endanger people and property.
In these circumstances, specifically required by current legislation, it becomes essential to verify implosive collapse , i.e. a controlled failure mode that minimizes risks to the surrounding environment.
A key element in fire safety design is to ensure that structures maintain an adequate level of safety during the evacuation of occupants and, where necessary, avoid sudden collapse. In this regard, the traditional and innovative approaches based on the FSE (Fire Safety Engineering) method offer different solutions to optimize building design, especially for structures characterized by great heights, such as automated vertical warehouses (MAV).
In the traditional approach, verification of overturning distances remains one of the cornerstones, requiring that the minimum distance from property boundaries be equal to the height of the building; however, this entails a significant land requirement, often incompatible with urban or economic constraints.
The FSE method , on the other hand, introduces an approach based on the verification of the collapse dynamics , favoring a design that allows a controlled implosive collapse in the event of a fire. This method drastically reduces the need for soil, making it an effective alternative to overcome the constraints of traditional regulations without compromising safety. Thanks to this methodology, it is possible to optimize the use of soil and still ensure compliance with fire regulations and urban planning regulations.
Methods for increasing the fire resistance of structural elements
Interventions to increase the fire resistance of structural elements are based on the application of specific materials and techniques that improve the insulating and protective properties of the structures. In general, these interventions may include the use of protective plasters, intumescent paints, fireproof false ceilings and specialized coatings. The solutions vary depending on the material of the structure: reinforced concrete, steel, wood, load-bearing masonry or aluminum, with targeted approaches for each of them.
The choice of the most suitable method depends on the characteristics of the element to be protected, the required resistance class and the conditions of use. Each intervention requires careful preparation of the surfaces, the use of certified materials and installation in compliance with technical regulations, to guarantee safety, durability and compliance with fire regulations.
AS Engineering: experts in fire resistance checks
AS Ingegneria 's commitment is distinguished by its ability to address the fire resistance of structures with precision and experience , applying tabular and analytical methods to ensure safety and regulatory compliance. Through targeted and personalized interventions, we support our customers in the protection of historic, residential, school and industrial buildings, while enhancing their unique characteristics.
Among the most significant projects, our intervention on the Ex Casinò Municipale di San Pellegrino Terme stands out , a symbol of Italian Liberty architecture. Following the detailed survey using laser scanner technology, integrated with an accurate historical documentary analysis, we were able to define the structural elements of the building and then verify its fire resistance, preserving the beauty and functionality of this architectural jewel.
In the educational sector, we worked on the school buildings of Agrate Brianza , a complex of over 21,000 m2, where we were responsible for identifying the structural typologies, characterising the materials through experimental tests and verifying the fire resistance of the representative structural elements.
In the field of fire resistance in industrial contexts, several notable buildings stand out, including:
Industrial building in via Fantoli, Milan , where we analyzed pillars, beams and bidirectional floors in reinforced concrete for a surface area of 10,000 m2.
SAES GATTERS industrial building, Lainate (MI) , characterised by a 3,150 m2 prefabricated structure, for which we verified the fire resistance of pillars, main beams and prefabricated tiles.
Industrial building Certosa 247, Milan , a complex building redevelopment project on 10,500 m2, including changes to intended uses, local reorganizations of the structural layout and the insertion of new stairwells. In this project we verified the fire resistance of all structural elements belonging to five different macro-substructures, each characterized by construction specificities.
In the tourism and recreational sector, we have dealt with the expansion and redevelopment of Bormio Terme , a project in view of the Milan-Cortina 2026 Olympics. The project involves the construction of a new underground “Adventure Pool” in reinforced concrete with a laminated wood roof and spans of up to 15 m, the strengthening of the Termarium and the Relax areas, and a new roof for the “Swimming Pool” made of laminated wood with variable intrados beams, capable of crossing spans of 22.50 m. For this project we carried out fire resistance checks on the existing structures of the Swimming Pool and the new structural elements.
These interventions represent only a part of the work carried out by AS Ingegneria , a team that combines advanced technical skills and deep attention to detail, ensuring tailor-made solutions for every need. Thanks to a methodical approach and the use of the most modern technologies, we work to preserve the safety and value of buildings , offering our customers a very high quality service.
