In accordance with SNiP 21-01-97 "Fire safety of buildings and structures" fire hazard building materials is characterized by the following indicators:

combustibility;

flammability;

flame spread over the surface;

smoke generating ability;

toxicity of combustion products.

By combustibility, building materials are divided into non-combustible (NG) and combustible (G). Combustible building materials are divided into four groups:

G1 - low combustible;

G2 - moderately combustible;

G3 - normally combustible;

G4 - highly flammable.

According to flammability, combustible building materials are divided into three groups:

81 - flame-retardant;

82 - moderately flammable;

83 - flammable.

According to the spread of flame over the surface, combustible building materials are divided into four groups:

RP1 - non-propagating flame;

RP2 - weakly propagating flame;

RP3 - moderately propagating flame;

RP4 - highly propagating flame.

Group building materials on the spread of flame is set only for the surface layers of the roof and floors (including for carpeting).

According to the smoke-generating ability, combustible building materials are divided into three groups:

D1 - with a low smoke-generating ability;

D2 - with moderate smoke-generating ability;

D3 - with a high smoke-generating ability;

According to the toxicity of combustion products, combustible building materials are divided into four groups:

T1 - low-risk;

T2 - moderately hazardous;

T3 - highly dangerous;

T4 - extremely dangerous.

Fire and explosion hazard conditions when using substances and materials

To ensure the fire and explosion safety of the processes of production, processing, storage and transportation of substances and materials, it is necessary to use data on the indicators of fire and explosion hazard of substances and materials with the safety factors given in Table. 3

Way to prevent fire, explosion	Regulated parameter	Fire and explosion safety conditions
Prevention of the formation of a combustible environment


Limitation of flammability and combustibility of substances and materials	Flammability of a substance (material)	Flammability of a substance (material) should not be more regulated
Prevention of education in
combustible environment (or introduction into
her) ignition sources

Reproducibility of the method for determining the fire hazard index at a confidence level of 95%;

Safe temperature, °С;

Permissible flash point, °С;

Flash point in a closed crucible, °С;

Upon receipt of substances and materials, application, storage, transportation, processing and disposal.

To establish requirements fire safety to the design of buildings, structures and systems fire protection classification of building materials according to fire hazard is used.

Indicators of fire and explosion hazard and fire hazard of substances and materials

The list of indicators required to assess the fire and explosion hazard and fire hazard of substances and materials, depending on their state of aggregation, is given in Table 1 of the Appendix to Federal Law FZ-123 (“Technical Regulations on Fire Safety”).

Methods for determining the indicators of fire and explosion hazard and fire hazard of substances and materials are established by regulatory documents on fire safety.

Indicators of fire and explosion hazard and fire hazard of substances and materials are used to establish requirements for the use of substances and materials and calculate fire risk.

The list of indicators necessary for assessing the fire hazard of substances and materials, depending on their state of aggregation

Fire hazard indicator	Substances and materials in various states of aggregation			Dust
Fire hazard indicator	gaseous	liquid	solid	Dust
Safe experimental maximum clearance, millimeter	+	+	-	+
The release of toxic combustion products from a unit mass of fuel, kilogram per kilogram	-	+	+	-
Flammability group	-	-	+	-
Flammability group	+	+	+	+
Flame Spread Group	-	-	+	-
Smoke generation coefficient, square meter per kilogram	-	+	+	-
Emissivity of the flame	+	+	+	+
Fire and explosion index, pascal per meter per second	-	-	-	+
Flame Spread Index	-	-	+	-
Oxygen index, volume percent	-	-	+	-
Concentration limits of flame propagation (ignition) in gases and vapors, volume percentages, dusts, kilogram per cubic meter	+	+	-	+
Concentration limit of diffusion combustion of gas mixtures in air, volume percent	+	+	-	-
Critical surface heat flux density, Watt per square meter	-	+	+	-
Linear speed of flame propagation, meters per second	-	-	+	-
The maximum speed of flame propagation along the surface of a combustible liquid, meters per second	-	+	-	-
Max explosion pressure, Pascal	+	+	-	+
Minimum phlegmatizing concentration of gaseous phlegmatizer, volume percent	+	+	-	+
Minimum ignition energy, Joule	+	+	-	+
Minimum explosive oxygen content, volume percent	+	+	-	+
Lower working calorific value, kilojoule per kilogram	+	+	+	-
Normal flame propagation speed, meters per second	+	+	-	-
The toxicity index of combustion products, grams per cubic meter	+	+	+	+
Oxygen consumption per unit mass of fuel, kilogram per kilogram	-	+	+	-
The limiting speed of the disruption of the diffusion torch, meters per second	+	+	-	-
Burst pressure rise rate, megapascal per second	+	+	-	+
The ability to burn when interacting with water, atmospheric oxygen and other substances	+	+	+	+
Ability to ignite under adiabatic compression	+	+	-	-
Ability to self-ignite	-	-	+	+
Ability to exothermic decomposition	+	+	+	+
ignition temperature, degree Celsius	-	+	+	+
flash point, degree Celsius	-	+	-	-
autoignition temperature, degree Celsius	+	+	+	+
smoldering temperature, degree Celsius	-	-	+	+
Temperature limits of flame propagation (ignition), degree Celsius	-	+	-	-
Specific mass burnout rate, kilogram per second per square meter	-	+	+	-
Specific heat of combustion, Joule per kilogram	+	+	+	+

Classification of substances and materials ( with the exception of building, textile and leather materials) for fire hazard

Classification of substances and materials according to fire hazard is based on their properties and ability to form fire or explosion hazards.

By combustibility, substances and materials are divided into the following groups:
1) non-combustible- substances and materials incapable of burning in air. Non-combustible substances can be fire and explosion hazardous (for example, oxidizing agents or substances that release combustible products when interacting with water, atmospheric oxygen, or with each other);
2) slow-burning- substances and materials capable of burning in air when exposed to an ignition source, but unable to burn independently after its removal;
3) combustible- substances and materials capable of spontaneous combustion, as well as ignite under the influence of an ignition source and burn independently after its removal.

Test methods for combustibility of substances and materials are established by fire safety regulations.

Classification of building, textile and leather materials according to fire hazard

The classification of building, textile and leather materials for fire hazard is based on their properties and ability to form fire hazards.

The fire hazard of building, textile and leather materials is characterized by the following properties:
1) flammability;
2) flammability;
3) ability to spread flame over a surface;
4) smoke generating capacity;
5) toxicity of combustion products.

Surface flame propagation speed

According to the speed of flame propagation over the surface, combustible building materials (including floor carpets), depending on the value of the critical surface heat flux density, are divided into the following groups:

1) non-propagating (RP1) having a value of critical surface heat flux density of more than 11 kilowatts per square meter;

2) weakly propagating (WP2) having a value of critical surface heat flux density of at least 8, but not more than 11 kilowatts per square meter;

3) moderately spreading (RP3) having a value of critical surface heat flux density of at least 5, but not more than 8 kilowatts per square meter;

4) highly spreading (RP4) having a critical surface heat flux density of less than 5 kilowatts per square meter ..

Smoke generating capacity

According to the smoke-generating ability, combustible building materials, depending on the value of the smoke generation coefficient, are divided into the following groups:

1) with low smoke generating capacity (D1) having a smoke generation coefficient of less than 50 square meters per kilogram;

2) with moderate smoke-generating ability (D2) having a smoke generation coefficient of at least 50, but not more than 500 square meters per kilogram;

3) with high smoke generating capacity (D3) having a smoke generation coefficient of more than 500 square meters per kilogram ..

Toxicity

According to the toxicity of combustion products, combustible building materials are divided into the following groups in accordance with table 2 Annexes to Federal Law No. 123-FZ:

1) low-hazard (T1);
2) moderately hazardous (T2);
3) highly dangerous (T3);
4) extremely dangerous (T4).

Classification of combustible building materials according to the value of the toxicity index of combustion products

Hazard Class	Toxicity index of combustion products depending on exposure time
Hazard Class	5 minutes	15 minutes	30 minutes	60 minutes
Low-dangerous	over 210	over 150	over 120	over 90
Moderately hazardous	more than 70 but not more than 210	more than 50 but not more than 150	more than 40 but not more than 120	more than 30 but not more than 90
Highly dangerous	more than 25 but not more than 70	more than 17 but not more than 50	more than 13 but not more than 40	more than 10 but not more than 30
Extremely dangerous	no more than 25	no more than 17	no more than 13	no more than 10

Classification of certain types of substances and materials

For floor carpets, the flammability group is not determined.

According to flammability, textile and leather materials are divided into flammable and hardly flammable. A fabric (non-woven fabric) is classified as a flammable material if the following conditions are met during testing:

1) the flame burning time of any of the samples tested when ignited from the surface is more than 5 seconds;

2) any of the samples tested when ignited from the surface burns out to one of its edges;

3) cotton wool catches fire under any of the test specimens;

4) the surface flash of any of the samples extends more than 100 millimeters from the point of ignition from the surface or edge;

5) the average length of the charred area of any of the samples tested when exposed to flame from the surface or edge is more than 150 millimeters.

For the classification of building, textile and leather materials, the value of the flame spread index (I) should be used - a conditional dimensionless indicator that characterizes the ability of materials or substances to ignite, spread flame over the surface and generate heat. According to the spread of flame, materials are divided into the following groups:

1) do not spread flame over the surface, having a flame spread index of 0;

2) slowly spreading flame over the surface, having a flame spread index of not more than 20;

3) rapidly spreading flame over the surface, having a flame spread index of more than 20.

Test methods for determining the classification indicators of fire hazard of building, textile and leather materials are established by regulatory documents on fire safety

The most important quality of the material used in construction is its combustibility. Combustibility is the property of a material to resist the effects of a flame. Therefore, five flammability groups are legally defined. Four groups of combustible materials and one non-combustible. IN federal law No. 123, they are defined by abbreviations: G1, G2, G3, G4 and NG. Where NG stands for non-combustible.

The main indicator in determining the flammability group of a particular material is the burning time. The longer the material can withstand, the lower the combustibility group. Burn time is not the only indicator. Also, fire testing will evaluate the interaction of the material with the flame, whether it will support combustion and to what extent.

The combustibility group is inextricably linked with other fire resistance parameters of the material, such as flammability, release of toxic substances, and others. Together, the fire resistance indicators make it possible to judge the flammability class. That is, the flammability group is one of the indicators for assigning a flammability class, it precedes it. Let's take a closer look at the elements of assessing the fire resistance of a material.

All substances in nature are divided into. Let's list them:

Non-combustible. These are substances that by themselves cannot burn in air. But even they can, when interacting with other media, be sources of the formation of combustible products. For example, interacting with oxygen in the air, with each other or with water.
Fire resistant. Difficult-to-combustible building materials can ignite only when exposed to an ignition source. Their further burning when the ignition source ceases to occur independently cannot occur, they go out.
combustible. Combustible (combustible) building materials are defined as capable of igniting without an external source of ignition. Moreover, they quickly ignite if such a source is available. Materials of this class continue to burn after the disappearance of the ignition source.

It is preferable to use non-combustible materials in construction, but not all widely used building technology can be based on the use of products that can have such a remarkable property. More precisely, there are practically no such technologies.

The fire-fighting characteristics of building materials also include:

combustibility;
flammability;
the ability to release toxins when heated and burned;
intensity of smoke formation at high temperatures.

Flammability groups

The tendency of building materials to burn is indicated by the symbols G1, G2, G3 and G4. This series begins with the combustibility group of slightly combustible substances, designated by the symbol G1. The series ends with a group of highly flammable G4s. Between them is a group of materials G2 and G3, which are moderately combustible and normally combustible. These materials, including the group of low combustible G1, are mainly used in building technologies.

The flammability group G1 shows that this substance or material can emit flue gases heated no higher than 135 degrees Celsius and are not capable of burning independently, without an external ignition action (non-combustible substances).

For completely non-combustible building materials, fire safety characteristics are not investigated and standards are not established for them.

Of course, the G4 material group also finds its application, but due to its high tendency to burn, it requires additional fire protection measures. As an example of such additional measures, a floor-by-floor fire cut-off made of steel can act inside the ventilation facade structure if a windproof membrane with a combustibility group G4, that is, combustible, was used. In this case, the cutoff is designed to stop the flame inside the vent gap within one floor.

Application in construction

The use of materials in the construction of buildings depends on the degree of fire resistance of these buildings.

Main classification building structures according to fire safety classes looks like this:

To determine what combustibility materials are acceptable in the construction of a particular facility, you need to know the fire hazard class of this facility and the combustibility groups of the building materials used. The fire hazard class of an object is set depending on the fire hazard of those technological processes that will take place in this building.

For example, for the construction of buildings for kindergartens, schools, hospitals or nursing homes, only materials and NG combustibility groups are allowed.

In fire hazardous buildings with fire resistance of the third level, low fire K1 and moderate fire K2, it is not allowed to carry out outer lining walls and foundations made of combustible and slow-burning materials.

For non-load-bearing walls and translucent partitions, materials without additional fire hazard tests can be used:

structures made of non-combustible materials - K0;
constructions from materials of group G4 - K3.

Any building structures should not spread latent combustion. In the partitions of the walls, the places of their connection there should not be voids that are separated from one another by continuous fillings of combustible materials.

Confirmation of the class and degree of flammability

combustibility

Building materials are divided into non-combustible (NG) and combustible (G). Materials treated with flame retardants can have one of 4 groups: G1 - low combustible, G2 - moderately combustible, G3 - normal combustible, G4 - highly combustible.
Combustibility and flammability groups are set according to GOST 30244-94.

To carry out the test for combustibility, 4 samples are taken - boards treated with a flame retardant composition. A box is built from these samples. It is placed in a chamber containing 4 gas-burners. The burners are ignited in such a way that the flame acts on the bottom surface of the specimens. At the end of combustion, the following are measured: the temperature of the flue gases, the length of the damaged section of the sample, the mass, and the time of afterburning. After analyzing these indicators, wood treated with a flame retardant is classified into one of four groups.

Flame spread

Combustible building materials according to the spread of flame over the surface are divided into 4 groups: RP1 - non-propagating, RP2 - weakly spreading, RP3 - moderately spreading, RP4 - strongly spreading.

GOST R 51032-97 regulates methods for testing building materials (including those treated with flame retardants) for flame propagation. For testing, the sample is exposed to the heat of a radiation panel located at a small angle and heated to a certain temperature. Depending on the density of the heat flux, the value of which is set along the length of the flame propagation along the sample, the material treated with a flame retardant composition is assigned one of four groups.

Flammability

Combustible building materials according to flammability are divided into groups: B1 - hardly flammable, B2 - moderately flammable, B3 - flammable.

GOST 30402 defines methods for testing building materials for flammability. The group is determined depending on the heat flow of the radiation panel at which ignition occurs.

Smoke generating capacity

According to this indicator, materials are divided into 3 groups: D1 - with low smoke-generating ability, D2 - with moderate smoke-generating ability, D3 - with high smoke-generating ability.
Groups for smoke-generating ability are set in accordance with GOST 12.1.044. For testing, the sample is placed in special camera and is burned. During combustion, the optical density of the smoke is measured. Depending on this indicator, wood with a flame retardant applied to it is classified into one of three groups.

Toxicity

According to the toxicity of combustion products, 4 groups of materials are distinguished: T1 - low-hazard, T2 - moderately hazardous, T3 - highly hazardous, T4 - extremely hazardous. Toxicity groups are set according to GOST 12.1.044.

Preparing for the construction or renovation of a house, we meticulously compare the prices of building materials, their heat-insulating and noise-absorbing qualities, pay attention to the beauty of the texture and strength, durability and environmental friendliness.

At the same time, as a rule, we do not have time to assess the fire resistance and fire hazard. However, it is these two parameters that are extremely important for human health and life, since no one is safe from a fire.

Let's fill together the existing knowledge gap in the field of fire safety of popular building materials, and also consider their classification.

Fire safety and fire resistance are not equivalent concepts

We will immediately clarify the terminology, since most developers do not have a clear idea in this matter.

The term fire safety refers to building materials and describes their behavior when exposed to fire.

fire resistance- a concept that does not refer to materials, but to building structures, and characterizes their ability to resist the effects of fire without loss of strength and bearing capacity. Therefore, the expression fire resistance of building materials is incorrect.

One cannot speak, for example, about the fire resistance of drywall, but one can consider the fire resistance of the construction of a partition or ceiling sheathed with this material.

At the same time, fire safety standards necessarily take into account not only the type of lining, but also the material of the frame, the presence and type of insulation, the type of finish and a number of important parameters, each of which affects the overall fire resistance of the structure being tested.

Classification of materials according to the degree of fire safety

Article 13 of the "Technical Regulations" of the current fire safety requirements divides all building materials into two groups: combustible and non-combustible. The first group is divided into 4 subgroups. These are low combustible materials, denoted by the symbol G1, moderately combustible - G2, normally combustible - G3 and highly combustible - G4.

Since combustion is a process accompanied by a radical change in the physical and chemical structure of the material, additional parameters are introduced to evaluate fire safety: toxicity (low-hazardous-T1, moderately hazardous-t2, highly hazardous TZ and extremely dangerous T4), smoke-forming ability (D1-D3), ignorance (from B-1 to 3) and the ability to spread the flame on its surface (from RP-1 non-production Setting flame and strongly extending to RP-4).

Assessing the combustibility of building materials in fire tests, they are assigned the appropriate class - a comprehensive indicator of fire safety.

All non-combustible materials belong to the KM0 class, and combustible materials are divided into 5 classes from KM1 to KM5.

Non-combustible building materials include natural stone, metal, brick, concrete, ceramics, glass and asbestos cement. The category of combustible materials is much broader, since today there are hundreds of types of synthetic polymeric materials and compositions on the market used for construction and finishing work.

We know the evaluation criteria - we confidently look at the material certificate

A fire certificate, which any legally sold building material must have, is an objective indicator of its safety. This document should be used when making a purchase decision. We will also consider the fire safety certificates of the most popular building materials.

Drywall

Since this material is very often used as a structural material, its main indicator is fire resistance. A standard drywall sheet can withstand fire for 20 minutes, after which it collapses.

This material does not emit toxic gases and smoke and does not spread flame over its surface. All types of GVL and GKL (gypsum fiber and drywall sheets) are classified as non-combustible materials.

Sandwich panels

These designs are distinguished by good fire resistance, which depends on the thickness of the insulation.

With a polyurethane insulation 150 mm thick, a sandwich panel made of steel profiled sheet will last 45 minutes in case of fire. This time is enough to evacuate people from the fire area.

pvc siding

Regarding PVC siding, the fire certificate says that this material is moderately flammable G2 and moderately flammable B2. Its combustion toxicity is low T2.

SIP panels

This type of structure is widely used in frame construction. There are two types of sip panels - with an outer layer of cement-bonded particle boards and particle boards. OSB boards. The first belong to the class KM1 - that is, they are quite safe in terms of fire (slow-burning, low-flammable with low smoke-generating ability).

Sip panels with expanded polystyrene insulation have minimal fire safety, which requires reliable protection fireproof walls.

Let's see what is written in the fire certificate about these composite structures: highly combustible - G4, highly spreading fire - RP4, flammable - B3. Their toxicity index is very high - T4, smoke-generating ability - D3 (moderate).

Therefore, to say that such panels, in terms of fire characteristics, are able to replace treated with fire-resistant impregnation wooden beam, it is forbidden.

Styrofoam

This insulation is very often used for façade cladding and as filling for building envelopes, in particular sip panels, which we mentioned above.

Manufacturers have been able to reduce the flammability and flammability of polystyrene foam, however, there has been no progress in reducing smoke generation and toxicity. In addition, the cladding of the facade with foam plastic requires the mandatory installation of fire-fighting misfires in the form of seams from non-combustible mineral wool. Otherwise, in case of fire, the entire surface of the facade quickly burns out, and the residents receive a high dose of toxic gases.

Aerated concrete, foam concrete, expanded clay concrete blocks

Gas and foam concrete belong to the group of fireproof materials with ultimate fire resistance E1-180. This suggests that the walls of these materials can withstand fire without destruction for 180 minutes. At the same time, blocks of gas and foam concrete do not emit toxic gases and smoke.

Expanded clay blocks are superior in fire resistance, as they can withstand an open flame for at least 7 hours.

Mounting foam

This is foamed polyurethane, which today is produced in three modifications that differ in the degree of flammability. Foam index B1 is fire resistant. A seam of such foam with a depth of 30 mm and a width of 100 mm does not burn out in a fire within 45 minutes.

Mounting foam marked B2 has the ability to self-extinguish, and standard cheap class B3 foam is combustible and requires protection with plaster or gypsum putty.

Cellular polycarbonate

Let's look at the certificate of this popular material used for sheds, greenhouses and other translucent structures. This is a low-combustible material (G1) that does not spread flame over its surface (RP1).

It also looks good in terms of flammability (moderately flammable) and smoke production (moderate smoke generating ability). But in terms of toxicity, cellular polycarbonate belongs to the group of highly hazardous (T3). Therefore, it is best used for outdoor structures, and not inside residential buildings.

Ondulin

This material, by its design, is cardboard impregnated with modified bitumen with mineral filler. A comprehensive indicator of fire safety in this roofing material very low - K5 with a maximum flammability level of K4. Therefore, in the event of a fire, such a roof burns out very quickly.