How to make a monolithic overlap. How to make a concrete floor with your own hands

Concrete or individual blocks, monolithic overlap can be done independently. It must be resistant to vibration, and also have a fairly impressive strength. You can install such a structure between floors and under attic space. The slab can take a wide variety of shapes, which eliminates planning restrictions when designing a house.

Preparatory work

Before you start work, you should know how the formwork is installed, reinforced by reinforcement, as well as finishing pouring. When it is planned to equip a monolithic ceiling, the calculation should be made exclusively for spans within three meters. Other situations are also possible. If we are talking about longer spans, then a beam monolithic ceiling is used. If you are flooded reinforced concrete floor monolithic type, then you will have to make a reinforced concrete slab, the dimensions of which will be calculated taking into account the design parameters of the building. As an average calculation, a value of 1 to 30 can be taken into account. This suggests that for a span of 6 meters, a slab with a thickness of 200 millimeters will be needed.

Formwork calculation

Before a monolithic floor slab is poured, it is necessary to calculate the formwork. You can use a certain scheme for this. It takes into account the layout of wooden formwork beams and the placement of telescopic props. But you can use the ratio that was presented above.

Arrangement of formwork for pouring a monolithic slab

Monolithic overlap is poured into the formwork, which is based on a tripod. They allow you to install racks on uneven ground.

Monolithic overlap should begin to be equipped after support posts have been mounted over the entire surface of the site. The distance between them is determined according to the scheme, which takes into account the load created by the overlap. In this case, the thickness of the structure is taken into account. A unifork is installed at the upper end of the racks. The longitudinal beams are mounted, which are strengthened to the walls. On top of the beams, which are located along, are mounted cross beams. On top of the latter, waterproof plywood is covered, which can be replaced with steel shields.

The monolithic floor slab must be perfectly level, so the structure must be checked with building level, and if necessary, then you need to adjust the height by adjusting the racks. To prevent leakage cement mortar, which can seep through the cracks, roofing material should be laid on the formwork flooring. These manipulations must be performed before pouring the solution.

Floor slab reinforcement

After the calculation of the monolithic floor is made, you can proceed to further work. The pouring is preceded by a reinforcement procedure. For this, reinforcement should be used, the diameter of which varies from 8 to 16 millimeters. In this case, the grid cells can be square and have sides equal to 150 or 200 millimeters. After the reinforcing mesh is connected, it must be placed five centimeters higher in relation to the lower plane of the future slab. Reinforcement with mesh bottom and upper parts plates can be produced using rods that have different diameters.

The device of a monolithic floor quite often involves the use of rods of more impressive sizes when it comes to lower reinforcement. This is due to the fact that the monolithic slab works on bending. The reinforcement should be joined with some overlap, while the joints should be spaced apart.

Carrying out the pouring of a monolithic slab

The device of a monolithic overlap at the next stage involves pouring. At the same time, it is impossible to do without using special equipment, which acts as a concrete pump.

Filling technology

When choosing a brand of material for pouring the floor, you should prefer the one that is determined by the value "400". The concrete mixture should be poured in layers, the thickness and pouring period of each layer will depend on temperature factors that affect the setting time. It is important to take into account the depth of vibration processing. If the mixture is subjected to compaction using a manual vibrator, then the filling should be carried out at 1.25 of its working part. The entire thickness of the monolithic floor should be subjected to such an impact. In this case, the deep vibrator must be immersed through the last layer, penetrating 15 centimeters deep into the previously laid layer. During the entire pouring, it is necessary to analyze how integral the formwork remains, as well as its strengthening and supporting elements. When monolithic reinforced concrete floors are poured, the formwork must be constantly checked for defects. If any, then filing concrete mix should be terminated. This will eliminate the occurrence of flaws. Concreting of floors should not be carried out without technological breaks. In this case, it is necessary to make working seams. They are arranged exclusively in those places where there is the smallest bending moment.

Final works

As soon as monolithic reinforced concrete floors harden, and also gain their strength, which takes about 30 days, the formwork can be dismantled. If the second floor slab is being concreted, then even partial dismantling of the formwork props that hold the first floor slab is unacceptable ahead of schedule.

Features of the work

It is worth noting that pouring a monolithic floor is considered not the easiest and cheapest option to implement, but in the end it is possible to obtain a structure that is versatile and durable. This makes the monolithic reinforced concrete floor the most popular among the rest.

If the installation is done by hand, then moisture-resistant plywood is used for formwork, the thickness of which should not be less than 2 centimeters. As for the formwork boards, this parameter should not be less than 2.5 cm.

When erecting a building, in some cases there is a need to arrange a reinforcing element, which is called a belt. In this case, the reinforced concrete tape runs along the perimeter of the building and acts as a support for the structure.

In order to raise the mesh during the formation of the reinforcing layer, special stands made of plastic are used. The second layer of the mesh should be laid out at the same distance from the upper plane future design. To fasten two layers of meshes at the right distance, it is necessary to prepare special stands, which are made of reinforcing bars. All mesh layers and elements must be interconnected with wire.

It is important not only to reinforce a monolithic floor to obtain robust design, but also moisturizing after pouring, which is carried out within a week. Then constant hydration will no longer be required. However, it is still necessary to control the drying of the surface.

Prefabricated floor slabs

Quite often, the basement floor is made of prefabricated slabs, which are reinforced concrete products manufactured in the factory. In this case, the calculation of a monolithic overlap is not required. Such structures can be hollow or full-bodied. Installation of prefabricated slabs will be impossible without the use of a truck crane. These plates have other limitations, for example, expressed in the fact that factories produce structures whose length does not exceed 9 meters. This boils down to the fact that such slabs cannot be used for a basement floor with an impressive area. When laying the plates are mounted on a layer of mortar, the thickness of which is within 20 millimeters. After the installation is completed, the seams between the elements are cemented. These manipulations should not be delayed, as over time the gaps become clogged with debris.

Prefabricated-monolithic slabs

Quite often, prefabricated monolithic floors are also used, which have 4 elements in their composition. It is important to take into account their difference from those described above, which is expressed in the fact that such slabs can be laid without using a truck crane. Every master should note this for himself. Installation work you should start with the installation of reinforced concrete beams and laying blocks between them. The latter are laid out in one row from the two ends of the beams. This makes it possible to install the beams at the right distance from each other. After that, you can start working with the remaining blocks. Prefabricated monolithic ceilings must be reinforced, and then concreted.

According to the forum member ontwerper from Moscow, it is not so difficult to do it on your own. He cites well-known and little-known considerations for their manufacture as arguments. In his opinion, making overlaps with your own hands is beneficial for several reasons:

1. Availability of technologies and materials;
2. Convenience and practicality from an architectural and engineering point of view;
3. Such floors are durable, fireproof and have soundproofing qualities;
4. financial feasibility.

Monolithic works

Before pouring concrete, ontwerper advises to carefully consider the whole process and, first of all, order concrete from the factory. It is better than home-made - there is a quality control and quantity of fillers that improve concrete and prevent it from delamining for a long time. The composition should consist of heavy aggregates, have a strength class of B20-B30 (M250-M400), and frost resistance of F50.

Do not be lazy and check the vacation parameters, class-mark and time until the moment of concrete setting according to the documents.

If you need to supply concrete to the second, third floor or over a long distance, then you will not be able to do this without a concrete pump, and rolling concrete with shovels along endless chutes is a very difficult and inconvenient task.

AT winter time concrete can be ordered from antifreeze additives, given that additives usually increase the curing time, some of them provoke corrosion of the reinforcement, but this is acceptable if the additive is factory-made.

ontwerper prefers not to build in the winter, and does not recommend it to you. In extreme cases, do not prepare the solution yourself, use factory concrete.

Formwork installation

The main purpose of the formwork is to withstand the mass of freshly poured concrete and not deform. To calculate the strength, you need to know that one 20 cm layer of concrete mixture presses on a square meter of formwork with a force of 500 kg, to this you need to add the pressure of the mixture when it falls from the hose, and you will understand that all structural elements must be reliable.

For its manufacture, ontwerper advises using 18-20mm plywood laminated (coated) or plain (but it sticks more strongly). For beams, crossbars and formwork props, a bar with a thickness of at least 100x100 mm should be used.
After its assembly, it is necessary to check the horizontalness of all structures. Otherwise, in the future you will lose a lot of time and money to correct errors.

Reinforcement

The lower one is along the span, the lower one is across the span, the upper one is across the span, the upper one is along the span.

span- the distance between the supporting walls (for a rectangular slab along the short side). The lowest row is laid on plastic crackers specially designed for this, their height is 25-30mm. The top row - overlaps it across and is knitted with wire at all intersections.

Then next in line is the installation of a mesh separator - parts from reinforcement with a certain step, it can be done as you wish. On the dividers - the top across, - knit, on it the top along, - knit with wire at all intersections. top point the frame (top of the upper rod) should be 25-30 mm below the upper edge of the formwork wall, or the thickness of the concrete should be 25-30 mm higher than the upper reinforcement.

After the completion of the reinforcement, the frame must be a rigid structure that must not move when concrete is poured from the pump. Before pouring, check the compliance of the pitch and diameter of the reinforcement with the project.

Pouring concrete

After all the preparation, you need to take and distribute the concrete over the entire area, vibrate it. It is best to pour the entire slab at a time, if this is not possible, put cuts - intermediate walls inside the formwork contour, limiting concreting. They are made from steel mesh with a cell of 8-10 mm, setting it vertically and attaching it to the frame reinforcement. In no case do cuts in the middle of the span and do not make them from the board, PPS.

Curing

After pouring the slab, it must be covered to prevent precipitation from entering, and constantly watered. outer surface to keep it moist. After about a month, the formwork can be removed, and in case of emergency, this can be done no earlier than a week later and only the panels can be removed. To do this, you need to carefully remove the shield, and support the plate back with a stand. Racks support the plate until it is fully ready, about a month.

Strength of a monolithic floor: calculation

It boils down to comparing two factors:

1. Forces acting in the plate;
2. The strength of its reinforced sections.

The first must be less than the second.

Walls on a monolithic floor slab: we calculate the load

Let's make calculations of constant loads on a monolithic floor slab.

Self-weight of a monolithic floor slab with a load safety factor of 2.5t/m3 x 1.2 =2.75t/m3.
- For slab 200mm - 550kg/m3

Own weight of the floor with a thickness of 50mm-100mm - screed - 2.2t/m2 x 1.2= 2.64t/m3
- for floor 50mm - 110kg/m3

Brick partitions with a size of 120 mm lead to the area of ​​​​the slab. Weight 1st running meter partitions with a height of 3m 0.12m x1.2x1.8 t / m3 x 3m = 0.78t / m, with a step of partitions 4m long, approximately 0.78 / 4 = 0.2t / m2 is obtained. Thus, the reduced weight of the partitions = 300 kg/m2.

Payload for the 1st group of limit states (strength) 150kg / m3 - housing, taking into account the reliability factor of 1.3, we accept. Temporary 150x1.3 = 195kg/m2.

The total design load on the slab is 550+110+300+195=1150kg/m2. We will accept for sketch calculations the load in - 1.2t / m2.

Determination of moment forces in loaded sections

Bending moments determine 95% of the reinforcement of bending plates. Loaded sections are the middle of the span, in other words, the center of the slab.

Bending moments in a slab of reasonable thickness, square in plan, hinged - not pinched along the contour (on brick walls) for each of directions X,Y can roughly be defined as Mx=My=ql^2/23. You can get some values ​​for special cases.

• Slab in terms of 6x6m - Мх=My= 1.9tm;
• Slab in terms of 5x5m - Mx=My= 1.3tm;
• Slab in terms of 4x4m - Мх=My=0.8tm.

These are forces that act both along and across the slab, so you need to check the strength of two mutually perpendicular sections.

Strength test to the longitudinal axis

When checking the strength to the longitudinal axis of the section according to the bending moment (let the moment be positive, i.e. belly down), the section has compressed concrete from above and tensile reinforcement from below. They form a power pair, perceiving the moment force coming to it.

Determining the force in this pair

The height of a pair can be roughly defined as 0.8h, where h is the height of the slab section. The force in the reinforcement is defined as Nx(y)=Mx(y)/(0.8h). We get in the representation of 1 m of the width of the slab section.

• Slab in terms of 6x6m -Nx(y)= 11.9t;
• Slab in terms of 5x5m - Мх=My= 8.2t;
• Slab in terms of 4x4m - Mx=My= 5t.

Under these efforts, select reinforcement of class A-III (A400) - a periodic profile. The design tensile strength of reinforcement is R=3600kg/cm2. sectional area of ​​a reinforcing bar with a diameter Ф8=0.5cm2, Ф12=1.13cm2, Ф16=2.01cm2, Ф20=3.14cm2.

The bearing capacity of the rod is Nst=Ast*R F8=1.8t, F12=4.07t, F16=7.24t, F20=11.3t. From here you can get the required reinforcement pitch. Step= Nst/ Nx(y)

• Slab in plan 6x6m for fittings Ф12 Pitch=4.07t/ 11.9t=34cm;
• Plate in terms of 5x5m - for fittings F8 Pitch = 1.8 / 8.2 = 22cm;
• Slab in plan 4x4m - Ф8 Step=1.8/5=36cm.

This is strength reinforcement in each of the X and Y directions, i.e. a square mesh of bars in the tension zone of concrete.

In addition to strength, it is necessary to reduce the formation of cracks. For slabs of houses and residential premises with a span of up to 6 m, 200 mm thick, supported along the contour (i.e., on four sides), at any ratio a / b, it is possible to accept the lower working reinforcement from A III rods in two directions with a step of 200x200 with a diameter of 12 mm, the upper ( constructive) - the same from F8, thinner and less does not follow.

All this is a special case of a general approach that demonstrates the specifics of the task, but for its implementation it is necessary to look deeper and turn to specialists.

Posted by FORUMHOUSE ontwerper.

Editor: Roman Adamov

A strong and reliable partition between floors is very important element construction, to create it, a concrete floor is made. A monolithic concrete slab has several undeniable advantages over prefabricated traditional slabs. You should start with the fact that the creation of such an overlap does not require the use of a lifting edge, which greatly saves financial and time resources. Everything can be done with your own hands, from heavy equipment you only need a concrete pump, but its use is not mandatory. In addition, it is not difficult to make concrete floors with your own hands, it should be noted their sound-absorbing and heat-insulating properties.

Concrete floor plan.

If you make such a design correctly, then you can count on the fact that extraneous sounds will not bother, this is the difference from drywall partitions. And walk in a new way concrete floor very nice, while not creating the feeling of a swaying ship deck.

Materials and tools

In order to get started, you will need the following materials:

In order to carry out a concrete floor, you need a concrete solution.

• moisture resistant plywood, the thickness of which does not exceed 15-20 mm;
• bars and beams made of wood (they will need to be laid under plywood);
• supporting racks;
• concrete mortar;
• in order to create a frame, you will need knitting wire and fittings.

Of the tools you will need:

• jack;
• concrete pump (its use is optional);
• spirit level or level;

Frame and formwork

Scheme of formwork for concrete floor.

Construction should begin with the creation of formwork, while the appearance of cracks and different kind holes. Then you need to make sure that the jacks and racks under the formwork are firmly installed. This is a serious issue, as it is about security. Formwork is best made from moisture-resistant plywood (20 mm laminated material for this fit better Total). The formwork must be very strong, as the weight liquid concrete is 500 kg/sq.m if the layer thickness is 200 mm. Formwork must be done not only over the area of ​​\u200b\u200bthe room, but also around the perimeter so that the concrete mix does not flow out of the limits.

Now we need to form the frame. It is made from wire, reinforcement using special hooks, a mesh is obtained with a mesh size of 1.5 by 1.5 cm (you can make 2 by 2 cm). As for the diameter of the reinforcement for the main frame, it should be 15-20 mm. When the frame is made, it should be carefully checked for strength before proceeding with the pouring of concrete. From the type of reinforcement, you need to calculate the step that will be provided during installation. When the step is calculated, the total load on the concrete floors must also be taken into account.

The lower layer of reinforcement is laid across the bottom of the formwork, and not parallel to the span, so that the ends of the reinforcement rest on bearing beams. The fact is that it is on these beams that reinforcement should be laid, since it is this factor that largely determines the success of construction. The next layer of reinforcement is laid perpendicular to the previous one. After all the reinforcement has been laid in an appropriate way, it is necessary to securely fix all the points of contact of the perpendicular rows of reinforcement with wire. Then the bearing beams will be reliable and of high quality.

Concrete beams connected to the foundation are better than antiseptic wooden beams, since beams made of wood quickly become unusable.

Concreting process

The next step is concreting, here it is very important to fill very quickly. bonding material in concrete mortar is cement, gravel and sand act as fillers. It is necessary to fill the formwork with concrete not in one go, but it is necessary to maintain one direction. Concreting can be done manually, you can use a concrete pump. The concrete mixture is poured without interruption, then it is compacted with the help of internal vibrators so that voids do not form in the thickness of the concrete layer. All irregularities of the base should be controlled with a spirit level or level. To find out how thick the plate turned out, you need to use a probe. It must be borne in mind that the plate must be strong enough, this factor is very important.

Scheme of concreting.

While the concrete mortar hardens, it must be protected from direct sun rays. Wind and draft also have on him Negative influence. Any kind of mechanical impact experienced by concrete slab until it has hardened, is also not allowed. In order for the concrete slab to harden in favorable conditions, it is necessary to water it from time to time, this procedure must be done within a week. The slab remains with the formwork until it dries completely.

In order for the concrete floors to be made in-house high level, it is necessary in their manufacture to use materials only of the High Quality. As for the mortar for pouring concrete, it is better to use M-250 or M-400 concrete for this, such material incorporates special heavy fillers. An important milestone such work is to carry out all the necessary calculations, so you can save a lot of money.

In order for the calculations to be carried out with maximum accuracy, it is necessary to compare two main parameters - the strength of the reinforcement manufacturing and the mass that acts on the slab. For monolithic systems, the following factors are determined: the rigidity of the longitudinal axis, the magnitude of the forces in the most loaded sections of the floor, the force of daily loads on the slab.

Making concrete floors with your own hands also has the advantage that you can independently think through and lay all plumbing communications. In order for the plate to have good thermal insulation characteristics, you need to use boards. Before laying, the slab can be leveled with self-leveling compounds.

During construction, many people have a question about how to make the ceiling so that it is not only reliable, but also provides good sound and heat insulation of the premises. To solve this problem, it is best to make a choice in the direction reinforced concrete slabs or reinforced concrete monolithic ceiling.

Scheme of monolithic overlap.

If it is not always available to purchase reinforced concrete slabs of the required size, then you can make a monolithic structure yourself, the main thing is to make the calculation correctly and approach the work responsibly. For a monolithic floor to have high strength, it is being reinforced. The dimensions of the reinforcement used in each case are calculated individually and depend on the size of the overlapped area and on the load on the structure. allows you to get a solid construction of high quality.

One of the main advantages of monolithic overlap over use finished structures is that in this case there is no need to use heavy equipment, which is not always available during private construction.

Another advantage of a reinforced concrete monolithic floor is that in this way it is possible to cover any rooms that are not standard in size, while the step of placing the reinforcement in each case is calculated separately. Reinforcement of the structure allows to achieve its high strength. Before wooden structure monolithic also has advantages, as it is more durable and reliable. In order to carry out the correct calculation of all sections of a monolithic floor, you can contact special design organizations or do everything yourself using available programs that allow you to calculate the spacing of reinforcement, design ceilings for any purpose and various shapes.

Calculation of a monolithic floor

Do-it-yourself monolithic flooring scheme.

Availability of special computer programs help to make the calculation, but they do not replace the designer himself. If you do not have basic construction knowledge (do not understand the characteristics of concrete and reinforcement, do not understand what reinforcement is in a monolithic slab), then you will not be able to calculate a monolithic slab on your own. Some people start making a monolithic structure without making a preliminary calculation. In this case, they risk, since the overlap will either have less strength, or it will come out much more expensive. This is undesirable and unprofitable. Hiring professionals has always been quite expensive, so many people decide to make a monolithic structure on their own. How to calculate it correctly, we will consider further. First you need to decide on the thickness of the overlap. It depends on the load on the ceiling and the length of the span. In order to make an approximate calculation of the thickness of the floor, it is necessary to divide the maximum length between the supports by 30. For example, if the span is 6 m, then the slab should be 20 cm thick.

Scheme of the roof with corrugated board.

If the thickness of the overlap is 15 cm and the load on it is small, then reinforcement can be carried out in one layer. If you are doing the work yourself, then it is better to do it in two layers, at the top and bottom of the plate. Here the choice is yours, if you do everything yourself, then it is better to overpay for the material and get high floor strength. If the calculation is done by specialists, then you will save on the material, but overpay for the said work. Professionals can help you determine required size, cell pitch, reinforcement section. Often additional reinforcement is required to enhance the strength of the structure. In the lower part of the slab, it is made in the middle of the span, and in the upper part - in places of the greatest load: in technological holes, on supports, in places where heavy furniture or equipment is installed. It is necessary to take into account the step of the partitions that will be on the floor. For additional strengthening, reinforcement with a length of 0.4-1.5 meters is used. It is a solid slab, the thickness of which is usually 12-20 centimeters, which is made of concrete B15-B25 and reinforced with metal rods. In each case, the reinforcement spacing is calculated individually. This plate is based on bearing structures and can take many different forms. The device is carried out in three stages:

• formwork installation;
• reinforcement: a frame is made of reinforcement, the diameter of which is 8-16 mm, usually the step is 15-20 cm;
• surface concreting with B15-B25 class concrete.

Installation

Scheme of installation of reinforced concrete floor slabs.

In order to make a monolithic structure, you first need to complete the formwork. The forming surface in it is waterproof plywood. As the calculation shows, its thickness should be 18-21 mm. After the slab has hardened, the plywood can be removed and reused. If you are installing, you can use edged boards. But in this case, be prepared for the concrete to leak through the cracks. The boards can sag, rusts will appear in these places, which spoil appearance coatings. In the future, they must either be knocked down or leveled with plaster. It is especially necessary to carefully check the reliability of the installation of racks and the absence of cracks in the formwork, if the cracks are more than 3 mm, then they must be sealed. Otherwise, concrete milk will seep into them, and this leads to a decrease in the strength of concrete.

Formation of the reinforcing cage

Scheme monolithic slab overlap.

After the formwork has been installed, reinforcement can begin (using metal rods form the frame of a monolithic floor). Between themselves, the reinforcement is tied into a mesh using a knitting wire, as the calculation shows, a wire with a diameter of 0.8-1.2 mm is sufficient. Usually the cell spacing is 15-20 cm, respectively, their size is 15 × 15 cm or 20 × 20 cm. For the main reinforcement, reinforcement with a diameter of 8-12 mm is used, for places where it is necessary to strengthen the structure (support on walls, columns and spans), thicker reinforcement with a diameter of 12-20 mm is used. The thickness of the reinforcement in a monolithic slab is calculated individually in each case. The thickness of the protective layer of reinforcement must be at least 2 cm; for this, protective layer clamps are placed under it on the formwork. After the reinforcement is carried out, the entire frame must be carefully checked.

Floor slab concreting

Scheme of building a house.

After the formwork has been made on all surfaces of the floor and reinforcement has been carried out, its concreting begins. The concrete mixture can be delivered to the place of work or prepared directly on the site. Cement is used as the main binder, sand is used as a fine aggregate, and crushed stone is used as a coarse aggregate. As the calculation showed, the average weight square meter monolithic overlap with a thickness of 20 cm is 480-500 kg. It is best to lay the ready-made concrete mixture immediately over the entire thickness of the slab, while maintaining one direction of work. These works must be carried out continuously and the mixture should be well compacted with a vibrator. Most often, internal vibrators are used to compact the concrete mix. When carrying out free laying of concrete, the drop height can be up to 0.7 meters. If the base is even, then the control of the thickness of the overlap can be carried out using a probe. When it is uneven, then with the help of a level. The surface of the slab must be protected from wind and direct sunlight. Hardening concrete must not be exposed to mechanical influences such as shock or shock. In order for the hardening process to be most effective, it is necessary to periodically water the monolithic floor with water, in dry weather this should be done at least during the first 7 days. If the temperature environment above 15 ° C, then the first three days the concrete is watered every 3 hours during the daytime and once at night, and then no less than three times a day. At an air temperature of about 5 °C, it is necessary, on the contrary, to provide additional heating of the concrete. The calculation showed that the most optimal parameters for concrete hardening are air temperature +15°C and humidity of the order of 90-100%. Only after 28 days the concrete will acquire the design strength. It is possible to proceed to the dismantling of the formwork after the concrete has acquired 70% of the design strength.

Disadvantages of monolithic overlap:

• the complexity of the construction works, the need for reinforcement of the entire surface;
• if it is necessary to calculate and perform complex nodes, then you will have to involve specialists;
• the manufacture of formwork takes a lot of time and requires a lot of labor;
• if work is being done negative temperatures, then it is necessary to calculate the necessary additives or carry out additional heating of the floor before it hardens, which increases the cost of work by approximately 10-20%.

The main advantages of monolithic overlap:

• such ceilings can be made in rooms of any (even curvilinear) shape;
• the calculation shows that a monolithic floor 14 cm thick is sufficient to suppress airborne noise (if, for example, wooden floor, then in this case it is necessary to apply soundproofing materials, it is not necessary to do this);
• such ceilings allow you to make a takeaway for a terrace or balcony of any shape, and you do not need to use additional supports;
• if everything is done correctly, then the lower surface of such an overlap is smooth, which allows you to save on its finishing (no joints - no cracks, which cannot be said when using ready-made plates);
• no need to use crane.

It is not difficult to make a monolithic ceiling on your own, the main thing is to correctly calculate.

H eat stronger construction overlap, themes more reliable protection. Concrete slabs are especially good for this. But in order to lay them, a crane is required, which is both expensive and not always possible to use.

An alternative for an overlap device would be to use monolithic concrete. Its laying can be done in relatively small portions, the weight of which allows manual work.

But how to ensure that a home-made monolithic concrete floor has sufficient strength and does not crack or, worse, collapse? Is it possible and how to do it without using complex calculations and formulas? Yes, it's possible. But let's go in order...

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How is the concrete floor

To begin with, let's figure out how a concrete floor slab works and how it works. Without this, some points may be incomprehensible.

The strength of concrete, like others stone materials, is not the same depending on the direction of the load. Best of all, it withstands compression, and worst of all, it withstands stretching.

Moreover, the difference is so great that in the calculations of the strength of structures, the tensile strength of concrete is usually not taken into account at all!

But the floor slab rests on the edges, and is loaded over the entire surface. At least its own weight. Obviously, she will tend to bend. If we consider the cross section of such a plate, then in the upper part it is compressed, and in the lower part it is stretched. Moreover, the efforts will be maximum at the top and bottom, and in the middle of the section they will turn out to be zero (see Fig. 1).

Since, as we have already said, concrete is disgustingly resistant to stretching, it is reinforced with metal reinforcement. Without her conventional stove would break even under its own weight.

Reinforcement is needed not only at the bottom of the section. There are other places in the floor slab that experience tension, they also need to be reinforced. How and what stresses arise can be seen in Figure 1.

Interesting: The Parisian gardener Joseph Monier, who invented reinforcement, thus becoming the "father" of reinforced concrete, was nevertheless a complete ignoramus in construction. So, until the end of his days, he was sure that the reinforcement should be laid in center sections of bent structures. In fact, here it is absolutely useless.

We select reinforcement and brand of concrete

How more thickness slabs and concrete strength, the larger the diameter of the reinforcement, the stronger the overlap. But at the same time heavier and more expensive.

For the solid part, we use OSB3 with a thickness of 16 mm. It is cheaper than the waterproof plywood commonly used on a construction site, and then goes for, on, subfloors, etc.

We will find out the layout of beams and racks when using inventory formwork when we rent it. This scheme depends on both the load and the type of equipment.