Building a house is fraught with many nuances that many novice builders don’t even know about. In particular, one of these “pitfalls” is the floor assembly, which is an entire technology responsible for the durability of the house.
That is why it is necessary to approach the solution of this problem with all responsibility, and at least become familiar with the consequences of negligence.
Introduction to floor assemblies
Supporting unit for the floor slab on brick wall is nothing more than the junction of two planes: vertical and horizontal. Many private developers play with this point in different ways, but it doesn’t always work out correctly, much less reliably.
Therefore, to avoid adverse consequences associated with expensive repairs, it is necessary to prepare in advance.
Types of floor materials used
These floors themselves are made from reinforced concrete slabs, the most reliable materials available.
There are just some differences in production process, this is related to the structure type:
- Cellular concrete.
- Prefabricated monolithic– the most popular of all presented.
- Made from heavy concrete. This type applies to many materials, since admixtures of heavy concrete are present in various products.
- Multi-hollow.
All of the above floors brick buildings used in certain conditions, depend on the design of the structure, the load being carried out and the dimensions of the span.
They should be divided into two categories:
- Interfloor ceilings in brick house– used for multi-level houses. They are mounted into a load-bearing wall on a special lining that provides reliable fixation products. In this case, the depth from which the ceiling will lie on the wall is very important.
- The attic type does not experience such high loads, so it is mounted into the wall without a lining.
For your information! If you decide to build a multi-story brick house with your own hands, you should give your preference to a floor made of prefabricated reinforced concrete slabs. They have not only increased strength, but also enormous load-bearing capacity, and also, so to speak, affordable installation.
Support node - find a solution
In order for the support of floor slabs on brick walls to withstand high loads, it is not enough to use durable materials; the most delicate approach is required here.
- Firstly, it is necessary to correctly calculate the support unit. Keep in mind that it can only be implemented on a load-bearing wall, but cannot be connected in any way to a partition.
Note! Each product ( building material) has its own marking, which indicates its certain features: seismic resistance, load-bearing capacity and others. This applies not only to reinforced concrete slabs, but also to bricks used as load-bearing structures. For example, double sand-lime brick M 150 is not the most best solution for the construction of a multi-storey building.
- Secondly, all calculations and a plan for solving the problem must be checked against GOST 956-91 and additional design documents. Otherwise, you may be denied construction.
For example, check out the markings of PC 42.15-8T slabs, where PC is the floor with round voids, 42.15 is the dimensions of the product in decimeters (length 4180, width 1490). The number 8 is the maximum permissible load on the slab, which is equal to 800 kgf/m2, and the letter T following 8 is the index of the heavy concrete used for the production of this slab.
There is also a certain standard for how the support of floor slabs on a brick wall should look - from 90 to 120 mm. It is this size that should be maintained, adapting to it.
There are two main points to consider here:
- The reliability of the foundation of the house, which must be designed for high loads. It is necessary to avoid those places where the foundation can be weakened, which will lead to uneven shrinkage of the structure, resulting in curvature of the ceiling.
- The width of the foundation should in no case be less than brickwork. In this case, the deformation load-bearing walls is inevitable - the load of the ceiling will affect the bricks and weaken the cement mortar.
You also need to focus on the thickness of the slab in relation to the thickness of the load-bearing wall. And this is provided that high-quality building brick, which complies with standards and GOSTs.
Fixing floor slabs
Anchoring floor slabs in a brick house is used to strengthen the structure, increase strength and reduce the likelihood of material deformation. This method It is extremely difficult to do on your own, so it is better to entrust it to professionals, although the price may be unpleasantly high. The main thing in the construction business is reliability and durability.
One feature to be aware of is that the anchors can be positioned through the slab. However, there is a limit - 3 meters from each other, this is the permissible maximum.
For your information! The anchor is also used to fasten prefabricated reinforced concrete slabs together.
Now you understand what a unit for supporting a floor slab on a brick wall is, what is connected with it and what it affects. That is why you can protect yourself from any unfavorable moments even at the design stage.
Conclusion
It is important not only to lay the slabs correctly, but also to build a foundation, withstand the drying time of the mortar, and lay bricks with minimum thickness seam according to the instructions. You can do all this yourself, but if you are in doubt, it is better to entrust the work to professionals.
Reinforced concrete slabs are one of the most common types of floors. They provide high strength and allow you to install a rigid structure in the shortest possible time. Installation of floor slabs is a responsible task that requires certain knowledge in the field of construction. First things first.
Types of floor slabs
Before you start installing a horizontal structure, you need to select a type. Reinforced concrete prefabricated structures are produced in the form of:
- multi-hollow;
- flat (PT);
- tent panels with ribs located along the perimeter;
- with longitudinal ribs.
The most common choice is the use of reinforced concrete hollow-core. They are available in two types, depending on the manufacturing method:
- round hollow (PC);
- continuous molding (CB).
Round hollow core slabs are time-tested products that have been used in construction for several decades. Many regulatory documents and installation rules have been developed for them. Thickness – 220 mm. Products are installed according to serial sizes, which creates inconvenience during individual construction.
The manufacturing technology of these slabs involves the use of reusable molds for pouring, and before production non-standard products First you need to prepare the formwork. Therefore, the cost of the required size can increase significantly. Typical PC slabs have a length from 2.7 to 9 meters in increments of 0.3 m.
Scheme of reinforced concrete products with dimensions The width of reinforced concrete products can be:
- 1.0 m;
- 1.2 m;
- 1.5 m;
- 1.8 m.
Structures with a width of 1.8 m are purchased extremely rarely, since due to their large weight the installation process in the design position is greatly complicated.
PBs are used in almost the same way as the previous type. But their manufacturing technology allows you to give the product any length. Thickness – 220 mm. The width is the same as the PC series. The disadvantage is little experience in use and poor regulatory documentation.
Flat PTs are often purchased as additional elements for hollow-core slabs. They are available in thicknesses of 80 or 120 mm and are smaller in size, allowing them to cover narrow corridors, storage rooms, bathrooms.
Supporting the slabs
The laying of floor slabs is carried out after the preparation of the project or diagram on which the products are laid out. Floor elements must be selected so that they are sufficiently supported by a brick wall or expanded clay concrete blocks and laying without gaps in width.
Minimum support for PB and PC series depends on their length:
- products up to 4 m long – 70 mm;
- products longer than 4 m – 90 mm.
Visual diagram how to correctly and incorrectly support floor slabs Most often, designers and constructors accept the optimal wall support value as 120 mm. This value guarantees reliability even with small deviations during installation.
It would be correct to pre-position the load-bearing walls of the house at such a distance that it would be easy to lay the slabs. The distance between the walls is calculated as follows: the length of standard slabs minus 240 mm. The PC and PB series must be laid with support on two short sides without intermediate supports. For example, PC 45.15 has a size of 4.48 m, 24 cm is subtracted from it. It turns out that the distance between the walls should be 4.24 m. In this case, the products will lie with the optimal amount of support.
The minimum support of PT series products on the wall is 80 cm. Installation of such reinforced concrete slabs is possible with support points located on all sides.
The support must not interfere with the passage of ventilation ducts. Optimal thickness carrier interior wall made of brick – 380 mm. 120 mm on each side goes under reinforced concrete floors, and in the middle there remains 140 mm - standard width ventilation duct. In this case, it is necessary to lay it as correctly as possible. Shifting the product to the side vent will lead to a decrease in its cross-section and insufficient ventilation of the premises.
Summarizing what was said:
- PC and PB series up to 4 m are supported on both sides by at least 7 cm;
- PC and PB series more than 4 m - not less than 9 cm;
- PT series – at least 8 cm on two, three or four sides.
Slab storage
Product storage schemes different types After the scheme has been developed and the products have been purchased, they need to be placed on the building site for convenient installation in the design position. There are rules for storing materials:
- elements must be laid under a canopy;
- the storage location must be located within the access area of the crane;
- Pads are provided for support points.
Failure to comply with the last rule will result in a break in half. PC, PB and PT products work in such a way that the appearance of intermediate supports or a solid base leads to the appearance of cracks. Laying is done in the following order:
- laid on the ground wooden blocks or boards under the edges of the slab;
- on the boards crane I transfer the ceiling element from the car;
- boards or bars are placed again on the laid slab;
- unload the second slab from the machine;
- repeat points 3 and 4, maximum storage height is 2.5 m.
Masonry requirements
Scheme for calculating floor slabs In order to correctly install floor slabs, you need to ensure that special requirements to a brick wall:
- evenness of the masonry in the place where the floors are laid;
- laying in three rows until overlap reinforcing mesh with a 5 by 5 cm cell made of wire with a diameter of 3-4 mm;
- top row to frets with inside must be tychkovy.
If the slabs are mounted on expanded clay concrete blocks, an additional monolithic belt is installed under the floors. This design will help to evenly distribute the load from heavy floors onto expanded clay concrete blocks with less strength. The construction technology involves pouring a monolithic concrete strip 15-20 cm thick onto the blocks.
Laying floors
To carry out the work, a minimum of three people will be required: one performs the slinging, and two install them in the design position. If the installers and the crane operator cannot see each other, when installing the slab, another worker will be needed to give commands to the crane.
Scheme of laying reinforced concrete products Fastening to the crane hook is carried out with a four-branch sling, the branches of which are secured at the corners of the slab. Two people stand on both sides of the support and control its evenness.
When installing a PC, pinching into the wall is carried out in a rigid way, that is, bricks or blocks are laid on both the top and bottom of the slab. When using PB series floors, it is recommended to use hinged fastening. To do this, the slabs are not pinched from above. Many builders install the PB series in the same way as PCs and buildings stand, but it’s not worth the risk, because human life and health depend on the quality of the installation of load-bearing structures.
Another important feature of the use of products from the PB series is that it is prohibited to make technological holes in them.
These punches are needed for heating, water supply and sewerage pipes. Again, many builders, even when constructing multi-story buildings, neglect this. The difficulty is that the behavior of this type of floor under load over time has not been fully studied, since there are no objects built quite a long time ago. The ban on punching holes has reasons, but it is rather preventive.
Slab cutting
Sometimes, in order to install a slab, it is necessary to cut it. The technology involves working with a grinder and a disc on concrete. PC and PT slabs cannot be cut to length, since they have reinforced reinforcement in their support zones. If you support such a cut slab, then one edge will be weakened and serious cracks will appear along it. It is possible to cut PB slabs to length, this is due to the peculiarities of the manufacturing method. A timber or board is placed under the cut site, which will make the work easier.
Separation along the length is carried out along the weakened part of the section - the hole. This method is suitable for PC, but is not recommended for PB, since the width of the walls between the holes is too small.
After installation, the holes in the support areas on the walls are filled with lightweight concrete or hammered mineral wool. This is necessary to provide additional strength in areas where the walls are pinched.
What to do if it was not possible to distribute the products evenly across the width
Sometimes the dimensions of the room do not correspond to the width of the products, in which case all the spaces are combined into one. This space is covered with monolithic area. Reinforcement occurs with curved meshes. Along their length, they rest on the top of the ceiling and seem to sag in the middle of the monolithic section. For floors, concrete of at least B 25 is used.
Technology prefabricated floor on brick or blocks is quite simple, but requires attention to detail.
In construction, the installation of floor slabs should be treated responsibly, especially if you are building on your own, without a project, as we usually do, for example, on our summer cottages. If the project is approved and a team of qualified builders is working, then such questions do not arise.
Often the answer to a question of interest can be found in articles or books on construction intended for a wide range of readers. For example, you can read that “ Minimum distance“on which the slab should rest, colloquially called the “depth of support” of the ends of the floor slabs, should be at least 90-120 mm. These figures can be used as a guide without going deeply into the intricacies of the construction business.
If you figure out where these values were taken from and how true they are, then, in the words of Ostap Bender: “The laws must be respected.” In construction, as in any industry, there are regulatory documents.
To determine the “depth of support”, it is necessary to take into account not only the length of the floor slab, but also the material of the supporting surface, the brand of the slab (the load-bearing capacity of the slab is indicated), as well as the requirements for seismic resistance.
Improper installation of a slab on a supporting wall is a violation that will not be overlooked by regulatory authorities. As for the governing documents: there are GOST standards and Series of design documentation, which indicate the amount of support.
For example, in series 1.400-11/91 “Recommendations for the use of prefabricated reinforced concrete standard slabs in building coverings industrial enterprises» it is indicated that the length of support for the longitudinal ribs of the slabs, taken during design, must be no less than the following values:
Minimum support length in mm for slabs 6 m long
on steel structures- 70 mm
for reinforced concrete structures - 75 mm
on stone structures- 120 mm
Minimum support length in mm for slabs 12 m long
for steel structures - 90 mm
for reinforced concrete structures - 90 mm
for stone structures - 150 mm
In accordance with GOST 956-91, for floor slabs of any length manufactured by Moscow reinforced concrete products, the depth of support on a brick wall is set to 10 mm, excluding the length of the floor slab itself.
You should pay attention to the brand of the plate and the markings applied. Slab brands consist of alphanumeric groups. For example, according to the territorial catalog of the Moscow region, the brand PK 42.15-8T means: PK - name of the product - floor slab with round voids; 42.15 - dimensions of the product in decimeters - structural length 4180, width - 1490; 8 - for a design load of 800 kgf/m2; T - index for heavy concrete.
Signs of places of support on the slab are applied in accordance with GOST 13015.2 in the middle of each side of the support of the slab.
Thus, the more parameters are taken into account, the more accurately you will determine the minimum support of the floor slab.
Reinforced concrete slabs are one of the most common types of floors used in brick or panel houses for intermediate layers between floors. They are in great demand due to their high strength.
Thanks to reinforced concrete structures, the building becomes a single, stable and rigid structure. Specialized construction knowledge will be required to properly install and secure floor panels multi-storey buildings.
In the process of building a structure, one should take into account such an indicator as the support of the covering slabs on the walls.
Floors must have great strength Floor slabs are main part structural elements, as a rule, they are made of reinforced concrete. Their main function is to redistribute the load from the weight of everything in the house onto the walls, supports and foundation.
Also, thanks to the floors, it is possible to divide the total area of the house into floors, attics and basement. The material from which they are made must have great rigidity, strength, excellent sound insulation, fire resistance and water resistance, which is why reinforced concrete is used in production. Reinforced concrete products are:
- multi-hollow (PC);
- with longitudinal stiffeners (RB);
- flat floors;
- tent panels with stiffening ribs along the entire perimeter.
Round-hollow slabs have proven themselves well In the construction of multi-storey buildings, hollow-core reinforced concrete products are used much more often than others. Depending on the method of preparation, they are divided into round-hollow and continuous molding.
Round-hollow slabs are the most popular types of slabs. They are most often used in the construction of houses. This type of flooring has been used for more than twenty years. The strength of these structures has been tested under high loads. A huge number of regulatory documents have been written on the topic of installation and production of round-hollow panels.
According to GOST 9561-91, the thickness of the product should be 220 mm, length - from 2.7 to 9 m. The width of reinforced concrete surfaces is 1, 1.2, 1.5 and 1.8 m. They are divided by serial numbers. In the production of such floors, reusable forms are used for pouring concrete.
If it is necessary to produce atypical blanks that differ from standard sizes, then formwork of the required parameters for concrete is made. As a result, the cost finished products significantly higher than the standard type.
Plates with longitudinal stiffeners (PB)
They are used almost as often as the first type.
The production technology itself allows you to create products of absolutely any length.
The thickness, as in the previous case, is 220 mm, and the width completely coincides with the dimensions of the round-cavity panels.
To reduce high loads, slabs with transverse stiffeners are used. It is important that when stretched, concrete leaves the place of load and goes to the epicenter of compression, and the stiffener distributes it evenly over the entire plane. To reduce material consumption in the manufacture of slabs while maintaining all strength characteristics, stiffeners are also used.
Flat floors are used in private construction This type of flooring is often used for the construction of civil housing, which is made in the form of a solid slab with longitudinal ribs that work in bending. According to the design scheme, they are divided into non-beam and beam groups.
In the first case, the floor rests on columns with extensions (capitals); in the second case, the beams together with the panels work together as a single unit.
According to their structural characteristics, beam floors are divided into prefabricated beams, monolithic with beam floors, ribbed monolithic, prefabricated monolithic beams, beamless prefabricated, beamless monolithic, beamless prefabricated monolithic.
Most often, prefabricated beam structures are used in the construction of houses.
Over time, the strength of this structure decreases The tent panel is a special type of slab, which is framed along the contour by ribs. They always point downwards. In terms of strength characteristics, such a panel is much inferior to a hollow-core product. The maximum load for this type of product is 200-250 kg/m.
Another huge disadvantage is that the strength of the product decreases over time. The panel structure is made of heavy concrete grade M-200, reinforced with spatial frames of longitudinal and transverse ribs and welded mesh.
There is multiple reinforcement in the corner part of the slab, so it is difficult to achieve strong adhesion of the reinforcement to the concrete. When molding a product, reinforcement often shifts from its design state, therefore finished product turns out to be of low quality. Tent slabs from lightweight concrete do not meet the required strength and deformation indicators, therefore they are not recommended for use for the construction of civil housing.
Supporting slabs on walls
Installation of ceilings on the walls of a building occurs only after approval of a pre-signed project. It is necessary to select parts of the partition structures in such a way that the support of the floor slabs on the brick wall is sufficient without breaks along the entire perimeter. 
The minimum support of the PB and PC slab is determined depending on their length:
- 70 mm for floor slab lengths up to 4 m;
- 90 mm for a length of more than 4 m.
To increase reliability indicators, in practice, the support rate of the slabs on the walls is taken to be 120 mm, therefore, when designing houses, it is necessary to prepare a building plan in advance. Selection required sizes monolithic slabs is carried out so that the load-bearing walls are located at the required distance from each other, and the ceilings support the brick walls from above. In this case, the overlap of the slab should be 120 mm on both sides.
When using PT series products in construction, the minimum indicator at which they rest on the wall is taken to be 80 mm.
The installation itself of such panels is carried out with support points located under the slab on all sides. When applying the structure to brick walls, they should not interfere with or block the ventilation ducts.
With a standard wall thickness of 380 mm, when a 120 mm ceiling is applied on both sides, an empty space of 140 mm remains between the panels, just enough to ventilate the building. If the slabs are laid incorrectly, this will lead to blocking of the air exhaust channel. For more information on how to avoid mistakes when laying out floor slabs, watch this video:
Certain types are used for different types of buildings interfloor ceilings. During installation, it is necessary to comply with the installation technology, which is regulated by regulatory documents (SP 70.13330.2012).
Types by method of support
The slab used for interfloor separation is a reinforced reinforced concrete structure, with voids. There are holes in the slabs to lighten the weight of the structural element.
The choice of interfloor covering and the depth of its support depends on design features buildings. The following parameters are taken into account:
- purpose of the building (residential, industrial, public);
- the material from which the structure is constructed;
- wall thickness;
- types of loads acting on both the slabs and the building;
- seismic characteristics of the development area.
By type of support, interfloor slabs divided into three categories. Their selection is carried out at the project planning stage, taking into account calculations of the loads acting on load-bearing elements buildings.
On both sides
The support for such slabs is two opposite load-bearing walls. They are laid on capital elements, with narrow (transverse) sides. Most often, for this type, interfloor slabs with round voids are used, marked PC, 1PK, 2PK. They can withstand loads of up to 800 kg/m².
On three sides
They have reinforced end reinforcement and are laid on three load-bearing walls. They are mounted in the corners of the building, which have a U-shaped structure of load-bearing walls. They are marked PKT and can withstand loads of up to 1600 kg/m².
On four sides
Such slabs are reinforced with reinforcement at all ends, they are more rigid and have increased load-bearing capacity. Only used in complex structures where maximum distribution of high loads is required, or in cases where the construction of additional superstructures is planned. They are marked PKK, indicating increased strength. IN low-rise construction they are practically not used.
For low-rise and private construction, it is recommended to use round and oval-hollow floor slabs, supported on two sides.
Depth of the establishment on the walls
All floors, regardless of installation method, can be laid on a foundation or load-bearing walls made of brick, reinforced concrete panels, or foam blocks.
The depth of support is the distance to which the slab rests on the load-bearing element.
It is important to know how much you can support a hollow reinforced concrete product. This depth depends on the material from which the supporting structures are constructed.:
- brick - from 9 to 12 cm;
- panel - from 5 to 9 cm;
- aerated concrete or foam block - from 12 to 25 cm.
Failure to comply with the recommended laying depth can lead to the destruction of walls due to improperly distributed loads. Insufficient depth leads to coloring of the inner layer of masonry and plaster, or to cracking of panels. Excessive distance taken for support will lead to the destruction of the outer part of the wall.
Diagram of correct and incorrect support on a brick wall:
Excessive depth of support on the load-bearing wall creates cold bridges and improper distribution of loads, which, accordingly, leads to large heat losses and leads to the gradual destruction of the building.
Excerpt from SNIP
JV “Large-panel structural systems. Design Rules"
4.3.17 Depth of support of precast solid slabs on concrete and reinforced concrete walls depending on the nature of their support, they take no less:
- 40 mm - when supported along the contour, as well as two long and one short sides;
- 50 mm - on two sides and a span of 4.2 m or less, as well as on two short and one long sides;
- 70 mm - on both sides and a span of more than 4.2 m.
Leaning hollow core slabs formless molding on wall panels made on two sides, that is, according to a beam scheme with a support depth of at least 80 mm for slabs with a height of 220 mm or less, and at least 100 mm for slabs with a height of more than 220 mm.
In all cases, the maximum support depth for hollow-core slabs without formwork is assumed to be no more 150 mm.
Supporting hollow-core slabs without formwork on three or more sides (inserting the longitudinal side of the slabs into the walls) not allowed.
Armopoyas
Before installing the floors on the main structures,... It is carried out along the perimeter of the area of the main walls, along their entire width. Formwork is installed along the edge, then a reinforced frame of longitudinal, transverse and vertical reinforcing bars is mounted and filled with concrete.
When constructing an armored belt, the following requirements must be met:
- The height of the armored belt is from 20 to 40 cm (not less than the height of a standard aerated concrete block).
- The width must correspond to the width of the supporting element.
- The thickness of the reinforcement is at least 8 mm. The frame is tightly knitted with wire or fastened by welding.
- The concrete must match the brand of mortar used for masonry. The recommended grade of concrete used is at least class B15.
The armored belt serves to evenly distribute all loads. It also contains reinforcement fasteners, which are designed for reliable installation of interfloor ceilings. Since the armored belt is a cold concrete layer, it is provided with a thermal insulating coating.
Attention!
Floor slabs are installed only after the monolithic reinforcing belt has completely dried.
Support nodes
Support nodes are places where the slab is attached to supporting structure, or joints of vertical and horizontal elements building structures.
They are designed for reliable and correct fixation of floor slabs on permanent elements. Laying the slab and fixing it to the wall is done using mortar and rigid reinforcing compounds.
Nodal connections must meet the following requirements:
- the end sides of the slabs should not be closely adjacent to the masonry;
- thermal insulation is performed between the masonry and the ceiling;
- It is recommended to close the hollow holes with special liners to prevent heat loss;
- The connection between the ceiling and the reinforced belt is made by rigidly connecting the reinforcement belt reinforcement with the reinforcing rods of the slab by welding.
The nodes depend on the number and type of capital elements. For support on two sides, they are made on transverse load-bearing walls, and for support on three or four sides - on both transverse and longitudinal walls. The nodes are also performed when the load-bearing elements are columns, trusses and floor beams.
In areas with increased seismic activity, it is recommended to construct support units using movable hinged joints.
When laying floor slabs, it is necessary to take into account all the parameters necessary for correctly supporting them on the load-bearing elements. The selection of slabs, calculation of nodes, reinforced belt and support depth are made at the building design stage.
Useful video
The video clearly explains why it is impossible to lean deeply into the wall. But I would argue with the maximum depth of 30 cm. It should be no more than 15 cm.
