Determination of the degree of fire resistance of buildings and structures. Fire resistance of the building
The degree of fire resistance of buildings and structures
Fire resistance increases the chances of a building surviving and maintaining human life... Fire resistance depends on the materials from which the building is built and the purpose of the structure in relation to the functions performed. There are different categories of the degree of fire resistance, which are numbered in Roman numerals from one to five.
Production and storage facilities are endowed with high resistance to fire, because they have high degree the possibility of ignition. Shopping and entertainment centers are highly susceptible to fire hazards, where there are high chances of ignition and spread of fire across the territory. Now the degree of resistance of the building to fire determines the basis fire safety.
SNIP
Basically, buildings and structures have type I fire walls, or rather, fire compartments. The degree of resistance to fire is determined by the minimum limit of fire resistance of materials and by the rate of capture of the territory, that is, structures and frames.
The minimum threshold for fire resistance of a building is 25. Therefore, it is possible to use unprotected metal structures. For all types of buildings, building codes allow cladding plasterboard materials to increase fire resistance.
Usually, the degree of fire resistance is determined by the type of purpose of the building:
- by category of fire or explosion hazard.
- the fire compartment must be within the boundaries of the floor area.
- Number of storeys of the building.
By combustibility, building materials are divided into the following groups:
- Non-flammable
- Hard to burn
- Fireproof
When installing frame structures, non-combustible materials should be used. Combustible materials can be used for buildings of I-IV degrees of fire resistance, except for lobbies.
Building materials are classified according to toxicity and smoke generation during the combustion of products.
Algorithm of actions for determining fire resistance for different types of buildings
Residential buildings (houses)
The fire resistance of a house has five degrees, which characterize each material from which the house is made.
Constructive characteristics of a residential building:
- For houses of this fire resistance class, work is required from non-combustible materials. The building should be made of bricks, concrete blocks or stone. For insulation, fire-resistant materials are required. The roof must be made of tiles, metal tiles, corrugated board or slate, that is, materials that are resistant to fire. For floors, reinforced concrete slabs must be used.
- The building is made of blocks and bricks. The slabs can be wooden, but covered with protective materials such as plaster or non-combustible slabs. The wooden truss system must be treated with impregnations that protect against fire. For insulation, it is not necessary to use non-combustible materials, you can use objects with fire resistance limits G1, G2.
III. The structure must be made of a metal frame, this also applies rafter system... insulation should be performed with fire resistance limits G1, G2 or fire-resistant. For outer cladding at home it is necessary to use non-combustible materials.
IIIb. Cottage executions on a frame basis should be impregnated with fire-resistant substances. Sheathing is also subject to impregnation, insulation from groups G1, G2 or non-flammable materials.
- Wooden frame protected by plastering materials. Fire-resistant treatment should be on attic floors. There are no special requirements for the cladding of the house, so it can be made from any materials.
IVb. Similar to the previous group, only the building is one-story. Metallic materials should be applied for frame structures... The enclosing structures must be made of non-combustible materials. Materials of the G3 and G4 groups must be used when laying insulation.
- All categories of houses that are not included in this list apply. There are no special requirements for this group in relation to their resistance to fire.
Public buildings
Basically, residential buildings are classified according to functional fire safety into the following categories:
- F 1.2 Dormitories
- O 1.3 Multi-apartment buildings, including families living with people with disabilities.
Passageways in houses should be 3.5 m wide, and the height is required to be at least 4.25 m. It is necessary that through the passageways along the staircase be placed at a distance of no more than 100m from each other. The upper floor defines the height of the structure, including the attic, excluding the technical floor, located at the very top of the building. The difference in the boundaries of the points of passage for fire-fighting vehicles between the top and bottom determines the height of the floor of the building.
The next class of buildings, F 1.3, can be determined based on a bulleted list, as well as on the maximum allowable area of the fire compartment located on the floor.
- The degree of fire resistance of a public building is divided into five groups.- I, II, III, IV, V.
- According to the class of constructive fire hazard, structures are determined: I- C0, II-C0, C1, III- C0, C1, IV-C0, C1, C2, V- are not numbered.
- The maximum permissible height of the structure in meters, as well as the area for the fire compartment located on the floor: I-75m-; II-С0-50, С1-28; III-C0-28, C1-15; IV-CO-5-1000m2, C1-3m-1400m2, C2-5m-800m2. Next are the figures for the permissible height without numbering (C), 3m-1200m2, 5m-500m2, 3m-900m2; V-not numbered-5m-500m2 and 3m-800m2.
Inside buildings containing wooden walls, ceilings, and partitions should be treated with fire-resistant materials such as varnish and plaster. This applies to buildings such as schools, preschools, hospitals, pioneer camps and clubs.
For bus stations, the inner area does not need to be limited, because there is a fire extinguishing system there. In relation to the first, the area of the bus station can be increased to 10,000 m2, in the event that there are no storage or storage rooms at the bottom of the station in the basement rooms.
Industrial buildings
Industrial buildings are defined as structures that produce goods in the form of semi-finished products, as well as finished products... Manufactures are divided into many industries and each have their own nuances and subtleties, they are repair, weaving, chemical, tool, metallurgical, mechanical assembly and many others.
The degree of fire resistance of industries is especially important, since some work with explosive or poisonous substances that can harm the environment. natural environment and directly to the person.
Industrial buildings are classified into five grades. Following the flammability and fire resistance of the main structures and the materials from which they are made, determine the degree of fire resistance of the building.
Buildings of the 1st class are determined by the IInd degree, for the IInd-IIInd. For ІІІ and ІV numbering is not required. Therefore, the fire safety of industrial buildings directly depends on the fire resistance of building materials.
Based on the structures and architectural structures, industrial buildings are divided into single-storey, multi-storey and mixed-storey buildings.
Warehouses
The limit of resistance to fire and its spread throughout the territory determines the degree of fire resistance of structures. Therefore, different building materials have been developed for this, which determine the degree of fire resistance.
The most vulnerable are warehouse premises from wood materials, but the degree of fire resistance can be increased by various impregnations, as well as plaster. The fire resistance of warehouses is passive protection that prevents or reduces the spread of fire inside the structure.
To increase the degree of fire resistance of metal structures, fire treatment is used, it can be plaster, ceramic or concrete tiles. Intumescent paints are considered very effective, as they allow more time to reach critical temperatures.
Also, to increase fire protection, windows should be treated with special impregnations, often polymer foam is used or the openings are replaced with special glass blocks. Doorways should be made of non-combustible metallic materials such as aluminum.
These measures will be able to increase the fire resistance of the warehouse and protect human life.
Developed by the laws of SNIP, it is possible to determine the degree of fire resistance of buildings and structures, to understand to what class and type they belong. These standards give a clear description of the building and make it possible to determine the safety of the structure necessary for the protection of labor or the preservation of human life. Therefore, the norms and purpose of the building use the appropriate materials that are necessary for the implementation of frame structures, insulation and cladding of the building.
When assessing the fire performance (properties) of various buildings or structures Special attention given consideration to the degree of fire resistance. Fire resistance means the functional ability of structural components of structures to suppress the spread of fire without losing their performance characteristics... These properties include bearing and enclosing capacity. Let's consider these concepts in more detail.
Fire resistance limit of a building: definition, factors affecting its values
With the loss of the bearing capacity, the integrity of the building is violated, and the loss of the enclosing capacity entails the appearance of cracks and through-type holes, up to the penetration of fire into the buildings, followed by combustion.
The fire resistance limit of a building is the time from the start of combustion in a fire until the appearance of signs of loss, namely, such as:
- the appearance of through-type cracks;
- an increase in temperature indicators on the unheated part above 140 ° C or anywhere above 180 ° C in comparison with the temperature of the entire structure before testing;
- loss of bearing functional characteristics by the structure.
The value of the fire resistance limit is influenced by the dimensions and physical properties materials. The thicker the walls, the longer (in time) the fire resistance will be. The degree of fire resistance of a building is influenced by:
- number of storeys of the structure;
- square;
- type of building (administrative, residential, etc.);
- quality and degree of refractoriness of materials.
The fire resistance of a building depends on the fire resistance building structures... They are divided into three main groups:
- fireproof (stone, brick, metal structures);
- hardly combustible (combustible materials, the surface of which is protected with a non-combustible mixture);
- easily combustible (wood).
Classification of buildings according to the degree of fire resistance
The fire resistance of a building is determined in strict accordance with building codes and rules (SNiP). So, according to the degree of fire resistance, all buildings are divided into five main groups. First group. Buildings that are most protected from the negative consequences of a fire. The main materials used for these structures are concrete and stone, which are resistant to high temperatures and fire.
Second group also covers buildings with refractory structures, as in the first case, with a slight allowance for the use of unprotected elements in steel structures. By the third grade include buildings in the structural structure of which there are non-combustible and non-combustible materials. If the structure includes combustible materials, then they must be treated with a special fire retardant mixture.
Buildings that are assigned fourth degree of fire resistance, should have fireproof walls in their construction, and non-combustible materials should be used for load-bearing walls. For structures included to the fifth group, the use of combustible materials is typical, however, for load-bearing walls, as well as for buildings of the fourth degree of fire resistance, materials of a non-combustible nature are used. The degree of fire resistance of the building (structure) must coincide with the explosion and fire safety of the premises.
Buildings made of bricks have a high degree of protection against fire - the first degree of fire resistance. Brick is a material that is resistant to combustion processes - it does not burn or smolder, and therefore most developer companies prefer to build houses from this material.
Factors that affect the degree of fire resistance of a residential building
The degree of fire resistance of any residential building is influenced by its number of storeys and area - the higher the residential building and the wider in area, the higher the degree of fire resistance. Basically, brick, stone or concrete is used for residential buildings, therefore they are endowed with the first degree of fire resistance. If brick and concrete block elements are used for the construction of such a structure, then this is the second class of fire resistance. For houses built on metal frame, with cladding made of non-combustible materials, assign the third degree of fire resistance.
Houses based on timber frame assign the fourth degree of fire resistance, and the fifth class includes houses that are most susceptible to fire.
In connection with the fires occurring in administrative and residential premises, great attention is paid to such a criterion as the fire resistance of buildings during the construction of buildings. The fire resistance of any building is calculated taking into account the above features and building codes and regulations (SNiP).
The degree of fire resistance of a building is the ability of a structure to withstand a fire for some time without collapsing. Based on this indicator, it is possible to assess any structure in terms of fire safety. It depends on the degree of fire resistance of the building how quickly the fire will spread through its premises and structures. For obvious reasons, this indicator will largely depend on the materials from which the structure is being built.
The definition of the degree of fire resistance of building materials must be approached from the position: are they combustible or not. Therefore, the standard classification divides them into "NG" - non-combustible or "G" - combustible. The latter are divided into several classes:
- G1 - slightly flammable;
- G2 - moderate;
- G3 - normal;
- G4 - strong.
There is another parameter that determines the fire resistance of building materials - this is their flammability, denoted by the letter "B". There are three classes here:
- B1 - materials that are flammable with great difficulty;
- B2 - moderately flammable;
- B3 is easy.
The next characteristic of the degree of fire resistance of building materials is the possibility or impossibility of flame propagation over their surfaces. Denoted this parameter the abbreviation "RP". So:
- RP1 - do not spread the flame;
- RP2 - poorly distributed;
- RP3 - moderately;
- RP4 - strong.
Attention! The "RP" indicator is determined only for floor bases and their coatings, as well as for roofs. To the rest structural elements it has nothing to do with it, except perhaps for wooden houses.
SNiPs do not indicate that the smoke and toxicity of the emitted combustion products affect the degree of fire resistance of the building. And it is right. But in the event of a fire, where the main task is not only to extinguish it, but also to evacuate people in time, these two factors play important role... Therefore, they must be indicated in the building passport.
Smoke or smoke emission coefficient of building materials is indicated by the letter "D". According to this characteristic, all buildings are divided into three groups:
- D1 - with low smoke emission;
- D2 - with moderate;
- D3 is a big selection.
In terms of toxicity during combustion, all building materials are divided into four groups:
- T1 - low hazard;
- T2 - moderate;
- T3 - high;
- T4 - extremely dangerous for humans.
Summarizing all of the above, we can finish about the degree of fire resistance of building materials by the fact that in SNiPs all the above-mentioned indicators (and there are five of them) are combined into one common one, which is denoted by the abbreviation "KM".
According to the "KM" indicator, building materials are divided into five classes, where the KM1 class is the representatives in whom all the above-described characteristics have a minimum value. Accordingly, the class KM5 - c maximum values... KM0 is a class of non-flammable.
Having dealt with the building materials, we turn to the fire resistance of buildings and structures. It should be noted that not all buildings have identical materials throughout the structure... That is, not always in all construction projects in each of their parts (floors, premises, etc.), the same building materials are used. Therefore, the classification made according to fire resistance is considered conditional. But in any case, all construction objects are divided into three classes: non-combustible, difficult to burn, combustible.
The degree of fire resistance of a building - how to determine. The calculation is based on the time from the onset of ignition to the moment of destruction or the appearance of defects. Therefore, it is important to understand what defects load-bearing structures can be taken into account to say exactly that the structure is at the limit of destruction.
- Appear through holes and cracks through which the flames of fire and smoke penetrate.
- The heating temperature of the structures rises within the range from + 160C to + 190C. This refers to the non-burning side. For example, if a room is on fire, and the wall on the other side heats up to the above indicators, then this is a critical moment.
- The supporting structure is deformed, leading to collapse. This mainly applies to metal assemblies and structures. By the way, unprotected steel profiles belong to the KM4 category. At a temperature of + 1000C, they simply begin to melt. Reinforced concrete products belong to "KM0".
As for the speed and time of combustion, then, as mentioned above, it all depends on the materials from which they are built. For example, concrete structure 25 cm thick burns out in 240 minutes, brickwork in 300 minutes, metal structure over 20, wooden door(entrance, treated with fire retardants) for 60, a wooden structure sheathed with plasterboard 2 cm thick, burns out in 75 minutes.
Classification by the degree of fire resistance of buildings, structures and fire compartments
All building objects are divided into five degrees. And this indicator must be indicated in the building passport.
Attention! The fire resistance of a building can only be determined by an authorized agency. It is they who give the assessment, determine the class that is entered in the passport.
So, the degree of fire resistance of buildings and structures is a table of five fire resistance classes (I-V), which determine the fire hazard of a structure.
| Class | Design features |
| I | Objects erected entirely from non-combustible materials: stone, concrete or reinforced concrete. |
| II | Structures in which metal assemblies are partially used as load-bearing structures. Brick houses belong to the same class. |
| III |
Buildings belonging to the first category, only in their structures it is allowed to use wooden floors covered with plaster or gypsum boards... To cover wooden floors, here you can use sheet materials belonging to the group of "hard-to-burn". As for roofs, wood can also be used here, only with a treatment with flame retardant compounds. |
| IIIa | Frame houses made of a metal base (steel profiles), which have a low degree of fire resistance. They are sheathed with non-combustible materials. here you can also use a fireproofing material. |
| IIIb | Wooden houses or buildings from composite materials, the basis of which is wood. Buildings must be processed by fire protective compounds... The main requirement for them is construction away from possible sources of fire. |
| IV |
Buildings erected of wood, the structures of which are covered on all sides with plaster mortars, gypsum boards or other insulating materials capable of holding back the effects of fire for some time. The roof is necessarily exposed to fire protection. |
| IVa | Building structures assembled from steel profiles, untreated with protective compounds. The only thing is the floors, which are also assembled from steel structures, but using non-combustible heat-insulating materials. |
| V | Buildings and structures that are not subject to any requirements regarding fire resistance, combustion rate, and others. |
Having dealt with the classes of the degree of fire resistance of buildings, it is necessary to designate the types of this characteristic. There are only two positions here: the actual fire resistance, denoted by CO f and required - CO tr.
The first is the actual indicator of the erected building or structure, which was determined based on the results of a fire-technical examination. Results are based on table values, which are shown in the photo below.
The second is the implied (planned) minimum value of the fire resistance of the building. It is formed on the basis of normative documents(industry or specialized). This takes into account the purpose of the building, its area, number of storeys, whether explosive technologies are used inside, whether there is a fire extinguishing system, etc.
Attention! Comparing the two types of fire resistance, it is always necessary to take as a basis the ratio that CO f should not be less than CO tr.
Conclusion
The classification of buildings and structures according to the degree of fire resistance must be taken seriously. Considering this indicator, it is necessary to determine the requirements for the fire safety system. And the lower the limit of fire resistance of a building, the more investments will have to be made when organizing a fire protection system.
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CODE OF RULES FOR FIRE PROTECTION SYSTEM - PROVIDING FIRE RESISTANCE OF PROTECTED OBJECTS - SP 2-13130-2009 (approved by the Order of the Ministry of Emergency Situations of the Russian Federation dated ... Actual in 2018
6. Determination of the required degree of fire resistance of buildings, structures, structures, depending on their number of storeys, class of functional fire hazard, area of the fire compartment and fire hazard occurring in them technological processes
The choice of the size of the building and fire compartments should be made depending on the degree of their fire resistance, the class of constructive and functional fire hazard.
With combinations of these indicators not provided for in this section, the floor area and the height of the building are taken at the worst of these indicators for the building in question of the corresponding class of functional fire hazard, or special technical conditions In accordance with the requirements of Art. 78 N 123-FZ.
In design, construction, reconstruction, overhaul and technical re-equipment of facilities in addition to the requirements of this Code of Rules should be guided by the provisions.
6.1. Industrial buildings
6.1.1. The degree of fire resistance, the class of constructive fire hazard, the height of buildings and the floor area within the fire compartment for industrial buildings (class F5.1) should be taken according to Table 6.1.
Table 6.1
| Category of buildings or fire compartments | Building height<*>, m | Fire resistance of the building | Floor area, sq. m, within the fire compartment of buildings | |||
| one-story | two floors | three floors or more | ||||
| A, B | 36 | I | C0 | Not ogre. | 5200 | 3500 |
| A | 36 | II | C0 | Not ogre. | 5200 | 3500 |
| 24 | III | C0 | 7800 | 3500 | 2600 | |
| IV | C0 | 3500 | - | - | ||
| B | 36 | II | C0 | Not ogre. | 10400 | 7800 |
| 24 | III | C0 | 7800 | 3500 | 2600 | |
| IV | C0 | 3500 | - | - | ||
| V | 48 | I, II | C0 | Not ogre. | 25000 | 10400 |
| 7800 <**> | 5200 <**> | |||||
| 24 | III | C0 | 25000 | 10400 | 5200 | |
| 5200 <**> | 3600 <**> | |||||
| 18 | IV | C0, C1 | 25000 | 10400 | - | |
| 18 | IV | C2, C3 | 2600 | 2000 | - | |
| 12 | V | Not normal. | 1200 | 600 <***> | - | |
| G | 54 | I, II | C0 | Not limited | ||
| 36 | III | C0 | Not ogre. | 25000 | 10400 | |
| 30 | III | C1 | Also | 10400 | 7800 | |
| 24 | IV | C0 | -"- | 10400 | 5200 | |
| 18 | IV | C1 | 6500 | 5200 | - | |
| D | 54 | I, II | C0 | Not limited | ||
| 36 | III | C0 | Not ogre. | 50000 | 15000 | |
| 30 | III | C1 | Also | 25000 | 10400 | |
| 24 | IV | C0, C1 | -"- | 25000 | 7800 | |
| 18 | IV | C2, C3 | 10400 | 7800 | - | |
| 12 | V | Not normal. | 2600 | 1500 | - | |
| <*>The height of the building in this table is measured from the floor of the 1st floor to the ceiling of the upper floor, including the technical one; with a variable ceiling height, the average floor height is taken. The height of one-story buildings of fire hazard class C0 and C1 is not standardized. | ||||||
| <**>For woodworking industries. | ||||||
| <***>For sawmills with up to four frames, woodworking shops for primary wood processing and wood chipping stations. | ||||||
6.1.2. The degree of fire resistance, the class of constructive fire hazard, the height of buildings and the floor area within the fire compartment for livestock, poultry and fur farming buildings, the degree of fire resistance and the floor area between fire walls should be taken according to Table 6.2.
Table 6.2
| Production category | Allowed number of floors | Floor area between opposite walls of buildings, sq. m | ||
| one-story | multi-storey | |||
| II | V | 9 | Not limited | Not limited |
| III | 3 | 3000 | 2000 | |
| IV | 2 | 2000 | 1200 | |
| V | 1 | 1200 | - | |
| II | D | Not limited | Not limited | Not limited |
| III | 3 | 5200 | 3500 | |
| IV | 2 | 3500 | 2000 | |
| V | 1 | 2000 | - | |
| Building category | Fire resistance of the building | Floor area, sq. m, within the fire compartment | |
| V | I, II, III | C0 | 9600 |
| IV | C0, C1 | 4800 | |
| IV | C2, C3 | 2400 | |
| V | Not normal. | 1200 |
Table 6.5
6.5.1. The permissible height of a building of class F1.3 and the floor area within the fire compartment should be determined depending on the degree of fire resistance and the class of constructive fire hazard according to Table 6.8.
| Fire resistance of the building | Building constructive fire hazard class | The highest permissible building height, m | The largest allowable floor area of the fire compartment, sq. m |
| I | C0 | 75 | 2500 |
| II | C0 | 50 | 2500 |
| C1 | 28 | 2200 | |
| III | C0 | 28 | 1800 |
| C1 | 15 | 1800 | |
| C0 | 5 | 1000 | |
| 3 | 1400 | ||
| IV | C1 | 5 | 800 |
| 3 | 1200 | ||
| C2 | 5 | 500 | |
| 3 | 900 | ||
| V | Not standardized | 5 | 500 |
| 3 | 800 |
6.5.2. Buildings of I, II and III degrees of fire resistance are allowed to be built on with one attic floor with load-bearing elements having a fire resistance limit of at least R 45 and a fire hazard class K0, regardless of the height of the buildings set in Table 6.8, but located no higher than 75 m. floors must meet the requirements for the structures of the building to be built.
When applying wooden structures constructive fire protection should be provided to ensure the specified requirements.
6.5.3. In buildings of I and II degrees of fire resistance, in order to ensure the required fire resistance limit of more than R 60 of the load-bearing elements of the building, it is allowed to use only structural fire protection (cladding, coating, plaster, etc.).
6.5.4. Bearing elements of two-story buildings of IV degree of fire resistance must have a fire resistance limit of at least R 30.
6.5.5. Fire hazard class and fire resistance limit for interroom, including cabinet, collapsible, with doorways and sliding partitions are not standardized.
6.5.6. Public premises<1>should be separated from the premises of the residential part by fire-prevention partitions of the 1st type and ceilings of the 3rd type without openings, in buildings of the 1st degree of fire resistance - by the ceilings of the 2nd type.
<1>Public premises - in this section - premises intended for the implementation of activities in them for servicing the residents of the house, residents of the adjacent residential area, and others permitted for placement in residential buildings by the State Sanitary and Epidemiological Supervision authorities.
6.5.7. The load-bearing structures of the coating of the built-in-attached part must have a fire resistance limit of at least R 45 and a fire hazard class K0. If there are windows in a residential building that are oriented towards the built-in and attached part of the building, the level of the roof at the junctions should not exceed the floor level above the residential premises of the main part of the building. Insulation in the coating must be made of materials of the NG group.
6.5.8. Single-family residential buildings, including blocked ones (functional fire hazard class F1.4)
6.5.8.1. Blocked houses of constructive fire hazard classes C2 and C3 must additionally be separated by solid fire walls of the 1st type and fire hazard class of at least K0 into fire compartments with a floor area of no more than 600 sq. m, including one or more residential blocks.
6.5.8.2. Firewalls must intersect all flammable structures in the house.
In this case, type 1 fire walls, dividing the house into fire compartments, must rise above the roof and protrude beyond the outer wall cladding by at least 15 cm, and when used in the coating, with the exception of the roof, materials of flammability groups G3 and G4, they must rise above the roof by at least 60 cm and protrude beyond the outer surface of the wall by at least 30 cm.
The straight horizontal distance between any openings located in adjacent fire compartments must be at least 3 m, and in adjacent residential blocks - at least 1.2 m.
When the outer walls of adjacent fire compartments are adjacent at an angle of 136 ° or less, the area outer wall forming this angle, total length at least 3 m for adjacent fire compartments must be designed in such a way that it meets the requirements for the corresponding fire wall.
6.5.8.3. For houses up to two floors, inclusive, requirements for the degree of fire resistance and class of constructive fire hazard are not imposed.
6.5.8.4. In houses with a height of 3 floors, the main structures must meet the requirements for building structures of the III degree of fire resistance: the fire resistance limit of load-bearing elements must be at least R 45, floors - REI 45, non-load-bearing outer walls - RE 15, decks of attic coverings - RE 15, open trusses, beams and purlins of roofless roofs - R 15. Fire resistance limit interior partitions not regulated. The class of constructive fire hazard at home must be at least C2.
With a floor area of up to 150 sq. m it is allowed to take a fire resistance limit of load-bearing elements of at least R 30, of floors - at least REI 30.
6.5.8.5. Houses with a height of 4 floors must be at least III degree of fire resistance and class of constructive fire hazard at least C1.
6.5.8.6. The building structures of the house should not contribute to the latent spread of combustion. Voids in walls, partitions, ceilings and coatings, limited by materials of flammability groups G3 and G4 and having minimum size more than 25 mm, as well as the sinuses of attics and attics should be divided by blind diaphragms into sections, the dimensions of which should be limited by the contour of the enclosed space. Blind diaphragms should not be made of thermoplastic foam.
6.5.8.7. A built-in parking lot for two or more cars must be separated from other premises of the house (block) by partitions and ceilings with a fire resistance rating of at least REI 45.
The door between the parking lot and living quarters should be equipped with a seal in the porches, a self-closing device and should not go out into the sleeping area.
6.6. Public buildings for administrative purposes and administrative buildings manufacturing enterprises
6.6.1. The degree of fire resistance, class of constructive fire hazard, allowable height buildings and floor area within the fire compartment for public buildings for administrative purposes and administrative buildings of industrial and warehouse enterprises (detached buildings, extensions and inserts) (class F4.3) should be taken according to table 6.9.
Table 6.9
| Fire resistance of buildings | Structural fire hazard class | Allowable building height, m | ||||||
| 1 | 2 | 3 | 4, 5 | 6 - 9 | 10 - 16 | |||
| I | C0 | 50 | 6000 | 5000 | 5000 | 5000 | 5000 | 2500 |
| II | C0 | 50 | 6000 | 4000 | 4000 | 4000 | 4000 | 2200 |
| II | C1 | 28 | 5000 | 3000 | 3000 | 2000 | 1200 | - |
| III | C0 | 15 | 3000 | 2000 | 2000 | 1200 | - | - |
| III | C1 | 12 | 2000 | 1400 | 1200 | 800 | - | - |
| IV | C0 | 9 | 2000 | 1400 | 1200 | - | - | - |
| IV | C1 | 6 | 2000 | 1400 | - | - | - | - |
| IV | C2, C3 | 6 | 1200 | 800 | - | - | - | - |
| V | C1 - C3 | 6 | 1200 | 800 | - | - | - | - |
6.6.2. In buildings of the IV degree of fire resistance with a height of two floors or more, the elements of load-bearing structures must have a fire resistance limit of at least R 45.
6.6.3. In buildings of I and II degrees of fire resistance, in order to ensure the required fire resistance limit of more than R 60 of the load-bearing elements of the building, it is allowed to use only structural fire protection (cladding, coating, plaster, etc.).
The use of thin-layer fire-retardant coatings for steel load-bearing structures in buildings of I-II degrees of fire resistance is possible, provided they are used for structures with a reduced metal thickness in accordance with GOST R 53295 of at least 5.8 mm. The use of thin-layer coatings for reinforced concrete structures is possible subject to an assessment of their fire resistance limit with applied fire protection agents.
6.6.4. In buildings of I, II, III degrees of fire resistance for attic floor it is allowed to take the fire resistance limit of load-bearing building structures R 45 with the provision of their fire hazard class K0 when it is separated from the lower floors by a type 2 fire-prevention ceiling. In this case, the attic floor should be divided by type 1 fire partitions into compartments with an area: for buildings of I and II degrees of fire resistance, no more than 2000 sq. m, for buildings of III degree of fire resistance - no more than 1400 sq. m. Fireproof partitions should rise above the roof: not less than 60 cm, if at least one of the elements of the attic or non-attic covering, with the exception of the roof, is made of materials of groups G3, G4; not less than 30 cm, if the elements of the attic or non-attic covering, with the exception of the roof, are made of materials of groups G1, G2.
Fireproof partitions may not rise above the roof if all elements of the attic or non-attic covering, with the exception of the roof, are made of materials from the NG group.
In the attics of buildings up to 10 floors inclusive, it is allowed to use wooden structures with constructive fire protection, ensuring their fire hazard class K0.
6.7. Public buildings for administrative purposes
6.7.1. The degree of fire resistance of sheds, terraces, galleries attached to the building, as well as other buildings and structures separated by fire walls, may be taken one degree of fire resistance lower than the degree of fire resistance of the building.
6.7.2. When equipping premises with installations automatic fire extinguishing The areas indicated in Table 6.9 are allowed to be increased by 100%, with the exception of buildings of IV degree of fire resistance of fire hazard classes C0 and C1, as well as buildings of V degree of fire resistance.
If there are open openings in the ceilings of adjacent floors, the total area of these floors should not exceed the floor area specified in Table 6.9.
The floor area between the fire walls of one-story buildings with a two-story part occupying less than 15% of the building area should be taken as for a one-story building.
6.7.3. If there are automatic fire extinguishing installations on the attic floor, the area of the compartments specified in clause 6.6.4 can be increased by no more than 1.2 times.
6.7.4. The enclosing structures of the transitions between buildings must have fire resistance limits, equal limits fire resistance of the enclosing structures of the main building. Pedestrian and communication tunnels must have a fire hazard class K0. The walls of buildings in the places where passages and tunnels adjoin them should be provided with a fire hazard class K0 with a fire resistance limit of REI 45. Doors in the openings of these walls leading to passages and tunnels should be type 2 fireproof.
6.7.5. In buildings above 4 floors, tempered or reinforced glass and glass blocks should be used as translucent filling of doors, transoms (in doors, partitions and walls, including the inner walls of staircases) and partitions. In buildings with a height of 4 floors or less, the types of glass-transparent filling are not limited. In buildings over 4 stories high, staircase doors leading to common corridors, the doors of lift halls and lobbies-sluices must be deaf or with reinforced glass.
6.8. Public buildings
6.8.1. The floor area between the fire walls of the 1st type, depending on the degree of fire resistance, the class of constructive fire hazard and the number of storeys of buildings, should be no more than indicated in table. 6.9, enterprise buildings consumer services(Ф3.5) - in table. 6.10, trade enterprises (stores, F3.1) - in table. 6.11.
| Fire resistance of buildings | Structural fire hazard class | Allowable building height, m | Floor area within the fire compartment, sq. m, with the number of floors | |
| for one-story | for multi-storey (no more than 6 floors) | |||
| I | C0 | 18 | 3000 | 2500 |
| II | C0 | 18 | 3000 | 2500 |
| II | C1 | 6 | 2500 | 1000 |
| III | C0 | 6 | 2500 | 1000 |
| III | C1 | 5 | 1000 | - |
| IV | C0, C1 | 5 | 1000 | - |
| IV | C2, C3 | 5 | 500 | - |
| V | C1 - C3 | 5 | 500 | - |
2. In buildings of I and II degrees of fire resistance, in the presence of automatic fire extinguishing, the floor area between the fire walls can be increased by no more than twice.
3. When placing storerooms, office, utility and technical premises on the upper floors of store buildings of I and II degrees of fire resistance, the height of the buildings can be increased by one floor.
6.8.2. In buildings of I and II degrees of fire resistance, in the presence of automatic fire extinguishing, the floor area between the fire walls can be increased by no more than twice in relation to that established in table. 6.9.
6.8.3. The floor area between the fire walls of one-story buildings with a two-story part occupying less than 15% of the building area should be taken as for one-story buildings in accordance with Table. 6.9.
6.8.4. In station buildings, instead of fire walls, it is allowed to install water deluge curtains in two strands, located at a distance of 0.5 m and providing an irrigation rate of at least 1 l / s per 1 m of curtain length with an operating time of at least 1 hour, as well as fire curtains, screens and other devices with a fire resistance rating of at least E 60.
6.8.5. In the buildings of air terminals of the 1st degree of fire resistance, the floor area between the fire walls can be increased to 10,000 sq. m, if the basement (basement) floors do not contain warehouses, storerooms and other rooms with the presence of combustible materials (except for luggage storage rooms and staff dressing rooms). Storage chambers (except for those equipped with automatic cells) and dressing rooms should be separated from the rest of the basement with type 1 fire partitions and equipped with automatic fire extinguishing installations, and control rooms with fire partitions.
6.8.6. In terminal buildings, the floor area between fire walls is not limited, provided that it is equipped with automatic fire extinguishing installations.
6.8.7. The degree of fire resistance of sheds, terraces, galleries attached to the building, as well as office and other buildings and structures separated by fire walls, may be taken one degree of fire resistance lower than the degree of fire resistance of the building.
6.8.8. In sports halls, indoor ice rink halls and pool bath halls (with and without seats for spectators), as well as in halls for preparatory sessions pools and firing zones of indoor shooting ranges (including those located under the stands or built into other public buildings) when their area is exceeded in relation to that established in table. 6.9 fire walls should be provided between the halls (in shooting ranges - a firing zone with a shooting gallery) and other rooms. In the premises of the lobbies and foyer, when their area is exceeded in relation to that established in table. 6.9 instead of fire walls, type 2 translucent fire partitions can be provided.
6.8.9. In buildings of I, II, III degrees of fire resistance, the implementation of the attic floor is determined by the requirements of clause 6.6.4.
6.8.10. The enclosing structures of the transitions between buildings (buildings) must have fire resistance limits corresponding to the main building (building). Pedestrian and communication tunnels should be designed from materials from the NG group. The walls of buildings in the places where passages and tunnels adjoin them should be made of materials of the NG group with a fire resistance limit of R 120. Doors in the openings of these walls, leading to passages and tunnels, must be type 2 fireproof.
6.8.11. For storage of explosive materials, as well as X-ray films and other flammable materials (liquids), separate buildings should be provided for at least II degree of fire resistance.
Storerooms of flammable materials (goods) and flammable liquids in public buildings and structures should be located at the outer walls with window openings and separate them with type 1 fire partitions and type 3 ceilings, providing for the entrance through the vestibule-gateway.
6.8.12. The degree of fire resistance of buildings of baths and
6.8.19. Doors of pantries for storing flammable materials, workshops for the processing of flammable materials, switchboards, ventilation chambers and other fire-hazardous technical rooms, as well as pantries for storing linen and ironing rooms in children's preschool institutions must have a fire resistance rating of at least EI 30.
6.8.21. Buildings of specialized schools and boarding schools (for children with physical and mental disabilities) should be no higher than three floors.
6.8.22. In boarding schools, dormitories should be located in blocks or parts of a building, separated from other rooms by fire walls or partitions.
6.8.23. Overlapping over basements buildings of schools and boarding schools of III and IV degrees of fire resistance must be fire-fighting type 3.
6.8.24. The degree of fire resistance, class of constructive fire hazard and the highest height of buildings educational institutions and institutions for advanced training (F4.2) should be taken depending on the number of seats in classrooms or halls according to table. 6.14.
6.8.39. Sliding partitions must be protected on both sides by materials of the NG group, ensuring the fire resistance limit of EI 45, with the exception of buildings of the V degree of fire resistance.
The degree of fire resistance is an indicator that determines the possible resistance of a room. direct impact fire. The indicator is determined according to the rules of SNiP. This general definition, allowing you to assess the established level of safety of any building for the purpose, as well as the materials from which it is built.
The speed of the area of fire propagation per unit of time in a particular room depends on the parameters of fire resistance. All types of buildings and structures, depending on the resistance to fire and the speed of fire spread, are divided into five categories and are designated by Roman numerals.
By their ability to ignite, structures are classified as follows:
- Fireproof;
- Difficult to burn;
- Combustible.
This classification is arbitrary, since within the same building, different rooms can be made from different materials... Residential or industrial buildings are considered non-combustible if non-combustible materials were used in their construction.
Hardly combustible are called those that are made of non-combustible or combustible materials that have additional fire protection. For example, a wooden door is covered with a special varnish, asbestos and roofing steel. Combustible are those that are highly flammable and the rate of spread of the fire is high.
How to determine the degree of fire resistance of a building
The basis for determining the degree of fire resistance of any room is taken from the time of ignition of structural materials until the appearance of obvious defects in these structures.
- The appearance of cracks or a violation of the integrity of the surface, which can cause the penetration of flame or combustion products;
- Heating the material by more than 160 C, or more than 190 C, at any point on the surface;
- The deformation of the main nodes, which causes its collapse, is thus lost load bearing capacity support structures.
The safest, in terms of fire, are considered to be reinforced concrete support structures, provided that the concrete contains cement with a high level of fire resistance. Unprotected metallic materials are considered to be the least fire hazardous.
Classification of materials and their fire resistance
The actual degree of fire resistance depends on the materials that were used in the construction of buildings and structures.
All building materials are classified according to the following characteristics:
- Release of toxic substances;
- Flammability;
- Flammability;
- Smoke formation;
- The spread of fire over the surface of the structure.
According to GOST 30244-94 non-combustible materials, fire resistance indicators are not standardized and may not be determined.
By the time of deformation of the structure, the standards of fire resistance are determined:
- 300 minutes - bricks made of ceramics or silicates;
- 240 minutes - concrete with a thickness exceeding 250 mm;
- 75 minutes - wood with a plaster coating with a thickness of at least 20 mm;
- 60 minutes - standard Entrance door that is pre-treated with a fire retardant;
- 20 minutes. - metal structures.
The cause of destruction of ordinary concrete is the presence of bound water, mass fraction which is about 8%. Metals have a high degree of flammability, since at temperatures above 1000 C, they pass from a solid state to a liquid state.
Hollow bricks and concrete with a porous structure are among the most resistant to high temperatures and open flames. Buildings made of these materials have I-II degrees of fire resistance and structural fire safety class.
Rules for determining the fire resistance of buildings
The degree of fire resistance and the class of fire hazard is determined by the authorized services. Any production has a degree of fire resistance and a class of constructive fire safety
According to SNiP 21.01-97, all buildings can be subdivided into 5 main degrees of fire resistance of structures. The required degree of fire resistance is always indicated in the passport of a boiler room, industrial or residential building. And so the fire resistance is subdivided:
| Fire resistance | Characteristic |
| I | Everything external walls must be made of synthetic or natural stone, porous concrete or reinforced concrete... Ceilings are made of plates or other non-combustible materials, which must be classified as "non-combustible" protection class. The safest building in terms of the possibility of the occurrence and spread of fire. High level security. These include boiler rooms without fail. |
| II | This degree of fire resistance is similar to I, the difference lies in the possibility of using open steel structures. (Materials for a brick house) Brick houses have a II degree of fire resistance and a class of constructive fire safety |
| III | The third level of security assumes that all the main elements of industrial buildings must be made of synthetic or natural stone. wooden floors are possible if they are covered with plaster or plaster. Installation is also possible as a cover sheet materials, belonging to the class "hardly combustible". Elements of coatings are not standardized for the occurrence and spread of fire, but roof ceilings made of wood are treated with special solutions, which prevent fires. |
| ІІІ а | Buildings constructed according to the type of frame structures, which are made of "bare" steel. Guardrail profiles made of steel or other non-combustible materials. It is possible to use non-combustible heaters. |
| ІІІ b | Wooden houses on one floor have III b degree of fire resistance and a class of constructive fire safety. Everything wooden elements amenable to fire retardant treatments to limit the spread of fire. Boundary structures are made of wood or composite materials containing wood. All protective structures are subject to a mandatory fire retardant treatment in order to prevent possible fire, overheating of the structure. It is unacceptable to erect such ceilings near a heat source and high temperatures. |
| IV | 4 degree of fire resistance assumes construction wooden house... Fire protection is carried out by applying gypsum, plaster or other insulating materials to the wood. Elements of coatings do not have special requirements for the occurrence and spread of fire, but wooden roof ceilings must undergo fire-retardant treatment. |
| IV a | Single-storey buildings that are made of steel, which does not have protective insulating coatings. Ceilings are also made of steel, but with insulating non-combustible materials. |
| V | This degree of fire resistance of buildings includes all objects (industrial, residential) to which there are no special requirements regarding the fire resistance threshold and the rate of fire. |
SNiP
People asking the question: what is the degree of fire resistance of a building and how to determine it should understand that all appropriate manipulations of determining the degree of fire resistance from a container to a large industrial building do the fire services.
According to the generally accepted rules of SNiP, boiler rooms have I degree of fire resistance and a class of constructive fire safety. All stoves must be separated from the main boiler room by fireproof partitions of appropriate thickness, which depends on the volume of the fuel chamber.
If the boiler room uses gaseous or liquid fuel, then the room is equipped with materials that can be quickly dismantled. The SNiP rules for the boiler room, depending on the daily heat production, normalize the thickness of both the main and interior walls, as well as the materials from which they are made. According to the degree of fire resistance, such buildings belong to the first group.
