A staircase is an integral part of buildings with multiple floors. In private houses, many craftsmen equip stair flights with their own hands, since the price for the services of professional companies is too high. However, along with the usual structures serving to communicate the floors, there are also evacuation ones, which are called smoke-free.
The presence of smoke-free stairs is dictated by the SNIP for a number of buildings, therefore, many architects, when designing a particular structure, are obliged to provide for them. In this article, we will look at the features and types of smoke-free staircases that exist today.
Modern stairs, based on the characteristics of their location in the building, are divided into 3 types:
- 1st, in which the staircase is in the staircase located inside the building.
- 2nd, the staircase is open, but at the same time it is located inside the building.
- 3rd - open and outside the building.
We are talking about structures designed for evacuation purposes..
In turn, they are of two types:
- Regular:
- L 1 - when the structure has open or glazed openings in the outer walls. They should be located on each floor.
- L 2 has open or glazed openings in the roof.
- Smoke-free.
Types of smoke-free stairways
First, let's take a look at what a smoke-free staircase is. Its difference lies in the fact that in the event of a fire, OFPs (smoke, fumes, etc.) do not penetrate into it.
Types of smoke-free staircases:
- Smoke-free staircase type H1. This design allows you to get directly into the building only through the balcony, which in this case is a smoke-free area. In other words, it will be impossible to get into the building through it. Thus, entering on any floor, a person will have to go through the balcony, which is an air zone, and only then he will get into the corridor, hall, etc.
- Smoke-free staircase H2. We are talking about a room with fire walls, where a continuous supply of fresh air is carried out by means of ventilation boxes in the type H2 structure.
- The design of the H3 type assumes that the stairs are located in the staircase, which can only be accessed by means of a tambour-sluice with fire walls. In this room, air is pressurized by means of ventilation boxes. Doors in such systems, as a rule, are made of fire-prevention ones, equipped with an automatic doorway.
Implementation of evacuation from smokeless cages
Doors leading from such staircases are evacuation doors, and therefore they must meet all the requirements of SNIP for smoke-free staircases, in particular SNIP 21.01.97 *, which states: the emergency passage must have a width of more than 1.2 meters, its height must be more than 1.9 meters. Such parameters refer to premises A 1.1, that is, when it comes to evacuating more than 15 people at the same time.
Advice!
It is necessary to provide for such a width of the opening that would be sufficient for convenient transportation of the stretcher with an adult.
In the event that the exits leading from the smokeless cages do not comply with the SNIP requirements, then such structures should be considered as spare, which can be used in case of evacuation.
Advice!
Those exits that do not comply with the SNIP and are considered spare are not considered as evacuation exits in the initial design, that is, in addition to them, the architect must provide full-fledged exits that meet the standards.
These outputs include:
- Exits to the balcony, which is open from all sides or from one side.
- To the transition that leads to the adjacent section of the building, which has class F 1.3.
- To the veranda / balcony, which is equipped with an outdoor one.
In turn, exits that lead to:
- From the premises located on the first floor of the building to the street. In this case, the exit should be carried out:
- Through the foyer or lobby.
- Through the corridor.
- Through the lobby.
- Through the corridor and lobby.
- From premises located on any floor, except for the first:
- To the stairs that lead to the street.
- To a corridor that ends with a type 3 staircase or smoke-free cage.
- In the foyer or hallway, which has an exit to the staircase or staircase belonging to the 3rd level.
- To the adjacent room, which is located on the same floor and has access to the street.
The following output options are allowed:
- Evacuation basement and basement exits should be provided in the lobby.
- From the foyer, dressing rooms, sanitary and smoking rooms, the placement of which falls on the basement or basement floors, the exit should be provided to separate stairs belonging to the second type, or the lobby of the first floor.
- Evacuation exits from premises for various purposes should be provided for type 2 stairs.
- The exit to the outside from the basement or basement floor can be equipped with a vestibule, including a double one.
Requirements for the width of marches
The width of the march for the stairs, which is intended for the evacuation of people from the building, must be at least:
- 1.35 m, if we are talking about buildings of class F 1.1.
- 1.2 m if there are more than 200 people in the building.
- 0.7 meters for stairs that lead to single workstations.
- For all other cases, the width of the flight of stairs should be up to 0.9 meters.
The tread width must be at least 25 cm with a step height of less than 22 cm. Otherwise, during a panic, the risk of injury to evacuees increases. The steps should never be too large or too small.
Some nuances
Instructions for arranging smoke-free stairs are based on the features of each of these structures.
Let's consider them in more detail:
- H1. If we are talking about buildings exceeding 30 meters in height, then in this case all stairwells of category H1, according to the regulations, must be smokeless. Each unit must be provided with natural lighting from the windows, in addition to which the span is equipped with an emergency source of lighting for the stairs.
The H1 type is excellent for high-rise residential and public buildings. Such a flight of stairs can be accessed from the vestibule or corridor through the open external air zone of the loggia, through the external passage, balcony or gallery. At the same time, the width of the air zone is at least 1.2 meters, and the width of the approach to this zone should be less than 1.1 meters.
Advice!
Such structures are best placed in the inner corners of buildings.
Remember that the distance from the staircase exits to the adjacent window must be more than 2 meters, which will ensure effective smoke-free air zone.
- Based on the requirements of SNIP 31.1, it is allowed to design sites of the type H2 and N3 in large cities for buildings with a height of 28 to 50 meters.
Advice!
These types of cages are also applicable to lower buildings that are residential or public.
Cell H "can be accessed by means of a corridor or an airlock, it is also possible to pass through the elevator hall, but only if the elevator is equipped with E130 class fire doors.
Smoke-free cages of the H2 type are distinguished by a device for pressurizing the air flow, which is supplied to the territory of the stairs in the event of a fire. It is advisable to delimit such cells vertically, creating compartments every 8 floors to reduce the volume of air, as a result of which an air pressure is created.
- Blocking the passage with personal belongings of residents (boxes, sports equipment, strollers, etc.).
- De-energize the fire panel equipped with a smoke protection system in the new house after acceptance by the fire department.
- Hang cables and wires other than those required by fire safety regulations.
- Cut through doors in blind partitions (fireproof).
- Forcing furniture, locking or clogging emergency exits and balcony hatches.
Requirements for fire barriers
SNIP 21-01-97 * specifies the following requirements for fire barriers:
- Such barriers are intended to prevent the spread of fire and combustion products from a room with a fire source to other rooms of the building.
- Fire protection barriers include walls, ceilings and partitions.
- Such barriers must be characterized by fire resistance and fire safety.
Fire resistance in this case is determined by the fire safety of such structural elements:
- Structures that are responsible for the stability of the obstacle.
- Structures that are supporting for a fire barrier.
- Fasteners.
- The enclosing part.
- Overlappings and partitions of the vestibule sluices should also be made fireproof.
Conclusion
Evacuation stairs are an integral part of any multi-storey building. In the event of a fire, they must ensure the safe exit of people in the building to the street, therefore, their correct arrangement is very important. You can glean all the useful information on this topic in the video in this article.
The most terrible element at all times was considered to be fire. Much water has flowed under the bridge since Prometheus taught people to use his benefits. But until now, the issue of fire safety is acute. A fire is especially dangerous in multi-storey buildings that simultaneously accommodate a large number of people.
Types of smoke-free staircases
Most fire victims die from smoke and carbon monoxide poisoning, which is why smoke-free escape routes are so important in this regard if a fire is suspected. The main routes of evacuation from multi-storey buildings were and remain flights of stairs. Building codes and regulations (SNiP) provide for the construction of smoke-free staircases of three types: H1, H2 and H3.
Smoke-free staircases are divided into the following categories by building codes:
- Н1 - stairs, the entrance to which is through an open space outside the building;
- H2 - staircases with additional air pressure;
- Н3 - staircases, the entrance to which is carried out through specially created zones with air pressure.
General requirements for smoke-free stairs
According to fire safety rules, all non-smoke stairs must be equipped with emergency lighting. The width of the doorway must be at least 1.2 meters, and its height must exceed 1.9 meters. Exits from the flights of stairs should not be arranged along the width of the span. If a smoke-free cage is arranged through a wall with an elevator shaft, then a ventilation hole is arranged in this wall at the level of the upper floor for free air access.
Personal belongings must not be placed in the passageways to smoke-free staircases and on staircases. It is forbidden to independently mount partitions not provided for by the construction project. Also, passages in existing fire bulkheads must not be cut.
Smoke-free staircases should be equipped with handrails made of non-combustible and low heating materials.
The device of smoke-free stairs of the first type (H1)
In buildings over thirty meters, in accordance with the "Building codes and regulations", staircases must be arranged according to the H1 smoke-free class. This type requires the construction of stairs, which can be accessed from the floor areas through the open air space. The design feature of such structures is that they are not directly connected to the floors of the building.
Usually, H1 cells are located in the corners of buildings and structures from the windward side and have balcony-type transitions, fenced with protective screens.
The passage can be performed in the form of a loggia or an open gallery, the width of the passage must be at least 1.2 meters. The width of the wall between the aisles, as well as the gap to the nearest window, cannot be less than two meters.
The width of the passage must ensure the transportation of people injured by the fire on a stretcher!
The device of smoke-free stairs of the second type (H2)
Ladders arranged according to the H2 type are recommended in buildings, the upper floor of which is located at a height of twenty-eight to fifty meters. The air backpressure in the H2 cells is arranged according to the stove draft principle and can be constant or open during a fire alarm. It is also possible to have an autonomous back-up device from air electric pumps.
The principle of operation of a smoke-free staircase (PD - pull ventilation system)
Electric pumps providing air pressure must be supplied with an uninterruptible power supply.
The thrust (or thrust) must be carefully calculated when designing the ventilation. The pressure should be such that any person can open the fire doors on the stairs. On the lower floor, the pressure on the door should be no less than twenty pascals, on the upper floor, no more than one hundred and fifty pascals.
Entrance to the stairways H2 is arranged through vestibules or sluices equipped with fire doors of the corresponding category.
It is advisable to arrange vertical partitions every seven or eight floors in smoke-free cages of the second category. The air supply is mounted in the upper zones of the resulting compartments.
The device of smoke-free stairs of the third type (H3)
A third type of smoke-free staircase also uses air pressure. The difference from the cages, arranged according to the H2 type, lies in the arrangement of special rooms for the passage of people with self-closing doors on closers. The dimensions of the premises must be at least four square meters. Air supply in cages of this class is carried out both into the space occupied by the stairs and into the airlocks arranged in this way. Air traction can be carried out on a permanent basis or automatically turned on during a fire or smoke.
Materials for making
The main material used in the construction of smoke-free evacuation passages is concrete. Concrete is fireproof, durable and easy to use. The use of steel structures, such as railings or doors, is an addition to the concrete base. Also, the use of metal spans can be justified in lightweight building structures.
The use of wooden elements is possible in small quantities, for example, wooden door handles or handrails, provided they are treated with fire-fighting compounds.
Other types of building materials are practically not used in the construction of smoke-free stairs.
Other types of evacuation structures
Other structures can be used as an alternative to smoke-free stairs. For example stairwells of category L1 and L2 with natural light through window openings.
Also, various outside residential and public buildings are arranged. In the event of a fire, evacuation is carried out along such stairs and fire-fighting equipment is delivered.
This article described in detail the construction of smoke-free staircases. Why are they needed, what are the varieties. In addition, the general principles of fire safety in relation to staircases are considered. Our site is dedicated to stairs and everything connected with them, so ask questions, suggest interesting topics for articles - our authors will fulfill any wishes of site visitors.
Jargon used in the design of building fire safety.
On the website of the VNIIPO EMERCOM of Russia, the opinion of the specialists of this institute is given regarding the use of the specified name in relation to stairwells of the H2 type, the exit to which goes through the vestibule-sluice with air pressure.
Considering that the EMERCOM of Russia periodically "cleans" the question-answer headings on its websites, we consider it necessary to cite this opinion here, with a link to the original source.
The question asked by VNIIPO EMERCOM of Russia:
VNIIPO's answer:
The use of the phrase "smoke-free staircases H2 + H3" is essentially a typical jargon that has nothing to do with the normatively established classification, but on a number of grounds contradicts the fire safety requirements. In particular, according to the provisions of the Federal Law of July 22, 2008 No.
№ 123-ФЗ "Technical regulations on fire safety requirements" fire-technical classification provides only three types of smoke-free staircases: Н1, Н2 and Н3.
Moreover, for staircases of the H2 type, smoke-free (or prevention of the spread of combustion products into their volumes during fires in buildings) is provided by forced-air smoke ventilation by supplying external air to these volumes to create excess pressure in them relative to rooms, corridors, halls adjoining on different floors. Floor-by-floor entrances to smoke-free staircases of type H2 are arranged through single or parallel doorways (it is allowed to arrange floor entrances through consecutive doorways in vestibules, provided solely according to the operating technology, but not for additional fire protection). In turn, for staircases of the H3 type, smoke-free is achieved by means of a device at all floor entrances of tambour-sluices, which are protected by forced-air smoke ventilation, which provides external air supply to one of such tambour-sluices (when leaving the floor on which a fire has arisen) from creation of excess pressure in it relative to adjacent premises, corridors, halls.
note
Thus, each of the considered established types of smoke-free staircases corresponds to a specific design of a separate staircase in conjunction with the space-planning elements of the building.
Consequently, the used symbolic addition "H2 + H3" is clearly meaningless: it physically combines various spatial structural elements - two separate staircases of different designs (while, according to the laws of algebraic addition, a casuistic non-existent type of smoke-free staircases - H5 is obtained).
In addition to the noted absurdity of physical perception, such an innovation of "smoke-free staircases of the H2 + H3 type" does not allow to fully implement the existing regulatory framework in all aspects of the use of smoke-free staircases in buildings for various purposes.
In this regard, even if we exclude from consideration the impossibility of the physical embodiment of this "innovation" and analyze only the forced combination of the principles of ensuring smoke-free, characteristic for both types of staircases, then regardless of the design features of the construction part of buildings, it becomes necessary to install entrances of non-smoky staircases of the H2 type of vestibule locks, protected by inlet smoke ventilation (graphic interpretation of this conclusion is given in Figs. 1 and 2).
At the same time, according to the current requirements of SP 7.13130, such use of vestibules on all floors is not required.
For example, when arranging an internal exit from a smoke-free staircase of the H2 type into the lobby of the lower floor of the aboveground part of the building (without dividing it into fire compartments), a standard separation of such an exit from the lobby by a vestibule is required, protected by inlet smoke ventilation (Fig. 3).
At the same time, on the overlying floors, an additional device of vestibule locks at the exits to the stairwell is not required.
In the case of dividing the building part of the building into fire compartments, the device of vestibules protected by supply smoke ventilation is necessary at the floor exits to the smoke-free staircase of the H2 type only on the floors of the lower fire compartments, while maintaining the usual single doorways on the floors of the upper fire compartment (like this shown in Fig. 4).
Thus, taking into account the noted features of the design of smoke-free staircases, it is necessary to unconditionally fulfill the current regulatory fire safety requirements in accordance with the established fire-technical classification - without any unreasonable, including jargon, "innovations".
Fire safety classification of staircases
Having visited the houses built according to the projects of various construction companies, you will notice that the stairwells in them are very similar and have only minor differences. The reason for this is the current safety standards introduced to maximize the prevention of casualties in the event of fires.
Standardization of these elements helps citizens to quickly leave the building, and firefighters and rescue teams make it much easier to fight fires, since they know the design in advance.
So what types of stairwells are there?
Depending on the presence or absence of insulation, conventional (L) and smoke-free structures (H) are distinguished.
Type L1
This type of staircase assumes its integration with the corridor leading to the apartments and the elevator. Lighting of stairways of this design occurs naturally through small glazed windows, or through openings on the walls facing the street.
Homeowners in such houses must show a responsible attitude to safety and not block possible evacuation routes. An important requirement is the ban on the placement of power cables in the stairwell, since their failure can turn the means of ensuring the safe exit of citizens outside into a trap.
There is a limitation in the use of such a structure: it can be used in buildings whose height does not exceed 28 meters (the indicator is determined along the floor line of the last floor). In practice, we are talking about houses consisting of no more than 10 floors.
Type L2
This design option, like the previous one, is not isolated from the corridors of the rest of the building. Its main difference from type L1 is lighting, which is carried out in a natural way through glazed or open openings in the coating (overhead lighting).
Staircase type L2 is approved for use in buildings with a height of no more than 9 meters. This is due to the fact that the only light source can be blocked by smoke, which can disorient citizens during the evacuation.
Type H1
In buildings with a height of more than 28 meters, it is imperative to use smoke-free staircases. This requirement is due to the fact that if using the usual structure for citizens evacuating from the upper floors, there would be a high risk of carbon monoxide poisoning. Another factor is the limited capacity of fire and rescue equipment.
The H1 type is most often found in high-rise buildings. It involves the separation of the staircase from the corridors near the apartments and elevators using an open passage, which is a loggia or balcony. In the event of a fire, smoke goes out into the street through the passage, without getting on the stairs.
H2 type
The design of the staircase H2 differs from the previous version in that the passage to it is closed.
Isolation from the source of smoke is provided by means of forced ventilation. It starts to work after receiving a signal from sensors that detect the presence of smoke and allows you to create an air pressure. In order not to create a dangerous draft of air from the fire source, the exit to the stairs is separated by sealed doors.
The ventilation system itself is located inside the staircase.
The structure H3 is distinguished into a separate type of staircase. However, it differs only in the location of the air pressurization system, which is located inside the transition.
Requirements for smoke-free staircases
Along with the safety standards that determine the design of the staircase, there are requirements related to its individual elements. And this is necessary because each of them can affect the overall effectiveness of the building's fire protection.
Fire doors
Regulatory requirements provide for the presence of fire barriers. Fire doors filling the openings are one of their elements. They must have the following properties:
- Metal outer part;
- Filler made of fire-resistant substances;
- Metal coating with non-combustible painting materials.
Fire door marking involves the use of the letters E, I together with a numerical value, where:
- E characterizes the loss of the integrity of the door, as a result of the formation of holes and cracks in it, through which flame or smoke penetrates;
- I denotes the loss of the heat-insulating function, at which a temperature effect occurs, destroying the surface of the door, which is not facing the flame.
- The numerical value determines the number of minutes after which the above changes will occur.
Dimension of stairs for evacuation
The current standards determine the dimensions of many elements of the staircase:
- The width of the flight of stairs;
- The slope of the stairs and the size of the steps;
- Height of the fence;
- The width of the landing.
The staircase must have a width not less than the same parameter of the exit (door) to it.
Separate requirements are established for buildings used as kindergartens, hospitals, institutions for the elderly and the disabled, as well as, if applicable, to accommodate boarding school students during sleep. The required march width in these cases is 1350 mm. This allows you to speed up the evacuation of these categories of citizens.
In the event that more than 200 hundred people simultaneously stay in a building on floors above the first, the width of the staircase should be 1200 mm. Such a solution will also speed up the evacuation, while minimizing the risks of crush and panic.
The slope of the stairs should be 1/1 and the minimum tread depth should be 250 mm. The riser should be no more than 220 mm high.
Ladders must be equipped with a guardrail (handrail), the minimum height of which is 1200 mm.
The staircase must have a width equal to the width of the flight of stairs. This is done in order to eliminate the bottleneck effect and panic caused by it.
Walls
The main requirement for the internal walls of a smoke-free staircase is the absence of any openings, except for the door.
In the case of using walls as one of the elements of fire barriers, they, like fire doors, must have fireproof properties. In this case, the parameter R is added to the indicators E and I, which characterizes the time of preservation of the bearing properties in the event of a fire.
Illumination standards and light aperture
The outer walls of the staircase must have windows with a glazing area of 1.2 sq. m. The distance from the staircase to the window cannot be less than 1.2 m. This is done so that natural light falls on the flights of stairs.
H1 cages are equipped with opening windows, while the height of the opening device cannot exceed 1.7 m.
Due to the presence of forced ventilation systems, the stairwells H2 are equipped with windows that cannot be opened.
Indoor open staircase
An internal open staircase is understood as a transition between floors located outside the staircase. If at least one side is missing a wall, then the staircase fits this definition.
Often this design is decorative and has limited evacuation use. The current regulations require a redundant outlet.
Double ladder
This design is based on the use of two symmetrical flights of stairs, which are directed towards a common area. This solution is becoming more widespread due to its decorative properties.
From a safety point of view, the structure should have a site and a subsequent single (if any) march, ensuring the minimization of congestion during the evacuation of citizens.
Smoke-free staircases (Н1, Н2, Н3) and fire escape stairs
The current level of development of scientific and technological progress does not in any way affect the existence of the fact that fire for thousands of years has been and remains one of the most dangerous enemies of the human dwelling.
Despite the widespread introduction of rules prescribing the use of exclusively non-combustible materials for interior decoration, the statistics remain inexorable: people's housing today is by no means invulnerable.
Often the only thing left for residents in the event of a fire is to flee, that is, to evacuate. The safest escape route from multi-storey buildings is fire escape stairs.
Fire is not the only danger for people in case of fire. Smoke is also dangerous. But the most terrible invisible enemy is carbon monoxide.
A person may not notice its effect (unlike ordinary burning, carbon monoxide has neither smell nor color). Carbon monoxide poisoning is fast-paced.
After a few minutes, the victim may lose consciousness, after which he has practically no chance of salvation.
Therefore, in every house, smoke-free staircases are necessarily equipped as the most important condition for rescuing residents during a fire. What types of smoke-free stairs and stairwells are there?
Stairs are an integral part of buildings
The staircase is an integral part of multi-storey buildings. A distinction is made between the usual structures serving to communicate the floors, as well as evacuation stairs, that is, smoke-free.
The presence of the latter is the most important condition for ensuring the evacuation of people in case of fire. For a number of buildings, it is dictated by SNIP, therefore, it is necessarily provided for by architects when creating a project of structures.
Evacuation ladders: purpose
Evacuation ladders must be present in high-rise buildings. Such structures ensure the safety of residents during a fire or in case of other emergencies.
Arrangement of escape stairs in various types of buildings is subject to certain standards regarding their size, configuration and location.
Regardless of the type of model, the general purpose of these structures is to ensure the safe exit of people from the building if necessary.
Residents of the house, employees and visitors of the institution, using the escape stairs, can leave the premises without danger to life and health. The evacuation exit is designed to protect them from fire and smoke. It is very important to ensure free access to it for everyone in the building.
Evacuation ladders can be used as an alternative exit from the premises. This is true for structures that are not equipped with a separate back door. Fire safety rules prohibit the operation of buildings above three floors that are not equipped with an escape ladder.
Location
Separate requirements apply to the location of the escape stairs. Usually their placement is designed at the back of public buildings or from the end, if an open-type exit is planned.
With the proposed arrangement of an emergency exit inside the building, a separate room or corridor is allocated for such a staircase. This is necessary in order to ensure the safety of people descending in the event of a fire and to prevent blocking of the often only possible exit from the house.
Such a room must be equipped with a fire-resistant door that is capable of holding back the flame for at least 1 hour. At the same time, it is important to ensure the sealing of the joints and the rapid removal of smoke.
Each floor must be equipped with an exit to the staircase. Its width depends on the size of the passage and steps. Semi-closed models provide for a location within the premises of the platform, the door from which leads to an external staircase. This is an excellent option for situations where it is not possible to completely isolate the passage from the smoke.
For open outdoor types, a special rule applies: the distance from the edge of the stairs to the wall must be at least 100 cm. This reduces the risk of fire entering the emergency exit and prevents heating of the structure and safety handrails.
Materials (edit)
Since this structure is intended for use in extreme situations, including in case of fires, certain requirements determine the choice of materials used for its construction. The main condition is to ensure the strength and fire resistance of the stairs. Therefore, the most popular materials are concrete and metal.
The use of materials that are highly flammable, crumble or release toxic substances when heated is strictly prohibited.
SNIP and GOST requirements
The GOST and SNiP standards regulate the norms according to which all types of stairs are established. They also apply to evacuation models.
- The standard slope of an escape staircase is such that the ratio of the lengths to the height of the span is 2: 1.
- For 1 march, the presence of 3-18 steps is permissible. For 2-march, their number should not exceed 16 pieces.
- The width of the tread should serve to ensure comfort of movement, the optimal size is 24-29 cm.
- The step height is usually 20-22 cm.
- The width of the stairs is provided by the requirements such that 2 people can simultaneously walk along it. The smallest permissible value is - 1 m. It is allowed to reduce the dimensions for external structures up to 70 cm.
- The area between the flights should correspond in size to the width of the stairs and the exit to it.
- To ensure the safety of evacuation from the building in the event of a fire, it is necessary to provide an exit to the stairs, which leads to an open space or to a separate room, protected from fire and smoke.
Classification
Evacuation ladders are classified by material type, location, and design features. There are three main types of modern escape stairs, which differ in characteristics such as purpose, width and configuration:
- located on special smoke-free staircases inside the building;
- is located inside the building, and is not fenced off by walls;
- located outside and is an emergency exit structure.
The latter is used exclusively for evacuation, while the first two types of stairs sometimes replace the main entrance.
About acceptable types of structures
For evacuation, straight flights are also used, equipped with intermediate platforms. In some cases, when there is not enough space for their location, vertical structures like firefighters are installed parallel or with a slight slope to the wall.
It is strictly prohibited
Fire safety rules prohibit the construction of stairs:
- with winder steps;
- with curvilinear and irregular spans;
- screw;
- with steps of unequal sizes.
What are smoke-free staircases?
The presence of such structures in the house is designed to ensure maximum safety of life and health of people in case of fire. They are marches of a certain size, which should be located in areas of the structure suitable for them.
One of the main requirements for an emergency exit is its isolation from smoke. Smoke-free staircases are distinguished by the fact that during a fire, OFP (fumes, smoke, etc.) do not fall into them.
The presence of these structures ensures successful evacuation of people in multi-storey buildings in case of fire. Various requirements are imposed on them depending on the specific type.
Types
Smoke-free staircases are divided into several types, which can be classified by their specific design features, location, access to them and principles of operation. Staircase types:
- The H1 is considered the base model. The design is characterized by the availability of access through an open area. It is necessary to have a smoke-free approach to the emergency exit.
- H2 is designed to provide air pressure in the event of a fire.
- Н3 is analogous to Н2, but provides for the exit to the march by means of a tambour-gateway. It also provides the same additional air pressure, which is supplied both during a fire and on a permanent basis.
Requirements
Fire safety in stairwells is ensured by rules that provide for the safety of a person's life:
- Emergency lighting is installed in all smoke-free staircases.
- The width of the doorway should be from 1.2 m, and the height from 1.9 m.
- The width of exits from the flights of stairs should not be narrower than the width of the span.
- When installing a smoke-free cage adjacent to the elevator shaft, a ventilation hole is arranged in the wall to ensure free air access (at the level of the upper floor).
- It is prohibited to place personal belongings in the passages to smoke-free staircases. The staircase should be uncluttered, as rubbish can become an obstacle to the evacuation of people and the work of firefighters.
- Independent installation of partitions not provided for by the construction project, as well as cutting passages in existing fire bulkheads, is prohibited.
- It is imperative to equip non-smoke staircases with handrails made of non-combustible and low heating materials.
Smoke-free stairs H1
“Building codes and regulations” state: in buildings, the height of which is more than 30 m, smoke-free staircases of the H1 type must be arranged.
This view requires the installation of ladders that can be accessed from the landing using the open air space for advancement. The location of H1 can be a veranda, a balcony or a fenced staircase outside the premises.
This is due to the need to provide natural isolation from the smoky part of the building of the evacuation exit. The best option for placing this type of staircase is the corner of the building. The most advantageous position is the inner corner, equipped with additional piers.
Their design feature is the lack of direct communication with the floors of the building.
The usual placement of H1 cells is in the corners of buildings on the windward side. They are characterized by the presence of transitions of a balcony type, as well as fences with the help of protective screens. The transition is carried out in the form of an open gallery or loggia, the width of the passage must be from 1.2 m.The width between the aisles, as well as the gap from the pier to the window, must be at least 2 m.
Smoke-free stairs H2
The staircase Н2 is located in a building, the upper floor of which is located at a height of 28-50 m. An air support is created in the Н2 cells (the principle of stove draft).
It can be permanent or it opens in the event of a fire alarm.
It is also possible to install an autonomous backpressure using air electric pumps that provide air pressure, which must be equipped with uninterruptible power supplies.
When designing ventilation, the thrust force (or back-up) must be correctly calculated. The pressure should ensure that the fire doors to the stairs can be freely opened. The pressure on the lower floor should be at least 20 pascals, on the upper floor - no more than 150 pascals.
The tambours or locks through which the entrance to the stairwells H2 is provided are equipped with fire doors. In smoke-free cells of this category, it is advisable to install vertical partitions with an interval of 7-8 floors.
Smoke-free stairs H3
The smoke-free staircase H3 is also built using air pressure. Their difference lies in the construction of special walk-through rooms with self-closing doors. Their dimensions must be at least 4 square meters. m.
In cells of this type, air is pressurized into the space occupied by the stairs and into special locks. Air traction is carried out on a constant basis or automatically turns on in case of fire or smoke.
Basic materials
When creating smoke-free evacuation passages, concrete is most often used. It is a fireproof, durable and easy-to-use material. Steel structures are used in addition to the concrete base, for example, in the manufacture of fences or doors. Metal spans are also justified in lightweight structures.
Wooden elements are used in small quantities: wooden handrails or door handles, which must be treated with fire-fighting compounds.
Despite the development of science, technology and technology, as well as scientific and technological progress, fire, like thousands of years ago, remains one of the main enemies of human habitation. It would seem that houses have long been built from bricks and concrete that are not subject to the fire element. Rules have been introduced everywhere, prescribing the use of only non-combustible materials for interior decoration, but inexorable statistics indicate that before the invulnerability of people's housing is achieved from fire, oh, how far away.
Requirements for fire safety of stairs and staircases
Often, all that remains for residents in the event of a fire is to flee, that is, to evacuate. Moreover, the routes of retreat (evacuation) are usually prepared in advance. It is dangerous to evacuate from a burning house using an elevator: if the fire barely touches the power cables of the elevator mechanics, and people will be walled up in a de-energized box.
The safest way of evacuation from multi-storey buildings is stairs. Building codes and regulations (SNiP) impose many serious requirements on the stairs of high-rise buildings, designed to maximize their safety in the event of a fire.
First of all, there is almost no finishing of the spans - cement plaster is painted with fireproof paint or chalk mortar. Particularly severe requirements are imposed on high-rise buildings (16 floors and above), because even the highest fire escapes and lifts cannot save the residents of the upper floors of such houses in the event of a fire.
But the danger in a fire is not only fire, but also smoke, as well as a terrible invisible enemy - carbon monoxide. The danger of the latter is that a person may not notice its effect (carbon monoxide should not be confused with ordinary fumes, carbon monoxide has no smell or color) until it is too late. Carbon monoxide poisoning develops rapidly, after a few minutes a person loses consciousness, after which he has no chance of salvation.
Therefore, the most important property of staircases and staircases of multi-storey buildings is their smoke-free.
Types of smoke-free staircases
Stairwells are divided into three types according to the method of achieving non-smoke - H1, H2 and H3.
Various smoke-free staircases are now integral elements of modern multi-storey buildings. Why? Because in the event of a sudden fire, they can become the only way to salvation. For structures of such a plan, there is a special classification. And this article describes the features of types H1, H2, H3, which need to be considered in more detail.
The main purpose of all smoke-free cells
The aforementioned staircases are flights of certain dimensions and are located in the most suitable zones of multi-storey buildings. Such structures should serve as emergency exits for people in specific buildings. First of all, we are talking about situations directly related to fires.
After all, significant smoke pollution of the upper space of buildings is a consequence of any fires, regardless of their scale. And many people die in such situations not from the flame itself, but from the extremely negative influence of all kinds of toxic fumes and smoke. Therefore, evacuation exits must be isolated from smoke.
However, this is not all. With the help of the stairs, the photos of which can be seen in the article, rescuers have the opportunity to get to the interior of the houses in order to quickly extinguish the fire and take the injured residents outside. These structures even allow people to be carried on stretchers in case of emergency.
Key varieties of unique designs
After watching videos located on different network resources, it becomes clear that all smoke-free cells are divided into three main types:
Standard requirements for such structures
Absolutely all non-smoke staircases must meet one hundred percent of certain mandatory requirements. Basically, they relate to both the dimensions of the entire structures and the dimensions of the marches themselves:
- The minimum height of the ceilings located in the areas where the marches are located must be at least 190 cm. Only in this way it will be quite convenient for the average person to move along the evacuation routes.
- Having studied the features of types H1, H2, H3, you can find out that the width of the passages in the so-called "air zones" should reach 120 cm. But the dimensions of the paths leading to them cannot be less than 110 cm, this is really extremely important. Indeed, in this way, completely unimpeded movement of two people is ensured and the transfer of victims on a special stretcher.
- The steps of the flights of stairs must have the same parameters. As for the slope, it usually does not exceed 40 degrees.
- A maximum of 18 ordinary steps can be located on one march, this is clearly seen in the photo below.
All kinds of fences made exclusively of non-combustible materials are considered mandatory elements of smoke-free structures. They allow not only to minimize the risk of injury to people, but also greatly facilitate movement.
Useful information about H1 cells
Various specialized videos perfectly demonstrate that high-quality H1 class smoke-free structures must be installed in buildings with a height of about 30 m. They are directly connected to the floors of buildings. And structures of a similar plan are located precisely in the corners of houses (from the windward side).
These staircases are equipped with balcony-type transitions, which are fenced off with reliable protective screens. Their width cannot be less than 1.2 m. But the dimensions of the walls between such passages must already reach 2 m.
What you need to know about constructions of class H2?
It is noteworthy that smoke-free staircases of the H2 type are mainly settled in buildings, the height of which ranges from 28 to 50 m.The list of their main features includes:
Although in such structures, they sometimes equip autonomous air supports from electric pumps. These devices are equipped with uninterruptible power supplies. But for this, it is necessary to very carefully calculate the thrust force even when designing mandatory ventilation.
Construction of smoke-free structures of the H3 type
Having considered the main features of the types H1, H2, H3, one can understand that the stairwells of the third class are still different from other structures. They are complemented by special areas intended for the passage of people, in which self-closing doors are installed on innovative door closers. Their dimensions must be at least 4 square meters. meter, not less.
Separately, it is worth mentioning the air pressure. At such structures, it is carried out not only in the space occupied by the stairs, but also in the existing locks. In addition, the backwater can be turned on automatically during fires, or it can be supplied on a permanent basis.
Materials used for the manufacture of staircases
Modern smoke-free structures, the photos of which are in this article, are created exclusively from materials that can resist heat well and do not ignite in direct contact with fire. For example, these include concrete. It is absolutely fireproof, and flights made from it have increased strength.
Sometimes metals are also used for cells of such a plan. However, these materials are used only in cases where it is simply not possible to build more massive structures. Craftsmen reinforce both the inner parts of the concrete flights and the fences with metal elements. All this is clearly visible in the video.
Why is it worth contacting our specialists?
In order for smoke-free staircases to perform their functions fairly well, they must be made only of the highest quality materials in accordance with all the rules. Using the services of our specialists, customers can easily purchase very beautiful, most reliable, and most importantly, really durable structures in Moscow at the lowest prices.
Experienced craftsmen create such structures in accordance with generally accepted requirements and norms. In addition, they always take into account the wishes of the clients during their work. That is why our designs are extremely popular today.