Modern construction has gained enormous momentum. Volumes and variations building materials allow you to have a fairly large choice, which the customer exercises in terms of profitability, comfort and economic costs. At the initial stage of design and construction of residential and industrial buildings, a dilemma often arises: which is better - reinforced concrete floor slabs or a monolith? Let's try to figure it out.
Both flooring options are popular and widely used. But due to many factors, each type has its own advantages and disadvantages.
For attic and single-story floors there is no need to use reinforced concrete slabs. Wooden or metal beams will be sufficient. Reinforced concrete slabs are used to cover multi-storey buildings, sports complexes, shopping centers, industrial buildings, cottages, and car garages. In addition, they are used in the construction of tunnels and heating mains. If we are talking about private construction, then we can definitely say that the choice should be made in favor of reinforced concrete floor slabs. Using a monolith in this case will lead to unreasonably high costs. Although, in the absence of the technical possibility of using slabs, of course, there will be no other option but a monolith.
Reinforced concrete slabs are divided into three groups - solid (monolithic), ribbed and hollow. Solid ones are not very practical; they are rarely used in construction due to their high mass. Ribbed ones are characterized by high strength and resistance to mechanical stress. They are mainly used for covering non-residential buildings, for example, hangars, industrial buildings, garages. Hollow ones have a low level of thermal conductivity and relatively low weight, which minimizes the load on the foundation. For residential buildings, as a rule, hollow core slabs are purchased. This type of flooring remains the most popular. The pricing policy will directly depend on the size of the product: the larger the slab, the higher the price. Hollow-core slabs, compared to other types of floor slabs, have a fairly reasonable price.
The advantage of floor slabs, however, is not only in price. When comparing quality characteristics, the monolith loses, since monolithic slabs are manufactured on site, and floor slabs are manufactured in a factory. Moreover, if there is a large area that needs to be covered, the monolith will not provide sufficient strength. Whereas hollow core slabs have high strength and can withstand up to 800 kg/m2 of flooring. Moreover, their weight is much less than other types of reinforced concrete slabs. They are quite sufficient for covering residential premises, urban and even industrial buildings. Another advantage can be considered the fact that for the installation of floor slabs you practically do not need unnecessary equipment and materials. Installation is carried out as follows: slabs are laid on a previously prepared cement mortar using a crane. The next step is to fill the seams between them. The whole process is not that labor-intensive and takes relatively little time.
A significant advantage is the availability of reinforced concrete floor slabs. Crushed stone and sand, which are used to make concrete, are quite popular and common materials. In almost every city you can find a production plant reinforced concrete products. Accordingly, high-quality factory-made, reliable materials protecting the reinforcement frame ensure the durability of the floor slabs. The disadvantages, perhaps, include the fact that for laying floor slabs you will need special equipment, which is not always available in private construction.
The technology for manufacturing monolithic slabs usually requires a relatively long time, additional tools and materials. It is worth considering that the concrete of monolithic floors hardens for at least 28 days, i.e. the installation speed will be low and the price will be high. When installing a monolith, you cannot do without making formwork, laying concrete, securing it with reinforcement, and installing supports. Agree, the process is labor-intensive. Reinforced concrete floor slabs, in turn, present difficulties when climbing the desired height. Sometimes pruning is required, which also increases time costs. Floor slab sizes are usually standard: the same length and width. This should be taken into account when creating a project, because they must correspond to the layout of the house.
The slabs are supported by opposite load-bearing walls on both sides. A balcony that is constructed using a floor slab extending beyond the outer wall is considered unacceptable. The fact is that the supporting area of the floor slab is right at the edge, and not in the center or somewhere in the span. In the future, under loads, this can provoke the collapse of the balcony. Yes, and in the cold season the slab will freeze not only outside, on the balcony, but also from the inside, indoors. Temperature changes will very quickly lead such a “structure” to dampness and the appearance of fungus.
It should be taken into account that in a prefabricated floor the monolith can be used partially, in some areas, for example, small places where the slab cannot be placed, ventilation shafts, etc. It is used in joints between slabs or between a slab and a wall. Also, sometimes there is a need for monolithic beam sections, monolithic sections on metal beams with a slab on top or bottom. Before constructing monolithic sections, reinforcement is carried out and formwork is installed. The diameter of the reinforcement is selected in accordance with the width of the section. For wide areas you will need larger fittings.
When making a choice between floor slabs or a monolith, you should also consider how reliable the load-bearing wall material is. For example, a cinder block has a weak load-bearing capacity, and the thickness brick wall in order to support the floor slab it must reach at least 24 cm. As a rule, a special “monolithic belt” is made in masonry walls under the floor slab. It is a reinforced concrete beam and is necessary in the places where the slab is supported, where the heaviest load is concentrated. The so-called belt is also used in areas with weak soil, which is deformed by moisture and subsides under the weight of the building, as well as in multi-story buildings.
The advantageous characteristic of the floor slab is the flat surface of the floor and ceiling, which is quite difficult to implement in the monolithic version. But monolithic floors also have advantages. With their help, the most daring ideas can be realized, planning non-standard premises, both its external outlines and internal parameters. For example, you can position the walls at your discretion, without adjusting to the placement of the prefabricated floor. Of course, in a monolithic ceiling there are also certain restrictions, in particular, in the distance between supports, which is not recommended to be exceeded by more than 6 m. Although, if conditions allow and there is an accurate calculation by a qualified specialist, then more is permissible. A good option would be to combine materials. At non-standard forms The ceiling walls can be partially made of a monolith, and, where possible, a prefabricated ceiling.
In places where close access to the object under construction is impossible, and only carrying concrete by hand is feasible, a big advantage will be the fact that when laying monolithic coatings you can do without special equipment.
Comparing the sound insulation properties of materials, it can be noted that the insulation performance of monolithic slabs is very low. If we consider specifically interfloor sound insulation, then the monolith in this case will act as a resonator that transmits all noise to the lower floors. Floor slabs, in turn, are characterized by high levels of sound insulation and thermal insulation.
In terms of strength, as one of the most important qualities, reinforced concrete floor slabs also have an advantage. The conditions for their manufacture are designed in such a way that the entire structure is protected from sagging and deflection. A special formwork, inside of which steel reinforcement is located in a state of high tension, ensures the integrity and reliability of the slab. Monolithic slabs lose significantly on this point, because the key to their strength is many more parts, which, even if all technologies are followed, will not give a 100% guarantee. Of course, reliable formwork and proper reinforcement play an important role in the quality of a monolithic floor. Often, large unevenness, which then has to be leveled with plaster, appears precisely because of formwork defects. The accompanying materials must be of high quality, and this, in turn, requires considerable financial costs.
In non-standard conditions, for example, in the event of a fire, a monolithic slab will behave as follows: bends and sagging will appear, the slab may “twist”. Floor slabs, namely hollow slabs, have the highest fire resistance rates.
To summarize, we can say that it is advisable to make a choice in favor of monolithic slabs only if it is not possible to use reinforced concrete slabs. These are buildings of complex shapes and small sizes. Otherwise, reinforced concrete slabs will be much more economical, more reliable and easier to install.
Installation of a monolithic floor slab
Installation of reinforced concrete floor slab
Provides sustainability not only reliable foundation, but also a system of durable floors. They are also necessary in any case in order to equip a basement or garage under it, and build a roof above it. Overlapping structures take up to 20 percent or more of all construction costs. Therefore, their installation is a very serious and responsible matter.
Installation of interfloor ceilings in a timber house
- Interfloor;
- Basement;
- Basement.
The greatest load in the house falls on the basement and basement. Their horizontal partitions must withstand the weight of kitchen equipment, as well as the heaviness interior walls dividing the first floor into an entrance hall and a dining room.
Scheme for arranging concrete interfloor slabs
In addition, they, together with the foundation, must ensure stable rigidity of the body made of any material: wood, brick, aerated concrete. For some, it rises above ground level. If it is heated, then the structure covering it is practically no different from interfloor devices.
The horizontal partition, designed to separate floors, has a relatively small load: its own weight, furniture, residents. It is important that for a comfortable stay it has good sound insulation. or this problem is not so acute. Moisture insulation and insulation are important for them.
Types of floors by material
- Wooden;
- Reinforced concrete;
- Metal.
However, in some cases, when building a house, you can do without them, because according to the structural design, the following types of floors are used:
Some ceiling systems are supported on horizontal beams. They are not required for the installation of other beams; slabs of the required sizes ordered at the factory are sufficient. They are laid in the house using lifting equipment. And monolithic floors are poured directly on the construction site. Prefabricated monolithic devices between floors are a combination of beam supports and a concrete monolith.
Coffered horizontal structures are usually used for arranging the ceiling. On their lower side there are ribs that make up rectangles, which together resemble the surface of a wafer. They are used very rarely in private housing construction. A tent roof is a flat slab bordered by ribs. Usually one is enough for the ceiling of the entire room, to the size of which it is made. 
Arched devices are necessary when it is necessary to cover the shaped spans of houses. In private one and two-story houses aerated concrete slabs are used. The overlapping structure made from it has very good sound insulation and retains heat for a long time, so additional insulation in interfloor partitions may be unnecessary. The material is light, odorless, and does not emit any fumes or harmful substances.
Its fire resistance is also very high. But it needs effective waterproofing, as it absorbs environmental moisture well.
In construction practice, mixed partitions are used various materials. Wooden beams are reinforced with metal to increase strength. U monolithic structures A variety of permanent formwork is used. Sometimes their main part is hollow concrete panels, and the ceiling semicircular bay window– aerated concrete slabs, which can be easily given any shape and thickness using a hand saw.
Option for aerated concrete block floor construction
This variety of materials expands the architectural capabilities of ceiling devices, their sound insulation and insulation.
Requirements for floors
General requirements apply to all interfloor devices:
- Strength is the ability to withstand the weight of all building elements.
- Rigidity that allows you not to bend under the weight of your own weight or heavy things on the floor.
- Effective thermal insulation and sound insulation of floors.
- Fire resistance, which is characterized by resistance to fire for some time.
- Service life corresponding approximately to the time of use of the entire building.
Wooden beams
In construction country houses Solid larch or pine beams are widespread. They are used for the installation of floors 5 m wide. And for large spans, glued ones are used, the strength of which is much higher.
Installation of floors made of wooden beams
Rounded timber is a wonderful building material for floors. It is laid with the north side down, identifying it at the end by the density of the growth rings in the wooden log. In Rus', huts have long been built with the stronger side of the round timber facing out.
A wooden I-beam has high strength. Its profile is the letter “H”, glued together in the factory from three parts. Some craftsmen assemble it in a home workshop or in the country. Interfloor partitions using them provide effective insulation and excellent sound insulation.
Scheme of the construction of wooden floors made of logs
They are very convenient not only for lining the ceiling, laying insulating materials and laying the subfloor, but also for installing all communications. The niches in the I-beam seem to be specially designed for hidden installation of water supply pipes, gas pipelines and electrical wires.
Wooden beams are used in almost any low-rise dwelling: wooden, block. But most of all they are suitable for buildings made of aerated concrete blocks. This material is porous, inferior in strength to all others and cannot withstand the point load of load-bearing beams. Since wood is not heavy, aerated block walls can easily withstand its weight. Installation of the overlapping structure is possible without the use of complex technical means. And it will cost the developer relatively inexpensively.
Laying wooden beams
Builders are aware of the shortcomings of wood and try to reduce them to a minimum. Before installing the ceiling, all wooden parts are treated with antiseptics to prevent rotting and damage by insects. The places where timber beams come into contact with brick, concrete slabs and aerated concrete blocks are insulated with various materials.
And in order to increase fire safety, the wood is treated with solutions that do not allow it to flare up immediately when an open fire appears.
Installation of interfloor structures begins with pre-prepared load-bearing beams. They are laid parallel to the short wall of the home. The laying step depends on the width of the span, but on average it is 1 m. Next, you will need simple materials that provide insulation, and you cannot do without the following tools:
The process of laying a wooden floor from beams and boards
- saws;
- hammer;
- assembly knife;
- roulette;
- construction stapler.
The beams are reinforced with anchors in the niches of the brick wall. But before laying, they make an oblique cut at the ends of the timber and impregnate it with an antiseptic. The area of contact between the wood and the brick is tarred and wrapped in roofing felt. The ends of the supports in the niches must be tightly closed. The cracks can be eliminated with polyurethane foam.
Then floor joists are laid on the supporting beams, and rubber pads are placed under them to reduce the vibration of the structure. The ceiling is lined underneath. Attic and basement ceiling systems require insulation. Interfloor partitions can do without it, but good sound insulation is required.
The intended purpose of the ceilings can be between floors and attics. They can be made of wood or reinforced concrete (monolithic and prefabricated). The type of flooring must be selected in accordance with the type of house, as well as the purpose of the floor itself.
The design of the floors must take into account the calculated permanent and temporary loads. On a permanent basis design load the dead weight of the structure is included, including coating materials and insulation.
Temporary (variable) loads are the weight of furniture, boiler, plumbing and other equipment, as well as people in the room. If we are talking about permanent stone houses, then their interfloor ceilings are usually made of reinforced concrete.
Wooden structures are used, as a rule, in the construction of attic floors and interfloor ceilings wooden houses. When calculating temporary loads, it is necessary to take into account that the load on basement and interfloor floors is on average twice as high as the load on attic floors.
Reinforced concrete floors
This type of flooring is used only in those houses that are built of brick, stone or concrete. An important advantage of reinforced concrete floors is their very high load-bearing capacity. These floors require additional insulation, since they have a low level of thermal insulation and a high level of sound permeability. Depending on the manufacturing method, there are monolithic and prefabricated floors.
Factory-produced slab floors made of prefabricated reinforced concrete have a calculated load-bearing capacity, their nomenclature is provided for by the project. Thanks to the use of such overlaps, it is possible to significantly reduce the time construction work, save costs.
Precast concrete factories produce a wide range of slabs:
- solid,
- hollow,
- made of heavy and light concrete.
Today, hollow core slabs are the most popular. This is facilitated by their low cost and better performance in terms of heat retention and sound insulation. In addition, hollow products have less weight, i.e. there will be less load on the foundation and load-bearing walls.
To install these prefabricated floors, it is necessary to use specialized lifting equipment. The slabs are laid on a bed made of sand cement mortar. The bed is placed in those places where the ceilings will rest on load-bearing walls.
Leveling the slabs
The alignment of the slabs when installing interfloor ceilings is carried out along the lower surface, while drawing the horizontal line using a level, level or spirit level. The support on load-bearing walls must be at least 12 cm - 14 cm. If the slabs have prestressed reinforcement, then they should be supported only on the ends (support by the middle of the surface and the side edges of the slab is not permissible).
If the construction site is not equipped with lifting equipment, i.e. installation of prefabricated slabs is impossible, then monolithic reinforced concrete floors are created.
Monolithic type ceilings
Monolithic type ceilings are slab, beam, ribbed and with liners. These floors are made directly on site, cast into specialized formwork.
Since monolithic floors are a very important structure, they must be manufactured strictly according to the design and by qualified craftsmen.
Most often, a monolithic slab floor is used. The areas where this structure is supported on load-bearing walls must be at least 10 cm and at the same time exceed the thickness of the slab itself. The reinforcement cage is placed from the bottom of the slab (in the tension section of the structure).
The ends of the reinforcement should be located at a distance of 3 cm - 5 cm from the formwork. When making monolithic consoles, the reinforcing layer is placed on the top of the structure.
For a monolithic floor, the maximum span length should not be more than 3 m. If the distance is greater, then a monolithic beam floor is used. In this design, reinforced concrete beams are installed and the outlets of the reinforcement of these beams are connected to the reinforcement of the monolithic slab.
On load-bearing walls, the support of the beams should be at least 20 cm - 25 cm. The cross-section and installation pitch of the beams is indicated by the project. Reinforced monolithic belts are created along the load-bearing walls, and beams are attached to them with anchors.
Technology for making monolithic floors
The design of monolithic floors with liners is rarely used today. The technology for making such floors involves placing ceramic liners of various shapes in the gaps between the load-bearing beams.
During the production of a monolithic ribbed floor, the liners serve as formwork for the slab and ribs. The disadvantages of this design are the complexity of implementation, as well as high level sound permeability.
Wooden floors
The advantage of wooden floors is their ease of assembly, which does not require the use of specialized mechanization. In addition, such floors have excellent thermal insulation properties. The load-bearing capacity of wooden floors is ensured by wooden beams.
The cross-section of the beams is calculated taking into account the total magnitude of the loads, as well as the span length between the supporting walls. Beams are made of glued or solid timber. On small spans, paired, pre-fastened beams from boards of at least 50 mm can be installed.
The ends of the beams must rest on load-bearing external walls. If we are talking about long-span structures, then the middle part of the beams is additionally supported by load-bearing internal walls. Lay the beams to the center from the edges, setting the step according to the calculations for the project.
The step size can only be changed to a smaller size than the value planned by the project. The position of the outer beams in mandatory verified using a level or building level. Intermediate beams can be aligned along the rail or along the thread. All wooden structural elements are treated with antiseptics and fire retardants.
Installation of floors in a stone house
If wooden floors they are arranged on stone walls, then the beams are tarred or wrapped in roofing felt before being embedded in the wall. In the process of supporting beams on load-bearing external walls, the gap between the end of the beam and the wall is laid with mineral wool insulation.
In this case, it is necessary to leave a ventilation gap - this will prevent the formation of condensation on the wood. The beams are attached to the walls using anchors that are embedded in brickwork or monolithic reinforced concrete belt.
Installation of floors in a log house
If the overlap is arranged in log house, then the beams are tightly cut between the crowns (no additional fastenings are used). If the ceiling is erected in a frame building, then the beams are supported on the frame, secured with staples, pins or nails.
In order to save heat and provide sound insulation, the space between the beams is filled with insulation. They do it this way: sheets of glassine are laid over a continuous boardwalk, then thermal insulation material is placed or poured onto the glassine.
What the cross-section of the beams should be can be found out from specially designed tables.
When installing wooden floors, special attention must be paid to the passage of chimney, stove and boiler pipes through the floor. The distance between the pipe and the wooden structural element must be at least 25 cm. A heat-insulating gasket must be installed around the pipe itself. For this, sheet basalt or asbestos is used.
Floors made of precast reinforced concrete (floor slabs).
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Today, reinforced concrete slabs are the most commonly used type of interfloor slabs. According to their load-bearing capacity, they are divided into three main groups: Load-bearing capacity: 400 kg/m2 or 4 load Load-bearing capacity: 600 kg/m2 or 6 load Load-bearing capacity: 800 kg/m2 or 8 load Currently, slabs with load-bearing capacity are mainly produced capacity of 800 kg/m2, with very rare exceptions you can find 600 kg/m2 and not 400 kg/m2 at all. And at the same time, there is SNIP 2.01.07-85 “Loads and Impacts”, which determines the necessary and sufficient load-bearing capacity of floors depending on the type of premises. In accordance with SNIP (clause 3.11 table 3), the load-bearing capacity of the floors of an apartment in a residential building is 150 kg/m2, and the largest value is 500 kg/m2 and is reserved for book depositories, archives, stages of entertainment enterprises, stands for standing spectators, as well as for premises for raising cattle. Now let's figure out what a load-bearing capacity of 800 kg/m2 means in relation to the house in question. Let's take as an example the most loaded room, namely the Kitchen-Living Room (with an area of 27.3 m2). When using reinforced concrete slabs, the load-bearing capacity of this room will be: 27.3 m2 * 800 kg/m2 = 21,840 kg, if we subtract the weight of furniture and interior elements from this value (maximum 500 kg), we will get a residual load-bearing capacity of 21,340 kg. Now let's determine how many people can withstand such an overlap with an average person weighing 100 kg. Number of people = 21,340 kg / 100 kg = 213 people! It is clear that such a number of people simply cannot fit in this room. If we talk about the possibility of this room from the point of view of the people present, then this is no more than 20 people at “peak” load. In other words, you will get a safety factor of 10! In civil engineering, the safety factor does not exceed 0.5, and for military designers/builders it does not exceed 5! |
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In fact, by using reinforced concrete slabs, you get high load-bearing capacity, the value of which exceeds the standard by 5 times! In this case, under no circumstances will you use the high load-bearing capacity “for its intended purpose,” since there is not enough room area to place a significant load on it. From the point of view fire safety, sound insulation, thermal insulation, the version of reinforced concrete slabs does not stand out in any way compared to other types of floors. It is based on the above that the bearing capacity standard for apartments in residential buildings is set at 150 kg/m2. If we carry out similar calculations, but in accordance with the standard value, we get: 27.3 m2 * 150 kg/m2 = 4,095 kg, if we subtract the weight of furniture and interior elements from this value (maximum 500 kg), we get the residual load-bearing capacity 3,595 kg. Now let's determine how many people can withstand such an overlap with an average person weighing 100 kg. Number of people = 3,595 kg / 100 kg = 36 people! It is clear that such a number of people simply cannot fit in this room. If we talk about the possibility of this room from the point of view of the people present, then this is no more than 20 people at “peak” load. In other words, you will get a safety factor of 1.8! Let me remind you that in civil engineering the safety factor does not exceed 0.5, and for military designers/builders it does not exceed 5! That is why the standard of 150 kg/m2 is sufficient for normal operation of residential premises! P.S. When designing lightweight, economical LVL timber floors, we set a load-bearing capacity of 180 kg/m2, thereby slightly exceeding the standard and obtaining a safety factor of at least 2! |
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Calculation of costs for installing precast reinforced concrete floors over a cold underground using floor slabs of the PNO series. The calculation also includes materials for thermal insulation and leveling the base for finishing the floor.
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1. PNO slab 1m2/ 1125 RUR 2. Mortar for joints M200 0.126tn / 315 rubles 3. Leveling screed M200 thickness 50mm 0.100tn / 250 rub. 4. Extruded foam 5. Vapor barrier film 1m2 / 22 rubles 6. Reinforcing mesh 200x200x5mm 1m2 / 60 rub. 7. Leveling screed M300 thickness 50mm 0.100tn / 260 rub. 8. Finishing screed 5mm 0.0075tn / 203 rub. Total cost of materials for 1m2 = 2,969 rubles |
1. Installation of PNO slabs 1m2 / 600 rubles 2. Concreting slab joints 1 piece / 288 RUR 3. Performing a leveling screed M200 thickness 50mm 1m2 / 400 RUR Total cost of work for 1m2 = 2,488 rubles |
Total materials and work for the installation of prefabricated reinforced concrete floors: 5 407-00 rub/m2.
Floors made of monolithic reinforced concrete.
Scope of application: Interfloor ceilings in construction.
We calculate the costs of constructing 1 m2 of floor structure.
Calculation of costs for installing a monolithic concrete floor over a cold underground. Besides the material load-bearing structure The calculation also includes materials for thermal insulation and leveling the base for finishing the floor.
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1. Ready-mix concrete B 25 1m2/ 880 RUR 2. Reinforcement (12mm and 6mm) 0.02t / 500 rub. 3. Extruded foam listyrene, thickness 150mm 0.150m3 / 734 RUR 4. Vapor barrier film 1m2 / 22 rubles 5. Reinforcing mesh 200x200x5mm 1m2 / 60 rub. 6. Leveling screed M300 thickness 50mm 0.100tn / 260 rub. 7. Finishing screed 5mm 0.0075tn / 203 rub. 8. Rent of formwork for a month 1 unit / 400 rubles Total cost of materials for 1m2 = 3,059 rubles |
1. Installation / dismantling of formwork 1m2 / 600 rubles 2. Installation of arm. frame 0.02t / 200 rub 3. Laying concrete taking into account cost of a concrete pump 1m2 / 580 rubles 4. Laying extruded foam listyrene, thickness 150mm 1m2 / 100 RUR 5. Laying vapor barriers. films 1m2 / 100 RUR 6. Installation of reinforcing mesh 1m2 / 150 rubles 7. Performing a leveling screed M300 thickness 50mm 1m2 / 600 RUR 8. Performing finishing screed 1m2 / 200 rubles Total cost of work for 1m2 = 2,530 rubles |
Total materials and work for installing a monolithic floor: 5,589-00 rub/m2.
Floors on wooden beams.
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| Below is a calculation of the costs of installing a floor using classic edged lumber - wooden beams. The span between the supports is considered to be 4.7 meters. To costing materials for thermal insulation and leveling the base for finishing the floor are also included. Wooden elements of the rafter structure are made of wood coniferous species with humidity no more than 20%, pre-treated with protective compounds in accordance with the requirements SNiP 2.03.11-85 "Protection building structures from corrosion", Chapter 3 "Wooden structures", as well as the requirements of SNiP 2.01.02-85 “Fire safety standards” clause 1.8. For a span of 4.7 meters, with a center-to-center distance of 500mm when using wooden beams 200*100 mm provides the following overlap indicators: Load-bearing capacity 300 kg/m2, Weight of floor structures 140 kg/m2 |
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We calculate the costs of constructing 1 m2 of floor structure.
Calculation of costs for installing a floor made of wooden beams over a cold underground. In addition to the material of the supporting structure, the calculation also includes materials for thermal insulation and leveling of the base for finishing the floor.
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1. Lumber 1.97 m3 / 15,760 rub. 2. Fasteners 1 piece / 3600 rub. 3. Fire and bioprotection 1 piece / 7800 rub. 4. DSP 20mm 39m2 / 13380 RUR 5. DSP 10mm 39m2 / 8350 RUR 6. URSA PureOne 200mm 7.8m3 / 11,270 RUR 7. Vapor barrier and tape 1 piece / 2000 rub. 8. Leveling screed M300 thickness 50mm 3.9t / 10140 RUR 9. Finishing screed 5mm 0.29tn / 7920 RUR Total cost of materials for 39.25 m 2 = 80,220 rub. |
1. Installation of the floor frame 350 RUR / 13,650 RUR 2. Fire and bioprotection 200 rub / 7800 rub 3. Installation of 10mm DSP 200 RUR / 7800 RUR 4. Installation of 20mm DSP 200 RUR / 7800 RUR 5. Installation of PureOne insulation 200 RUR / 7800 RUR 6. Laying vapor barriers. films 100 rub / 3900 rub 7. Performing a leveling screed M300 thickness 50mm 600rub / 23400rub 8. Performing finishing screed 200 RUR / 7800 RUR Total cost of workfor 39.25 m 2 = 79,950 rub. |
Total materials and work for the installation of floors on wooden beams: 4 081-00 rub/m2.
Floors on beams made of LVL timber.Scope of application: Interfloor ceilings in construction, frame housing construction, rafter system.
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Below is a calculation of the costs of installing a floor using LVL timber. The span between the supports is considered to be 4.7 meters. The calculation also includes materials for thermal insulation and leveling the base for finishing the floor. Load capacity 300 kg/m2 Weight of floor structures 55 kg/m2, the total “free” load-bearing capacity of the floor is 245 kg/m2 (according to SNiP “Loads and Impacts” for residential buildings the standard is 150 kg/m2). In the calculation presented below, the center-to-center distance between the beams is taken to be 625 mm to ensure waste-free installation of a 1,250 mm wide CBPB slab To simplify calculations, the following costs are given for a room of 8.3x4.7 m. |
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We calculate the costs of constructing 1 m2 of floor structure.
Calculation of costs for installing LVL beams over a cold underground. In addition to the material of the supporting structure, the calculation also includes materials for thermal insulation and leveling of the base for finishing the floor.
Total materials and work for the installation of floors on beams made of LVL timber: 2 942-00 rub / m 2.
What's in the bottom line?
Costs for erecting a floor structure for a house according to project 83-08.
Base area 124 m 2
Option 1. Floors made of precast reinforced concrete = 5,407 rub./m2 * 124m2 = RUB 670,468
Option 2. Floors made of monolithic reinforced concrete = 5,589 rub./m2 * 124m2 = RUB 693,036
Option 3. Floors on wooden beams = 4,081 rub./m2 * 124m2 = RUB 506,044
Option 4. Floors on beams made of LVL timber = 2,942 rub./m 2 * 124 m 2 = RUB 364,808!
Worth noting:- glued beams do not create creaks
- in our projects, the ends of the beams are not embedded in the body of the wall, the beams are fastened on brackets, even capillary suction of moisture from the wall structure is eliminated, the floor materials always remain dry, as a result, the service life of the floor is equal to the service life of a stone house
- the space between the beams is completely filled with non-combustible mineral wool material, the subfloor, as well as the lining of the beams, is made using materials that do not support combustion: DSP, fire-resistant plasterboard, this design has high fire resistance ratings, because there is no free air around the beam necessary for the combustion process.
Today LVL timber has the best price/quality ratio. It is this material that is preferred in many private and public facilities, for example, the balconies of the Mariinsky Theater or the supporting frame of the dome of the new Oslo airport are made of LVL timber.
Additional benefits of choosing modern construction technologies.
Application in construction modern materials and solutions, such as LVL timber for floors and rafter systems or porous ceramic blocks Cayman30 for external load-bearing walls, allows you to achieve savings not only within the framework of the current technical solution, without compromising the necessary and sufficient consumer properties and characteristics, but also significantly reduce the costs of other stages, as well as obtain higher quality construction.
As an example, we can cite a situation where the replacement of reinforced concrete floors with floors using LVL of timber and 44 conventional ceramic blocks for thermally efficient ceramic blocks Cayman30, for external and internal walls, significantly reduces the weight of the house.
Difference within house project 83-08 is:
- on floors 147.8 tons
- along the walls 37.9 tons,
Replacing a monolithic strip foundation with a monolithic pile-grillage foundation will also lead to a general reduction in the load on the foundation, by approximately another 99 tons.
In total, the total reduction in the weight of building structures, and as a consequence of the pressure on the foundation, is 284.7 tons.
Even before the construction process begins, at the design stage of the future structure, the question of choosing a floor arises. They represent reinforced concrete structures, which are used in the construction of any object. With the help of these universal building elements, load-bearing structures of buildings are also created. – a reliable building material that is necessary in any frame construction. According to statistics, the number of these elements is 30% of the total number of reinforced concrete products used in the construction of buildings.
Void layout diagram
To ensure strength and durability of the structure, the slabs are additionally reinforced.
For this purpose, both conventional and prestressed reinforcement are used. After reinforcement, the floor is used as a load-bearing structure and can withstand loads of up to 6 kPa. Correct installation and operation of these building elements ensures a fairly long term their service, up to several decades.
General classification
These products can be divided by type into:
- beam;
- beamless.
What other types of floor slabs can there be? Other division:
- monolithic;
- prefabricated;
- prefabricated monolithic.
Floors are also divided according to cross-sectional shape:
- ribbed;
- hollow: with round, oval and vertical voids;
- solid.
The ceiling includes the following components: structural, upper and lower. The supporting structure is created by the structural part; it transfers the payload and its weight to the supports. In this regard, the main factor when calculating the floors of a building is the permissible load rate.
The lower part of the ceiling is made of plaster, tile materials or various types of cladding. Upper part form floor structures and leveling screeds. To a greater extent, the lower and upper parts provide heat and sound insulation.
The structural part of the floor is assembled from prefabricated or monolithic slabs. It is better to make a monolithic floor from reinforced concrete; sometimes prestressed concrete is used for these purposes; some elements can be made from ordinary or lightweight concrete; ceramic liners can also be used.
Massive floors are made of monolithic concrete or prefabricated monolithic and reinforced concrete structures. Massive floors include:
- reinforced concrete hollow-core;
- solid reinforced concrete products;
- reinforced concrete steel-stone and ribbed floors;
- slab and beam products.
Calculation of permissible load
In order to understand what loads the floor slabs can withstand, you need to make a calculation. This should also be done in order to avoid destruction of building structures. There is no need to explain what will happen if the calculations turn out to be incorrect and cracks creep along the walls.
It is better to calculate loads in two categories: static and dynamic. Anything that is nailed to the slab, lying or hanging, is considered a static load. Dynamic - everything that moves, jumps and falls. There are loads that are distributed unevenly and evenly, concentrated, etc. When calculating loads for the construction of an ordinary residential building, these indicators are not needed. For this process, uniformly distributed loads are taken into account, which are determined by kg-force (kgf/m) or Newtons per m.
For ordinary floors of a residential building, a distributed load of 400 kg per 1 sq.m. is taken into account. To this figure add the weight of the slab, which is approximately 2.5 c. Screed and ceramics can add another 100 kg. The resulting weight is about 750 kg, which must be multiplied by a safety factor of 1.2. As a result, we get a value equal to approximately 900 kg/sq.m.
Void analogues
Diagram of the device of empty formers
When answering the question of which slabs are most often used in construction, it should be noted that this depends on the type of object being built. But still, three types are more often used: hollow, ribbed, monolithic. Hollow ones are used for the construction of buildings made of brick, concrete and wall blocks. Thanks to the air cavities, their thermal insulation and sound insulation properties are better than those of other types.
The presence of voids significantly increases the performance characteristics of these building elements. They have better sound insulation and heat insulation properties, because the cavities dampen vibrations and create an air layer that creates additional heat. The production of such slabs requires a significantly smaller amount of raw materials, which ensures their relatively low cost and makes this building material a fairly economical structural element.
Hollow-core floor slabs are laid on load-bearing walls - external or internal. First of all, a cushion is formed from cement mortar, after which these structural elements are laid, then they are secured with anchors. Hollow-core slabs are installed in such a way as to reduce heat loss in cold bridges to a minimum. In places where they support load-bearing walls, that is, at the ends, these structural elements are reinforced. You can do this in different ways: they come with a smaller diameter of voids at the edges, their ends can be filled with concrete, and other methods are used.
Hollow core slabs are used in the construction of various types of structures and buildings. Their widespread use is due to their high performance characteristics. Such structural elements are used not only in residential construction, but also in industrial construction. These are used, for example, in the construction of many tunnels and heating mains.
When making these building materials, the underside is leveled, after which they are ready for further finishing. Subsequently, this side will become the ceiling in one of the rooms. Since the second side will be the base of the floor, it appearance does not play a special role in production.
In hollow ones they are used different options sections. The voids can be oval, round, and there are also designs with vertical voids. Such slabs are also produced with ribs that increase the rigidity of this structural element. IN residential buildings Such slabs are placed with the ribs upward; in industrial buildings, the ribbed part will be on the lower side.
Types of designs
Thanks to hollow cores, it becomes possible to make holes in the ceiling intended for different systems. This is good, for example, for editing ventilation systems. All these building elements have high strength, and their production technology is such that the output will be slabs with precisely specified parameters.
Such structural elements are made from different types concrete. It depends on what buildings they are supposed to be installed in. Hollow core slabs can be made from both heavy concrete and structural concrete, which is characterized by high density and at the same time lower weight. Silicate concrete can also be used for the manufacture of these elements.
The floors differ from each other in width, length, maximum load and section height. The fact that these products have a long service life and their strength characteristics are quite good is also due to the use of steel ropes and stressed reinforcement in their production.
Ribbed types
This type is best used for constructing roofs for various industrial buildings and structures. They are used, for example, for garages, hangars, warehouses, etc. These are mainly unheated premises and have a fairly large area.
Large ribbed slabs meet the requirements of a non-running coating system used in the construction of single-story buildings. industrial premises. This system is based on the need to enlarge elements and reduce the number of installation units.
Products with a width of 3 m are more economical than slabs with a width of 1.5 m. This is due to the fact that their installation requires less labor. In addition, they do not create bends in the rafter system with 3 m panels in the upper chord. But slabs with a width of 1.5 m will have a higher load-bearing capacity due to the reduced distance between the ribs.
Slabs with a span of 6 m are prestressed, but they can be made without it. But the 12-meter structural elements are made exclusively prestressed. The weight of these can reach 4 tons. Floor slabs are ribbed structures in the form of a system of several transverse and two longitudinal ribs. It is on them that the thin monolithically connected shelf will lie.
It is best to use class B25 and B30 concrete as the basis for the mixture for making ribbed slabs. Three types of reinforcement can be installed in the longitudinal ribs: from seven-wire strands; in the form of rods, made of steel class A-3b; high-strength wire of periodic profile. In addition to the reinforcement, welded frames are installed in the longitudinal ribs. They are made either from steel of class A-1 and A-3, or from cold-drawn round wire. Welded mesh is used to reinforce the slab flanges.
To perform reliable installation of these products to a reinforced concrete beam, steel tabs are made from the corners at the ends of the longitudinal ribs, to which anchors are welded. Such embedded parts help protect the ends of the ribs from destruction during the transmission of forces. The slabs must be welded to the supporting structure at least at three corners.
Holes are provided in the slabs to allow ventilation shafts and various pipelines to be passed through the roof. There can only be one round or rectangular hole in one slab.
Monolithic structures
These slabs are solid reinforced concrete structures. Compared to other types of similar structural elements, their strength is better, it is the greatest. They are used mainly in the construction of multi-storey buildings, in places where the power load is increased. Monolithic reinforced concrete structures, forming a solid horizontal plane, are erected directly at the construction site.
The shape of such an overlap can be any. This allows you to remove planning restrictions from the house design that are present when prefabricated concrete structures are installed.
Let's consider what stages are included in the construction process:
- formwork installation;
- laying the reinforcement frame;
- pouring cement;
- dismantling the formwork after strength has been gained.
For the manufacture of formwork, edged boards or plywood are used. It is better to use the latter material, because it allows you to create a flat surface with fewer seams. Metal formwork is also a pretty good option.
Under horizontal metal or wooden beams, on which the flat structural elements of the formwork rest, vertical posts are placed. It is desirable that they be metal and adjustable in height, because with their help it is easier to set the horizontal plane required for pouring. After assembly, the formwork must have absolute rigidity and withstand not only the mass of poured concrete and the weight of the reinforcement, but also various additional loads.
When assembling the reinforcement frame of a monolithic floor, you need to take care to ensure its even spatial geometry. The first layer of reinforcement must be raised 20-50 mm above the plane of the formwork. This distance is . The change in its value depends on the thickness of the ceiling and design parameters. A protective layer is necessary to prevent corrosion of the reinforcement and ensure fire resistance of the structure.
In order to raise the reinforcing layer above the formwork, it must be installed on special plastic clamps designed for different thicknesses of the protective layer and the cross-section of the reinforcement. The second reinforcement layer is raised above the first with the help of supporting reinforcement elements.
Material storage
From the purchase of reinforced concrete floor slabs to their intended use, a certain period of time may pass, sometimes it can be quite long, and the products may also be located in unsuitable weather conditions. Improper storage can lead to serious decline quality characteristics reinforced concrete products.
There are several rules that should be followed when storing these building materials. First of all, there must be no contact between the slabs and the ground. They need to be laid on parallel wooden beams located on a cleared, level area.
There should also be no contact between individual products; they should be placed conveniently to avoid damage to the slabs. Therefore, they can only be stored with the loops up; each product must be laid wooden blocks. They are placed 25-30 cm from the edges, in the area of the loops. Regardless of how many products will be stored at the same time, it is unacceptable for the stack height to exceed 2.5 m. Even if only 2-3 slabs turn out to be superfluous, a separate flat area should still be allocated for them.
After the stack is laid, it must be completely covered with plastic film. If this is not possible, a canopy should be installed that protrudes 1 m beyond the edges of the slabs to protect the concrete from precipitation during crosswinds.
To protect products during the warm period from various living organisms, fungi, mold, insects, you need to treat them with some kind of repellent or antiseptic before storing them. Although even for fairly long-term storage of slabs, it may be sufficient to simply protect them from the formation of dirt and moisture on the products.
