When constructing various buildings and structures for both residential and industrial purposes, an important stage is the choice of material and the implementation of the floor. With the help of such structures, high-rise buildings are divided into floors. During the operation of a building, floors are subject to high loads, so it is important to choose the right material and install it correctly.
The main types of floors
Based on their purpose, structures are divided into three groups:
- attic: such structures separate the top floor and the attic space under the roof of the building. To create an usable attic area, it is recommended to use reinforced concrete slabs that can withstand a load of 400 kg/m2;
- interfloor: such floors are used to divide into separate floors. When choosing a material for their creation, the degree of load of interior partitions, interior items, various equipment, people, and so on is taken into account. Experts recommend using reinforced concrete slabs marked 6At and higher;
- basement: such structures separate the space of the lower level, which includes garages, basements and other rooms. The technical requirements for the material for these floors (degree of load, rigidity, strength) are similar to those for interfloor floors. Additionally, experts recommend insulating the structure and waterproofing it.
Based on the type of construction, floors are usually divided into the following categories:
- Full-bodied:
The body of the product consists of a solid material, for example, concrete, without any voids. Such slabs have a straight rectangular shape. The thickness is 10-16 cm. Most often they are used to cover underground technical channels.
- Hollow:
Such floors are made in the form of rectangular slabs with small voids around the perimeter (most often round, less often square). The most popular are products with a thickness of 22 cm, while the hole diameter can be 14-15.9 cm. Manufacturers also offer floor slabs with a thickness of 30, 26 and 16 cm.
- Monolithic:
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Such plates are characterized by high strength and wear resistance. They are made from reinforced concrete structures with continuous reinforcement. Recommended for the use of interfloor slabs in residential multi-storey buildings and modern residential complexes.
- Ribbed:
Such products are shaped like the letter P (from the end part). Their main difference is that the edges of the slab are reinforced with special beams. The products are characterized by increased load-bearing properties, so they are often used for floors of public buildings, multi-storey and industrial buildings. Due to the high cost of such a product, it is not advisable to use it when constructing a private house, summer house or country cottage.
- Lightweight:
The main difference between these slabs is their low weight compared to similar slabs. The structure of the product is multi-hollow. It is recommended to install such a floor on those construction sites where the foundation is of insufficient strength. An example of these products are slabs made on the basis of polystyrene concrete.
Types of floors by material
- Concrete floors: such structures are usually used in the construction of large objects (multi-story buildings, industrial workshops, and so on). The main component for their production is concrete of various types: silicate, light and heavy. Concrete floors are divided into several subtypes:
- precast: The overall floor structure consists of several individual concrete slabs bonded together. These are factory-made products;
- monolithic: a solid slab that is concreted to specific dimensions directly on the construction site;
- monolithic on a supporting profiled sheet: the installed corrugated sheet is a permanent formwork for concreting a monolithic slab. As a rule, such structures are used to create interfloor ceilings, which simultaneously serve as a supporting structure and a base for the floor.
- Wooden floors: such structures are characterized by low weight and ease of installation. They are often used in the construction of private houses from various materials: brick, timber, various blocks. Wooden floors are divided into subtypes:
- solid wood beams: the length of the solid wood floor is up to 6 meters.
- glued laminated timber: the length of this type of floor is up to 12 meters.
- Metal floors: metal beams are used to cover large areas with increased load. They are made from high-rolled steel according to the strict requirements of GOST standards.
Features of beam structures
Beam floors are a more economical option compared to slabs.
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The installation procedure is simpler, but the finished structure successfully withstands heavy loads. 
Experts recommend using this type of floors in the construction of private houses or low buildings (up to several floors). The beam web is secured using special supports. Such an overlap is placed horizontally or at some angle. Thus, the load from the beam falls on the supports: walls, columns, and is then redistributed between other structural elements.
The strength of the product, as well as the maximum loads, are determined depending on:
- beam material;
- method of its fastening;
- shape and cross-sectional area.
Truss is another modern way of arranging floors. The design is a rod system. To form it, linear rod elements are used, which are connected at certain nodes, which bear the load. This type of floor includes trussed beams - a structure made of a continuous beam (two- or three-span) and a girder. Similar structures are used for arranging high-rise buildings.
The stability and strength of the entire building, as well as its service life, depend on the correct choice of material for creating floors. When choosing a specific product, first of all, you should take into account the overall architectural design of the construction site. It is important to make some technical calculations so that the finished floor can successfully withstand the required load and be durable and reliable. In addition, the selected products are subject to requirements for thermal conductivity, fire safety, water and sound insulation.
With sufficiently high technical characteristics, the selected structures should have the lowest possible weight and thickness. It is very important not to make mistakes when performing calculations, so it is better to entrust this task to an experienced and qualified engineer.
Advantages and disadvantages of various floors
Most often in construction, reinforced concrete slabs are used as flooring. Compared to monolithic concreting, reinforced concrete structures are characterized by a number of undeniable advantages. Most of the models have voids in their design, which increases the sound insulation of the room, reduces the overall weight of the structure, and, therefore, the load on the foundation of the construction site.
When implementing popular designs, customers are always faced with the need to select interfloor slabs. The choice lies among the three most commonly used types of floors: slab reinforced concrete, monolithic reinforced concrete and wood. We will devote this series of two articles to the most practical and popular floor covering used in low-rise residential buildings - prefabricated reinforced concrete slabs.
Here are a number of important questions we will consider:
- Key differences between hollow-core floor slabs and slabs produced by formless molding.
- Rules for installing floor slabs.
- Tips to avoid violation of installation technology.
- Rules for storing slabs in an on-site warehouse.
Features of choosing hollow core slabs
At first glance at hollow-core floor slabs, it may seem that they differ from each other only in length, thickness and width. If you decide, for example, to build a house from foam blocks, the projects must indicate specific technical characteristics of hollow core floor slabs. But in addition to overall dimensions, other data is indicated based on GOST 9561-91.
1. Reinforcement method
An important difference between floor slabs is the method of their reinforcement, which is determined by the type of slab. A distinction is made between reinforcement using conventional and prestressed reinforcement. The option when the working reinforcement is prestressed is much more common.
2. Number of supporting sides
The choice of certain floor slabs should be influenced by such an indicator as the permissible number of sides for supporting the slab. The bulk of hollow products are designed to rest only on the short sides. Such plates include:
- PB. Support occurs on both sides.
- 1 PC – double-sided support of a hollow core slab 220 mm thick with a cavity diameter of 159 mm.
If the plan of a residential private house assumes the presence of spans, which must be covered with slabs supported on more than two sides, then the following types are used:
- 1PKT - three-sided support of a slab 220 mm thick with the same void size.
- 1PKK is a slab that can be supported on all sides.
3. Floor slab production technology
Floors of PC brand:
Manufacturing method
It is the manufacturing method that is the main difference between different types of slabs. Thus, PK brand slabs with a thickness of 160-260 mm and a load-bearing capacity of 800 kg/m2 are manufactured using formwork.
Reinforcement of products
PK-type slabs up to 4.2 m long are produced without prestressing reinforcement and are characterized by a larger permissible deflection compared to PB.
PC-type slabs are also made in length and more than 4.2 meters, but at the same time they are characterized by an important feature. They have stops at the ends and are made prestressed. Such slabs must not be cut due to the fact that the cut stop stops working, and the adhesion of the reinforcement to the concrete will occur only along the side surface. These deformations cause a sharp decrease in the load-bearing capacity of the products.
PC slabs, having hollow holes measuring 114-203 mm, make it possible to safely punch holes in the slab for a sewer riser with a diameter of 100 mm.
Floors of PB brand:
Manufacturing method
The formless continuous casting method is used in the production of PB slabs, which have a thickness of 160-330 mm and a load-bearing capacity of 800 kg/m2 and above. The difference between the so-called extruder plates and PC plates is a smoother and more even surface.
Reinforcement of products
It is worth noting that prestressed reinforcement is used in PB slabs, regardless of the length of the product. Due to the presence of stretched and compressed zones, the likelihood of concrete cracking is eliminated.
Standard sizes of slabs and their cutting
PB brand slabs can be produced to any size according to customer specifications and have a length of 1.8-9 m. In addition, the slabs are subjected to longitudinal or oblique cutting at angles from 30 to 90°. It is important that the load-bearing capacity of the slab is maintained. This property significantly expands design possibilities, because the plan of a cottage house can have any shape, not tied to the standard dimensions of the floor slabs.
Features of punching holes
Products of the PB brand are distinguished by excellent surface smoothness, geometric accuracy, lightness and excellent load-bearing properties. But due to the fact that the voids in the slab are 60 mm in size, punching through holes becomes somewhat more complicated. Before starting this type of work, it is necessary to check with the manufacturer about the technology in order to avoid damage to the reinforcement.
So, in this part of the series we told you about the important properties of floor slabs, their characteristics and production. Read on how to lay slabs correctly and avoid mistakes!
Finally, you can familiarize yourself with the main stages of floor slab production:
If you want to build yourself a small cottage or a two-story house, then you will have to face the problem of choosing between floors. After reading this article, you will learn about what they are, as well as the advantages, disadvantages and features of each type of floor.
Interfloor ceilings are an extremely important part of the house; they must not only withstand significant loads, but also have sufficient sound insulation. Agree, it’s unpleasant when on the first floor you can hear every step that is taken on the second floor. Also, interfloor ceilings add strength to the entire structure and take on some of the deformation loads.
All floors are divided into interfloor, attic, basement and basement.
What requirements must the floors between floors meet?
Primary requirements:
- High structural strength, that is, the possession of load-bearing capacity. This parameter must be calculated during design.
- Significant floor rigidity. Deflections and movements, even minimal ones, can lead to the destruction of the entire house. The permissible deflection value for interfloor ceilings should not exceed 1 in 250, and for attic floors - 1/200.
- The overlap should be maximum light, thin. It should not create excessive load on the walls.
- The interfloor ceiling must become a barrier to fire, that is, it must have high fire resistance. This characteristic is regulated by fire safety standards.
- High thermal insulation properties. Floors do not always separate living rooms, but they can separate rooms where there is a significant temperature difference.
- Good sound insulation. This parameter is extremely important, and we must not forget that not only the walls of the building, but also the interfloor floors need this parameter.
All requirements are mandatory and are suitable for any type of floor. Sometimes additional requirements are imposed on interfloor ceilings, for example, water tightness, or gas tightness, or a special appearance.
Types of interfloor ceilings
According to their design, floors are divided into:
- beam- they consist of load-bearing beams and filler;
- beamless- made from homogeneous elements, for example, panels or slabs;
The latter may be:
- from wooden beams;
- with metal beams;
- with reinforced concrete beams.
In this type of floor, the basis is beams placed equidistant from each other. After installing the beams, filling elements are laid between them, which play the role of a fence.
Interfloor ceilings made of wooden beams
This type of flooring is most common in private housing construction, in particular in the construction of wooden, frame and even brick buildings.
Application:
- wooden beams are used as an interfloor ceiling if the span width is no more than five meters;
- as an attic floor, if the attic is not residential and the span is less than six meters.
Most beams are made of pine or larch. On their upper part there is a flooring that can be used as a subfloor.
Advantages of floors made of wooden beams:
- speed of installation - no special devices are needed to erect such a structure;
- light weight - such an overlap will not create a significant load on the walls of the house;
- environmental friendliness - the tree does not contain any harmful substances.
Flaws:
- weak resistance to fire - even with good treatment, the tree will still catch fire;
- there is a chance of beams rotting or being damaged by bark beetles;
- such an overlap will not be able to withstand significant loads.
Beam-type ceilings consist of beams, floors, bevels and insulation.
Interfloor ceilings made on metal beams
If we compare them with the previous type, they are more reliable, durable and significantly thinner than wooden ones. True, floors of this type are not built so often. Lightweight concrete inserts, wooden beams or panels, or reinforced concrete slabs are used as filler.
An I-beam, rolled profile, angle or channel is used as a load-bearing element of this floor.
Advantages of floors on metal beams:
- it is possible to cover a large span (from 6 meters);
- metal beams do not burn, do not rot, and are not afraid of any bug;
- they are very durable.
Negative sides:
- moisture causes metal to rust;
- metal beams have low sound and heat insulation rates;
- the enormous weight of such a ceiling - one square meter can weigh more than 400 kilograms.
To prevent metal beams from “ringing” so much, their ends can be wrapped in felt.
Such floors are erected if the span is from 3 to 8 meters. You can't lift them with your hands, so you definitely need to use a crane. The weight of one beam can reach 400 kilograms.
Advantages of this type of flooring:
- can cover longer distances compared to wooden ones;
- they have higher heat and noise insulation parameters than ceilings on metal beams.
Flaws:
- huge weight and impossibility of installation manually, only with the use of special equipment.
Beamless interfloor ceilings
Such floors do not have a so-called frame and are created using homogeneous elements. The latter are placed close to one another. Slabs or panels are used as elements. They are a monolithic slab, which is both a load-bearing and enclosing structure.
Types of beamless floors:
- prefabricated;
- monolithic;
- prefabricated monolithic.
This type of flooring has gained the greatest popularity in the construction of brick structures. For the construction of this type of floor, two types of panels are used:
- solid- made of lightweight concrete;
- hollow-core- holes are made in them, which act as “stiffening ribs”.
Positive qualities of prefabricated floors:
- they are more durable than wooden ones, and are also not subject to rotting, corrosion, and are not afraid of various bacteria;
- excellent strength - they can withstand significant loads, up to 200 kg/m2.
Negative sides:
- since they have significant weight, when installing them you cannot do without special equipment;
- slabs are usually made only in standard sizes, so they may not fit.
Building this type of floor is quite expensive, but you will pay for quality and durability.
Unlike the previous type, they can be of any shape and size. A monolithic interfloor ceiling is a solid slab with a thickness of 8 to 12 centimeters, made of M200 concrete. The weight of one square meter of this design can reach 500 kilograms.
Advantages of monolithic floors:
- high surface quality;
- no need to carry out additional loading and unloading operations;
- there is no need to seal seams;
- the opportunity to order the kind of ceiling you can imagine.
Flaws:
- It is mandatory to install wooden formwork;
- very heavy, so the load on the walls increases;
- quite high price.
Prefabricated monolithic floors between floors
This type belongs to modern developments. In it, the space between the beams is filled with hollow blocks, and then the entire structure is filled with concrete.
The positive aspects of prefabricated monolithic floors include:
- less weight than reinforced concrete ones, so you can do without special equipment;
- good thermal insulation characteristics;
- the ability to create floors of complex shapes.
Negative points:
- inappropriate for use in low-rise construction, since the process of erecting such a structure is quite labor-intensive.
The choice of flooring largely depends on the size of the spans and the material from which the house is built. For light wooden and frame buildings, wooden beam floors are suitable, and for heavy brick ones it is better to use floors made of metal beams or reinforced concrete. In any case, you should not save on this and during design it is better to consult with a specialist about the choice of flooring.
Video: Soundproofing floors using the example of a wooden house
Marking different types of foundation for a house
Even before the construction process begins, at the design stage of the future structure, the question of choosing a floor arises. They are reinforced concrete structures that 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. Proper installation and operation of these building elements ensures a fairly long service life, 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. The upper part is formed by 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 soundproofing and thermal 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. This can be done 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 also 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, its appearance does not play a special role in production.
In hollow cores, different cross-section options are used. 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 up; in industrial buildings, the ribbed part will be on the bottom side.
Types of designs
Thanks to hollow ones, it becomes possible to make holes in the ceiling intended for different systems. This is good, for example, for installing 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.
Similar structural elements are made from different types of 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 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 be only 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.
Vertical posts are placed under the horizontal metal or wooden beams on which the flat structural elements of the formwork rest. 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 a serious decrease in the quality characteristics of 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 laid 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 facing up; each product must be lined with 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 that the height of the stack exceeds 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.
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