IIIa from SNiP 2.01.02-85* APPENDIX 2 Reference
SAMPLE CONSTRUCTION CHARACTERISTICS OF BUILDINGS
DEPENDING ON THEIR DEGREE OF FIRE RESISTANCE
1. Fire resistance level
2. 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
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-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

IIIa
Buildings predominantly have a frame structural design. The frame elements are made of unprotected steel structures. Enclosing structures - made of profiled steel sheets or other non-combustible sheet materials with low-flammability insulation

IIIb
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.

IV
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

IVa
The buildings are predominantly one-story with a frame structural design. The frame elements are made of unprotected steel structures. Enclosing structures - made of profiled steel sheets or other non-combustible materials with combustible insulation

V
Buildings, the load-bearing and enclosing structures of which are not subject to requirements for fire resistance limits and fire spread limits

Note. The building structures given in this appendix must meet the requirements of Table. 1 and other standards of this SNiP.

The highest degree of fire resistance is I (mausoleum).

During the construction of any building, the organization of emergency exits, evacuation routes in emergency cases, and the location of funds must be considered at the project stage. But these points can be considered only if you know the degree of fire resistance of the building. Difficulties may arise with this at present, since most often the same type of structures are erected in cities. But next we will try to understand how fire resistance is determined and what it depends on.

What is fire resistance?

This is the ability of structures and individual designs withstand the onslaught of fire without destruction or deformation. It is the degree of fire resistance of the building that will determine how quickly the fire can spread throughout the structure if a fire breaks out.

All indicators are determined taking into account SNiP. These standards make it possible to determine the level of not only the building, but also all the materials that were used during construction.

Classification by flammability

Fireproof.
Resistant to fire. They can be made of combustible materials, but which have a special treatment or coating on top. An example is wooden door, lined with steel or covered with asbestos.
Combustible. Have low temperature ignite and burn quickly when exposed to fire.

Basis for determining fire resistance

The determining basis for determining the degree of fire resistance of a building is the time that has passed from the moment of the fire to the appearance of the first noticeable defects. These include:

Cracks and damage to the integrity of the surface, which can facilitate the penetration of flame or combustion products.
Increasing the temperature of materials by more than 160 degrees.
Deformation of supporting structures and main components, which causes the collapse of the entire structure.

Buildings built from wooden structures have a low degree of fire resistance; reinforced concrete ones are considered the safest in terms of fire, especially if they contain cement with high level fire resistance.

Dependence of fire resistance on materials

The ability of a building to withstand fire largely depends on the materials from which it is built. They can be classified based on the following characteristics:

The degree of fire resistance of building structures depends on the time required for the material to deform:

Ceramic or silicate bricks begin to deform 300 minutes after the start of the fire.
Concrete floors, more than 25 cm thick, after two hours.
It takes 75 minutes for plaster-coated timber structures to begin to deform.
An hour will pass before the door treated with fire retardant begins to deform.
20 minutes of exposure to fire is sufficient.

The degree of fire resistance of brick buildings is quite high, which cannot be said about metal ones, which already turn into a liquid state at 1000 degrees.

Assignment of fire safety category

According to regulatory requirements, only after the structure has been assigned a certain fire safety category can the degree of fire resistance of the building be determined. And this is done based on the following signs:

Based on changes in thermal insulation performance when compared with the state before the fire.
According to the barrier effect, which eliminates the formation of cracks in structures.
By reducing the ability to perform load-bearing functions.

When determining the degree of fire resistance of a building, the area of the structure and the quality of all materials used must be taken into account.

Characteristics of degrees of fire resistance

Their determination is made on the basis of SNiP; resistance to fire of the main functional designs. Let's consider how many degrees of fire resistance of buildings and structures exist and what are their main characteristics:

Types of fire resistance

Special requirements for the ability to withstand fire are imposed on all building structures. The following indicators are important for them:

Ability to perform a load-bearing function.
Thermal insulation.
Integrity.

The safety of the building also plays an important role. Experts today divide the fire resistance of structures into two types:

Factual.
Required.

The actual degree of fire resistance of a building is the ability to withstand fire, which was determined during the examination. The criteria for evaluation are the existing regulations. For designs different types fire resistance limits have already been developed. This data is very easy to find and use for your work.

Required fire resistance is the indicators that a building must have in order to comply with all fire safety standards. They are determined by regulatory documents and depend on many characteristics of the structure:

Total area of the building.
Number of floors.
Purpose.
Availability of means and installations for extinguishing fires.

If during the inspection it turns out that the actual degree of fire resistance of buildings and structures is equal to or exceeds the required one, then the structure complies with all standards.

Fire hazard classes

To determine the fire resistance of the entire building, structures are divided into several categories, and buildings into several classes.

KO - non-fire hazardous. There are no materials in the premises that quickly ignite, and the main structures are not characterized by spontaneous combustion and combustion at temperatures close to 500 degrees.
K1 - low fire danger. Minor damage may be allowed, but not more than 40 cm. There is no combustion, no thermal effect occurs.
K2 - moderate fire danger. Damage can reach 80 cm, but there is no thermal effect.
K3 - fire hazard. Integrity violations of more than 80 cm, there is a thermal effect and fire is possible.

CO. All utility rooms, the main structures and stairs with openings correspond to the KO class.
C1. There may be minor damage to leading structures up to K1, and external ones up to K2. Stairs and openings must be in excellent condition.
C2. Damage to main structures can reach K2, external K3, and stairs up to K1.
C3. Stairs with openings are damaged up to K1, and everything else is not taken into account.

Rules for determining the resistance of a building to fire

It is not enough to know about the importance of fire resistance of buildings and structures; it is also important to be able to determine it. And for this there are some rules:

1. Testing a building requires having a plan at hand, and you will also need:

Code of Practice for Fire Resistance reinforced concrete structures.
Guidelines for Determining Fire Resistance Limits.
Manual for SNiP “Preventing the spread of fire.”

2. The fire resistance limit is determined by the time the structure is exposed to fire. When the structures reach one of the limits, the fire is stopped.

3. Before starting testing, you need to study the documentation for the building, which contains information about the materials and their approximate fire resistance.

4. It is necessary to pay attention in the documents to the existing conclusion on the application special technologies to improve fire safety.

5. A preliminary study of the building also involves consideration of all utility rooms, staircases and stairwells, attic compartments. They may be constructed from other materials or may have visible damage at the time of testing.

6. Modern architecture very often used in construction Newest technologies, which may affect strength and fire resistance. These points also need to be taken into account.

7. Before carrying out the fire resistance determination, it is necessary to prepare extinguishing agents, check the serviceability of the hoses, and call the fire brigade.

When all preliminary measures have been carried out, you can proceed directly to the practical determination of fire resistance.

Practical definition of fire resistance

When starting the practical part, it is important to take the architect's plan with you, even if it has been carefully studied. Further actions are:

An indicator of the fire resistance of a material will be the time of exposure to fire and the speed of its spread. For different buildings, this figure can vary from 20 minutes to 2.5 hours. The combustion speed is even less - from instantaneous to 40 cm per minute.

This is how the fire resistance of a building is calculated in practice.

Ways to increase fire resistance

It is not always possible to use only non-flammable or low-flammable materials during construction, so ways to increase their resistance to fire come to the rescue.

The most commonly used are the following:

If multi-component chemicals to increase fire resistance, it must be taken into account that some of them contain organic matter, which decompose at temperatures above 300 degrees, releasing toxic substances. Therefore, it is better to give preference to coating on mineral based with liquid glass.

It is not difficult to determine the fire resistance of buildings and structures. It is important to carry out everything preliminary preparations and we can consider that most of the work is done. The calculation can be considered more costly than complex. The most important thing is to be especially careful during testing and control the temperature in the oven.

The approach to the construction of any buildings and structures should be based on safety and different points vision. And not the last place here is Fire safety. In emergency situations, human lives depend on the resistance of the structure to fire.

Fires caused by humans have become quite common and widespread. Thousands of fires occur every year, causing a range of unpleasant consequences. Therefore, during the construction of structures great importance has a fire resistance rating for the building. Each constructed object is assigned a specific fire resistance number, according to the existing classification. Next, we will consider the classification in more detail and describe the parameters of each class.

What is the degree of fire resistance?

Fire resistance level of the structure	Fire safety class of the structure	Maximum permissible height of the structure, cm	Allowable floor S, cm2
I	Co Co Cl	7500 5000 2800	250000 250000 220000
II	Co Co Cl	2800 2800 1500	180000 180000 180000
III	Co Cl C2	500 500 200	10000 80000 120000
IV	Without rationing	500	50000
V	Without rationing

SNiP 31-01-03

This definition is understood as the ability of structures to restrain the expansion of the flammable area without the building losing its ability to further operate. The list of these properties consists of enclosing and load-bearing abilities.

If the structure loses bearing capacity- it will certainly collapse. It is by destruction that this definition is meant. As for the barrier ability, its loss is considered to be the level of heating of materials to the formation of cracks or holes through which combustion products can spread into adjacent rooms, or heating to the temperature at which the combustion process of the material begins.

The indicator of the maximum degree of fire resistance of structures is the time interval from the moment of fire formation to the appearance of signs of such losses (measured in hours). To test the performance of materials under fire conditions, a prototype is taken and placed in equipment for such experiments - a special furnace. In a kiln environment, the test item is subjected to high-temperature fire, which places stress on the material that is specific to the specific project.

The degree of fire resistance, when determining its limit, also depends on the ability to increase the temperature at individual points or the average value of the increase temperature indicators on the surface, which is compared with the original one. The structural elements of the structure made of metal have the minimum resistance to fire, and the maximum resistance is reinforced concrete, in the manufacture of which cement with cement was used. high performance fire resistance. The maximum fire resistance level can reach 2.5 hours.

Also, when determining the ability of a structure to withstand fire, the limit of fire spread is taken into account. It is equivalent to the extent of damage in areas that were outside the combustion zone. This figure can be 0-40 cm.

We can safely say that the degree of fire resistance of structures directly depends on the ability of the materials used in its construction to withstand high temperatures, affecting the surface in a fire environment.

According to the degree of combustion, materials are divided into 3 groups:

Fireproof (reinforced concrete structures, brick, stone elements).
Refractory (materials from the combustible group, the fire resistance of which is increased by treatment with special means).
Combustible (quickly ignites and burns well).

To classify materials, a special set of documents is used - SNIP.

How is it determined?

The degree of fire resistance is a representative of the most significant parameters of a structure, not inferior in importance to the design features in terms of fire safety and functional characteristics. But what should you pay attention to in order to determine it with utmost accuracy? To do this, you need to consider the following construction parameters:

Number of storeys.
Actual area of the structure.
Nature of the building's purpose: industrial, residential, commercial, etc.

To determine the degree of fire resistance (I, II, etc.) it is necessary to determine exclusively the regulatory documents and those given in SNIP. Also for such purposes and design high-rise buildings DBN 1.1-7-2002 is used, to determine the fire safety of multi-storey structures, 4 DBN V.2.2-15-2005 are used, and to become familiar with the fire safety requirements for structures with a large number of floors, 9 DBN V.2.2-24:2009 are used. Only the use of special documentation will allow you to obtain the most full information about the degrees of fire resistance of buildings with different design features.

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Classification of buildings and structures by fire resistance.

In assessing the fire safety qualities of buildings and structures, their fire resistance is of great importance.

Fire resistance is the ability of building structural elements buildings to perform load-bearing and enclosing functions in fire conditions for a certain time. It is characterized by fire resistance.

The fire resistance limits of facility structures must be such that the structures retain their load-bearing and enclosing functions throughout the entire duration of the evacuation of people or their stay in places of collective protection. In this case, fire resistance limits must be assigned without taking into account the impact of extinguishing agents on the development of a fire.

The fire resistance limit of building structures is determined by the time (hours) from the start of the fire until one of the signs occurs: a) the formation of through cracks in the structure; b) an increase in temperature on the unheated surface of the structure by an average of more than 140 ° C or at any point on this surface by more than 180 ° C compared to the temperature of the structure before testing, or by more than 220 ° C regardless of the temperature of the structure before testing; d) loss of load-bearing capacity of the structure.

The fire resistance limit of individual building structures depends on their dimensions (thickness or cross-section) and physical properties materials. For example, the stone walls of a building are 120 mm thick. have a fire resistance limit of 2.5 hours, and with a thickness of 250 mm the fire resistance limit increases to 5.5 hours.

The degree of fire resistance of a building depends on the degree of flammability and the fire resistance limit of its main building structures. All buildings and structures are divided into five degrees according to fire resistance (Table 32).

Table 32 Classification of buildings and structures by fire resistance.

Fire resistance degree	Basic building structures
Fire resistance degree	load-bearing walls, walls stairwells, columns	external curtain panel walls and external half-timbered walls	slabs, decking and other load-bearing structures of interfloor and attic floors	slabs, decking and other load-bearing structures of coverings	internal load-bearing walls (partitions)	fire walls
I	Fireproof (2.5)	Fireproof (0.5)	Fireproof (1.0)	Fireproof (0.5)	Fireproof (0.5)	Fireproof (2.5)
II	Fireproof (2.0)	Fireproof (0.25); fire-resistant (0.5)	Fireproof (0.75)	Fireproof (0.25)	Fire-resistant (0.25)	Fireproof (2.5)
III	Fireproof (2.0)	Fireproof (0.25); fire-resistant (0.15)	Fire-resistant (0.75)	Combustible	Fire-resistant (0.25)	Fireproof (2.5)
IV	Fire-resistant (0.5)	Fire-resistant (0.25)	Fire-resistant (0.25)	»	Fire-resistant (0.25)	Fireproof (2.5)
V	Combustible	Combustible	Combustible	»	Combustible	Fireproof (2.5)

Note. The fire resistance limits (h) are indicated in parentheses.

This division into degrees was introduced by SNiP II-A. 5-70, which gives nine notes to keep in mind when using the table.

When constructing important facilities, it is necessary to approach the choice of materials and technologies with great responsibility. One of important parameters is the ability of all components of buildings to withstand fire. How to determine the degree of fire resistance of a building, what factors influence the limit of this property? Only a specialist can answer these questions. It is thanks to the knowledge acquired during higher education educational institution, you can think through evacuation routes in advance, correctly position fire exits and do everything possible to ensure that the building and all its inhabitants are not harmed during a fire.

Currently there are many the latest solutions, used in architecture. That is why determining the fire resistance of buildings and structures causes some difficulties.

Safety in case of fire, the conditions for the spread of flame in them directly depend on the flammability and ability to resist fire of the materials that were used during construction and finishing. These qualities for building components are established during the design of the facility. Much depends on the fire and explosion hazard category of the premises located in a particular building. But first things first, so that you can high accuracy determine the degree of fire resistance of any structures.

What is meant by fire resistance rating?

Before answering the question of how to determine the degree of fire resistance, you need to understand what it actually is. This is an indicator that allows you to determine the possible resistance of a particular room to the effects of fire. It can be calculated according to the rules of SNiP. This general position, which makes it possible to give accurate assessment and establish the level of safety of a building for any purpose, as well as the materials from which it was constructed.

The fire resistance value determines how quickly a fire can spread in certain room. And this directly affects the safety of people. All types of buildings, depending on their resistance to fire and the speed of fire spread, are divided into 5 categories.

Rules for determining the fire resistance of buildings

To correctly determine the fire resistance of a particular structure (be it a residential building or industrial building), Must have:

architectural plan;
rules for ensuring the durability and safety of reinforced concrete structures from fire;
a manual that allows you to determine the limits for these parameters of structures to SNiP;
a guide to SNiP - helping to prevent the spread of a fire.

The durability limit of any construction project is determined by the time of exposure to fire on the tested structure. When the condition reaches one of the limits, the fire is stopped artificially. Before you begin testing, you must carefully study the construction documents. This includes what building materials were used, the characteristics of the building, possible estimates of fire resistance and other points.

It is necessary to more carefully study the presence or absence of application information in the documentation for the structure modern technologies, which could help improve fire resistance levels. During the period of preliminary consideration of the structure's design, all premises should be examined, including utility rooms, stairwells and others. It is possible that completely different materials were used during their construction. After all, builders often, in order to reduce the amount of the estimate, save when arranging utility rooms and staircases, which leads to a sharp decrease in their strength and resistance to fire. IN extreme situations It is these areas of the building that cause the fire to spread.

During construction modern buildings often architects use innovation. But in most cases certain areas are not as strong as the rest of the structure. Therefore, this point is important to consider. It is worth taking all the necessary measures in advance so that in the event of a fire you can quickly deal with the fire:

hire a fire brigade;
Check the serviceability of hoses and fire extinguishers.
equip a fire shield.

Only after all safety standards have been fully complied with can you begin work. After the preparatory activities, you can move on to the practical ones.

What is SNiP?

Often answering the question of how to determine the degree of fire resistance of a building, one has to come across such a definition as SNIP. But what is it?

"Building norms and rules" is a collection of legislative documents that were previously approved by the authorities of the Russian Federation and regulate the rules for the construction of urban and rural buildings. In addition, such a document includes projects developed by architects and engineering studies.

After carefully studying such paper, any owner will be able to independently understand all the drawings and determine the condition of the structures. In any situation you need to use special reference books. This is the only way to easily determine the 2nd degree of fire resistance of buildings or any other. This is precisely why special documentation is required.

But how to determine SNiP for a specific building using reference manuals and a passport for the building? Experienced specialists in this case, carefully read the code of SNiP (01.21.97) “On the safety of structures and buildings during a fire.” And in order to properly prepare for the tests, you need to carefully study another SNiP (03/31/2001), which describes in detail all the laws relating to the construction and operation of buildings in the Russian Federation.

What are the levels of fire resistance of buildings?

As we said earlier, there are 5 degrees of fire resistance, and they depend on the degree of fire and the resistance limit of the main structures. Below is a table of fire resistance of buildings and structures.

Degrees of fire resistance	Design characteristics
1 degree of fire resistance of the building	Buildings with load-bearing and enclosing structures, erected using artificial and natural stones, concrete or reinforced concrete using non-combustible types of materials in the form of sheets or slabs.
	Identical to grade 1, but only steel structures are allowed to be used in building coverings.
	Facilities with load-bearing structures and fences made of stone materials, reinforced concrete and concrete. Floors can be made of wood, protected on top with a layer of plaster, low-flammable sheet materials, or slabs. There are no special requirements for fire resistance limits for coatings, but in the attic everything wooden structures must be treated with special protective composition from fire.
	The buildings are mainly of frame type. All structures are made of unprotected steel. Fences made of steel profiled sheets and other sheet materials that are not afraid of fire.
	Mostly buildings on one floor with frame structure. The frame is made of wood, which has previously undergone special treatment to protect it from fire. Fences made of panels with element-by-element assembly, made of wood or materials. All wood structures must be reliably protected from high temperatures.
	Buildings with supporting structures and fencing made of wood and other flammable materials, which are protected from the effects of fire by a layer of plaster or materials in the form of slabs. There are no special requirements for ceilings. But the elements of the attic made of wood must undergo careful treatment with fire retardant compounds or materials.
	The buildings are mostly on one floor with wireframe diagram. The frame is made of steel, and the fence is made of profiled sheets or other elements with flammable insulation.
	Structures for which there are no special requirements for fire resistance and fire spread.

Types of fire hazards of building structures

All construction projects must meet the requirements fire safety. Determines the degree of fire resistance of a building under Federal Law 123, which specifies all the requirements and criteria. Today there are 4 classes of fire hazard for construction projects:

K0 - not fire hazardous.
K1 - low fire hazard.
K2 - moderately fire hazardous.
K3 - fire hazard.

When determining the fire resistance of buildings, it is necessary to take into account:

number of floors;
functional fire hazard;
area of the building and fire compartment;
fire hazard of processes taking place inside the building;
building category;
distance to the nearest buildings.

When all these factors are taken into account, determining fire resistance will not be difficult.

Objectives and scope of application of technical regulations

As mentioned earlier, it is impossible to determine the resistance of any structure in relation to fire without Federal Law 123, but in addition, it is necessary to take into account SP 2 13130 2012. The degree of fire resistance of buildings should be determined by:

design, construction, overhaul, during reconstruction, changes in functionality;
development, adoption and implementation of the Federal Law on technical regulations, which include fire safety requirements;
at the stage of developing documentation for protected objects.

If all these requirements are met, in the event of a fire you will not have to find out where the mistake was made.

Instructions for determining the fire resistance limit

Those who are about to start construction ask themselves one of critical issues: "How to determine the degree of fire resistance of buildings?" Using our instructions, anyone can complete this task. Even during registration project documentation the calculated indicator for each parameter is indicated. But it is better to check and compare all the data yourself, guided by SNiP. The limit for this property can be considered the time that passes from the beginning of the effect of fire on the structure until critical changes occur. The overall indicator is determined by the maximum resistance values. In this case, this must be taken into account for all elements: partitions, vertical design, which are load-bearing, doors, windows and others.

It is worth including information about the level of ignition into the calculation. building materials.

Analyze the entire building project in detail. Information about the main elements used in construction may not be enough to obtain more realistic data. Therefore, it is better to review everything and check it personally, examining each area, including utility rooms and stairwells. To study this entire mechanism in detail and carry out calculations correctly, you need to use the manuals for SNiP.

How can you improve the fire resistance of a building?

So that load-bearing supports can withstand a fire, and everyone who is in the building at that time can escape, there are several methods for increasing fire resistance. First of all, it is worth choosing the right materials that have been certified and fully comply with fire safety standards. Fortunately, currently construction market there are plenty of such raw materials. But people’s lives depend on skillfully and, one might say, professionally carried out measures to protect buildings from fire.

Today there is a huge variety quality materials European and domestic producers, with which you can provide fire protection.

How to carry out high-quality fire protection?

The best protection against fire is concreting and brick finishing. Another one important function- This is a strengthening of the structure. Brick is mainly used for vertically located structures; reinforcement of the concrete layer is also used. Its thickness is selected individually for each object. Cladding made of sheets, slabs and screens is used to protect columns, beams, and posts. It is also good to use plaster.

The finishing is good because it provides reliable protection from fire, but is also inexpensive. But it also has its drawbacks. Cladding requires special skills, and the thickness of the layer must be selected correctly.

Finally

It is not at all difficult to determine the fire resistance level of buildings 3 or 5. Difficulties, of course, may arise. But if you have everything at hand Required documents, a set of rules, then difficulties will be quickly resolved. After studying the plan and the condition of all building structures, determining fire resistance can be expensive, but not that difficult. The main thing is to adhere to safety precautions during testing, be careful and attentive, and control the temperature in the oven.

IN modern times With such a huge scale of construction, it is important that the fire resistance of buildings and materials from which residential buildings, offices and important institutions are constructed comply with the standards. The lives of citizens depend on it. It is no secret that many accidents occur as a result of the use of inappropriate materials and violations of construction techniques.