An obligatory part of a residential and industrial building is the foundation for the house. It provides stability, reliability, and a long service life of the building. It is important to thoroughly study before starting construction how to build a foundation for a house, as well as study design features and the purpose of different types of bases. Foundations are built in strict accordance with the requirements of technology. Let us dwell in more detail on the sequence of actions for their construction.
Foundation for a house - varieties and features of foundation foundations
The design features of the foundations allow them to be used as a reliable base for various buildings. The choice of the base structure is a serious task, solved on the basis of an analysis of a set of factors. It should be borne in mind that the choice the best option natural factors affect, as well as the mass and design of the future building.
The foundation of any structure is its foundation, on which the future of the erected object depends
The following types of foundations are widely used in the construction industry:
- columnar. It is easy to build it for a wooden one or on your own. A distinctive feature of the columnar foundation is that it allows you to erect buildings on sites with a significant slope. Support elements are located at the points of intersection of the walls, as well as evenly along the entire contour of the building. With such a device, the base does not allow equipping a basement. The design has proven itself positively in problem areas. The columnar base ensures the stability of buildings located in areas with an increased depth of soil freezing;
- tape. The reinforced concrete base of the structure follows the contour of the building and is concreted with a kind of tape. How to do strip foundation under the house, professional builders know. It is important to construct a strip base on soils with deeply located aquifers and an insignificant depth of freezing. Brick houses, block buildings, utility structures, as well as protective structures should be located on strip foundations. Massive structures of heavy stone should not be erected on a strip base. The design of the strip foundation allows you to arrange the basement. You can build the foundation yourself or using the services of professional builders;
One of the most popular types of foundations for any individual buildings is a strip foundation. - slab. If it is necessary to make a reliable foundation for a building located on problem soils, a slab option is used. Structurally, the slab foundation is a massive concrete slab, reinforced with a reinforcing cage made of steel wire... The slab construction is characterized by an increased level of costs, which pays off long-term operation buildings. To ensure the required margin of safety, it is necessary to perform strength calculations and assess the load capacity of the slab base;
- pile-screw. Increased load capacity, short duration of installation activities, as well as an affordable price are the main features of the foundation on pile or screw supports. The base of the pile-screw type is widely used in areas with various types of soil, except for rocky. A significant drawback of the pile-screw base is the gradual destruction of steel supports as a result negative influence corrosion processes.
Thinking about how to make a foundation for a house, study in detail the types of foundations, their design features, and also consult with professional builders.
How to make the foundation for your home yourself
Installation and installation of the foundation for the house is a responsible complex of measures carried out according to a certain algorithm. When building the foundation for a house, you should follow the technological sequence of operations and be guided by the requirements of the project.
Do not think that in each individual case, you can rely only on a specific type of foundation for future construction. The main stages in the construction of the foundation base:
- Performing markup.
- Production earthworks.
- Formwork construction.
- Assembly and installation of the reinforcement cage.
- Pouring concrete mortar.
- Compaction of the array with deep vibrators.
When making the foundation, pay attention that reliable waterproofing of the foundation will protect the building from moisture absorption and avoid dampness. Let's dwell on the specifics of the main stages.
Foundation markup
The marking operation involves the transfer of design coordinates to the real conditions of the construction site. For marking activities, wood and metal pegs are used, as well as a construction cord.
When doing markup, stick to the following algorithm:
After you decide on the type of future supporting structure and are ready to start the construction itself, it's time to mark the foundation - Drive the pegs along the front and stretch the construction cord. The spacing between the pegs driven into the soil must exceed the size of the facade by 50 cm.
- Mark the coordinates of the corners of the building on the cord, and drive in the stakes. Draw marking lines through the marked points, perpendicular to the front of the building.
- Measure in perpendicular lines the distance corresponding to the length of the side walls of the building and mark using the existing wooden or steel pegs.
- Pull the cord between the hammered pegs. The resulting markings correspond to the outer contour of the future house. Check the correctness of the generated markup using the project.
- Check the correspondence of the corners by determining the difference in the diagonals. Equal length indicates right angles. The deviation of the lengths of the diagonals is allowed up to 2 cm.
- Mark the inner contour of the foundation line, stepping back from the outer contour to the inside of the future foundation, 40 cm on each side. Drive in the pegs in the appropriate places.
The markup performed affects the location of the future structure, its configuration, as well as strength properties.
Earth activities
Excavation work is one of the most time consuming operations in the construction process. Earth activities are carried out different methods:
Determine the depth of the soil water and the composition of the soil - manually using bayonet and shovels. The manual method is characterized by laboriousness and requires the involvement of an increased number of workers to complete the task at a given time;
- using special construction equipment. The mechanization of earthworks can significantly speed up their implementation, which reduces the duration of the overall construction cycle.
The depth of the formed pit is determined by the type of foundation being built:
- shallow tape base is located below the zero level of the soil by 70-80 cm;
- the depth of a standard foundation, depending on the level of soil freezing, can be 160-180 cm.
When healing the soil, pay attention to the following points:
- ensure the verticality of the walls of the trench;
- install, if necessary, props to prevent soil shedding;
- level the bottom of the sump and check the levelness with a spirit level.
The cushion of rubble and sand provided by the project requires an increase in the depth of the trench by 15-20 cm.
The procedure for the construction of crushed stone-sand bedding:
- Pour sand on the base of the pit, ensuring a layer thickness of up to 15 cm.
- Moisten the sand mass and compact it thoroughly.
- Refill sand and re-compact.
- Lay a 15-20 cm layer of gravel on the sand and tamp.
To prevent siltation of gravel-sand bedding for shallow foundations, laying geotextile fabric at the bottom of the pit will allow.
Along the perimeter of the future building, dig a trench of the required depth, level the bottom with sand Installation of formwork for the foundation
Installation of panel formwork requires special training. It is important to decide on the choice of building material that can withstand the load from the weight of the concrete mixture.
For the manufacture of formwork used:
- edged wood with a thickness of 2-2.5 cm;
- moisture resistant plywood;
- sheet steel.
The use of plywood and boards at a low price can help reduce costs.
The sequence of actions for the installation of the formwork:
When installing the formwork, pay particular attention to the rigidity of the panel structure and the absence of gaps.
Reinforcement is a prerequisite for building a good foundation
The space frame made of steel reinforcement, laid in the foundation, increases its strength and ensures durability. For the manufacture of the frame, rods with a cross section of 1-1.6 cm are used, connected with an annealed wire.
The order of assembly of the frame:
- Cut the bars into pieces of the required size.
- Tie a flat lattice from the rods using knitting wire.
- Assemble the frame from two flat lattices using transverse rods.
Place the assembled frame on special supports that guarantee a fixed distance to the concrete surface.
Insert the reinforcement cage and fill the pit with concrete with periodic compaction Pouring the foundation for the house on your own
Before concreting, mark the level of the grout inside the panel formwork. The use of concrete produced at specialized enterprises makes it possible to manufacture a foundation with increased strength. When making the foundation, we use a concrete solution based on M400 Portland cement, fine gravel and coarse sand.
Prepare the solution using the following technology:
- Prepare ingredients in proportions appropriate to the recipe.
- Mix sifted sand with gravel and Portland cement.
- Add water gradually until the desired consistency is achieved.
- Stir the solution thoroughly until smooth.
The order of the stages of pouring the foundation:
- Pour a twenty centimeter layer of concrete.
- Check the filling of the voids in the reinforcement mesh.
- Add the rest of the concrete.
- Remove air inclusions with reinforcing bars.
- Tamp the concrete with a vibrator.
After completing concreting, level the surface with a rule or a trowel. Dismantle the formwork after the final hardening of the concrete.
How to build a foundation for an extension to a building
When thinking about arranging the foundation for an extension, adhere to the following recommendations:
- observe the equal depth of the foundation base of the attached structure and the main building;
- ensure a rigid connection of the reinforcement lattice of the main structure with the frame of the extension.
Filling is carried out in the same way as for the main foundation.
When planning to build a foundation for a house from expanded clay concrete blocks or other building materials, it is important to determine the type of foundation, as well as study the technology. Knowing the technological nuances, it is not difficult to make a concrete or auxiliary structure. Professional builders will advise, if necessary, how to properly fill or a residential building. As a foundation, you can use the foundation, it is easy to find on our construction portal... The construction of the foundation is a responsible process in which there are no trifles.
At the design stage, the question arises, which foundation is better to choose for the future home. The solution to this issue is important for the developer. The cost of the foundation foundation of a structure can be one third of the total estimated cost of construction, so you need to choose the most reliable and durable foundation. When determining the best foundation, the owner of the future home should always be guided by the compliance of the price and quality of the foundation.
The main factors determining the choice of the foundation
Consider the main conditions that affect the choice of the foundation for the house. The properties of the subsoil are determined by its composition, the level of groundwater and the depth of soil freezing.
Soil composition
According to their bearing capacity, soils are divided into three groups:
Weak soils
Peaty, sandy and clayey soils are considered weak soil bases. For example, peat bogs are so unreliable that they often avoid the construction of any structures.
Clay soils are generally prone to swelling. Heaving, that is, a sharp increase in the volume of the soil under the influence of moisture saturation, can cause the foundation structures to be pushed out to the surface of the earth. In the same way, frozen soil layers affect the supporting structures of the structure.
Weak sandy soils do not have a high bearing capacity and can contribute to subsidence and destruction of the foundation of the house. On soils of this type, pile foundations are laid with a grillage, monolithic reinforced concrete slabs, both resting on piles and without them.
Rocky foundations and rocky soils
Rocky foundations are the strongest. On such soils, strip monolithic and prefabricated reinforced concrete foundations are erected. Columnar supports with a grillage also perfectly serve as a reliable foundation for buildings on such soils.
Dense soils
Dense soils are formed from bonded rocks that can withstand heavy loads and are immune to heaving.
On dense soils, monolithic and prefabricated reinforced concrete foundations are mainly erected, and columnar foundation supports are also widely used. Dense soils are reliable and acceptable for all types of foundations.
The depth of soil freezing and the level of groundwater
These two factors determine the depth of the foundation. To create a reliable foundation for the structure, the depth of the foundation is determined below the freezing soil layers and below the groundwater level.
When building low-rise houses from lightweight structures, the foundation is made shallow above groundwater, but below the depth of soil freezing.
Guided by the calculated value of the load from the house on the entire supporting area of the foundation, the type of foundation, its dimensions and configuration are determined.
If several types of foundations can be applied to an object under construction, then the decision which foundation is best done based on the cost of its construction and reliability.
The main types of foundations
Strip foundations
In terms of depth, strip foundations are shallow and deep foundations. Shallow tapes are used mainly in the construction of low-rise buildings from lightweight structures (foam blocks).
In other cases, foundation strips are laid below the water table, creating powerful base structures with high bearing capacity. Strip foundations are either monolithic reinforced concrete or precast concrete strip.
Strip monolithic reinforced concrete foundations
Monolithic reinforced concrete foundation is one of the most common types of foundations for buildings and structures. The device of such a supporting part of the house requires large costs for the production of earthworks and reinforcement works, as well as for the installation and dismantling of the formwork. All this is justified by the great strength and high load-bearing capacity, which makes it possible to erect multi-storey buildings from heavy structures.
What is the best foundation to lay on dense soils? The solution to the issue, of course, will be made in favor of the construction of the strip foundation.
The question of which foundation is better for a house with a complex configuration of walls in the plan will also not raise doubts in favor of choosing a strip monolithic base.
Precast concrete strip foundations
Compared to monolithic belts, precast concrete blocks are more economical. Installation of precast concrete blocks does not require labor costs for the installation of formwork, work on reinforcement and concrete pouring of the foundation.
From precast concrete blocks, both shallow and deep foundations are mounted. Precast concrete factories offer a wide range of precast foundation blocks.
What is the advantage of prefabricated blocks over a monolithic base? Installation of blocks does not require the production of time-consuming work on the installation and dismantling of the formwork, as well as on its reinforcement. The construction time of the foundation is significantly reduced due to the absence of time costs for concrete hardening. Reinforced concrete blocks are easy to transport and store.
Columnar foundations
Columnar supports are placed in the plan on the line of the bearing walls, in the corners of the perimeter of the house, as well as in places where the loads from various internal technical equipment Houses.
Columnar supports can be shallow and deeply buried. Support pillars can be used instead of strip foundations. Supports are placed with a step of 1.5-2 meters. When comparing the strip base with the support pillars, the economy of the arrangement of columnar supports is noticeable.
The savings lie in significantly less excavation and no formwork. However, one should not forget about the costs of installing the grillage. All doubts about the choice of the type of foundation will be resolved by a comparative technical and economic calculation.
Slab monolithic foundation
A monolithic reinforced concrete slab can act as an independent supporting structure of a building, and play the role of a pile foundation grillage.
Such structures are erected on soft soils. A reinforced concrete slab has a high bearing capacity, but is an economically expensive structure.
Piles
The main purpose of the piles is to transfer the load from the building through the soft soils to the denser soil layers.
The most common types of piles:
- Reinforced concrete piles;
- Bored supports;
- Casing;
- Shell piles;
- Metal screw supports;
- Wooden supports.
Reinforced concrete piles
Reinforced concrete piles are manufactured at the plant. The markings for the installation of piles are made on the bearing lines of the load-bearing walls, in the corners of the structure and in places where vertical loads are concentrated. Iron concrete supports installed using piling equipment.
Bored piles
Reinforced concrete pipes are installed in drilled holes. Reinforcement cages are installed inside the pipes. Then it is poured with concrete with layer-by-layer compaction. Bored piles are used in densely built-up areas. In such places, the pile driver can cause unwanted deformations in the bearing layers of the soil. All this can adversely affect the foundations of nearby buildings and structures.
Bored piles are mainly used in industrial construction.
Casing pipes and shell piles
Casing pipes and shell piles are used in the construction of large industrial facilities. Installation and assembly of supports of this type is possible with the use of high-tech equipment.
Screw piles
Screw piles came to civil engineering in the second half of the last century from the military industrial sphere. For the rapid formation of a reliable base for small structures, they are indispensable. Developers apply screw piles not only on soft clay soils, but also on dense soils.
Small screw supports are installed by two people by rotating the pipe using a lever. A lever in the form of a pipe is threaded through a hole in the upper part of the support and, by the efforts of two workers, a rotational translational vertical movement is given to the pile.
Watch a video detailing the pros and cons of screw bases.
The pile foundation is prepared in 5-7 days, depending on the size of the construction field.
Wooden supports
Wooden poles with pointed ends are driven into the ground with a hand tool or a copra. Most often, wooden piles are used in the construction of light outbuildings.
Before you start building a house with your own hands, it is worth asking the owners of neighboring houses about the foundation structures of their buildings. Such information will help to make the best choice foundation for your home.
Any house is built strictly according to the project, which is developed by specialists. One of critical points construction planning is considered to be the calculation of the foundation. But some of the buildings have to be built on their own. These include baths, garages, gazebos and even small residential buildings. In such cases, it is important to select and design a high-quality and reliable foundation. Moreover, the cost of the foundation from all work sometimes reaches 1/3. If you make a mistake, then redoing the base of the house is sometimes not possible, and always costly. And no one will return the effort and time spent at all. How to calculate the foundation for a house, choose the right one, you can learn from this article.
The foundation of the house is primarily the basis for the structure, the quality of which will determine how long the building will last. Any construction of a house from beams is built according to the approved documentation, in which the calculation of the foundation is not the last place.
A properly designed foundation will protect the building from flooding and will save the construction of a house from laminated veneer lumber and any other from cracking and destruction. The platform should be designed so that it can withstand the weight of the house without any problems and at the same time distribute the load evenly on the ground.
The calculation of the foundation includes:
- Calculation of the load for various types of soil.
- Calculation of cubic capacity (determination of how much building materials necessary).
- Calculation of the cost of the foundation, including work and materials.
The most common mistakes when installing the base can be seen in the video:
What kind of base design to choose
In the construction of wooden houses I use structures:
- Tiled.
- Tape.
- Columnar.
- Pile.
There are territories where it is rational to use a mixed-type platform, for example, a belt-pile platform. This is a modification of one of the main types. But this complex construction and builders are trying to change the composition of the soil to one of the basic types. So swampy is dried and sand is washed, or part of the soil is simply taken out and covered with slag, which, by ramming, turns into concrete.
Choose a base depending on the house under construction. The heavier the structure, the more massive the foundation. For the construction of a house from a profiled bar or rounded logs, tape or columnar types are used. Moreover, the tape is made shallowly buried.
The depth is calculated based on two main factors:
- The depth of the groundwater table.
- Freezing of soil in the area of future construction.
There are average norms for the depth of the sole on various soils:
- Sandy loam - 125cm
- Clay and loam - 150 cm
- Sand and gravel - 100 cm
This is the maximum occurrence of the base of the house in accordance with the building GOST, but it also indicates the maximum occurrence indicators:
- For dry soil - 70 cm,
- For wet, with a close occurrence of groundwater - 120 cm.
If the house has basements according to the plan, then the sole of the structure should be at least 40 cm below the floor level.
Each type of foundation has its own pros and cons. So, for example, columnar, they are erected in a short time, the tape one is considered one of the most durable due to the rigid connection of the structure both across and along. Monolithic expensive, it is built in rare cases when the soil is highly mobile.
What loads affect the foundation
Two forces always act on the base:
With the correct calculation, the foundation must withstand the weight of the house, furniture, residents, snow and wind, as well as the pressure from the soil swelling. The weight of the building during planning is calculated in accordance with special tables, which indicate the approximate weight of a particular material. Calculating how much a house costs with these tables is not difficult. The weight of the house by 1 cm 2 / kg must exceed the load that the soil can withstand. So for some types of soil, this load is leveled:
- Gravel and coarse sandstone - 3.5-4.5 kg / cm 2.
- Fine sandstone - 2-3 kg / cm 2
- Loamy solid soil - 3-6 kg / cm 2.
- Crushed stone - 5-6 kg / cm 2.
When making a calculation, one should not forget that the base structure itself also has a certain weight. In any case, the design calculation is always individual for different sites and buildings.
All loads on the foundation are divided into permanent (roof, walls, floor beams, waterproofing, etc.) and temporary (snow, wind, etc.).
The total load is calculated (the house itself, the foundation, the insulation system) and during operation (furniture, people living, etc.).
After construction, the house shrinks, so does the foundation. The soil under it is compacted and the foundation "sags" - this value is called settlement. If the sediment is uneven, then the foundation will quickly crack and fall apart. To avoid this, you need to accurately calculate the area of the foundation, and calculate the load on it.
How is the load on the foundation calculated
Having determined the size of the house, it is not difficult to calculate the area of the foundation for it. This is done to correctly calculate the load. The load depends on what material the house is going to be made of. In the regulatory construction documentation the specific gravity of the foundation is given depending on various materials:
- Brick and concrete - 1880-2200 kg / m 3,
- Household stone - 1600-1800 kg / m 3,
- The weight of the walls of a wooden house:
- Frame - panel - 30-50 kg / m 2,
- Timber, rounded and chopped logs - 70-100 kg / m 2.
To determine the load, it is important to know the weight of the floors:
- Basement floors - 100-300 kg / m 2,
- Attic floors - 150-300 kg / m 2,
- Reinforced concrete floors - 500 kg / m 2.
Specific gravity roofs:
- Sheet steel - 20-20 kg / m 2
- Roofing material - 30-50 kg / m 2
- Slate - 40-50 kg / m 2
- Ceramic tiles - 60-80 kg / m 2.
Let's see how you can use these metrics in a real-world example:
According to the plan, the poor house has dimensions of 8x5 with one inner wall... The height of the building is 3 m. In order to find out the length of the walls: 5 + 8 + 5 = 18 m. We calculate the area of the walls: 18x3 = 54 m2.
To calculate the area of the basement floors, we will compose the product of the length and width of the house: 5x8 = 40 m 2. Attic floors have the same area with the basement, which means also 40 m2.
The next step is to calculate the weight and area of the foundation
Foundation area and weight
It is not difficult to calculate the foundation, consider a specific example:
For the construction of the house, a strip foundation with a sole of 1.5 m was chosen, to this figure you need to add 50 cm, above the ground level. The height of the foundation will be equal to 1.50 + 0.50 = 2 m. Then the length is calculated: (5 + 8) x2 = 26 m. The internal partition has a length of 5 m. 26 + 5 = 31 m.
We calculate the volume of the foundation by the product of length and height and width. Take a width of 50 cm, 0.5x31x2 = 31 m 2. Now, according to the above data, we will calculate the weight of the foundation: Reinforced concrete weighing 2400 kg / m3, 31x2400 = 74,400 tons. The supporting area of the foundation will be 31000x50 = 15,500 cm 2.
To determine the total weight of the structure, you need to add the weight of the house to the weight of the foundation and divide by the resulting reference area. So we get a weight of 1 kg / cm 2.
If the permissible area for a certain type of soil is higher, then you need to change the width of the platform for the belt, and the number of posts for the columnar. But at the same time, the total weight of the structure will increase, so the calculations must be started anew.
How to calculate concrete for a foundation
In order not to make the purchase of unnecessary building materials, it is important to make an accurate calculation of the cubic capacity of the foundation. To calculate the cubic capacity, it is important to take into account two factors: the type of foundation and the complexity of its design. For the convenience of readers, consider the calculation of various kinds foundation separately.
Calculation of the volume of the strip base
It is easiest to calculate the cubic capacity of the strip foundation. To do this, add up the length, width and height. Let the width be 50 cm, the height we have already calculated above 1.5 m. The length is calculated along the perimeter 5+ (8 + 5) x2 = 45 m. The cubic capacity is calculated: 0.5x45x1.5 = 33.75 m 3. We round off this data and add 10% (stock), we get 37 cubic meters of concrete.
Calculation of the cubic capacity of a columnar base
Column foundation can have various shapes (circle, square, etc.). Let's calculate, for example, the cubic capacity of round pillars. To do this, you need values: diameter, cross section, column height. The area is calculated by multiplying the Pi number by the radius x 2. Cross-section for a column with a radius of 15 cm: 3, 14x0.075m = 0.2355 m. Knowing the radius and height, you can calculate the volume: 0.2355x1.5 = 0, 353 m 3. This number must be multiplied by the number of pillars in the foundation.
Calculation of cubic capacity for a tiled base
To calculate a monolithic rectangular slab, you need to know its area and thickness. The planned house has a size of 5 x 8, therefore the area of the slab will be 40 m 2. Experts recommend using a monolith 10-15 cm thick. We calculate the cubic capacity at 10 cm thickness: 40x10 = 400 m 3.
On a monolithic foundation, stiffeners are made around the perimeter. To calculate their area, you need to know their length and width. In a 5x8 structure, I mount the stiffeners every 2.5 m. There will be 3 such ribs in width and 4. The total length will be equal: (5x3) + (8x4) = 47 m.
Now we calculate the cubic capacity. The width of the rib is equal to the thickness of the slab - 10 cm. This means that the area of one rib is exactly 0.1 x 0.1 = 0.01 m 2. We multiply the area by the length 47 = 0.47 m 3.
How to determine the amount of rebar and wire
To create a rigid and durable structure, iron reinforcement is used in the installation. Its amount depends on the type of foundation, loads and soil. Reinforcement with a large diameter is used to obtain a platform with a greater load capacity. But the weight of the foundation with reinforcement increases. If the soil is hard, then the foundation will be deformed minimally, which means that the reinforcement needs a minimum diameter.
Number of reinforcement for strip base
The reinforcement for the strip foundation is taken with a diameter of 10-12 mm, since the structure itself can withstand heavy loads. Lay it in two rods, regardless of the depth of the base. Experts recommend laying the reinforcement 10-15 cm from the top pouring point. At the same time, vertical rods do not have a load, so you can use the cheapest ones.
For a house with dimensions of 5x8, the length of the strip base is equal to 45 m.When reinforcing 4 rods, the consumption will be: 45x4 = 180 m.Add transverse ones with a foundation height of 150 cm and a width of 50 cm in increments of 40 cm: (8 / 0.4) x0.5 = 10 m. Add them to the length: 180 + 10 = 190 m.
A knitting wire is needed for one connection of 30 cm. Length 45 m and a step of 40 cm: 45 / 0.4-112.5. We multiply this figure by the size of one connection: 112.5x 0.3 = 33.7 m of knitting wire is needed for the 1st level foundation.
The number of reinforcement for a columnar base
To reinforce the columnar base, thick reinforcement from 40 mm is used. The reinforcement does not carry any load horizontally, so here you can take the most inexpensive one. On average, 4 rods are used in the frame of one pillar. Knowing the number of posts, it will not be difficult to calculate the size of the reinforcement.
For a structure with a height of 1.5 m with a diameter of 15 cm, 4 rods are needed, with a step of 7.5 cm and binders at 3 points. Thick reinforcement needs: 1.5x4 = 6m. For a thin bundle: 30 cm (for one node) x3 = 90 cm. If 20 pillars are used in the foundation, then the number is multiplied by this figure.
A knitting wire is needed to connect one rod at 3 points. This number is multiplied by the number of rods and by vertical connections: 3x4x30 = 72 m.
The number of reinforcement for a monolithic base
For dense, stable soil, you can take thin reinforcement from 10 mm. For heavy construction and unstable soil from 14 mm. Fasten the bundle with a step of 20-30 cm.
For a 5x8 platform, you need 27 pieces in length and 17 pieces in width. Since the strapping is needed double: (17 + 27) x2 = 88. This number must be multiplied by the length of the rod, you get the footage of the reinforcement.
How to calculate the cost of a foundation
After the calculations of the cubes have been made, the amount of reinforcement is easy to calculate the cost of the foundation. The work and the price of formwork boards + earthworks and equipment are added to the main cost.
On average, the cost for a turnkey construction starts from 15,000 m 2. But you can save money and do all the work yourself.
The cost of a ready-made concrete solution ranges from 700 rubles / cubic meter, but you can reduce costs by making concrete yourself. To do this, you need sand, gravel and cement M250 or 400. The average price for cement is from 800 rubles. per bag of 40 kg. KamAZ sand costs from 2,500 rubles, it is enough to fill the foundation.
Costs are also reduced when performing partial work, for example, digging a trench and making formwork with your own hands, and pouring concrete into it, entrusting it to specialists.
In any case, you should not save on the basis of the house, as it must be reliable and durable. And how to calculate and not overpay, we told in detail.
Build a house from scratch on your own is a difficult task, but doable. Careful calculations, competent selection of building materials and high-quality implementation of each process will help to cope without the involvement of specialists. The most important stage is the laying of the foundation, because the durability and reliability of any building depends on the strength of the base. It will take about 2-3 months to make a foundation for a house with your own hands.
For the construction of residential buildings, a strip foundation is most often used. It can be shallow, if the house is one-story and small in area, or standard - laid at a depth of 1.8-2 m. The width of the base tape is usually 40 cm, but it can be increased depending on the specific load of the building. When designing a house, one should immediately take into account possible extensions and arrangement of basements and semi-basements. The presence of a common base will significantly simplify the installation of a veranda or other structures that may be needed later.
In order not to be mistaken with the parameters of the foundation, you need to carefully calculate the total load on square meter soil and compare it with the permissible values.
When calculating the load, the following factors are taken into account:
Calculations are made using special tables, for each factor separately. After that, all the loads are summed up, which determines the depth of the foundation in this area and the permissible width of the base of the base.
Base marking
To mark the site for the foundation, you will need pegs, a strong thin rope and a tape measure. First, they remove everything that can interfere with the marking - stones, bushes, dry stumps, etc. Determine the line of the facade of the house relative to the site and mark it with a rope stretched between the pegs. The distance from one beacon to another should be 30-40 cm more than the width of the facade. Mark the location of the corners of the house on the rope, and through these points 2 perpendicular lines are drawn, in length slightly exceeding the length of the side walls.
Now measure the distance from the corner of the facade to the corner of the back wall and mark the points on both lines, and then pull another rope, parallel to the first. The intersections of the ropes form the corners of the building, and it is from these points that the diagonals of the resulting rectangle must be measured. If the diagonals are equal, the markings are correct. After that, the inner boundaries of the foundation tape are designated, stepping back from the marking lines 40 cm inside the perimeter. The pegs should be positioned outside the perimeter to better define the corners of the base. The last ones are the internal load-bearing walls, the base for the veranda or porch.
When the markings are ready, they begin to dig trenches for the foundation. This can be done with shovels or with the help of special equipment, which will be many times faster and more convenient. For a shallow foundation, the depth of the trenches is 60-70 cm, for a conventional foundation - from 1.8 m, depending on the level of soil freezing. The bottom of the trench should be at least 20 cm below this level. The depth is measured from the lowest markup point.
The walls of the trenches must be leveled vertically, if the soil crumbles, props are installed. After excavation, the bottom must be checked against the horizontal, all irregularities are cut off with a shovel, excess soil is removed. The location and width of the trenches must fully comply with the project. The next stage is the installation of a sand and gravel cushion, designed to reduce the load from the building on the base of the soil.
The arrangement of the sand and gravel layer is as follows:
- the bottom of the trenches along the perimeter is covered with a thin layer of coarse-grained river sand;
- spill sand with water and ram it thoroughly;
- another layer of sand is poured and compacted again;
- fine gravel is poured and leveled with a layer of 15 cm;
- tamp the surface.
For a shallow basement, the inner surface of the trenches is lined with geotextiles before backfilling with sand. This material protects the sand bed from erosion by groundwater and siltation.
Formwork installation
The foundation of a residential building must rise above the ground surface by at least 15 cm. In flooded areas, the height of the above-ground part of the base can reach 50-70 cm. The formwork is assembled taking into account the required height using available materials.
When installing the formwork, you will need:
The boards are fastened into rectangular shields, fixing with transverse bars with outside... Self-tapping screws are screwed in from the inside to make it easier to dismantle the formwork. For the same reason, it is recommended to use screws, not nails. When assembling, you should consider the location of the sewer holes and make cutouts of the appropriate diameter in the boards. At the end, the shields are covered with a film that will not allow the tree to absorb water from the solution.
The formwork is installed in parts on both sides of the trenches, and then reinforced with transverse bars every half a meter. Shields are placed strictly vertically, observing the same distance between opposite sides along the entire length of the perimeter. Outside, the formwork is propped up with timber struts. There should be no gaps between the lower edge of the boards and the upper edge of the trenches, otherwise the mortar will flow out.
The presence of a reinforcing frame in the thickness of the foundation allows you to strengthen the base and extend its service life several times. For the manufacture of the frame, steel reinforcement with a section of 10-16 mm is usually used. It is very important to tie the rods correctly in order to distribute the load evenly over the entire area.
For work, you will additionally need:
- knitting wire;
- building level;
- Bulgarian;
- trimming a plastic pipe;
- roulette.
The armature is cut with a grinder along the length and width of the trenches, after which a lattice with cells from 30 cm is knitted from it.To do this, 4-5 longitudinal rods are fastened with transverse sections every 30 cm.
It is categorically not recommended to use welding for the connection, since it weakens the attachment points and promotes corrosion of the rods. The frame should be three-dimensional, therefore horizontal gratings are placed at 3-4 levels, tying up with vertical rods.
Additional fastenings should be made at each corner of the foundation and at the intersections of the load-bearing internal walls. You can lower the frame into the trenches in parts, and already inside, tie them together. To avoid corrosion as much as possible, the reinforcement should not be laid directly on the sand: take the old plastic pipe, cut it into rings 4-5 cm wide and put it under the lattice in the corners and every 50-60 cm along the trenches. About 5 cm should be left between the side walls and the edges of the frame, the same applies to the upper edge of the reinforcement.
When the grating is fixed inside the formwork, on inside shields indicate the level of concrete pouring. You can do this using a fishing line: small nails are stuffed at the ends of the formwork and a fishing line stretched strictly horizontally is fixed on them. It should be located 5 cm above the edges of the reinforcement mesh and run along the entire perimeter at the same horizontal level.
It is recommended to fill in the solution at a time, but not with the total mass, but in layers. Each layer should be no thicker than 20 cm; this will allow it to be evenly distributed between the reinforcement cells and to reduce the amount of air voids. For the manufacture of the mixture, they take cement M400 or M500, fine-grained crushed stone and coarse-grained river sand.
It is very important to correctly observe the proportions when mixing, otherwise the quality of the solution will be below normal. 1 bucket of cement requires 3 buckets of sifted sand and 5 buckets of rubble. Water needs to be taken about half of the total volume, add it in portions so as not to overdo it. The solution should be neither too liquid nor too thick: high-quality concrete has a uniform consistency, when the shovel is turned over, it slowly slides down in total mass.
After pouring the first portion, the solution is leveled with a shovel and pierced along the entire length of the trenches with a piece of reinforcement to release the air that has accumulated in the solution during mixing. It is very effective to compact concrete with a vibrator; it increases the strength of the monolith several times. The remaining layers are poured in the same way until the surface of the concrete is leveled with the stretched fishing line. The formwork is tapped with a hammer, after which the top of the mortar is leveled with a rule or a trowel.
It takes about a month to strengthen the foundation. To prevent the surface from cracking, it is constantly moistened and covered with polyethylene from rain. In hot weather, the concrete should also be protected from direct sunlight to avoid cracking. The formwork can be dismantled 10-15 days after pouring, and construction work can be continued after 28-30 days.
Video - Do-it-yourself foundation for a house
The foundation is the foundation of the house, and it is not a figure of speech at all. The durability of the building completely depends on how correctly the type of foundation is chosen and how it is executed. The rickety houses and the cracked walls of the summer cottage only once again convince of the increased responsibility of the work associated with the design and arrangement of the foundation. The first thing that everyone who starts construction should do is choose the type of foundation for a private house, and for this it is necessary to take into account a lot of factors and know the key features of all types of foundations.
# 1. Foundation types by prefabrication type
Depending on whether factory elements are used in construction, or all of them are formed directly on the site, the foundations are divided into:
- monolithic... For their manufacture, a formwork is arranged, into which it is poured;
- prefabricated monolithic obtained by filling ready-made constituent elements with concrete;
- prefabricated foundations are erected from reinforced concrete products produced at the plant.
Naturally, monolithic foundations much stronger than precast-monolithic and, moreover, prefabricated, but they require more time and effort to equip.
# 2. Foundation types by design
All foundations used in private construction can be divided into four groups:
- strip foundations- this is a solid canvas of reinforced concrete (much less often from), which is laid under all the load-bearing walls of the house and looks like a closed loop or tape, which is where the name comes from. The most common type;
- slab foundations also called "floating", they represent a solid monolithic concrete slab, which allows you to most evenly distribute the load;
- columnar foundations, as the name suggests, is a system of pillars made of concrete, brick, stone, less often wood, and located at an even distance from each other at the locations of the bearing walls and corners of the future house. For reliability, the pillars are connected by a grillage (the frame that connects all the pillars), but they can do without it. This type of foundation is suitable for small light houses;
- pile foundations They consist of supports that are screwed in or driven into the ground (the supports of a columnar foundation are installed in pits) to a relatively large depth. Piles can be reinforced concrete or metal, used on loose and heaving soils.
The choice of the type of foundation for a house depends on the number of storeys and dimensions of the latter, the materials of the walls and ceilings, as well as on the type of soil, the level of its freezing, the depth of groundwater, the presence of underground waters, the need to equip the basement. 
No. 3. Strip foundation for a private house
The most common type of foundation when building a private house, it is considered a tape. It is a tape or concrete frame that is laid under load-bearing walls... A sand-and-gravel cushion is formed under the concrete, which allows more evenly distributing the load on the soil and frees it from the need to carry out more serious soil preparation before laying the foundation. The sand and gravel cushion acts as a drainage and protects against the effects of groundwater. The foundation requires and.
The main advantages of the strip foundation include:
- the ability to withstand decent loads, therefore it is used in the construction of both relatively light and 2- and 3-storey brick buildings;
- the ability to use such a foundation for arranging a basement;
- the form of the strip foundation can be any (with the exception of prefabricated structures);
- the minimum amount of earthworks.
Minuses:
The strip foundation is of two fundamentally different types:
- monolithic;
- made.
Monolithic strip foundation formed by arranging the formwork, and pouring a sand-concrete or rubble-concrete mixture. It can be of any shape, and due to its integrity, excellent heat and waterproofing qualities, as well as strength, are provided.
Precast strip foundation create from ready-made, which greatly simplifies and speeds up installation. Individual parts are fastened with cement with reinforcement, the structure is inferior in strength to monolithic, and its main disadvantage- insufficient waterproofing at the junction of blocks, which in areas with increased level groundwater and in marshlands may lead to a premature resolution of such a ground. Much less often prefabricated foundations equip brick, but their service life is less than that of concrete ones. 
Separately, it is worth highlighting discontinuous strip foundation, which is laid not in a solid line, but in hotel areas, but clearly under the load-bearing elements. This design allows you to save a lot when erecting lightweight buildings.
In cases where when soft soil is located under the strip foundation, its base must be expanded, and they do this at the expense of ledge formation, resulting in a stepped structure: the main load will be placed on the wide part (sole). Formation of a foundation is also possible trapezoidal: the bottom wide part will become the main support. If groundwater located at a shallow depth, it is recommended to use and additionally protect it with bituminous mastic. 
As is clear from the above, a strip foundation can be built from the following materials:
Based on the depth of occurrence, the foundations are divided into:
- shallow(depth 50-70 cm) - an option for loose soils, i.e. those that are not very susceptible to frost heaving;
- deep-seated are laid at a depth of 20-30 cm below the level of soil freezing. They are used for erecting heavy structures and in places with difficult soil.
No. 4. Slab foundation for a private house
The slab foundation is equipped in areas with loose, heaving and moving soil. A monolithic concrete slab, located under the entire future structure, prevents the negative effects of ground movements and allows you to evenly distribute the load of the house on the soil. Under the action of soil swelling, this type of foundation is able to evenly rise and fall again (therefore it is called floating) - cracks in its structure and load-bearing walls of the house do not appear. 
The slab foundation is made of several layers:
- geotextile;
- sand and gravel pad;
- insulation layer:
- concrete with a reinforcing reinforcing frame.
The thickness of the main concrete layer ranges from 30 to 100 cm, only monolithic structures so the concrete is prepared and poured into the formwork on site. In rare cases, ready-made precast concrete slabs, but this method is allowed only when erecting small light structures, since the strength of such a foundation is not very high. 
The sand and gravel layer is used to level the base, sometimes it is replaced with low strength concrete. It is imperative to use when organizing such a foundation. If you need to build a large house in area, then it is recommended to do on a concrete monolith expansion joints- the foundation is simply cut into several smaller parts. This helps prevent cracking.
Pros of a slab foundation:
Minuses:
- the inability to equip the basement;
- high cost, it is the most expensive of all types of foundations for a house, so its use is justified only in areas with loose soil;
- the need for an even terrain, otherwise the site must be properly planned.
No. 5. Column foundation for a private house
The columnar foundation consists of pillars equidistant from each other, recessed into the ground. The pillars can be:
- concrete with reinforcement;
- brick;
- wooden;
- stone;
- rubble concrete.
The most durable are concrete and rubble concrete, they can withstand serious loads, brick pillars are inferior to them, and wooden ones can only be used as a base for small wooden buildings (, etc.). Pillars to increase strength and reduce mobility from above can be connected with reinforced concrete strapping beams. 
It is recommended to equip a sand layer with a thickness of about 50 cm under the columnar foundation - it will prevent swelling. The pillars are installed at a distance of 2-3 m from each other along the contour of the house, in the corners of the structure and at the locations of the load-bearing partitions. Columnar foundation can be:
- monolithic... All supports are created on site, used reinforced concrete or rubble concrete and wooden formwork;
- made. For its construction, factory-made concrete supports are used. They are installed on special "glass cushions" with a thickness of about 0.15 m.
The calculation of the number and depth of the posts is made taking into account the type of soil and structure. If the building is small and light, then it is even allowed to use a shallow (this is about half the standard depth) and an unburied foundation (40-50 cm). 
Advantages columnar foundation:
- relative simplicity and low cost of arrangement;
- ideal for small houses on stable ground.
Flaws:
No. 6. Pile foundation for a private house
It consists of a pile system, long pointed posts that are driven or screwed into the ground straight or at an angle. The large length of such elements allows them to be used in areas with weak and loose soil, because they are installed at such a depth as to rely on stronger and denser soil layers that do not freeze in winter. This principle allows the use of a pile foundation even in the most difficult conditions. Tied from above with a concrete slab or beam - grillage... This type of foundation is used for the construction of wooden, panel board and other light houses, as well as fences. According to the technology of installing piles, there are:
Among the main advantages of a pile foundation:
- the ability to install on any type of soil, there is no dependence on the level of groundwater;
- reduction in the amount of consumed concrete;
- reduction in the number of earthworks;
- relative speed of installation.
Flaws:
No. 7. What is important to consider when choosing the type of foundation?
It is better to entrust calculations and design of the foundation to specialists, especially when it comes to big house with heavy load-bearing walls and ceilings. If private house or a small cottage is being built on their own and are lightweight, then many people prefer to do without detailed calculations, which is not entirely true. To avoid mistakes, it is necessary to take into account a lot of factors, and the main principles for choosing the type of foundation for a house and its arrangement are:
- on highly heaving soils, the foundation must be equipped below the level of soil freezing. In conditionally non-porous ones, the depth of the foundation can be 0.5-1 m;
- the average and maximum depth of soil freezing are variable values, and it is not always easy to determine them. The relevant data must be held by the organization that owns land plot, together with other soil characteristics, otherwise you will have to conduct your own research. The most unreliable way is to ask the neighbors on the site, but the soil can be heterogeneous, therefore, such data is not always accurate;
- the denser and wetter the soil, the more it freezes in the cold season. The most difficult one in this regard is clay soil, which not only swells, but also unevenly. Most effective method preventing possible deformations - replacing complex soil with sand or arranging a sand cushion;
- sandy soil It is considered ideal for the construction of any kind of foundation and the construction of houses made of bricks and other materials, it passes water well, almost does not swell. Rocky soils practically do not swell, do not freeze and do not change their properties under the influence external factors, but it is difficult to organize the foundation in them due to the increased hardness. Clay soils require either the arrangement of a sand cushion or the use of piles;
- if other massive structures are located near the proposed construction site, then you should definitely take into account total ground load;
- on silty and heaving soils, it is better not to use a strip and columnar foundation;
- a pile foundation is justified only when other options do not fit at all - it is expensive to arrange.
The foundation will last for many years, if you do not forget to also take care of its waterproofing and insulation. Much also depends on the quality of the materials used and the responsibility of those who build the foundation.
