Slab foundation - we will make a truly reliable foundation on our own! How to make a monolithic slab foundation with your own hands Features of pouring the base

The slab foundation is an effective basis for building a house on a site located on heaving soils. The complex of features of such a foundation ensures the reliability of the structure. At the same time, the foundation of a monolithic slab can be of several types, and their features are also different.

Pros and cons of slab base

The slab foundation is a shallow base, which ensures the reliability of the building when the ground moves. The base has a "floating" ability, which minimizes the risk of the structure warping during seasonal freezing or thawing of the soil. Thus, the foundation and the building installed on it, as it were, "float" on the upper layers of the soil. This is optimal for heaving, clayey areas, but such structures are practical on any other type of soil.

The foundation slab has a simple design that is efficient in operation. This is due to the following advantages of such a foundation compared to other options:

• the minimum amount of earthwork contributes to savings in the construction process;
• ideal for complex, heaving soils, as it ensures the stability of the structure;
• the service life of a high-quality slab foundation is more than 150 years;
• the possibility of using any material for building a house;
• a simple device does not require a lot of time to build.

In the process of creating a slab foundation, a large amount of concrete, reinforcement and other materials are needed. This leads to significant financial costs, which is the disadvantage of such a foundation for the house. To equip the plate, you need the most even initial surface. Otherwise, laying the foundation layers will be impossible or of poor quality. At the same time, all communications calculations must be planned at an early stage. The disadvantages of the slab construction are pronounced, but when building on heaving soils, the base is the only option.

The stability of the slab base allows you to build houses with a height of 2 floors. At the same time, it provides protection of the structure from distortions as a result of soil freezing, as well as the durability of structures.

Features of the floating foundation

The floating foundation is a type of slab construction. Often floating is synonymous with slab, but they have some differences. The floating version is presented in several forms with the following features:

• floating grating - a base having cruciform stiffeners with a step of 1 to 3 m. The method has a lower cost, and during operation, distortions of the building are excluded. The key to the reliability of the structure is the accurate calculation of all parameters, depending on the features of the future structure;
• a columnar floating option cannot be created on clay soil, but it is optimal for rocky and gravel sands in the construction of log cabins, frame or panel houses. The foundation cushion consists of sand and waterproofing, which replace the fertile soil layer. The step between the pillars is 1.5–2.5 m;
• the floating slab is a one-piece low-depth base. At the same time, it is important to stabilize the state of the heaving soil by organizing drainage, replace the layer of inert soil, and protect it from freezing. This avoids violation of the integrity of the building during the movement of the slab as a result of swelling of the soil.

A floating foundation differs from a slab foundation in that it can be created in several ways. The choice of a particular one depends on the material of the building, the characteristics of the soil, the weight of the structure. In any case, an accurate calculation of all parameters is needed, otherwise the structure may squint as a result of soil movement.

Finnish foundation

The foundation, in which the slab is not connected to the basement / foundation part, perceives only operational loads. Communications in the form of a warm floor do not pass through the base, because they are mounted at the stage of finishing the structure. The Finnish version is designed for the subsequent arrangement of a warm floor. The base is suitable for buildings without an underground floor.

The Finnish base involves insulation with foam or other materials for arranging the foundation. This process is carried out from the inside of the structure. At the same time, the bottom plate does not have thermal insulation, and for waterproofing, welded or glued films are used.

Foundation device monolithic slab

The slab type base includes several layers, each of which performs a specific function. The key to proper organization is the preparation of the pit, because the foundation should be as even as possible. The design is a "pie" consisting of several layers of materials. The peculiarity lies in the fact that when the soil is displaced, it is not the “pie” layer that moves, but the entire slab along with the structure. Thus, the distortion of the building, the appearance of cracks are prevented.

The slab base is optimal for a two-story building made of blocks or bricks. In this case, the house can be installed on loose or subsidence soils. To achieve the greatest reliability of the structure, it is necessary to carefully calculate the parameters of the foundation, determine the composition of the “pie”, and select materials.

Swedish plate: foundation features

The base, equipped according to the type of Swedish plate, involves insulation and is suitable for low-rise buildings. At the same time, the main slab is isolated from the ground with a layer of insulation made of extruded polystyrene foam. The layer thickness is 200 mm. It serves for thermal insulation, distribution of the load on the soil, depreciation of frost heaving of the soil.

The Swedish plate is distinguished by a short construction period, which is about 14 days. One of the main requirements for the construction is the preliminary leveling of the soil, which is the key to the reliability of the foundation. The structure is a combination of a strip base and a concrete floor, but there is a good thermal insulation layer.

Construction technology

The exact technology for erecting a slab base depends on the type of soil of the site, the features of the future building, and the quality of the materials used. The main stages of construction are adjusted depending on these factors, and the key to quality is the correct calculation of the thickness of each layer and other parameters of the foundation.

You need to create a foundation on the most flat area. To do this, dig a pit, the depth of which is determined when calculating the parameters of the base. The perimeter of the pit should be 1–2 m larger than the dimensions of the future foundation on each side. The most even surface of the recess will ensure the correct distribution of the load on the ground. After using special equipment for digging, you can process the surface manually, removing irregularities with a shovel and other tools.

The second stage of work involves laying sand and gravel backfill. This layer is necessary to drain groundwater, compensate for the load when the soil moves, and prevent the rise of water to the bottom of the foundation slab. For sandy soil, the thickness of the backfill layer is about 15 cm, heaving soils require an increase in this indicator to 30–45 cm. A mixture of sand and fine gravel is distributed along the bottom of the pit and compacted. This will protect the structure from moisture and deformation.

After preparing the surface, you should proceed to the direct construction of the foundation. Perform the following actions:

1. Boards 50 mm thick are installed around the perimeter of the future structure. The pit should be larger than the foundation by a meter on each side, but the formwork is mounted clearly according to the size of the building. The height of the formwork is equal to the thickness of the foundation - it is leveled with the help of laces and the building level horizontally. If alignment cannot be done, marks on the boards themselves must be set before pouring. The thickness of the foundation can be different - on average it is 20–30 cm (for heavy buildings this figure is higher, for light ones it is lower).
2. Waterproofing is laid after the installation and fixing of the formwork. For this, bituminous materials in rolls are used. Waterproofing sheets are placed in the formwork to the full height, making an overlap. The strips are welded together. The overlap is necessary to prevent the formation of holes at the joints of the formwork elements, provide better waterproofing properties, and also facilitates easy removal of the formwork after the concrete has hardened.
3. The reinforcement is needed for strengthening, its thickness depends on the load on the slab (usually from 10 to 14 mm). The frame must be knitted in 2 rows. The lower row is mounted on special clamps that provide a gap of 5 to 7 cm between the waterproofing layer and the reinforcement. Knitting is carried out with a special hook (grid pitch from 20 to 25 cm), and knitting wire is used as the material. The next row is created in such a way that the metal reinforcement after pouring is immersed in concrete by at least 5 cm. The rows must be fixed with vertical structures from the same reinforcement, which will provide support for the top row of reinforcement. This method prevents delamination of the foundation during loads.

After preparing the frame, concrete is poured. The mixture must be grade M200 or more. It is important to fill at one time, because this affects the strength of the structure. Intervals between fillings should be kept to a minimum, as long interruptions have a negative effect on the adhesion of the material. After pouring, the surface should be leveled using the rule, and then the prepared base is left for 28 days to fix.

The ideal conditions for fixing the structure are an air temperature of +20 °C and a humidity of about 80%. At a higher temperature, the next day after pouring, pour the foundation with water and cover with a film. In cold weather, the base needs heating. With prolonged "preservation" you need to cover the foundation with a film.

Video: pouring and slab foundation

Calculation of the slab base

The durability of the structure depends on the exact determination of the parameters of the foundation. For the calculation, you should know the bearing capacity of concrete, as well as the soil on the site. The main characteristics can be found in SNiP and other regulatory documents.

An example calculation looks like this:

• with a bearing capacity of soil of 2 kg / cm 2 and concrete of 150 kg / cm 2, the foundation should not exert a load on the soil exceeding 2 kg / cm 2. Therefore, during construction two-story house with a size of 10x10m and an area of ​​100 m 2, a foundation slab with a thickness of 200 mm is created. The approximate weight of the base is 100 tons;
• the weight of the building, the walls of which are 250 mm thick, is 200 tons, and the total mass of the foundation and the building is 300 tons. This indicator is divided by the area of ​​\u200b\u200bthe building and it turns out that the pressure on the ground is 0.3 kg / cm 2;
• professional calculation involves taking into account climatic factors, the depth of groundwater and other factors.

To determine the thickness of the foundation slab, it is necessary to take into account the type of building under construction. For example, for a residential two-story house made of frame materials, an indicator of 200–250 mm is optimal. In this case, volumetric reinforcement in two rows is used. For a residential building, the height of which is 2 floors, concrete, brick, timber or logs can be used in the construction.

For light structures, such as a garage, porch or utility buildings, a lighter foundation is used. In this case, the thickness of the plate is 100–150 mm, the reinforcement is carried out in one row using metal meshes.

Features of pouring the base

Pouring the concrete mixture onto the reinforcing layer is a particularly important step in the construction of the slab foundation. For this purpose, concrete grade M200 is used, but the composition M300 is often used. The reliability and strength of the foundation for the building depend on the quality of the mixture, the uniformity of the pouring. Therefore, the fill has the following features:

• pouring a solid slab is carried out at a time;
• Finnish or Swedish tiles can be poured in parts: first strip foundation and then the middle;
• the time between pouring batches of concrete should be kept to a minimum;
• it is important to observe the bonding period of concrete.

In dry and warm weather, fixing the foundation will occur as efficiently as possible. High humidity, precipitation and low air temperature require covering the structure with a film.

Photo gallery: pouring a slab foundation

The slab foundation is optimal for difficult soils, but can also be created on more stable soil. In any case, it is important to follow the construction technology and carry out an accurate calculation of the parameters.

How to make a slab foundation with your own hands? In private construction, when choosing the type of foundation, the installation of a strip foundation is most often used. However, the construction technology includes a number of difficulties, which makes the use of this option impractical even when constructing a small building. In this case, the best option would be a hand-made device of a monolithic foundation.

Do-it-yourself monolithic foundation is poured around the perimeter of the future building. It will have a uniform distribution of loads over a large area, which makes it an indispensable option for construction in unstable soils. Step-by-step instructions will describe in detail how to properly implement a slab foundation. Installation is quite simple.

Construction structure and scheme

During installation, the foundation slab does not need a large depth of occurrence. It must be located close enough to the surface of the earth. This is because the slab under the house must float on the soil below. It is then that the most optimal strength characteristics will be manifested, and soil buckling in winter will not pose a danger to the house.

The structure of the slab foundation with your own hands is as follows:

1. Ground base. This is usually the bottom of the pit, which must be compacted.
2. Sand pillow. The foundation slab can be of different designs: sand, crushed stone or combined with gravel. Purpose - uniform distribution of soil loads and vibrations. It can be performed in several layers with different materials.
3. reinforcing layer. It is designed to protect the previous layer from blurring and silting. Production has several ways of arranging geotextiles, depending on the conditions of construction. It can be used between the first and second layers to prevent the movement of soil particles, as well as between sand and gravel backfills. The function is the same everywhere. The presence of a backfill of gravel or crushed stone above the sandy layer prevents the capillary movement of moisture.
4. Concrete preparation. In some cases, construction technology does not imply this layer in order to save money. But it plays a very important role - giving a clear geometry for the further process of pouring a monolithic foundation slab. After the device of concrete preparation, the installation of waterproofing will be performed much better.
5. Waterproofing. It acts as a barrier to the movement of ground moisture. It is recommended to install at least two layers of rolled waterproofing (polymer-bitumen).
6. Monolithic structure (slab).
7. Reinforcing belt. The standard version is as follows: two interconnected reinforcing bars for maximum rigidity. The protective layer of concrete should be approximately 50 millimeters.

This is how the structure of manufacturing monolithic foundations looks like. However, a monolithic slab can be made in several ways in relation to the construction conditions. The classic version is a solid construction, the width of which is respected over the entire working area. It is excellent for a stable ground base. The main drawback is the small thickness of the slab, which, due to the close location of the upper edge to ground level, negatively affects the walls. An alternative is the use of reinforcement (stiffening ribs) located above or below the structure.

Technological process

It consists of a number of individual works that need to be given special attention. A do-it-yourself foundation slab for a house has the following step-by-step instructions:

Step-by-step instruction.

Training

The device of a monolithic slab includes a thorough study of the characteristics of the soil and the calculation of the structure. Survey work can be carried out visually without the involvement of specialists. Usually carried out in two ways:

1. Through the shafts.
2. By drilling wells.

For a shallowly buried monolithic foundation slab, pits with a depth of 50 centimeters are sufficient. The main parameters to be determined are:

1. Soil type.
2. The bearing capacity of the soil.
3. Determination of the groundwater level mark.

When calculating the structure, the parameters of the soil base and the total load of the building are taken into account. The standard option for private construction is to make a slab 15 centimeters wide with a single type of reinforcement. A full calculation is performed by civil engineers working according to building codes (SP, SNiP, STB and others), which contains information on how to pour the foundation slab.

Marking the territory and digging a pit

1. To properly arrange the foundation slab, it is necessary to take out the axes. Do-it-yourself marking of the foundation slab is as follows:
2. A right angle is drawn from the starting point.
3. It is applied to the surface of the earth (with a peg).
4. The length of the foundation is cancelled. After that, two points will appear, with which you need to carry out the operations described above (accuracy 10 mm).
5. A demolition of the building is being carried out, on which the sides of the slab are being designed.
6. A cord is laid along the border.

The depth of the pit for a monolithic foundation slab will be summed from the thicknesses:

1. Insulation.
2. Waterproofing.
3. Preparations.
4. Foundation cushion.

The device of a monolithic foundation slab implies its location above ground level. The perimeter is equipped with drainage pipes with a certain slope. Do-it-yourself monolithic slab should provide for the location of engineering networks in advance.

slab base

The pouring of the foundation slab implies a multilayer threshold. It is handmade and has step by step actions. Initially, the pit is covered with a reinforcing layer (geotextile). The basic rule is that its installation should extend beyond the edges of the monolith by one meter.

Also, the technology of the device of a monolithic foundation implies a pillow made of bulk materials. It is recommended to use a two-layer sand - 20 centimeters of sand and gravel. It is forbidden to use small fractions of sand, as after a while strong shrinkage will occur, which will violate the integrity of the structure. The substrate device for a monolithic slab can have a thickness of up to 30 to 50 centimeters.

Important: when installing the foundation slab, each layer should be compacted separately. For these purposes, it is recommended to use a vibrating plate.

The next stage is the production of concrete footing. When concreting the constructed frame, “skinny” grades (B7.5 or B12.5) are used. Its thickness ranges from 50 to 70 millimeters. Filling can be done:

1. Manually (step by step photos will help).
2. Mechanized technology.

The construction of a monolithic structure can be continued only after two weeks. The final set of strength will occur in 28 days, given the favorable weather. During this period, you need to take care of the structure (you can learn this from various videos). The base of the foundation made should be 10 centimeters wider in terms of the slab parameter.

Further, the monolithic foundation slab is equipped with a waterproofing layer. Often, its role is played by standard dense polyethylene. However, it is better not to save on this. It may be the installation of waterproofing from penetrating compounds.

Warming was always done as the final step. The construction of a monolithic foundation prohibits the use of standard options as a heater (polystyrene or mineral wool). The use of extruded polystyrene foam is recommended. The thickness is selected relative to the climatic region of construction, in most cases 100 millimeters is enough.

Armature reinforcement

Installation of fittings in private construction is based on the minimum parameters that are in a special manual. There you can find a lot of information on how to make a monolithic foundation with your own hands. The total sectional area of ​​the reinforcement should be more than 0.3 percent relative to the total foundation section. Structurally, the minimum diameter of the rods is 10 or 12 mm (depending on the side). The minimum tiled size of foundation reinforcement for a private house is 40 millimeters.

Formwork

The pouring technology may include the following types of formwork:

1. Removable (wooden).
2. Non-removable (styrofoam).

Thanks to the second type, a do-it-yourself stove is less expensive, and installation is easier. The pouring of a monolithic slab should not be carried out from a great height. It must be compacted. It is better to use a concrete pump through which a mixture of poor quality does not pass.

Formwork installation.

To make the foundation of a monolithic slab with your own hands, you need to install high-quality formwork. Its main purpose is to give the body of the slab the necessary shape at the time the concrete sets the required strength. Slab foundation technology is often equipped with formwork from boards. They need to be arranged in such a way that there are no gaps.

The construction of the formwork of the slab foundation can be carried out from inventory boards, which will save time and money.

Make a slab foundation with your own hands step-by-step instruction it will be easier from boards of the same thickness that need to be moistened. They must be installed as evenly as possible so that the foundation slab arrangement is correct.

concrete care process

How to make a high-quality slab foundation with your own hands? Proper care must be taken:

1. Covering - to prevent evaporation of the liquid.
2. Humidification - should be performed with a certain frequency.

The construction of a slab foundation involves spraying it every 2-3 hours (depending on the weather) during the installation process for a whole week. This is necessary to prevent cracking. The slab foundation technology includes the removal of the formwork after two weeks. It is recommended to wait for a full set of concrete strength.

List of required tools

How to make a slab foundation with your own hands without using special tools? For the foundation, a monolithic slab will need:

1. Concrete mixer (without it, pouring the slab will be difficult).
2. Cart for pouring a monolithic foundation.
3. Shovels and buckets.
4. Building level so that the foundation device is correct.
5. Roulette (high-quality pouring of a monolithic foundation slab will not do without).
6. Welder. The monolithic slab foundation construction technology includes the connection of reinforcement using this apparatus.
7. Master OK.
8. Square, for checking the accuracy of angles.
9. Fittings.
10. Crusts, jointing and rammers. Without them, the do-it-yourself foundation slab will not have an aesthetic appearance.
11. Do-it-yourself monolithic slab foundation will not do without ready-made concrete or components for its manufacture.

Conclusion

For more information on how to fill the slab, you can see a do-it-yourself monolithic foundation with step-by-step photos. As a rule, installation, foundation manufacturing and pouring technology are not difficult. It is enough to know the structure of monolithic structures and follow the step-by-step instructions (rules) with your own hands.

The construction of a slab foundation is economically justified with unsatisfactory bearing capacity of the soil in the building spot, high groundwater level, high content of clay that swells when freezing. Do-it-yourself construction of a slab is possible on a flat area with a guaranteed absence of third-party communications.

When pointing out the main drawback of the slab base - high cost, the opponents of this technology do not take into account that the slab is also an overlap, a floor on the ground, and allows you to integrate a heating system into it. This, ultimately, is cheaper than a deep strip base, the amount is quite comparable to MZLF with a safety margin of 300%.

The scheme of the pie of a slab of a private house protected from frost heaving looks like this:

• sand - 15 - 20 cm, replaces heaving soil;
• crushed stone - 15 - 20 cm, is a draining layer;
• communications - necessary for life support systems;
• drainage - laid along the perimeter, collects water from the ground, removes it from concrete structures;
• concrete preparation - a thickness of 5 - 10 cm, is used as a rigid base for rolled waterproofing, which in its absence will be torn by sharp corners of rubble;
• waterproofing - two - three layers, roll materials based on polyester, fiberglass are recommended (Technoelast, Linocrom, Bikrost), the layer protects the concrete structure from moisture;
• thermal insulation - 15 - 30 cm, retains the geothermal heat of the bowels under the sole of the house, heaving soil does not freeze through, there are no heaving forces;
• stiffeners - increase the strength of the slab, are made across the long wall of the house and along the perimeter, directed downward from the sole;
• armored belt - two reinforcing meshes with a cell of 20 x 20 cm from bars 12 - 16 mm;
• warm floor - water circuits laid on top of the reinforcement or between the grids;
• concrete - thickness 20-50 cm, provides rigidity, strength of the slab;
• flanging - from expanded polystyrene, protects the plate at the ends;
• blind area insulation - expanded polystyrene sheets increase the perimeter of thermal insulation, cutting off lateral freezing.

The main advantages of the slab foundation are:

• lack of special equipment - all work can be done by hand;
• minimal excavation - it is enough to remove the fertile layer.

The main costs are for reinforcement, insulation, waterproofing and ready-mixed concrete, which is better to order for guaranteed filling of the formwork in one step.

Step-by-step instructions for installing a slab foundation

Step-by-step diagram of the slab foundation device

Research and calculation

Soil sampling

When designing a monolithic slab, it is necessary to take into account the experience of similar structures in the region, the results of surveys (ground water level, the nature of the soil, the bearing capacity of the formation), the terms of reference (number of storeys, wall, roofing materials). Surveys include at least five geological pits (corners + middle of the slab).

The result of the research is the characteristics of strength, deformation of different layers of soil in the building spot, forecasting changes in the chemical composition during the operation of the dwelling, the degree of aggressiveness of groundwater.

It is necessary to compare several solutions to identify the best combination of construction budget and technical characteristics. Step-by-step calculation instruction:

• concrete grade - M200 and higher for a slab, M50 for preparation, according to the foundations of structures, buildings;
• GWL depth - anti-corrosion measures in the presence of perched water;
• when calculating prefabricated loads, the weight of the slab is not taken into account on sandy soil;
• the bearing capacity, deformations that can destroy the structure are calculated.

For this, special programs are used that have proven the performance of the foundations made according to their results in real operating conditions. The main documents at this stage are:

• soil classification -;
• enclosing structures, bearing -;
• anticorrosive of the power frame of the building -;
• design, manufacture of MZF -.

Unlike strip foundations, the slab has an increased bearing area, prefabricated loads from the building are distributed evenly, and the strength margin is very large.

Marking and earthworks

We remove the fertile layer of soil

The plate is forbidden to fill in the fertile layer. The layout of the house looks like this:

• axes - carried out in the building spot with a cord fixed on pegs installed further than the perimeter of the drainage system;
• pit - 0.5 meters more than the slab on each side (for drainage), the slab protrudes at least 10 cm beyond the dimensions of the building (depending on the project).

Due to the small amount of work to remove the fertile layer (20 - 40 cm) for a residential building, the work is done by hand without the involvement of special equipment. At this stage, it is necessary to ensure the protection of the monolithic structure from soil moisture (top water). To do this, drains are laid around the perimeter:

• geotextile, going to the edges of the ditch;
• a layer of compacted rubble;
• perforated pipe (corrugated or smooth in a dornite filter) with a slope towards the underground reservoir;
• backfilling with a natural filter (crushed stone fraction 10/20);
• covering with the remaining geotextiles.

Drains must not be laid under concrete preparation or foundation slab. The height of the backfill should be flush with the crushed stone base pad.

In addition, after pouring the slab into the building, it is impossible to introduce communications, therefore cold water pipelines and sewers are laid at the same stage. They do not have to be buried below the freezing mark, since the thermal insulation of the sole of the slab will retain geothermal heat, the earth will not freeze under the cottage. Enough depth of 1 - 1.2 m.

Substrate

We arrange a sand cushion. Sealing is a must.

Another measure to reduce heaving forces is the substrate. It is made by hand using technology:

• layer-by-layer compaction of sand - 10 cm backfill, abundant moisture, tamping with a vibrating plate, the second layer of the same thickness;
• layer-by-layer compaction of crushed stone - fraction 10/20, similarly.

We lay down a layer of rubble.

Instead of crushed stone, sand, a mixture of ASGs can be used to a depth of 40 cm with compaction by the specified method. Only in this case, the monolithic foundation of the house will receive reliable support on the lower layer.

Concrete preparation and waterproofing

We do concrete preparation.

For a monolithic slab, a lower waterproofing cut-off is required to prevent corrosion of concrete and reinforcement inside it. Laying a waterproofing carpet made of rolled materials over a layer of crushed stone does not meet the operational conditions:

• the sharp edges of the stones break through the material;
• seams cannot be properly sealed.

Therefore, when building the foundation of a house with your own hands, concrete preparation is often used. This is a simple screed that solves two problems:

• providing a flat surface on which it is easy to stick the bituminous base of Bikrost, Linokrom, Technoelast, to reliably seal the seams;
• creation of an even base of the slab, strengthening its strength, stabilizing the geometry.

We install waterproofing.

The method of pouring into the formwork is standard, the thickness of the screed is 5 cm, reinforcement is not required. Roll materials provide a minimum construction budget, impregnation, primers are not used here. The recommended overlap of the strips is 15 - 20 cm, the seams are processed with hot or cold mastics on a bitumen basis. The edges of the waterproofing mat are extended beyond the perimeter of the concrete preparation so that, after pouring the slab, they can be run onto the sides and top surface.

We lay insulation under the entire area of ​​\u200b\u200bthe building.

Extruded polystyrene XPS is used as a heat insulator. It is laid in two layers (10 + 10 cm) closely for smooth boards. If stiffeners are provided in the project, the first layer is laid end-to-end with your own hands, in the second, gaps are created along the width of the ribs:

• along the perimeter;
• perpendicular to the long wall after 3 m.

In this case, the monolithic slab has a large margin of safety, the house is free from distortions during operation.

Reinforcement

We create a reinforcing cage in accordance with the project.

Reinforcement of the slab with armored belts is carried out according to normative documentation for reinforced concrete, concrete structures. reinforcement scheme looks like:

• manufacture of clamps - a smooth 6 mm bar, bent in the form of a square, a triangle;
• creation of reinforcing meshes - longitudinal, transverse bars of a periodic profile with a diameter of 12 - 16 mm, connected with a knitting wire or connected by welding (cell 15 x 15 cm);
• reinforcement of stiffeners - four longitudinal bars connected with clamps;
• laying the lower belt - installed on concrete pads (thickness 15 - 25 mm, section 10 x 10 cm) to provide a protective layer (the reinforcement must be recessed in concrete);
• installation of the upper belt - clamps are placed on the lower grid, the upper card is attached to them.

From the ends, the plate is reinforced with U-shaped clamps.

It is not desirable to use separate bars inside the armored belt. They need to be bent on curved sections, in places of communication input nodes with common grid maps. To save reinforcement, the cell in some cases is enlarged to 20 x 20 cm.

formwork

We install and strengthen the formwork.

To pour a monolithic structure with your own hands around the perimeter, you need to install the formwork. It is constructed from OSB, chipboard, plywood or edged boards in the form of shields. The inner surface is sheathed with roofing felt or film to prevent chipping of concrete during stripping. The main document in the construction of formwork are standards; .

Shields are mounted along the perimeter, to protect the structure from freezing, 10 cm of expanded polystyrene can be laid vertically inside them. This insulation is also laid under the blind area of ​​\u200b\u200bthe house to prevent lateral freezing. It is laid at the level of the sole of the slab, flush with the lower or upper layer of the heat insulator inside the formwork.

Pouring and curing concrete

Pour concrete into the formwork and level the surface. Sealing is a must.

Requirements for the design, manufacture of the MZF are specified in the standards, according to which the work is carried out. When filling, the following conditions must be met:

• filling the formwork with concrete in one step;
• the maximum interval between feeding the mixture with a mixer after vibrocompaction of the previous section is 2 hours in warm weather;
• it is forbidden to distill concrete with shovels around the entire perimeter from one place - it is necessary to rearrange the mixer or use a concrete pump;
• vibrocompaction is carried out until the appearance of cement milk, hiding the crushed stone and the absence of bubbles;
• the step of lowering the nozzle of the deep vibrator cannot exceed its radius of action;
• in winter, the mixture is heated with a cable laid inside the formwork, covered with film materials, steam heating;
• vibrator nozzles must not be leaned against the meshes of armored belts;
• stripping is possible on the fifth - seventh day under normal conditions;
• the mirror of concrete must be protected from precipitation, should be covered with burlap, moistened from a watering can in the heat.

Subject to technology, recommendations on the choice of materials, reinforcement cross-sections, the slab foundation will not require restoration, it will serve three generations of property owners, at least. All technologies listed meet the requirements of the specified normative documents, have operating experience in the regions of the Russian Federation.

Private developers, when choosing a foundation for a house or outbuildings, prefer a tape structure as a reliable, economical and easy-to-use option. But in some cases the only possible solution the foundation becomes a monolithic slab. Such a foundation is required when building on sandy soil, on hard and plastic loams, and plastic clay. The design may also be in demand when building a building on hard and plastic sandy loams, hard clays.

Features of the "pie" slab foundation

The foundation base of the slab type does not require deepening - its ability to "float" and resist the forces of frost heaving is fully manifested precisely when it is laid on the surface.

The basic version of the foundation pie is shown in the illustration:

Foundation layers from bottom to top:

1. Compacted soil - the bottom of the prepared pit.
2. Pillow - made of sand or a mixture of sand and gravel, crushed stone. Fall asleep in layers, leveled and rammed. The pillow dampens ground vibrations, reduces the intensity of the impact of loads from below on the foundation.
3. Geotextile. Dornit fabric protects the pillow from silting, reinforces it. Geotextiles can additionally be laid at the bottom of the pit, between layers of sand and gravel to increase the strength of the cake.
4. Footing. A thin leveling layer of concrete on top of the pillow helps to qualitatively waterproof the foundation and correctly install the reinforcing frame.
5. Waterproofing. Waterproof material protects the reinforced concrete foundation slab from moisture penetration from the ground. Waterproofing of a monolithic foundation slab is traditionally performed from two or more layers of rolled bituminous material.
6. Concrete slab. Actually, the foundation itself, the thickness of which depends on the magnitude of the loads on the foundation.
7. Armature frame. Reinforcement increases the strength of a monolithic structure, takes on tensile-compressive loads, preventing concrete cracking.

Varieties of slab foundation

There are several options for the execution of the slab for the foundation. Most often it is a monolithic slab, the thickness of which is the same over the entire area. The advantages of such a base include ease of installation, the disadvantage is the close location of the upper edge to the ground surface - in this case, the base of the walls may be exposed to moisture, which harms building structures.

In order for the edge of the slab to be located higher above the soil surface, it is not necessary to increase its thickness - this will significantly affect the cost of the foundation. A more practical option would be to equip a plate with stiffeners.

The monolithic structure is a flat base with reinforcing stiffeners protruding above the surface - it looks like a strip foundation on top of the slab. The ribs are located along the perimeter and under the future load-bearing walls inside, if provided for by the project.

The foundation slab with stiffening ribs upwards makes it possible to build a building with a basement or basement. In this case, the monolithic structure must be buried in the ground and grillage ribs of a suitable height should be designed. Subsequently, a layer of waterproofing is laid over the ribs and wall structures are mounted.

To increase the bearing capacity of the slab foundation without deepening it, a monolithic structure is made with stiffening ribs directed downwards.

There are two options for the execution of a monolithic slab with stiffeners down:

1. The stiffening ribs are formed by trenches dug in the ground below the level of pouring the reinforced concrete slab. A reinforcing frame is installed in the pits for the ribs, made as a single unit with the frame of the slab itself, after which the concrete mixture is poured.
2. A pit is being prepared with a flat bottom under the stove. A polymer plate insulation is laid on a waterproofed base - stiffeners will be formed in the gaps between the "islands" of the heat insulator and the walls of the pit. Before pouring the concrete mixture, a reinforcing cage is mounted.

Stiffeners should be located under load-bearing walls and capital internal partitions. If the project does not provide for partitions, but it is required to increase the rigidity of the slab, the ribs facing down should be parallel to the short side of the building in increments of up to 3 meters.

Laying a heat insulator, including extruded polystyrene foam under the foundation slab, not only allows you to equip stiffeners of the required dimensions, but also contributes to the insulation of the foundation base, reducing the cost of heating the house. This type of foundation is called a "Swedish slab". It is often supplemented with a water heating circuit.

Prefabricated slab base

Instead of a monolithic slab foundation, in some cases a precast concrete foundation is used. Finished structures are stacked close to each other. But this option can only be used on rocky soils that are not prone to heaving. In other cases, the base may deform over time under uneven heaving loads due to the lack of a rigid connection between the plates.

The base of prefabricated reinforced concrete slabs is used only in the case of the construction of outbuildings, baths, small light houses. A screed is made over the laid slabs. The technology of mounting a prefabricated foundation requires the involvement of special equipment for transporting and laying slabs.

Calculation of the thickness of the slab and reinforcing cage

When installing a slab foundation with your own hands, it is important to correctly calculate the thickness of the slab. Too thin base will not withstand the load. Pouring an excessively thick slab will lead to unnecessary financial costs.

Please note: each centimeter of slab thickness is 1 cubic meter of concrete mix per 10 square meters. m area.

The calculation should be entrusted to professionals or use a special program. The value is calculated based on the type of soil and loads on the foundation. Therefore, it is necessary to have geological exploration data on the site and a finished construction project. The standard thickness of the slab foundation is 200-300 mm.

The reinforcing frame for slabs up to 150 mm thick is made from a single mesh layer located along the central horizontal axis. For slabs of 200-300 mm, two parallel layers of mesh are required, installed with an indent of 30-50 mm from the bottom and top of the future slab. Reinforcement diameter - 12-16 mm, rod installation step - 200-300 mm.

Under the load-bearing walls, the installation step of the rods is reduced due to the more sparse arrangement of the elements in the central part of the slab.

The number of reinforcing bars and clamps for their fastening is most conveniently calculated using a specialized calculator.

Do-it-yourself foundation-slab: step by step instructions

The whole complex of works on the arrangement of the slab base of the house or outbuildings can be done on your own.

Preparatory stage

The area for the foundation is cleared of debris, trees and, after which the future excavation is marked. It is important to ensure that the stretched cords form right angles. For the accuracy of the geometry, the coincidence of the lengths of the diagonals of the marked rectangular section is checked.

On the marked area, it is required to dig a pit, taking into account the thickness of the sand and gravel cushion, footing, waterproofing and the design depth of the slab.

It is required to remove a layer of fertile soil with vegetation from the building spot, the depth of the pit is calculated relative to the prepared surface.

The bottom of the pit should be flat and horizontal, the soil should be carefully compacted. The foundation-slab construction technology may involve the use of geotextiles to create a barrier between the soil and the sand cushion - in this case, the sand does not silt and is not washed out when flood groundwater rises. Geotextile sheets are laid with an overlap of 30 cm and run onto the walls of the pit.

Pillow arrangement

At the bottom of the pit, sand is evenly poured with a layer of 100-120 mm. Then it is wetted with water and compacted with a vibrating plate. Then, according to the same principle, the next layer of sand is poured and rammed. The total thickness of the cushion must be at least 200 mm.

Common critical mistakes: using sand mixed with clay, unloading the entire volume of sand into the pit at once, followed by leveling.

The sand cushion is covered with a layer of gravel or crushed stone 120-150 mm thick. You can pre-lay geotextiles so that the layers do not mix. A layer of gravel is necessary to prevent capillary suction of moisture from the soil.

At the stage of arranging the pillow, it is required to lay all communications that will be brought out vertically through the thickness of the foundation slab.

Waterproofing

Formwork is mounted on the finished pillow along the contour of the future slab. For rigidity from the outside, the formwork is supported with spacers. The design must be airtight so that moisture does not leave the working mixture during concreting.

After the footing has dried, waterproofing is laid from a special polymer profile membrane or two or three layers of rolled bituminous material. Waterproofing should go to the walls of the formwork, the edges of the sheets are glued together with bituminous mastic or fused, heated by a burner.

Foundation insulation

In regions with cold winters, thermal insulation of the foundation slab is practiced when it comes to building a residential building, where it will serve as the base of the floor. The insulation under the foundation slab is laid in an even layer if it is designed flat. When arranging a slab with stiffeners pointing down. From the same insulation, platforms are formed in the designed places.

Reinforcement

Installation of the reinforcing cage begins with the bottom grid. To maintain the required clearance of 30 mm from the base, the reinforcement bars are placed on special plastic stands.

First of all, lay all the longitudinal rods. Then the transverse ones are attached to them with the help of wire twists or plastic clamps. Welding is not used - overheating of the metal at the attachment points weakens the structure.

In order to place the second tier of the lattice at the required height above the lower one, “spider” stands (they are also “frogs”) are used over the entire area (2 pieces per square meter) and U-shaped edge elements.

Concrete works

The pouring of a monolithic foundation slab should be done within one shift, otherwise it is impossible to achieve the required structural strength. Requirements for the working mixture:

• (strength class B22.5);
• mobility P3;
• water resistance coefficient W8 and more;
• frost resistance class F

It is necessary to provide a convenient entrance for the automixer, take care of the concrete pump or trays for supplying the working mixture to the formwork in advance.

The solution supplied to the formwork must immediately be evenly distributed over the entire plane. To compact concrete, eliminate air bubbles, you can not do without a deep vibrator. The surface is leveled with a rule or with the help of a vibrating screed.

The foundation of a monolithic slab should be covered with plastic wrap to protect it from precipitation, debris and accidental damage. A day later, for 5-7 days, it is required to wet the concrete surface with water. This will prevent drying and cracking of the top layer of the plate. After 10-15 days, the formwork can be removed - the concrete will have time to gain more than 50% strength. The construction of walls is started no earlier than a month after pouring - the concrete must fully mature.

Knowing how to make a foundation slab for a house, you can save a lot of money on the construction of a summer house or a country house, a garage. In order for the foundation to serve for more than one decade, it is important to strictly observe the technology of work and use high-quality materials.

Monolithic slab foundation technology - video

Before starting the construction of your own house, a person needs to carefully prepare and tune in to the upcoming work. One of the first and most important stages of construction is the arrangement of the foundation. In private housing construction, such a design as a monolithic slab is often used. This type of foundation has many advantages and a number of features that any developer should know.

The type of foundation under consideration is arranged on the basis in the form of a sand cushion. Filling technology involves the mandatory implementation of reinforcement. This design is designed for very high loads, therefore it is used mainly in the construction of large houses with more than one floor.

However, the size and weight of the building are far from the only determining factors. For example, in areas that are characterized by uneven seasonal ground movements, monolithic pouring on a sand cushion is the best option.

Also, such a foundation is perfect for regions with a high level of groundwater, being the most relevant for buildings with basements. The floating monolithic foundation has a relatively large area, which helps to reduce the overall load on the soil when compared with other types of structures.

Foundation pouring mix you can make it yourself or order it from a specialized company. If you have money, but no time, desire or experience in making concrete, you can simply buy a ready-made solution and save yourself the hassle.

Work on the installation of a monolithic foundation slab begins with the assembly of the formwork. Wooden inventory boards are suitable for the manufacture of this design. The walls of the pit can also perform the functions of the formwork, but in such a situation they will need to be insulated with roofing material or polyethylene. Otherwise, the earth will absorb the cement "milk", which will negatively affect the strength characteristics of the structure.

A monolithic slab foundation is the most reliable among other types of foundations used. Such a foundation is not afraid of exposure to moisture, it endures any load, which allows you to build full-fledged two- or even three-story mansions.

Before starting work, you should prepare everything that is needed to complete it.

Tools and material for the installation of a monolithic slab foundation

1. Concrete mixer or container of a suitable volume.

2. Wheelbarrow for transporting materials and ready-made mortar.

3. Several shovels and buckets.

4. Building level.

5. Measuring tape.

6. Welding machine.

7. Joints, rammers, picks.

8. Trowel.

9. Square.

10. Metal rods for creating a reinforcing cage and clamps for these rods.

11. Ready-made concrete or ingredients for its preparation.

12. Materials for waterproofing.

The formwork is arranged around the perimeter of the future building. The main function of this element is to give the foundation the desired shape until the poured concrete gains the required strength and can not hold the shape on its own. Formwork can be assembled from edged boards, but they must be combined in such a way that there are no gaps at the joints. If possible, inventory boards should be used to assemble the formwork. Such a step will reduce the time and effort spent at this stage of work.

It is better that the elements for assembling the formwork are made of coniferous wood. Larch is also suitable for the manufacture of spacers and various kinds of fasteners. Formwork boards should be no more than 15 cm wide. Make sure that all boards used have the same thickness as possible. Before assembling the formwork, the boards should be thoroughly moistened, and even better, raw wood should be used. The problem is that dry material will later absorb moisture from the laid concrete, and this will not have the best effect on the strength of the finished structure. The front side of the formwork system is finished with metal or plywood sheets.

It is important to first take care of reducing the adhesive force of concrete with the formwork material, so that in the future boards or boards can be removed with the least effort. It is enough to simply cover the front part of the formwork with oil, liquid clay mortar, etc. Additionally, such a coating will help to obtain a cleaner front surface of the monolithic foundation.

Determine the distance between the installed shields with a reference to the width of the future monolithic base. From the outside of the formwork panels, stakes are driven into the ground, thanks to which the structural elements will be fixed in a given position. Additionally, stakes must be attached to the shields with nails. To ensure that adjacent formwork panels do not disperse when concrete is poured, wooden planks must be nailed to the top of the panels.

Be sure to ensure that none of the fasteners are located where the concrete mixture will be poured in the future. Otherwise, it will no longer be possible to get these fasteners from the filled plate.

Formwork for the foundation should be installed as evenly as possible, because. the evenness of the finished foundation directly depends on this. Particularly important is the high accuracy of installation at the level of the base, i.e. the part of the base that is above the ground. After removing the formwork, professionals recommend wiping the base with a thin layer of cement mortar. Other cladding is done at the request of the owner, you can do just fine without it.

To increase the strength of the structure, a reinforcing belt is installed. Without reinforcement, the slab will be able to normally withstand compressive loads, but it will be powerless against tensile and bending loads. Competent reinforcement helps to eliminate this drawback. It is performed using special welded structures or individual metal rods.

Steel reinforcement is used to reinforce monolithic foundations.

It is important that the rods are free of grease and corrosion damage. Such things will contribute to the deterioration of the quality of adhesion of reinforcement to concrete, due to which the rigidity of the structure and its strength will noticeably decrease.

The frame is assembled from hot-rolled or round reinforcing steel. The bars must be with a periodic profile. In exceptional cases, the frame is assembled from square steel.

Depending on its purpose, reinforcement as part of a reinforcing structure can be working and distributive:

• working rods are designed to accept external and almost all internal loads created by the weight of the building;
• the functions of distribution valves are clear from its name - it is responsible for the distribution of incoming loads between the working axes.

That is, the armored belt is a full-fledged complex, each element of which works together with others.

The wire stranding method can be used to connect the reinforcement, but professionals in most situations advise using welded joints.

Before starting the arrangement of the frame, the reinforcement is straightened, sorted and cut. On average, as practice shows, about 100 kg of reinforcing material is spent per 1 m3 of concrete mixture. The assembly of the frame is carried out directly on the construction site.

When installing the formwork, make sure that the steel rods remain in place. The maximum allowable displacement is 20% of the single bar diameter. Check the formwork after installing the reinforcement and immediately repair any defects that appear.

Structural Concreting Guide

It is strongly not recommended to engage in concreting at low air temperatures. When if the base is poured in frosty weather, the concrete mixture must be insulated, because. when freezing, the material loses its strength and can simply crumble even under insignificant loads. In hot weather, the formwork for the foundation must be moistened before starting concreting, so that in the future the boards do not absorb moisture from the poured mixture.

The concrete is poured in layers. Each of these layers is necessarily compacted. It is best to use a special vibrator for this job. In its absence, it is possible to pierce the mixture with improvised tools. It is possible to understand that the mixture has sufficiently compacted by the cement milk that has protruded on the surface of the layer. The mixture can be applied with a concrete paver or manually.

Concreting must be done continuously, as only if this condition is met, it is possible to achieve high strength and solidity of the structure as a whole. In the event that it is impossible to complete the work in 1 day, you need to make working seams. Such a seam looks like a flat joint and is created between the previously poured and new layers of concrete. Working seams in this kind of foundations can have an exclusively vertical or horizontal position.

It is possible to resume work on concreting only if the strength of the poured mixture is not more than 1 MPa. This moment is easily checked by the vibrator used for compaction. If the previous pour layer liquefies during processing, concreting can be resumed. First, be sure to rinse the seams and clean off the cement film with a metal brush.

Soil must not be allowed to enter the concrete pour. This leads to a significant decrease in the strength of the foundation system and contributes to the appearance of cracks.

After pouring, concrete requires some maintenance. Especially great attention is required for about a week and a half after pouring. First of all, you should try to maintain optimal values ​​​​of humidity and temperature. It is best if the concrete hardens at a temperature in the range of + 18- + 25 degrees. It is impossible to allow any mechanical loads, shocks and any other influences that can lead to the destruction of the integrity of the structure.

A freshly poured foundation must be protected from the effects of cold, wind loads, direct solar radiation, because. all this will contribute to the removal of moisture from the concrete composition, which will inevitably lead to the formation of cracks. In the heat, the stove should be covered with some kind of moisture-absorbing material, for example, burlap or some kind of dense cloth, and periodically poured with cold water.

Determine the frequency of wetting individually, the main thing is that the foundation surface is always wet. If it is cold outside, the formwork must be additionally insulated by covering all open surfaces with mineral wool, sawdust or other suitable heat-insulating materials.

If the construction is carried out in frosty weather, the laid concrete must be additionally heated. Usually, for this, the structure is blown with warm air or steam. If possible, it is better to add cements of fast-hardening grades and with a high heat release rate to the composition of the mixture. The most commonly used method of electric heating of the foundation.

When to dismantle the formwork?

Boards can be removed approximately one and a half weeks after pouring the slab. It is possible to start laying floors, laying masonry and other similar work only after the structure has gained the required strength. It usually takes a month, but it is better to wait one and a half. If the device of the plate was carried out in full accordance with the technology, further shrinkage will be as uniform as possible and no distortions or other defects will appear.

The mentioned 10 days is the minimum period, but it is also not necessary to delay the dismantling of the formwork too much. The longer it stays in place, the stronger the adhesion of boards or panels to concrete will be, and the more difficult it will be to get rid of the formwork in the future without damaging the top layer of the monolithic base.

In the process of dismantling the formwork, be extremely careful. It is impossible to allow the corners of the structure to crumble (and by this time, as a rule, they still do not have time to gain the required strength). Any defects that appear after the dismantling of the formwork are recommended to be cleaned immediately with an iron brush, washed thoroughly clean water under strong pressure and rub with a "light" cement mortar prepared from 1 part of cement and 2 times the volume of sand.

If large “shells” are found, clear them to their full depth until you pass a layer of “weak” concrete. After this procedure, the surface must be again treated with an iron brush and rinsed with strong water pressure. For processing large "shells" it is recommended to use a rigid concrete mixture.

Before starting concreting work, consider in advance the placement of various technological cavities through which underground communications will be laid, such as water pipes, cables, etc. Such holes are made extremely simply. You take pipes of the required diameter and insert them into the right places on the formwork.

In the course of pouring the foundation, the pipes must be covered with rags or other material with similar characteristics. After all communication elements are equipped, existing gaps and any kind of holes must be sealed with a special silicone compound to prevent moisture from entering the system.

Thus, there is nothing super complicated in the independent construction of a monolithic slab foundation. It is only necessary to understand the instructions in detail and follow the instructions received at each stage of the construction of the foundation. Successful work!

Video - Do-it-yourself monolithic slab foundation