How to calculate how much concrete is needed for the foundation. How to calculate a strip foundation: calculation example, material. Minimum diameter of longitudinal reinforcement bars

Any house is built strictly according to the project, which is developed by specialists. One of the most important points in construction planning is the calculation of the foundation. But some of the buildings have to be built independently. These include bathhouses, 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, it is sometimes not possible to redo the foundation of the house, and it is always expensive. And no one will return the spent energy and time. You can learn how to calculate the foundation for a house and choose the right one from this article.

The foundation of a 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 made of timber must be built in accordance with the approved documentation, in which the calculation of the foundation is not the least important.

A properly designed foundation will protect the building from flooding and will save the construction of a house made of laminated veneer lumber or any other from cracking and destruction. The platform must be designed to easily support the weight of the house and at the same time distribute the load evenly onto the ground.

The foundation calculation includes:

Calculation of loads for various types of soil.
Calculation of cubic capacity (determining how many building materials are needed).
Calculation of the cost of the foundation, including labor and materials.

The most common mistakes when installing the base can be seen in the video:

Which base design to choose?

In the construction of wooden houses I use the following structures:

Tiled.
Tape.
Columnar.
Pile.

There are areas where it is rational to use a mixed type platform, for example, a strip-pile platform. This is a modification of one of the main types. But this is a complex structure and builders are trying to change the composition of the soil to suit one of the main types. This is how the swampy area is drained and sand washed in, or part of the soil is simply removed and covered with slag, which, when compacted, turns into concrete.

The foundation is chosen depending on the house being built. The heavier the structure, the more massive the foundation. To build a house from profiled timber or rounded logs, strip or columnar types are used. Moreover, the tape type is made shallowly recessed.

The depth of occurrence is calculated based on two main factors:

Depth of groundwater.
Soil freezing in the area of future construction.

There are average standards for the depth of the sole on various soils:

Sandy loam - 125cm
Clay and loams - 150 cm
Sand and gravel - 100 cm

This is the maximum occurrence of the foundation of the house according to the construction GOST, but it also indicates the maximum occurrence indicators:

For dry soil - 70 cm,
For wet areas with close groundwater - 120 cm.

If the house according to the plan has basements, then the base of the structure should be at least 40 cm below the floor level.

Each type of foundation has its pros and cons. So, for example, a columnar one is erected in a short time, a strip one is considered one of the most durable due to the rigid connection of the structure both across and along. Monolithic is expensive, it is built in rare cases when the soil is very mobile.

What loads affect the foundation?

There are always two forces acting on the base:

With proper calculation, the foundation must withstand the weight of the house, furniture, residents, snow and wind, as well as pressure from swelling of the soil. When planning, the weight of a building is calculated in accordance with special tables that indicate the approximate weight of a particular material. It’s not difficult to calculate how much a house costs using these tables. The weight of the house should be 1 cm 2 /kg greater than the load that the soil can withstand. So for some types of soil this load is equal to:

Gravel and coarse sandstone - 3.5-4.5 kg/cm2.
Fine sandstone - 2-3 kg/cm 2
Clay hard soil - 3-6 kg/cm2.
Crushed stone - 5-6 kg/cm2.

When making calculations, one should not forget that the base structure itself also has a certain weight. In any case, design calculations are always individual for different areas and buildings.

All loads on the foundation are divided into permanent (roof, walls, floor beams, waterproofing, etc.) and temporary (snow cover, wind, etc.).

The total load (the house itself, the foundation, the insulation system) and during operation (furniture, people living, etc.) are calculated.

After construction, the house shrinks, and so does the foundation. The soil underneath is compacted and the foundation “sags” - this value is called settlement. If the settlement is uneven, 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 assembled from. The regulatory construction documentation shows the specific gravity of the foundation depending on various materials:

Brick and concrete - 1880-2200 kg/m 3,
Household stone - 1600-1800 kg/m 3,
Weight of the walls of a wooden house:
Frame - panel - 30-50 kg/m2,
Lumber, rounded and chopped logs - 70-100 kg/m2.

To determine the load, it is important to know the weight of the floors:

Basement floors - 100-300 kg/m2,
Attic floors - 150-300 kg/m2,
Reinforced concrete floors - 500 kg/m2.

Roof specific gravity:

Sheet steel - 20-20 kg/m 2
Ruberoid - 30-50 kg/m2
Slate - 40-50 kg/m2
Ceramic tiles - 60-80 kg/m2.

Let's see how we can use these indicators using a real example:

According to the plan, the future house measures 8x5 with one interior 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, let’s create the product of the length and width of the house: 5x8=40 m2. The attic floors have the same area as the basement floors, which means also 40 m2.

The next step is to calculate the weight and area of the foundation

Foundation area and weight

Calculating the foundation is not difficult, let’s look at a specific example:

For the construction of the house, a strip foundation with a base 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 exactly 1.50 + 0.50 = 2 m. Then the length is calculated: (5 + 8) x 2 = 26 m. The internal partition has a length of 5 m. 26 + 5 = 31 m.

Let's calculate the volume of the foundation by multiplying the length and height and width. Let's take a width of 50 cm, 0.5 x 31 x 2 = 31 m 2. Now, according to the above data, let's calculate the weight of the foundation: Reinforced concrete weighs 2400 kg/m3, 31x2400 = 74,400 tons. The supporting area of the foundation will be 31,000x50 = 15,500 cm 2.

To determine the total weight of the structure, you need to add the weight of the house with the weight of the foundation and divide it by the resulting supporting 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 a strip one, and the number of pillars for a columnar one. But at the same time, the total weight of the structure will increase, so the calculations need to start again.

How to calculate concrete for a foundation

In order not to purchase unnecessary building materials, it is important to accurately calculate 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, we will consider the calculation of various types of foundations separately.

Calculation of the cubic capacity of the strip base

It is easiest to calculate the cubic capacity of a strip foundation. To do this, you need to add the length, width and height. Let the width be 50 cm, we have already calculated the height above 1.5 m. The length is calculated along the perimeter 5+ (8 + 5) x 2 = 45 m. The cubic capacity is calculated: 0.5 x 45 x 1.5 = 33.75 m 3. We round this data and add 10% (margin), we get 37 cubic meters of concrete.

Calculation of cubic capacity of a columnar base

A columnar foundation can have different shapes (circle, square, etc.). Let us calculate the cubic capacity of round pillars as an example. For this you need the following values: diameter, cross-section, column height. The area is calculated by multiplying the Pi number by the radius x 2. The cross section for a pillar with a radius of 15 cm: 3.14x0.075m = 0.2355 m. Knowing the radius and height, the volume can be calculated: 0.2355x1.5 = 0.353 m3. This number must be multiplied by the number of pillars in the foundation.

Calculation of cubic capacity for a slab base

To calculate a monolithic rectangular slab, you need to know its area and thickness. The planned house has dimensions of 5 x 8, therefore the area of the slab will be 40 m2. 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, stiffening ribs are made around the perimeter. To calculate their area, you need to know their length and width. In a 5x8 structure, I install stiffeners every 2.5 m. There will be 3 such ribs in width and 4 in length. The total length will be equal: (5x3) + (8x4) = 47 m.

Now let's 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 m2. We multiply the area by the length 47 = 0.47 m 3.

How to determine the amount of reinforcement and wire

To create a rigid and durable structure, iron reinforcement is used in installation. Its quantity depends on the type of foundation, loads and soil. Reinforcement with a larger 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 deform minimally, which means that the reinforcement will need a minimum diameter.

Quantity of reinforcement for strip base

The reinforcement for a strip foundation is taken with a diameter of 10-12 mm, since the structure itself can withstand heavy loads. They lay it in two rods, regardless of how deep the base is. Experts recommend laying the reinforcement 10-15 cm from the top pouring point. Vertical rods do not have a load, so the cheapest ones can be used.

For a house measuring 5x8, the length of the strip base is 45 m. With reinforcement of 4 rods, the consumption will be: 45x4 = 180 m. We add transverses 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.

Knitting wire is needed for one connection 30 cm. Length 45 m and pitch 40 cm: 45/0.4 - 112.5. We multiply this figure by the size of one connection: 112.5 x 0.3 = 33.7 m of binding wire needed for a 1-level foundation.

Quantity of reinforcement for columnar base

To reinforce the columnar base, thick reinforcement from 40 mm is used. Horizontally, the reinforcement does not bear any load, 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 pillars, it will not be difficult to calculate the size of the reinforcement.

For a structure 1.5 m high with a diameter of 15 cm, you need 4 rods, with a pitch of 7.5 cm and binders at 3 points. Thick reinforcement needed: 1.5x4=6m. For a thin bundle: 30 cm (for one node) x 3 = 90 cm. If 20 pillars are used in the foundation, then the number is multiplied by this figure.

Knitting wire is needed to connect one rod at 3 points. This number is multiplied by the number of rods and vertical connections: 3x4x30=72 m.

Number of reinforcement for a monolithic base

For dense, stable soil, you can take thin reinforcement from 10 mm. For heavy structures and unstable soil from 14 mm. The ligament is attached in increments of 20 -30 cm.

For a 5x8 platform you need 27 pieces in length and 17 pieces in width. Since a double harness is needed: (17+27)x2=88. This number must be multiplied by the length of the rod to obtain the footage of the reinforcement.

How to calculate the cost of a foundation

After the calculations of the cubes and the amount of reinforcement have been made, it is easy to calculate the cost of the foundation. Work and the price of formwork boards + earthworks and equipment are added to the basic cost.

On average, the cost of a turnkey structure starts from 15,000 m2. But you can save money and do all the work yourself.

The cost of ready-made concrete mortar ranges from 700 rubles per cubic meter, but you can reduce costs by making concrete yourself. To do this you will 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 entrusting the pouring of concrete to specialists.

In any case, you should not skimp on the foundation of the house, as it must be reliable and durable. And we explained in detail how to calculate and not overpay.

The calculation of a strip foundation consists of two main stages - collecting loads and determining the bearing capacity of the soil. The ratio of the load on the foundation to the bearing capacity of the soil will determine the required width of the tape.

The thickness of the wall part is taken depending on the design of the external walls. Reinforcement is usually assigned structurally (from four Ø10mm rods for single-story gas-block/frame buildings and up to six longitudinal Ø12mm rods for two-story brick buildings with an attic). Calculation of diameters and number of reinforcing bars is performed only for complex geological conditions.

The vast majority of online foundation calculators only allow you to determine the required amount of concrete, reinforcement and formwork with previously known dimensional parameters of the foundation. Few calculators can boast of collecting loads and/or determining the bearing capacity of soil. Unfortunately, the operating algorithms of such calculators are not always known, and the interfaces are often incomprehensible.

The exact result can be obtained using the calculation methodology set out in building codes and regulations. For example, SP 20.13330.2011 “Loads and impacts”, SP 22.13330.2011 “Foundations of buildings and structures”. Using the first document, we will collect loads, and the second, we will determine the bearing capacity of the soil. These sets of rules are updated (updated) editions of old Soviet SNiPs.

Load collection

The collection of loads is carried out by summing them of each type (permanent, long-term, short-term) and multiplying by the cargo area. In this case, load reliability factors are taken into account.

Constant loads include the dead weight of structures. For long-term ones - the weight of non-load-bearing partitions (in relation to private construction). Short-term loads include furniture, people, and snow. Wind loads can be neglected unless we are talking about building a tall house with narrow plan dimensions. Dividing loads into permanent/temporary ones is necessary to work with combinations, which can be neglected for simple private buildings by summing all loads without reducing combination factors.

At its core, load collection is a series of arithmetic operations. The dimensions of the structures are multiplied by the volumetric weight (density) and the load safety factor. Uniformly distributed loads (payload, snow, weight of horizontal structures) form support reactions on underlying structures in proportion to the load area.

We will analyze the collection of loads using the example of a private house 10x10, one floor with an attic, walls made of D400 gas block 400 mm thick, symmetrical gable roof, ceiling made of prefabricated reinforced concrete slabs.

Diagram of cargo areas for load-bearing walls at the floor level of the first floor (in plan.

Diagram of cargo areas for load-bearing walls at the roof level (sectional view.

Collecting the snow load poses some difficulty. Even for a simple roof, according to SP 20.13330.2011, three loading options should be considered:

Option 1 considers uniform snowfall, option 2 – asymmetrical, option 3 – the formation of a snow bag. To simplify the calculation and to form a certain reserve of bearing capacity of foundations (especially necessary for approximate calculations), you can take a maximum coefficient of 1.4 for the entire roof.

The end result for collecting loads on a strip foundation should be a linearly distributed (linear along the walls) load acting at the level of the base of the foundation on the ground.

Table for collecting uniformly distributed loads

Total: 1076 kg/m2

The standard value of snow load depends on the region of construction. It can be determined according to Appendix “G” SP 20.13330.2011. The self-weights of the roof, rafters, flooring and partitions are taken as an approximate example. These values should be determined by direct calculation of the weight of a particular structure, or an approximate determination from reference literature (or in any search engine for the query “own weight xxx”, where xxx is the name of the material/structure).

Let's consider the wall along the "B" axis. The width of the cargo area is 5200mm, that is, 5.2m. Multiply 1076kg/m2*5.2m=5595kg/m.

But that's not the whole load. You need to add the own weight of the wall (above and underground parts), the base of the foundation (approximately its width can be taken as 60 cm) and the weight of the soil on the edges of the foundation.

For example, let’s take the height of the underground part of a concrete wall to be 1 m, thickness 0.4 m. Volumetric weight of unreinforced concrete is 2400 kg/m3, load safety factor is 1.1: 0.4m*2400kg/m3*1m*1.1=1056kg/m.

In the example, we will take the upper part of the wall to be 2.7 m made of aerated concrete D400 (400 kg/m3) of the same thickness: 0.4 m * 400 kg/m3 * 2.7 m * 1.1 = 475 kg/m.

The width of the sole is conventionally assumed to be 600mm, minus the wall of 400mm, we get overhangs totaling 200mm. The density of the backfill soil is taken to be 1650 kg/m3 with a coefficient of 1.15 (the height of the thickness will be determined as 1 m of the underground part of the wall minus the thickness of the first floor floor structure, let the total be 0.8 m): 0.2 m**1650 kg/m3*0, 8m*1.15=304kg/m.

It remains to determine the weight of the sole itself with its usual height (thickness) of 300 mm and the weight of reinforced concrete 2500 kg/m3: 0.3m*0.6m*2500kg/m3*1.1=495kg/m.

Let's sum up all these loads: 5595+1056+475+304+495=7925kg/m.

More detailed information about loads, coefficients and other subtleties is presented in SP 20.13330.2011.

Calculation of soil bearing capacity

To calculate the bearing capacity of the soil, you will need the physical and mechanical characteristics of the engineering geological elements (EGE) that form the soil mass of the construction site. This data is taken from the geotechnical survey report. Paying for such a report often pays off handsomely, especially for unfavorable ground conditions.

The average pressure under the base of the foundation should not exceed the design resistance of the foundation, determined by the formula:

For this formula, there are a number of restrictions on the depth of foundations, their sizes, etc. More detailed information is provided in section 5 of SP 22.13330.2011. We emphasize once again that to apply this calculation methodology, a report on engineering and geological surveys is required.

In other cases, with some degree of approximation, you can use the averaged values depending on the types of IGE (sandy loam, loam, clay, etc.) given in SP 22.133330.2011:

As an example, we will set a loamy soil with a porosity coefficient of 0.7 with a plasticity number of 0.5 - upon interpolation, this will give the value R = 215 kPa or 2.15 kg/cm2. It is very difficult to independently determine the porosity and plasticity number; for a rough estimate, it is worth paying for at least one soil sample to be taken from the bottom of the trench by a specialist from the laboratory performing the survey. In general, for loamy soils (the most common type), the higher the moisture content, the higher the plasticity number value. The easier the soil is compacted, the higher the porosity coefficient.

Determining the required width of the sole (“pillow”) of the strip foundation

The required width of the sole is determined by the ratio of the calculated resistance of the base to the linearly distributed load.

Previously, we determined the linear load acting at the level of the foundation base - 7925 kg/m. Our accepted soil resistance was 2.15 kg/cm2. Let's bring the load into the same units of measurement (meters into centimeters): 7925 kg/m = 79.25 kg/cm.

The width of the base of the strip foundation will be: (79.25 kg/cm) / (2.15 kg/cm2) = 36.86 cm.

The width of the foundation is usually taken as a multiple of 10cm, that is, rounded up to 40cm. The resulting width of the foundation is typical for light houses built on fairly dense loamy soils. However, for structural reasons, in some cases the foundation is made wider. For example, a wall will be faced with façade bricks with 50mm thick insulation. The required thickness of the base part of the wall will be 40 cm of aerated concrete + 12 cm of cladding + 5 cm of insulation = 57 cm. Aerated concrete masonry can be “hung” by 3-5 cm along the inner edge of the wall, which will reduce the thickness of the base part of the wall. The width of the sole must be at least this thickness.

Foundation settlement

Another strictly standardized value when calculating a strip foundation is its settlement. It is determined by the elementary summation method, for which data from the geotechnical survey report will again be needed.

Based on the experience of construction and design, it is known that for engineering-geological conditions characterized by the absence of soils with a deformation modulus of less than 10 MPa, weak underlying layers, macroporous IGE, a number of specific soils, that is, under relatively favorable conditions, calculation of settlement does not lead to the need to increase the width of the base foundation after calculating the bearing capacity. The margin for the calculated draft in relation to the maximum permissible is usually obtained several times. For more complex geological conditions, the calculation and design of foundations should be carried out by a qualified specialist after carrying out engineering surveys.

Conclusion

The calculation of the strip foundation is carried out in accordance with current building codes and regulations, primarily SP 22.13330.2011. An accurate calculation of the foundation’s bearing capacity and its settlement is impossible without a geotechnical survey report.

In an approximate manner, the required width of a strip foundation can be determined based on the average load-bearing capacity of various types of soil given in SP 22.13330.2011. Calculation of settlement is usually not indicative for simple, homogeneous geological conditions within the framework of “private” construction (light low-rise buildings).

Making a decision on an independent, approximate, unqualified calculation of the width of the base of a strip foundation by the owner of the future building indisputably places all possible responsibility on him.

The advisability of using online calculators raises reasonable doubts. The correct result can be obtained using the calculation methods given in the standards and reference literature. It is better to use ready-made calculators to calculate the required amount of materials, and not to determine the width of the foundation base.

Accurate calculation of a strip foundation is not so simple and requires the availability of data on the soils on which it rests, in the form of a geotechnical survey report. Ordering and paying for surveys, as well as painstaking calculations, will pay off handsomely with a correctly calculated foundation, on which extra money will not be spent, but which will withstand the corresponding loads and will not lead to the development of unacceptable deformations of the building.

When the calculation of the bearing capacity of the soil has been made, and the load of the house has been determined, you can calculate the strip foundation, its volume and the amount of necessary material that will go on the strip of the load-bearing building structure.

Strip foundations are actively used in the construction of small outbuildings, private residential buildings and small administrative buildings. A concrete foundation strip can withstand significant loads, but this is only possible with a clear and correct calculation.

There is a classic shallow type tape; the depth of the tape base can be up to a meter; this base option is suitable for flat areas. The depth of groundwater is also taken into account.

Main stages of calculation

The strip foundation is also often erected in combination with piles, resulting in a pile-grillage foundation. But before starting construction work, it is necessary to calculate the load on the piles from the side of the future building so that they do not warp or become deformed. The main stage in the construction of a strip foundation is the calculation of the zero level of the strip for any residential building, even a bathhouse.

Calculation of a strip foundation consists of several main stages:

Determination of soil type to determine the possibility of using screw piles and strip grillage.
Calculation of the mass of the future structure;
Adjusting the dimensions of the foundation for design loads, taking into account the type of soil and the depth of soil freezing.

Any strip foundation, regardless of design and size, will be installed on the soil, the features of which should be taken into account before starting all design work.

The importance of determining soil type

The load-bearing capacity of the soil will determine the depth to which the piles need to be driven and a trench needs to be dug for formwork and tape filling; the calculated depth of the foundation is taken into account. Soil structure analysis can be done in three ways:

Dig vertical depressions in different places of the marked area for the future building or bathhouse, and analyze the structure of the soil.
Take soil cores for analysis at various depths using deep drilling;
Contact the geological service, and they will provide an approximate map of the soils in the area indicating the level of groundwater.

Most sections will show that the soil at different depths is not homogeneous. First comes a layer of loose fertile soil, which must be completely removed. Then loam or sand is possible; on such soil it is better to build a foundation directly on piles. A possible option is rocky soil (containing a significant amount of rocky components in the profile, more than 5% of the mass), which is ideal for a shallow strip foundation.

Any sandy or clayey dry soil, regardless of structure, has a bearing capacity of 2 kg/cm2. This is the initial value for the initial calculation of the future foundation design, as well as its depth. Most bathhouses and small village dachas are built from wood or brick. The soil can withstand the weight of a light building well, and it will be enough to calculate the required amount of building materials. But you can protect yourself by increasing the width of the sole.

If you have to increase the width of the foundation base, you must recalculate the required amount of building materials, as well as the thickness of the piles for the bathhouse, for example, if a pile-grillage foundation is used.

Geological exploration will answer the key question, at what level is the soil freezing boundary. Below this level, the soil is already maximally compacted, so it can withstand enormous loads. The optimal solution is to start building the base of the foundation below the frost line. The soil located above the freezing level is saturated with moisture, so it increases in size in winter. As a result, deformation of building structures occurs and any building, even a bathhouse, will simply collapse over time.

Calculation of the mass of the future building

The strip foundation is subject to load from the horizontal and vertical influence of the soil, as well as the building itself. Therefore, the mass of the future building plays an important role when choosing the type and overall dimensions of the foundation. The depth of occurrence is already there; it will be a zone below the freezing point of the soil. Calculation of the mass of a house, even an ordinary bathhouse, will be carried out according to the following parameters:

The mass of load-bearing walls and ceilings. Conventionally, we can take as an example an ordinary wooden bathhouse with wall dimensions of 10x10 meters and a height of 4 meters. In total, 400 m 3 of wood will be used for the construction of walls and ceilings, with a mass per cubic meter of 100 kg. Thus, the mass of load-bearing walls and ceilings will be 40 tons.
The mass of the roof and possible snow crust. It must be calculated individually in each case; the principle of the Pythagorean theorem applies here, taking into account the mass of roofing materials. The mass of snow that can simultaneously be on a gable roof with a slight angle of inclination is often taken to be 1 ton for a bathhouse.
The mass of the future foundation. It is also easy to calculate, because there are the overall dimensions of the foundation and its depth, and the mass of concrete required for its construction does not have to be calculated. Such data is provided by the manufacturer of building materials themselves.

After calculating and summing up all the obtained indicators, it becomes clear that a bathhouse with overall dimensions of 10x10 meters is quite capable of supporting a shallow strip foundation. It can be installed above the soil freezing level only if it is poured on a sand and gravel bed and waterproofing is provided.

Determining the dimensions of the base: example

Now you can begin to calculate the concrete needed to pour the foundation. The amount of fittings is most often not counted, since it will be minimal, given the mass of the bathhouse. Therefore, the volume of concrete is taken as the only correct indicator. For a bathhouse with an area of 100 m2, a concrete strip width of 0.4 m and a depth of 0.6 m, the required amount of concrete will be 100 x 0.4 x 0.6 = 24 m3. This is the volume of concrete that needs to be initially prepared in order to simultaneously pour the strip foundation for the bathhouse.

You can also take into account the reinforcing belt. It is made from longitudinal metal ribbed rods with a diameter of 12 mm and vertical rods with a cross section of 10 or 8 mm. Horizontal belts are installed at intervals of 20− 30 cm from depth to surface, but the edges must be hidden in the foundation at a distance of up to 5 cm from the surface.

Permanent formwork is often used, which provides additional load-bearing capacity to the base and makes the surface as smooth as possible. In this case, the vertical rods should be hidden in concrete, the interval between the belts is 50-60 cm. All connections should be made only with wire or clamps; it is better not to use welding.

It is recommended to make calculations of strip foundations for any building, even a small garage or outbuilding. Since only after correct calculation of the zero level, selection of optimal building materials and structures will there be a guarantee that the structure will last the longest possible period.

You can also calculate materials using our online calculator available in the menu.

Online foundation calculation calculator the site allows you to engage in full-fledged foundation design, facilitates calculations and helps save on materials, without neglecting building codes. The calculation method is based on an advanced mathematical model algorithm taking into account regulatory documents SNiP 2.02.01-83 (SP 22.13330.2011), SNiP 3.03.01-87 (SP 70.13330.2011), SNiP 52-01-2003 (SP 63.13330.2010) , SNiP 23-01-99 (SP 131.13330.2012).

Based on the results of the calculator, you will receive a detailed estimate for the construction of a turnkey foundation, a convenient and visual design drawing, a simple and understandable reinforcement tying diagram, as well as an interactive 3D model for assessing the resulting structure. We provide access to download all materials in OBJ, PNG and PDF formats.

You will be aware of the following parameters:

Foundation characteristics. Width, thickness, volume, depth, permissible loads on the ground.
Materials. Amount of reinforcement, tie wire, formwork boards, concrete, cement, crushed stone, sand.
Volume of earthworks. The required cubic capacity of soil that will have to be cleared for the foundation.

At the moment, calculations of strip foundations (full) and monolithic slabs (simplified) are available. Calculators for calculating pile, column and screw foundations should appear soon. Bookmark our site and don't miss their appearance!

The site foundation calculator will demonstrate your future structure based on the built-in calculation of materials and reinforcement. Using 3D visualization you can see what your reinforced frame should look like, down to the smallest details.

Foundation calculation

The construction of any house begins with the calculation of the foundation; it is the support for the entire overlying structure, and the durability of the entire structure depends on how well it is installed. When deciding to carry out the work of creating a foundation with your own hands, it is important to avoid mistakes in the initial calculations, and even more so, there is no need to try to save on materials. Remember that a well-designed foundation is the key to your safety.

Instructions

The average user does not have to be a construction specialist to use our service. The interface is intuitive, and the program will indicate any invalid value with red highlighting.

In most cases, you only need to enter a minimum amount of information:

estimated dimensions of the foundation;
brand of fittings to choose from;
brand of concrete.

In the process of calculating the foundation for a house, you may need to enter some additional values, but they can also be calculated on our calculators:

block calculator (load calculation).

We have prepared an introductory video for you, which explains step by step all the functionality and operating principle of the online foundation calculator.

Our calculator also allows you to make calculation of the volume (cubic capacity) of the foundation in m 3, so that they know in advance how much excavation work needs to be done.

Concrete is the most important component of the foundation; in fact, it is its “flesh” and most of the characteristics of the foundation depend on how high-quality the mixture is used. When choosing a solution, special attention should be paid to the indicator strength class (grade), which determines the maximum permissible compressive loads of a fully formed mixture. Expressed in kgf/cm², i.e. how many kg can 1 cm 2 of surface support?

For the most part, the grade of concrete is determined by the proportions of cement, sand (crushed stone, gravel) and water, as well as the conditions under which the solution hardened. In total, there are about 15 strength classes from TM50 (B3.5) to M800 (B60), but in private construction the most The most common brands are M100-M400. Accordingly, M100 concrete is suitable for light structures - garages, bathhouses, equipment, and M400 - for multi-story heavy buildings, for example, made of brick. But in the vast majority of cases, M300 grade concrete is chosen.

Using our calculator, you will receive a calculation of concrete for the foundation (volume, mass). All values will be available directly in the interface - you don't need to switch to other tabs. However, you are required to enter the grade of concrete used.

Calculating cement for your foundation has never been easier with our online calculator. Just fill in the fields in the tool and you will get the required values in the calculation results!

Reinforcement is the second most important component of the foundation (its “bones”), which allows you to compensate and level out the impact of tensile and bending loads. It is a well-known fact that concrete is not flexible and ductile, but it has high compressive strength. In order to combine these qualities and improve the performance characteristics of the foundation, as well as prevent deformation after the construction of the structure, the foundations are reinforced.

Foundation reinforcement represents the creation of a certain type of frame from connected horizontal, vertical and transverse rods. The most significant characteristic of reinforcement is its diameter and its choice depends on the type of soil, temperature characteristics, wall materials and dimensions of the structure being built. It is believed that for light buildings it is optimal to use 10 mm rods, 12 mm for single-story and low-rise buildings made of porous materials, 14 mm for low-rise buildings made of heavy materials, 16 mm for multi-story buildings and difficult soils.

The second important indicator is the tying pitch of the reinforcement. Usually it is selected by eye, based on the total mass of the structure and the type of underlying soil; the value should be in the range of 200-600 mm. The standard spacing used in private construction is 500 mm.

The built-in calculator for calculating reinforcement for the foundation allows you to calculate the number of rods, their total length, weight and volume. The result is provided both when calculating a strip foundation and a monolithic slab.

Our calculator will be useful when calculating the foundation for a house made of aerated concrete, foam concrete, brick and other building blocks!

Calculate the foundation for the house

In modern realities, almost anyone can calculate the foundation for a house - you do not need to have special knowledge and do not need to use the expensive services of specialists. However, before you start construction, you need to understand what type of foundation will be most rational for your site. Let us recall that the physical-geographical location and geomorphological conditions of the area have a direct impact on the type and cost of the future structure.

Factors for choosing the type of base

The soil- the most important factor in the construction of a house; the labor intensity of the process and the cost of constructing the foundation directly depend on its composition. In some cases, it comes to the point that it is more profitable to buy a new plot than to invest in transforming an existing one. Therefore, the very first thing you need to do on a new site is to determine the type of soil.

If you don’t have extra money, then you need to learn how to determine soils yourself. It is important to know that all types of soils are divided into rocky, clayey and sandy. Each type has its own set of unique properties, the most important of which are bearing capacity, heaving and freezing depth.

Groundwater- the second insidious companion of any builder. If you have a high aquifer level, then this is a very bad prospect for the future. In warm regions, endless flooding, dampness, mold and fungi will bother you. The dissolved harsh chemicals will slowly kill your foundation by loosening and dissolving the concrete.

In cold areas, the previous factors act to a lesser extent, but the forces of frost heaving can easily tear apart an improperly constructed foundation in a few winters. Therefore, it is extremely important to build a house on higher ground and avoid low-lying areas, especially if there are watercourses and ponds nearby.

Our articles in the section “ will help you conduct a soil analysis and find out the groundwater level. Foundations, soils, bases" You can calculate loads and other important parameters, according to SNIP, using the appropriate calculators on our website project.

Temperature- combines the two previous factors into a single whole. It is the last decisive factor that can influence the choice of base.

When building a foundation, the most important indicators are the depth of soil freezing and the level of groundwater. In a continental climate (with low temperatures in winter and high in summer), which occurs in most of Russia, every year the soil freezes to a significant depth and then thaws.

If the groundwater level is above the freezing mark, then heaving forces begin to act. The water contained in the soil freezes and turns into ice, thereby increasing its volume.

The power of this process cannot be underestimated, the force with which they can press on the foundation is tens of tons per square meter. Such an impressive impact will easily deform any structure and set it in motion.

Therefore, it is very important to know the standard depth to which the soil freezes annually. By laying the foundation below this level, you protect it from these destructive forces, but at the same time the cost of the foundation increases proportionately.

Types of foundations for a house

Based on these “input” conditions, we can now move on to an overview of the types of foundations. Their classification is based on design features and construction technology. The most popular are strip, monolithic, columnar, pile foundations and their combinations.

Strip foundation

Strip foundation- got its name because of its external resemblance to a ribbon. A monolithic or prefabricated reinforced concrete strip passes under all load-bearing walls of the building, exerting uniform pressure on the ground. One of the simplest and most affordable in private construction.

The labor intensity of the process is minimal, the installation technology is not particularly complicated and is relatively inexpensive. Suitable for most cases in the construction of low-rise buildings, it can easily withstand heavy loads. When the groundwater level is low, a shallow strip foundation is used, and when the groundwater level is high, a deep foundation is used.

In extremely problematic soils, when the tape has to be deeply buried by 2 m or more, the feasibility of using this type of base disappears and other options should be considered.

With us you can perform calculations for shallow and deep foundations. To determine which type is right for you, use our foundation depth calculator.

Monolithic slab

Slab foundation- a monolithic reinforced concrete slab located under the entire area of the building. Due to the large volume of excavation work and the huge costs of concrete, the cost of the structure increases significantly compared to tape. This is one of the most expensive, but at the same time effective types of bases.

Due to its homogeneity and large area of contact with the ground, this type of foundation easily tolerates significant vertical and horizontal loads. ;It is not afraid of the forces of frost heaving and high groundwater levels. It consistently performs on weak-bearing soils, and also withstands heavy houses made of brick and stone.

Columnar foundation

Columnar foundation is a structure made of pillars and ceilings, which is used in the construction of structures made of light materials. ;The foundation structure is extremely simple. Along the perimeter and in places of increased load (most often these are the intersections of walls), pillars are placed, which are connected on top by beams made of wood or metal.

This base has gained wide popularity due to the active construction of houses made of timber and SIP panels. It is economical, reliable and does not require waterproofing work. Protects your home from mold and premature destruction of wood. However, the foundation is extremely demanding on the soil; movement and heaving are strictly prohibited.

Pile foundation

Pile foundation- is a complex of numerous piles that create a stable frame for uniform load distribution across all structural elements. Foundations of this type are a salvation for owners of areas with unstable soils and difficult terrain. In addition to the fact that they allow you to securely fasten the building, they also strengthen the soil itself, preventing movement and landslides.

There are three main types of pile foundations:

On screw piles;
On bored piles;
On driven piles.

Each of them has its pros and cons, but the most common is the first type, as it combines low cost and meets all standards of private construction.

Building a house is a very important moment in every person's life, and a good foundation is the key to creating a reliable structure that will last for many decades. At first, foundations were calculated manually, later using a slide rule, adding machine, and calculator. With the advent of modern computers and the Internet, they began to be paid online, on special websites. This is why the strip foundation calculator was developed.

Types of foundations for a house

The base of the house is a continuous concrete strip. Its size must be sufficient to distribute the load on the plot of land.

A proper foundation is of great importance for a home. It retains moisture, insulates from the cold and resists the movement of the earth around it, and in order to correctly make all the calculations, you need a strip foundation calculator.

Today, concrete is mainly used to build foundations. It is easy to pour, spread and level in the prepared trench. Because of its ability to harden quickly, concrete provides compressive strength to support loads. Previously, the foundations of houses were made of brick or installed directly on solid ground, and were also built from natural stone.

The most common building base for a house is a wall made of poured concrete or concrete blocks with a support system. The vast majority of houses are built using the foundation calculation method (a calculator can be found on the Internet). Structural parts of the base:

Continuous concrete formwork.
A foundation wall made of poured concrete or reinforced concrete blocks.
Concrete floor slab.

These three elements are the structural components of the foundation system that serves to transfer the gravity of the load (the weight of the house) down to the ground. Concrete itself is not an ideal material for resisting the weight of a house as it is not very flexible, so steel reinforcing bars are inserted into it to resist any bending caused by the movement of the earth.

Foundation elements:

Sizing and pouring of the new foundation

The size of foundations built on soils that have low bearing capacity (such as clay soils) should be significantly wider than usual to provide greater stability. An excessive increase in the width and depth of the structure is not economically justified, so a reasonable option is to create foundations using reinforced concrete.

Reinforcing bars add tensile properties to the foundation, making the entire structure able to withstand tension and compression. The amount of reinforcement is set after the foundation has been calculated, for which purpose you can use an online calculator.

The size of the bases is influenced by several factors:

Selecting base width

It depends on the bearing capacity of the soil and the expected load of the structure. The higher the soil resistance, the smaller the width of the base for the same structure. If the base is mounted on an inclined surface, a stepped structure is used. Strip foundation is the most common type of foundation and the cheapest in cost. A strip of reinforced concrete supports the walls. An example is the online foundation calculator, taken from the site stroy-calculators.ru/lentochnii_fundament.php.

The depth of the trench may vary. The width of the base depends on the safe bearing capacity of the soil, and the thickness depends on the strength of the foundation material. According to the online calculator for a house of standard calculation No. 7 with a length of 14 meters and a width of 9 meters, the foundation must be at least 70 cm deep and 40 cm wide.

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Concrete foundations are made up of strips of reinforcement that provide a strong and level foundation. The load on the building is evenly distributed along the length of the foundation. Reinforcement has greater tensile strength than concrete - therefore, it can withstand significant loads.

The reinforcement structure is always made in advance and then installed in the formwork. The design of the reinforcing belt is simple, but before its manufacture it is necessary to make complex calculations that will ensure the reliability of the structure.

Stages of manufacturing a structure

It does not require special skills for construction, as well as special equipment, and the work on its construction can be completed independently. Main stages:

Digging a trench.
Installation of formwork.
Installation of reinforced belt.
Preparing and pouring concrete.

The benefits of an online calculator

The strip foundation (reinforcement and formwork) calculator will help you estimate the amount of building materials required for construction. As practice shows, the cost of building a foundation can reach one third of the total costs budgeted for the construction of a house or other building. The online application can simplify all assessments and plan the future monolithic structure. The developer will know the size of the foundation, the amount of concrete and other materials needed.

As a result of the calculations, the developer will receive the following data:

Since the app can be used as a concrete calculator, the quantity and cost of materials needed for the foundation can be easily determined. When planning, it should be taken into account that the composition of the mixture will depend on the brand of cement and the size of the gravel. The price for gravel and sand must be indicated per 1 ton, and the purchase is made for 1 m³. The online reinforcement calculator for strip foundations will help you perform all the calculations.

Before you start pouring the concrete mixture, you need to have the necessary supply of materials, such as reinforcement and building materials for formwork. It is better if you have the opportunity to purchase a ready-made concrete mixture: then you can pour the entire foundation at once. In any case, its filling must be completed in one day, otherwise phenomena may occur that lead to cracking of its structure.

Pros and cons of strip foundations

They have both positive and negative qualities.

Advantages:

Simplicity of design, the ability to build a foundation without expensive tools.
Ability to withstand heavy loads.
Easy to assemble, no special training requirements.
Long service life.

Flaws:

Not suitable for all soil types.
One-time pouring, the entire volume at a time, and preparing such an amount of concrete are quite problematic.

Reliable and durable strip foundations are suitable for many buildings and are the best option for building a house.