Fire resistance degree
fire resistance limit
Structural collapse;
Fire resistance limits:
— silicate brick — ~5 h
Table 3
| Fire resistance degree | |
| I | |
| II | The same. It is allowed to use unprotected steel structures in building coverings |
| III | |
| III a | |
| III b | |
| IV | |
| IV a | |
| V |
— impregnation with fire retardants;
- cladding;
- plaster.
- borax Na 2 B 4 O 7 * 10H 2 O.
asbestos cement sheets;
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| Topic qualifier: | ||
| last | There are 0 comments in the discussion | |
| We need the help of specialists in determining the degree of fire resistance of a building! The building is 3-storey, wooden attic structures, metal roofing. The walls are brick plastered. The interfloor ceilings are reinforced concrete, including the attic. Wooden structures treated with a fire retardant compound. A controversial question arises: what degree of fire resistance of a building is 2 or 3. In accordance with table. 21 FZ-123 and a guide to determining degrees of fire resistance, it turns out that the building is of the second degree of fire resistance, but the attic is confusing. The inspector claims that 3 is only due to wooden attic. I don't agree (maybe I'm wrong). A reasoned answer would be desirable. |
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| 5.4.5. Fire resistance limits and classes fire danger Attic roof structures in buildings of all degrees of fire resistance are not standardized, and the roof, rafters and sheathing, as well as the lining of eaves overhangs, may be made of combustible materials, except in specially specified cases. Gable structures may be designed with non-standardized fire resistance limits, while the gables must have a fire hazard class corresponding to the fire hazard class of external walls with outside. Information about structures related to elements of attic coverings is provided by the design organization in the technical documentation for the building. In buildings of I - IV degrees of fire resistance with attic coverings, with rafters and (or) sheathing made of combustible materials, the roof should be made of non-combustible materials, and the rafters and the sheathing in buildings of fire resistance class I should be subjected to fire treatment protective compounds I group of fire retardant efficiency, in buildings of II - IV degrees of fire resistance with fire retardant compounds not lower than group II of fire retardant efficiency according to GOST 53292, or carry out their structural fire protection, which does not contribute to the hidden spread of combustion. In buildings of classes C0, C1, the structures of cornices, lining of eaves overhangs of attic coverings should be made from materials NG, G1, or these elements should be sheathed with sheet materials of a flammability group of at least G1. For these structures, the use of flammable insulation is not allowed (with the exception of vapor barriers up to 2 mm thick), and they should not contribute to the hidden spread of combustion. |
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| Yakhont ® why are you considering the attic to determine the fire resistance limit of a building? An attic is not a floor (see the term building and the term attic), and rooms can only be placed on a floor. You need to consider the building down to the attic. And such structures as you described (brick walls, reinforced concrete floors, including attics), as a rule, give grade II. | ||
| II CO | ||
| II degree C0. The inspector is wrong. The topic of walls, flights and landings in the staircase, by the way, has not been disclosed. Maybe this is where the reason for the doubts about the third degree lies. |
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| Handsome inspector! The degree of fire resistance of a building can be determined by eye! Actually, the degree of fire resistance is included in the project)) | ||
| Construction norms and rules SNiP 2.01.02-85* "Fire safety standards" Appendix 2, these standards reveal how they are mainly distributed degree of fire resistance, and how can they be identified. They are ancient, but very understandable. The stairs and flights are not indicated in them. According to your description, it is undoubtedly II degree. The inspector is wrong. |
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| Thanks to everyone who responded! | ||
| Discussion closed | ||
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The conditions for the development of fire in buildings and structures are largely determined by the degree of their fire resistance. Fire resistance degree is the ability of a building (structure) as a whole to resist destruction in a fire. Buildings and structures are divided into five degrees according to the degree of fire resistance (I, II, III, IV, V). The degree of fire resistance of a building (structure) depends on the flammability and fire resistance of the main building structures and from the limits of fire spread on these structures.
Based on flammability, building structures are divided into fireproof, non-combustible and combustible. Fireproof are building structures made of fireproof materials. Refractory structures are considered to be those made of materials that are difficult to burn or of combustible materials protected from fire and high temperatures fireproof materials (for example, fire door, made of wood and covered with asbestos sheets and roofing steel).
The fire resistance of building structures is characterized by their fire resistance limit, which is understood as the time in hours after which 1 of 3 signs occurs during a fire:
1. Structural collapse;
2. Formation of through cracks or holes in the structure. (Combustion products penetrate into adjacent rooms);
3. Warming up the structure to temperatures that cause spontaneous combustion of substances in adjacent rooms (140-220 o).
Fire resistance limits:
- ceramic brick - 5 hours (25 cm-5.5; 38-11 hours)
— silicate brick — ~5 h
- concrete 25 cm thick - 4 hours (the cause of destruction is the presence of up to 8% water);
- wood covered with gypsum 2 cm thick (total 25 cm) 1 hour 15 minutes;
- metal structures - 20 minutes (1100-1200 o C-metal becomes plastic);
— Entrance door, treated with fire retardant - 1 hour.
Porous concrete and hollow bricks have greater fire resistance.
Unprotected metal structures have the lowest fire resistance limit, and reinforced concrete ones have the highest.
According to DBN 1.1.7-2002 “Fire protection. Fire safety of construction projects”, all buildings and structures are divided into eight degrees according to fire resistance (see table.
Table 3
Fire resistance of buildings and structures
| Fire resistance degree | Design characteristics |
| I | Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete using sheet and slab non-combustible materials |
| II | |
| III | Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete For floors, it is allowed to use wooden structures protected by plaster or low-flammable sheet and slab materials. Requirements regarding fire resistance limits and fire spread limits are not established for coating elements, while elements of attic coverings made of wood can be treated with fire retardant treatment |
| III a | Buildings predominantly with a frame structural design Frame elements - from unprotected steel structures Enclosing structures - from steel profiled sheets or other non-combustible sheet materials with low-combustible insulation |
| III b | The buildings are predominantly one-story with a frame structural design. Frame elements are made of solid or laminated wood, subjected to fire retardant treatment, which provides the necessary limit for the spread of fire. Enclosing structures are made of panels or element-by-element assembly, made using wood or materials based on it. Wood and other combustible materials. enclosing structures must be subjected to fire retardant treatment or protected from the influence of fire and high temperatures in such a way as to ensure the desired limit of fire spread |
| IV | Buildings with load-bearing and enclosing structures made of solid or laminated wood and other combustible and low-combustible materials, protected from the influence of fire and high temperatures by plaster and other sheet and slab materials. Coating elements are not subject to requirements regarding fire resistance limits and flame propagation limits, while the elements attic floors made of wood can be treated with fire retardant treatment |
| IV a | The buildings are predominantly one-story with a frame structural design. Frame elements are made of unprotected steel structures. Enclosing structures are made of steel profiled sheets or other non-combustible materials with combustible insulation. |
| V | Buildings, the load-bearing and enclosing structures of which are not subject to requirements regarding fire resistance limits and fire spread limits |
Protection of wooden structures from fire:
To protect wooden structures from fire, use:
— impregnation with fire retardants;
- cladding;
- plaster.
Fire retardants — chemical substances, intended to impart non-flammability properties to wood (French physicist Gay-Lussac. 1820 Ammonium salts).
Fire retardants - reduce the rate of release of gaseous products, reduce the yield of resin as a result of chemical interaction with cellulose.
For wood impregnation the following is used:
- ammonium phosphate (NH 4) 2 HPO 4
- ammonium sulfate (NH 4) 2 SO4
- borax Na 2 B 4 O 7 * 10H 2 O.
Deep impregnation is carried out in autoclaves at a pressure of 10-15 atm for 2-20 hours.
Soaking is carried out in a fire retardant solution at a temperature of 90 o C for 24 hours.
Impregnation with fire retardants transforms wood into the category of difficult-to-burn materials. Surface treatment prevents wood from burning within a few minutes.
Cladding and plaster - protect wooden structures from fire (slow heating).
Wet plaster - fire protection 15-20 min.
Facing materials: gypsum plaster(fire protection 10 min);
asbestos cement sheets;
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Fire resistance of buildings and structures
The conditions for the development of fire in buildings and structures are largely determined by the degree of their fire resistance.
Fire resistance degree is the ability of a building (structure) as a whole to resist destruction in a fire. Buildings and structures are divided into five degrees according to the degree of fire resistance (I, II, III, IV, V). The degree of fire resistance of a building (structure) depends on the flammability and fire resistance of the main building structures and on the limits of fire spread through these structures.
Based on flammability, building structures are divided into fireproof, non-combustible and combustible. Fireproof are building structures made of fireproof materials. Non-combustible structures are considered to be structures made of materials that do not burn easily or of combustible materials protected from fire and high temperatures by non-combustible materials (for example, a fire door made of wood and covered with sheet asbestos and roofing steel).
The fire resistance of building structures is characterized by their fire resistance limit, which is understood as the time in hours after which 1 of 3 signs occurs during a fire:
1. Structural collapse;
2. Formation of through cracks or holes in the structure. (Combustion products penetrate into adjacent rooms);
3. Warming up the structure to temperatures that cause spontaneous combustion of substances in adjacent rooms (140-220 o).
Fire resistance limits:
- ceramic brick - 5 hours (25 cm-5.5; 38-11 hours)
— silicate brick — ~5 h
- concrete 25 cm thick - 4 hours (the cause of destruction is the presence of up to 8% water);
- wood covered with gypsum 2 cm thick (total 25 cm) 1 hour 15 minutes;
- metal structures - 20 minutes (1100-1200 o C-metal becomes plastic);
- entrance door treated with fire retardant - 1 hour.
Porous concrete and hollow bricks have greater fire resistance.
Unprotected metal structures have the lowest fire resistance limit, and reinforced concrete ones have the highest.
According to DBN 1.1.7-2002 “Fire protection. Fire safety of construction projects,” all buildings and structures are divided into eight degrees according to fire resistance (see Table 3).
Table 3
Fire resistance of buildings and structures
| Fire resistance degree | Design characteristics |
| I | Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete using sheet and slab non-combustible materials |
| II | The same. It is allowed to use unprotected steel structures in building coverings |
| III | Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete For floors, it is allowed to use wooden structures protected by plaster or low-flammable sheet and slab materials. Requirements regarding fire resistance limits and fire spread limits are not established for coating elements, while elements of attic coverings made of wood can be treated with fire retardant treatment |
| III a | Buildings predominantly with a frame structural design Frame elements - from unprotected steel structures Enclosing structures - from steel profiled sheets or other non-combustible sheet materials with low-combustible insulation |
| III b | The buildings are predominantly one-story with a frame structural design. Frame elements are made of solid or laminated wood, subjected to fire retardant treatment, which provides the necessary limit for the spread of fire. Enclosing structures are made of panels or element-by-element assembly, made using wood or materials based on it. Wood and other combustible materials. enclosing structures must be subjected to fire retardant treatment or protected from the influence of fire and high temperatures in such a way as to ensure the desired limit of fire spread |
| IV | Buildings with load-bearing and enclosing structures made of solid or laminated wood and other combustible and low-combustible materials, protected from the influence of fire and high temperatures by plaster and other sheet and slab materials. Coating elements are not subject to requirements regarding fire resistance limits and flame propagation limits, while attic elements Wood floors can be treated with fire retardant treatment |
| IV a | The buildings are predominantly one-story with a frame structural design. Frame elements are made of unprotected steel structures. Enclosing structures are made of steel profiled sheets or other non-combustible materials with combustible insulation. |
| V | Buildings, the load-bearing and enclosing structures of which are not subject to requirements regarding fire resistance limits and fire spread limits |
Protection of wooden structures from fire:
To protect wooden structures from fire, use:
— impregnation with fire retardants;
- cladding;
- plaster.
Fire retardants are chemical substances designed to give wood non-flammable properties (French physicist Gay-Lussac. 1820 Ammonium salts).
Fire retardants - reduce the rate of release of gaseous products, reduce the yield of resin as a result of chemical interaction with cellulose.
For wood impregnation the following is used:
- ammonium phosphate (NH 4) 2 HPO 4
- ammonium sulfate (NH 4) 2 SO4
- borax Na 2 B 4 O 7 * 10H 2 O.
Deep impregnation is carried out in autoclaves at a pressure of 10-15 atm for 2-20 hours.
Soaking is carried out in a fire retardant solution at a temperature of 90 o C for 24 hours.
Impregnation with fire retardants transforms wood into the category of difficult-to-burn materials. Surface treatment prevents wood from burning within a few minutes.
Cladding and plaster - protect wooden structures from fire (slow heating).
Wet plaster - fire protection 15-20 min.
Facing materials: gypsum plaster (fire protection 10 min);
asbestos cement sheets;
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How to determine the actual fire resistance limit and fire hazard class of a building structure?
Question:
Is it possible to use wooden structures as load-bearing roof structures in a school building? The building has fire resistance degree II, functional fire hazard class F1.1.
Answer:
In accordance with Article 36 of the Federal Law of July 22, 2008 N 123-FZ “Technical Regulations on Fire Safety Requirements” (as amended on June 23, 2014), fire hazard building structures are divided into the following classes:
1) non-fire hazardous (K0);
2) low fire hazard (K1);
3) moderate fire hazard (K2);
4) fire hazardous (K3).
Currently, when determining the actual fire hazard classes of building structures, the following is used:
— GOST 30403-2012 “Building structures.
Test method for fire hazard."
Currently, when determining the actual fire resistance limits of structures, the following are used:
— GOST 30247.0-94 “Building structures. Test methods for fire resistance. General requirements»;
— GOST 30247.1-94 “Building structures. Test methods for fire resistance. Load-bearing and enclosing structures."
Based on the results of fire tests, test reports are drawn up (clause 12 GOST 30247.0-94, clause 10 GOST 30247.1-94, clause 11 GOST 30403-2012), which indicate the relevant data, including the actual fire resistance limits of building structures and actual fire hazard classes of building structures.
Accordingly, to determine the actual fire resistance limits and fire hazard classes of building structures, it is necessary to conduct fire tests in an accredited testing laboratory.
Based on information only about the material from which the building structure is made, it is impossible to determine the actual fire resistance limit and fire hazard class of the building structure.
In accordance with Part 10 of Article 87 of the Federal Law of July 22, 2008 N 123-FZ, fire resistance limits and fire hazard classes of building structures similar in shape, materials, design building structures that have passed fire tests can be determined by the calculation and analytical method established by regulatory documents on fire safety.
At the moment, information on the actual fire resistance limits and fire hazard classes of various building structures that have previously passed fire tests is given in the Collections “Technical Information (to help the inspector of the State Fire Service)”, published annually by the Federal State Budgetary Institution “All-Russian Research Institute of Fire Defense” of the Ministry of Emergency Situations Russia.
Building structures with actual fire hazard classes K1 (low fire hazard), K2 (moderate fire hazard), K3 (fire hazard) can only be used if the required structural fire hazard class of the building is allowed C1, C2, C3, respectively (Table 22 of the Federal Law of July 22 2008 N 123-FZ).
The required degree of fire resistance and the required class of structural fire hazard of buildings are determined in accordance with SP 2.13130.2012 “Systems fire protection. Ensuring the fire resistance of protected objects" (as amended on October 23, 2013) based on certain parameters of the designed building (for example, functional purpose buildings, height of buildings or structures, number of storeys, floor area within the fire compartment, category of the building for explosion and fire hazard, number of seats, etc.).
Further, in accordance with Table N 21 of the Federal Law of July 22, 2008 N 123-FZ, based on the required degree of fire resistance of the building, the minimum required fire resistance limits of building structures are determined.
In accordance with Table N 22 of Federal Law N 123-FZ, based on the required class of structural fire hazard of a building, the minimum required fire hazard classes of building structures are determined.
It is necessary to take into account that fire safety requirements will be met only if the building structure meets both the required fire resistance limit and the required fire hazard class at the same time.
Accordingly, it is initially necessary, based on SP 2.13130.2012, based on certain parameters of the designed building (for example, the functional purpose of the building, the height of buildings or structures, number of storeys, floor area within the fire compartment, number of seats, etc.) to determine the required degree of fire resistance and the required class of structural fire hazard of buildings.
Further, in accordance with Table N 21 of the Federal Law of July 22, 2008 N 123-FZ, based on the required degree of fire resistance of the building, the minimum required fire resistance limits of specific building structures are determined.
In accordance with Table N 22 of Federal Law N 123-FZ, based on the required class of structural fire hazard of a building, the minimum required fire hazard classes of specific building structures are determined.
Further, based on certain minimum required fire hazard classes and minimum required fire resistance limits of specific building structures based on fire test reports or information on actual fire resistance limits and fire hazard classes given in the Collections “Technical Information (to assist the inspector of the State Fire Service)”, select a building structure.
Based on information only about the material from which the building structure is made, it is impossible to determine the actual fire resistance limits and fire hazard classes of building structures.
In accordance with clause 5.4.5 of SP 2.13130.2012, fire resistance limits and fire hazard classes of attic covering structures in buildings of all degrees of fire resistance are not standardized, and roofing, rafters and sheathing, as well as lining of eaves overhangs, may be made from combustible materials, with the exception of specially specified cases.
Gable structures may be designed with non-standardized fire resistance limits, while the gables must have a fire hazard class corresponding to the fire hazard class of the external walls on the outside.
Information about structures related to elements of attic coverings is provided by the design organization in the technical documentation for the building.
In buildings of I-IV degrees of fire resistance with attic coverings, with rafters and (or) sheathing made of combustible materials, the roof should be made of non-combustible materials, and the rafters and sheathing in buildings of I degree of fire resistance should be treated with fire retardant compounds of group I fire retardant effectiveness, in buildings of II-IV degrees of fire resistance with fire retardant compounds not lower than group II of fire retardant efficiency according to GOST 53292*, or perform their structural fire protection that does not contribute to the hidden spread of combustion.
In buildings of classes C0, C1, the structures of cornices, lining of eaves overhangs of attic coverings should be made from materials NG, G1, or these elements should be sheathed with sheet materials of a flammability group of at least G1. For these structures, the use of flammable insulation is not allowed (with the exception of vapor barriers up to 2 mm thick) and they should not contribute to the hidden spread of combustion.
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CODE OF RULES FOR FIRE PROTECTION SYSTEM - ENSURING FIRE RESISTANCE OF PROTECTED OBJECTS - SP 2-13130-2009 (approved by Order of the Ministry of Emergency Situations of the Russian Federation dated... Relevant in 2018
6. Determination of the required degree of fire resistance of buildings, structures, structures depending on their number of storeys, functional fire hazard class, fire compartment area and fire hazard occurring in them technological processes
The size of the building and fire compartments should be selected depending on the degree of their fire resistance, the class of structural and functional fire hazard.
When combining these indicators not provided for in this section, the floor area and height of the building are taken according to the worst of these indicators for the building in question of the corresponding functional fire hazard class, or special ones must be developed technical specifications In accordance with the requirements of Art. 78 N 123-FZ.
During design, construction, reconstruction, major renovation And technical re-equipment objects, in addition to the requirements of this Code of Rules, one should be guided by the provisions.
6.1. Industrial buildings
6.1.1. Fire resistance degree, structural fire hazard class, building height and 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 level 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 an ogre. | 5200 | 3500 |
| A | 36 | II | C0 | Not an ogre. | 5200 | 3500 |
| 24 | III | C0 | 7800 | 3500 | 2600 | |
| IV | C0 | 3500 | - | - | ||
| B | 36 | II | C0 | Not an ogre. | 10400 | 7800 |
| 24 | III | C0 | 7800 | 3500 | 2600 | |
| IV | C0 | 3500 | - | - | ||
| IN | 48 | I, II | C0 | Not an 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 an ogre. | 25000 | 10400 | |
| 30 | III | C1 | Same | 10400 | 7800 | |
| 24 | IV | C0 | -"- | 10400 | 5200 | |
| 18 | IV | C1 | 6500 | 5200 | - | |
| D | 54 | I, II | C0 | Not limited | ||
| 36 | III | C0 | Not an ogre. | 50000 | 15000 | |
| 30 | III | C1 | Same | 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. Height one-story buildings fire hazard classes C0 and C1 are 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 structural 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 | IN | 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 level of the building | Floor area, sq. m, within the fire compartment | |
| IN | 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 structural fire hazard according to Table 6.8.
| Fire resistance level of the building | Structural fire hazard class of the building | Maximum permissible building height, m | The largest permissible 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 may 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 of K0, regardless of the height of the buildings established in Table 6.8, but located no higher than 75 m. The enclosing structures of this floors must meet the requirements for the structures of the building being built on.
When using wooden structures, structural fire protection should be provided to ensure the specified requirements.
6.5.3. In buildings of I and II degrees of fire resistance to ensure the required fire resistance limit of more than R 60 load-bearing elements buildings, it is allowed to use only structural fire protection (cladding, concrete coating, plaster, etc.).
6.5.4. Load-bearing elements two-story buildings 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 of interior, including cabinet, prefabricated, 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 partitions of the 1st type and floors of the 3rd type without openings, in buildings of the 1st degree of fire resistance - by floors of the 2nd type.
<1>Public premises - in this section - premises intended for the implementation of activities in them to serve 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 and attached part must have a fire resistance rating of at least R 45 and a fire hazard class of K0. If there are windows in a residential building oriented towards the built-in and attached part of the building, the level of the roof at the junction points should not exceed the floor level of the residential premises located above the main part of the building. The insulation in the coating must be made of materials from the NG group.
6.5.8. Single-apartment residential buildings, including blocked ones (functional fire hazard class F1.4)
6.5.8.1. Blocked houses of structural fire hazard classes C2 and C3 must additionally be divided by blind fire walls of type 1 and a fire hazard class of at least K0 into fire compartments with a floor area of no more than 600 square meters. m, including one or more residential blocks.
6.5.8.2. Fire walls must cross all house structures made of flammable materials.
In this case, fire walls of the 1st type, dividing the house into fire compartments, must rise above the roof and protrude beyond external cladding walls by at least 15 cm, and when used in coverings, with the exception of roofing, materials of flammability groups G3 and G4 - rise above the roof by at least 60 cm and protrude beyond outer surface walls 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- not less than 1.2 m.
When the external walls of adjacent fire compartments adjoin at an angle of 136° or less, the area outer wall, forming this angle, with a total length of at least 3 m for adjacent fire compartments, must be constructed in such a way that it meets the requirements for the corresponding fire wall.
6.5.8.3. There are no requirements for fire resistance and structural fire hazard class for houses up to two floors high.
6.5.8.4. In houses with a height of 3 floors, the main structures must meet the requirements for the structures of buildings 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 external walls - RE 15, deckings without attics - RE 15, open trusses, beams and purlins of roofless roofs - R 15. Fire resistance limit interior partitions not regulated. The structural fire hazard class of the house must be at least C2.
For floor areas up to 150 sq. m, it is allowed to take the fire resistance limit of load-bearing elements at least R 30, for floors - at least REI 30.
6.5.8.5. Houses with a height of 4 floors must have a fire resistance class of at least III and a structural fire hazard class of at least C1.
6.5.8.6. The building structures of the house should not contribute to the hidden spread of fire. 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 room. Blind diaphragms should not be made of thermoplastic foams.
6.5.8.7. A built-in parking lot for two or more cars must be separated from other rooms 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 must be equipped with a seal in the recesses, a self-closing device and must not open into the sleeping area.
6.6. Public administrative buildings and administrative buildings manufacturing enterprises
6.6.1. Fire resistance degree, structural fire hazard class, permissible height buildings and floor area within the fire compartment for public administrative buildings and administrative buildings of industrial and warehouse enterprises (free-standing buildings, extensions and inserts) (class F4.3) should be taken according to table 6.9.
Table 6.9
| Fire resistance level of buildings | Structural fire hazard class | Permissible height of buildings, 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 IV degree of fire resistance with a height of two floors or more, 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, to ensure the required fire resistance limit of more than R 60 of the building's load-bearing elements, it is allowed to use only structural fire protection (cladding, concrete coating, plaster, etc.).
The use of thin-layer fire-retardant coatings on steel load-bearing structures in buildings of I - II degrees of fire resistance is possible provided that they are used for structures with a reduced metal thickness in accordance with GOST R 53295 of at least 5.8 mm. Application of thin-layer coatings for reinforced concrete structures possible subject to 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 accept the fire resistance limit of load-bearing building structures R 45, ensuring their fire hazard class K0 when separated from the lower floors by a fire-resistant ceiling of the 2nd type. In this case, the attic floor should be divided by type 1 fire partitions into compartments with an area of: 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. Fire partitions must 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.
Fire 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, the use of wooden structures with structural fire protection is allowed, ensuring their fire hazard class K0.
6.7. Public administrative buildings
6.7.1. The degree of fire resistance of canopies, terraces, galleries attached to the building, as well as other buildings and structures separated by fire walls can be taken one degree of fire resistance lower than the fire resistance degree of the building.
6.7.2. When equipping premises with installations automatic fire extinguishing The areas indicated in Table 6.9 may be increased by 100%, with the exception of buildings of fire resistance degree IV of fire hazard classes C0 and C1, as well as buildings of fire resistance degree V.
If there are open openings in the ceilings of adjacent floors, the total area of these floors should not exceed the floor area indicated 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 transitions between buildings must have fire resistance limits equal to the fire resistance limits of the enclosing structures of the main building. Pedestrian and communication tunnels must have a fire hazard class of K0. The walls of buildings in places where passages and tunnels adjoin them should be of fire hazard class K0 with a fire resistance limit of REI 45. Doors in the openings of these walls leading to passages and tunnels must be fire-resistant type 2.
6.7.5. In buildings above 4 floors as a translucent filling of doors, transoms (in doors, partitions and walls, including internal walls stairwells) and partitions, tempered or reinforced glass and glass blocks should be used. In buildings with a height of 4 floors or less, the types of glass-transparent filling are not limited. In buildings with a height of more than 4 floors, the doors of staircases leading to common corridors, doors of elevator halls and airlock vestibules must be solid or with reinforced glass.
6.8. Public buildings
6.8.1. The floor area between type 1 fire walls, depending on the degree of fire resistance, the class of structural fire hazard and the number of storeys of buildings, should be no more than that indicated in Table. 6.9, buildings of consumer service enterprises (F3.5) - in table. 6.10, trade enterprises (shops, F3.1) - in table. 6.11.
| Fire resistance level of buildings | Structural fire hazard class | Permissible height of buildings, m | Floor area within the fire compartment, sq. m, with the number of floors | |
| for one-story | for multi-storey buildings (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 fire walls can be increased by no more than twice.
3. When placing storerooms, service, household 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 fire walls can be increased by no more than twice as compared to that established in the 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 threads, located at a distance of 0.5 m and providing an irrigation intensity 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 air terminal buildings of the 1st degree of fire resistance, the floor area between fire walls can be increased to 10,000 square meters. m, if the basement (basement) floors do not contain warehouses, storerooms and other premises with the presence of flammable materials (except for luggage storage rooms and staff dressing rooms). Storage rooms (except those equipped with automatic lockers) and dressing rooms should be separated from the rest of the basement by type 1 fire partitions and equipped with automatic fire extinguishing installations, and command and control centers with fire partitions.
6.8.6. In airport 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 canopies, terraces, galleries attached to the building, as well as service and other buildings and structures separated by fire walls can be taken one degree of fire resistance lower than the fire resistance degree of the building.
6.8.8. In sports halls, halls of indoor skating rinks and bathtub halls of swimming pools (with and without seats for spectators), as well as in halls for preparatory classes swimming pools and firing zones of indoor shooting ranges (including those located under stands or built into other public buildings) if their area exceeds that established in the table. 6.9 fire walls should be provided between the halls (in shooting ranges - a fire zone with a shooting gallery) and other rooms. In the premises of vestibules and foyers, if their area exceeds that established in the table. 6.9 instead of fire walls, translucent fire partitions of the 2nd type 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 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 places where passages and tunnels adjoin them should be made of materials from the NG group with a fire resistance limit of R 120. Doors in the openings of these walls leading into passages and tunnels must be type 2 fireproof.
6.8.11. For the storage of explosive materials, as well as X-ray films and other flammable materials (liquids), separate buildings of at least II degree of fire resistance should be provided.
Storerooms of flammable materials (goods) and flammable liquids in public buildings and structures should be located near external walls with window openings and separate them with type 1 fire partitions and type 3 ceilings, providing entry through a vestibule-gateway.
6.8.12. The degree of fire resistance of bathhouse buildings and
6.8.19. Doors of storerooms for storing flammable materials, workshops for processing flammable materials, electrical switchboards, ventilation chambers and other fire-hazardous technical rooms, as well as storerooms for storing linen and ironing rooms in children's rooms 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, sleeping quarters must be located in blocks or parts of the building, separated from other premises by fire walls or partitions.
6.8.23. Floors above basements buildings of schools and boarding schools of III and IV degrees of fire resistance must be fire-resistant type 3.
6.8.24. Fire resistance degree, structural fire hazard class and greatest height 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, providing a fire resistance limit of EI 45, with the exception of buildings of fire resistance class V.
Fire safety is one of the key criteria that is primarily taken into account when assessing the condition of real estate. In Russia, the main standards that determine the degree of fire resistance of a building are dated July 22, 2008. In addition to “ Technical regulations on fire safety requirements”, included in the set of its provisions, specialists use “” SNiP. There is a great demand for the authoritative “RTP Handbook” for managers organizing firefighting.
Concepts and terms
The degree of fire resistance of a building is considered as a classification standard unit that demonstrates its ability to withstand the effects of flame in the event of a fire.
For determining power exponent any structure or its individual compartment, use the totality of building materials used in its construction.
They are established according to a number of physical characteristics indicating that those being tested at the test site material samples under the influence of high temperatures lost their quality features. When conducting testing, the time during which destructive changes in states occur is taken into account. The obtained data is recorded. Directories are formed from them, indicating the results with letter markings:
- R– the period of time during which the load-bearing capacity is lost;
- E– the period leading to a violation of integrity;
- I– destruction thermal insulation properties under the influence of increasing temperature;
- W– speed of propagation of the most dense heat flow.
The general picture of the possible danger of structures consists of a combination of functional and design features. Along with them, the standard values of the limit and degree of fire resistance of buildings, presented in the tables of the Technical Regulations, are also taken into account.
What problems do they solve?
Structurally, any structure is complex system, combining many elements made from various materials– metal, brick and others. Each component has unique properties and resists fire in different ways.
An example is the ancient wooden houses. Previously, in emergency situations, they flared up like boxes of matches and burned to the ground in almost minutes because they were not treated with special impregnations. In contrast, the walls of a stone house are more resistant to fire. They retain their contours because they have higher fire resistance, the degree of which, in this context, should be considered as a tool that allows comparisons, optimization of design costs, and prediction of the likelihood of ambiguous results.
Reference data on what degrees of fire resistance buildings have is extremely important both for workers in the fire industry and for operational services, builders performing renovation work, technical and forensic experts. It is on them that justice relies when determining guilt or exonerating administrators or subjects economic activity in controversial or criminal cases based on damage resulting from fire.
Assessment methods
In order to establish how much the object being inspected corresponds to the required level of fire safety, inspectors proceed by comparing two basic values:
- The required degree of fire resistance of a building is determined by the minimum permissible values included in the standards relating to:
- number of storeys;
- appointments;
- operational category for fire and explosion safety;
- size of areas for fire compartments;
- volume and capacity;
- absence or presence of installations designed to extinguish fire.
- The actual degree of fire resistance of a building is determined by actual values calculated by applying fire resistance limits, summarized information about which is presented in certificates of conformity, technical passports, and manuals. Refined indicators are obtained by conducting fire tests and performing professional calculations. When examining typical buildings, they are limited to experimental testing.
Important! The test results are considered satisfactory when the values obtained from the actual reports received are greater than or equal to the standards defining the required fire protection.
The procedure for conducting assessment surveys
In practice, employees of the fire inspection service or department, when considering a specific task, receive the information they are interested in on the degree of fire resistance from the technical passport and project documentation.
- applications to Tech. The regulations contain explanations on how to correctly determine the degree of fire resistance of a building using Table 21. You can see it in the figure.
The vertical structure of the table shows the fire resistance limits for all positions:
- building structures, including internal and external load-bearing walls, interfloor, attic, non-attic and basement floors, columns;
- staircases, taking into account flights and landings;
- floorings, thermal insulation and insulation elements.
All information is linked to the lines where the five main degrees of fire resistance provided for buildings are presented various types. The main factor determining one or another of them is the magnitude of the fire load.
Using the table is not difficult for a person who has minimal experience or knowledgeable about the theory. The symbols, REI 30, indicate that the time resource of objects caught in the fire zone is extremely limited to an interval of 30 minutes, regardless of the exact sequence in which destruction occurs:
- loss bearing capacity;
- integrity violations;
- loss of thermal insulation protection, etc., or vice versa.
However, not all so simple. In any case, they suddenly pop up hidden nuances, unaccounted moments. Let's look at an example of common mistakes associated with calculating the degree of fire resistance depending on the quality and composition of the floors.
Note! Many business owners pay large fines only because of annoying mistakes made by unprofessional calculations. Business people lose funds that could be invested in business development. To avoid unnecessary expenses not difficult. Contact specialists for. Rely on their competence. They will bring the object and documents into full order, and you will forget about the unpleasant moments associated with supervision and inspections.
Floor materials
In the business environment, there has historically been an opinion that all construction projects that have reinforced concrete floors belong to at least II degree of fire protection. In turn, wooden floors are positions from III and below. This is an example of a misconception that needs to be cleared up.
Let's consider correct order attributions. Let's turn to the table. 21 in the appendix to Techn. regulations. Its rows indicate the categories of fire resistance of buildings, and how to determine these indicators is indicated by the minimum tolerance limits given in the columns. Based on this, only one conclusion can be drawn: those belonging to rows II and III do not have differences in the values of the overlap limits. It is equal to REI 45 – in both positions. Why?
Obviously, the required value does not depend too much on the floor material. There are other structural elements. They are more meaningful.
The technique is outdated, the stereotype remains
Indeed, earlier attribution methods based on approximate design features, which determines the degree of fire resistance of a building according to SNIP 2.01.02-85, which allowed for an analysis of the condition, as if “by eye”.
This approach was considered dubious. It made it possible to independently set the bar for compliance. Which did not form an objective order of assignment to a certain category.
Absence necessary information introduced the RTP into difficult situations when choosing a fire extinguishing program. The 1985 standard was canceled back in 1997. Today, new clearly defined provisions are in force. However, the previously developed stereotypical thinking remained. Reinforced concrete panels are still recognized as an indisputable factor for classifying a building as II. In turn, they continue to mistakenly enter in line III or IV.
The degree of fire resistance of a building is the ability of a building to withstand fire for a certain time without collapsing.
Based SNiP 21-01-97* "Fire safety of buildings and structures", clause 5.18 Buildings and fire compartments are divided into degrees of fire resistance according to table 4. You can also find out the degree of fire resistance in the design documentation or in technical passport on the building.
To determine the degree of fire resistance of a building according to this table, it is necessary to know the fire resistance limit of building structures (load-bearing elements of the building, external non-load-bearing walls, ceilings, coatings, decking, trusses, beams, purlins, interior walls staircases, flights and landings).
Table 4
According to clause 5.10 According to the same SNiP, the fire resistance limit of building structures is established by the time (in minutes) of the onset of one or sequentially several signs of limit states, standardized for a given structure:
Loss of bearing capacity ( R);
- loss of integrity ( E);
- losses thermal insulation ability (I).
The fire resistance limit of structures can be determined by allowance("Manual for determining the fire resistance limits of structures, the limits of fire propagation through structures and flammability groups of materials" (to SNiP 11-2-80) Approved by order of the Kucherenko Central Research Institute of Construction and Construction of the USSR State Construction Committee dated December 19, 1984 No. 351/l), or find out from the manufacturer of materials and structures. To approximately determine the degree of fire resistance of a building, you can use the table from applications 2 To inactive currently SNiP 2.01.02-85* "Fire safety standards".
Appendix 2. Approximate structural characteristics of buildings depending on their degree of fire resistance
Appendix 2
Information
Fire resistance degree |
Design characteristics |
| Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete using sheet and slab non-combustible materials. | |
| Same. It is allowed to use unprotected steel structures in building coverings. | |
| Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete. For floors, it is allowed to use wooden structures protected by plaster or low-flammability sheet and slab materials. There are no requirements for fire resistance limits and fire spread limits for coating elements, while attic wood roofing elements are subject to fire retardant treatment. | |
| Buildings predominantly have a frame structural design. The frame elements are made of unprotected steel structures. Enclosing structures are made of profiled steel sheets or other non-combustible sheet materials with low-flammability insulation. | |
| The buildings are predominantly one-story with a frame structural design. Frame elements are made of solid or laminated wood, subjected to fire retardant treatment, ensuring the required limit of fire spread. Enclosing structures - made of panels or element-by-element assembly, made using wood or wood-based materials. Wood and other combustible materials of enclosing structures must be subjected to fire retardant treatment or protected from exposure to fire and high temperatures in such a way as to ensure the required limit of fire spread. | |
| Buildings with load-bearing and enclosing structures made of solid or laminated wood and other combustible or low-combustible materials, protected from fire and high temperatures by plaster or other sheet or slab materials. There are no requirements for fire resistance limits and fire spread limits for coating elements, while attic wood roofing elements are subject to fire retardant treatment. | |
| The buildings are predominantly one-story with a frame structural design. The frame elements are made of unprotected steel structures. Enclosing structures are made of profiled steel sheets or other non-combustible materials with flammable insulation. | |
| Buildings, the load-bearing and enclosing structures of which are not subject to requirements for fire resistance limits and fire spread limits. |
Based 7.9, SP 55.13330.2016 "Single-apartment residential houses." Updated version of SNiP 02/31/2001, the degree of fire resistance and the class of structural fire hazard are not standardized for one-story and two-story houses.
The degree of fire resistance of a building is the ability of a building to withstand fire for some time without collapsing. Based on this indicator, any structure can be assessed in terms of fire safety. It is the degree of fire resistance of the building that determines how quickly the fire will spread throughout its premises and structures. For obvious reasons, this indicator will largely depend on the materials from which the structure is built.
Determining the degree of fire resistance of building materials must be approached from the standpoint of whether they are flammable or not. Therefore, the standard classification divides them into “NG” - non-flammable or “G” - flammable. The latter are divided into several classes:
- G1 – low-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 ignite with great difficulty;
- B2 – moderately flammable;
- B3 – easy.
The next characteristic of the degree of fire resistance of building materials is the possibility or impossibility of flame spreading over its surfaces. This parameter is designated by the abbreviation “RP”. So:
- RP1 – do not spread the flame;
- RP2 – weakly spread;
- RP3 – moderate;
- RP4 – strong.
Attention! The “RP” indicator is determined only for floor bases and their coverings, 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 smoke and the toxicity of emitted combustion products affect the degree of fire resistance of a building. And it is right. But if a fire occurs, where the main task not only extinguish it, but also evacuate people in time, these two factors play an important role. Therefore, they must be indicated in the building’s passport.
Smoke content or the coefficient of smoke emission from 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 – moderate;
- D3 – large discharge.
According to toxicity during combustion, all building materials are divided into four groups:
- T1 – low danger;
- T2 – moderate;
- T3 – high;
- T4 is extremely dangerous for people.
Summarizing all of the above, we can conclude about the degree of fire resistance of building materials by saying that in SNiPs all of the above 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 class KM1 are representatives for which all the above-described characteristics have a minimum value. Accordingly, class KM5 – with maximum values. KM0 is a non-flammable class.
Having dealt with building materials, we move on to the fire resistance of buildings and structures. It is necessary to indicate that not all buildings have identical materials throughout the structure. That is, not always all construction projects use the same materials in each part (floors, rooms, etc.) Construction Materials. Therefore, the classification by fire resistance is considered conditional. But in any case, all construction projects are divided into three classes: fireproof, difficult to burn, combustible.
The degree of fire resistance of a building - how to determine. The calculation is based on the time from the start of the fire to the moment of destruction or the appearance of defects. Therefore, it is important to understand what defects in load-bearing structures can be taken into account in order to accurately say that the structure is at the limit of destruction.
- Through holes and cracks appear through which fire flames and smoke penetrate.
- The heating temperature of structures increases 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 levels, then this is a critical moment.
- The supporting structure becomes deformed, leading to collapse. This mainly concerns metal components and structures. By the way, unprotected steel profiles belong to the KM4 category. At a temperature of +1000C they simply begin to melt. “KM0” includes reinforced concrete products.
As for the speed and time of combustion, as mentioned above, everything depends on the materials from which they are built. Eg, concrete structure 25 cm thick burns in 240 minutes, brickwork in 300 minutes, metal structure over 20, wooden door(input, treated with fire retardants) for 60, wooden structure, lined with plasterboard 2 cm thick, burns out in 75 minutes.
Classification according to the degree of fire resistance of buildings, structures and fire compartments
All construction projects are divided into five degrees. And this indicator must be indicated in the building’s passport.
Attention! The degree of fire resistance of a building can only be determined by authorized services. They are the ones who give the assessment and 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 the structure.
| Class | Design Features |
| I | Objects built entirely from non-combustible materials: stone, concrete or reinforced concrete. |
| II | Structures that are partially used as load-bearing structures metal components. Brick houses also belong to this class. |
| III |
Buildings belonging to the first category, only in their structures it is allowed to use wooden floors, closed plaster solutions or gypsum boards. To cover wooden floors can be used here sheet materials, belonging to the group of “difficult to burn”. As for roofs, wood can be used here too, only with treatment with fire-retardant compounds. |
| IIIa | Frame houses from metal base(steel profiles), which have a low degree of fire resistance. They are sheathed with non-flammable materials. here you can use insulation made of fire-resistant material. |
| IIIb | Wooden houses or buildings made of composite materials, the basis of which is wood. Buildings must be treated with fire retardants. The main requirement for them is to build away from possible sources of fire. |
| IV |
Buildings constructed of wood, the structures of which are covered on all sides with plaster mortars, gypsum boards or other insulating materials capable of containing the effects of fire for some time. The roof must be fire protected. |
| IVa | Building structures assembled from steel profiles, not treated with protective compounds. The only thing is the floors, which are also assembled from steel structures, but using fireproof thermal insulation materials. |
| V | Buildings and structures that are not subject to any requirements regarding fire resistance, ignition rate, etc. |
Having understood the classes of fire resistance of buildings, it is necessary to identify the types of this characteristic. There are only two positions here: the actual fire resistance, denoted SO f, and the required resistance, denoted SO tr.
The first is the actual indicator of the constructed building or structure, which was determined based on the results of a fire-technical examination. The results are based on the table values shown in the photo below.
The second is the implied (planned) minimum value of the building’s fire resistance rating. It is formed on the basis regulatory documents(industry or specialized). This takes into account the purpose of the building, its area, number of floors, whether explosive technologies are used inside, whether there is a fire extinguishing system, etc.
Attention! When comparing 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 by degree of fire resistance must be taken seriously. Taking into account this indicator, it is necessary to determine the requirements for the fire safety system. And the lower the fire resistance limit of a building, the more investments will have to be made when organizing a fire protection system.
