Calculations for slab foundations
- We work with a columnar foundation
- Strip foundation
- Leveling the floor
- Filling holes under the fence
Planning construction work, pay special attention to the calculation stage. This will allow you to purchase components, eliminating the possibility of subsequent shortages or, conversely, the formation of unnecessary residues. It is easy to cope with the task. But sometimes difficulties arise, in particular, regarding how to calculate how many cubes of concrete are needed for the foundation. This is not surprising, because it must be poured evenly so that it can dry well afterwards. The strength of the support, its reliability and durability depend on this.
The given criteria guarantee the quality of the building, exclude its deformation and cracking of the walls as a result of misalignment, which can happen if the foundation subsides unevenly. Help will be needed here. The main criterion is the type of base. The subtleties of the calculations will depend on it.
How to calculate how many cubes of concrete are needed: pouring a slab structure
We are talking about a monolithic slab. When figuring out how to calculate how much concrete is needed for the foundation, calculate the volume of the platform by multiplying the area (S) by the thickness. The first is calculated as follows: the length is multiplied by the width. For example, if you are building a house with sides of 6 and 6 m, S equals 36 m 2. The minimum thickness of a concrete mortar ball is 10 cm. So let’s formulate the formula: 36x0.1 = 3.6 m 3, having found out how much concrete will be needed for pouring. When planning a more solid twenty-centimeter structure, prepare 7.2 m 3 of batches, etc.
Often, to increase the strength of the platform, stiffening ribs are installed, placing them in the longitudinal and transverse directions. They are located at the bottom of the slab, and its top remains level. When determining what mass of concrete needs to be prepared to fill the recesses, calculate their total length and cross-section S.
For example, for the dimensions discussed above, with a step of 3 m, 6 structural recesses will be provided - 3 along and 3 across. The length of each is 6 m, the length is 36 m. The height (H) of the stiffeners is equal to the foundation being built. The section is made rectangular or trapezoidal. The width of the RJ will be 0.8-1 from N. So the S edge of a 10-centimeter slab will be: 0.1x0.08 = 0.008 m 2.
The final volume when multiplied by 36 m2 is equal to 0.288 m3. Based on the example given, the volume of the RZ is calculated for more impressive slabs. Afterwards, the two obtained indicators are added together. So you can easily calculate how many cubes of concrete are needed to build the planned foundation.
How to calculate how many cubes of concrete are needed: columnar foundation
Everything is simple here. Determine the number of columns. We measure their height and cross-sectional area. The last two parameters are multiplied. If you are installing poles with a circular cross-section, S is determined by multiplying the radius by 3.14. Calculating the amount of kneading is not difficult. Multiply the output by the number of pillars.
How to calculate how many cubes of concrete you need: strip foundation as the most popular option
A strip foundation is considered the most common type for a private house with one or two floors. It is suitable even for brick buildings characterized by a fairly large weight, only in this case it will be necessary to build a more solid support, increasing its width and level of recess into the ground.
Due to the popularity of tape technology, the question regarding its calculation also becomes relevant. At first glance, it may seem difficult to calculate how much concrete is needed for a strip foundation. But, adhering to generally accepted formulas, you can easily cope with solving the problem. Determine the following:
- The width of the tape is usually 20-40 cm. It all depends on the characteristics of the building and the blocks or panels from which the housing is built. The heavier the structure, the stronger and more solid the foundation should be;
- height - determined taking into account the underground and above-ground parts. In total, it usually turns out to be about 50 cm. In some regions it is necessary to deepen the base by 1.5 m at a ground layer N of 0.5 m, then 1.9 m is taken into account;
- The length of the tape is easy to calculate. This is the totality of the walls. Both load-bearing and additional structures are taken into account. For example, if our house is 6x6 and has one internal wall, the required figure is 30 m. We added up the perimeter and parameters of the internal wall.
By multiplying the listed values, you can easily and simply calculate how many cubes of concrete are needed for the foundation. So, if you have: 0.4 m, 30 m, 1.9 m, respectively, you will need 22.8 m 3 of concrete.
You can simplify the calculation process by using a special calculator. Enter the requested parameters here, and then you will see the finished result in just a couple of seconds. By deciding to calculate how much concrete you need to pour using a calculator, you get several significant advantages.
First of all, it's faster. One moment, and you have the number you are interested in. It takes longer to do the calculations yourself. Secondly, there can be no doubt about the accuracy of the readings, because the calculator works according to a strictly established algorithm. The main thing is to correctly set the initial data. At first glance, it may seem that it is not difficult to analyze simple examples on your own. But, often we forget to convert centimeters to meters, we make other inaccuracies, calculating erroneous numbers.
The question of how to calculate how much concrete is needed to pour the foundation has been resolved. But a similar task will arise before us again when it comes to interior works in the house, leveling the floor. Here, too, you need to decide on the volume so as not to be interrupted from the work process to purchase the missing product. The floor is leveled with Portland cement mortar, because this option is considered the most preferable. Unlike self-leveling mixtures, it is more affordable and allows you to eliminate significant level differences and surface defects.
How to calculate how many cubes of concrete are needed to level the floor
It is important to understand exactly how to calculate how much concrete is needed for the floor. If you incorrectly determine the tonnage of the solution, prepare it less, and then you will need to buy more ingredients. It is better to avoid such situations, because a high-quality screed must be poured in one go. Therefore, we will study all the features of the calculations in order to avoid mistakes.
We multiply the following quantities:
- floor area. Multiply the width by the length;
- screed thickness. Everything is simple here;
- consumption coefficient 1.02.
For example, S of the floor is 30 m2, the thickness of the screed is 0.05 m. To carry out the work, we will need 1.53 m3 of cement mortar. Things are more complicated when there are differences in the base. Then the height of the concrete layer is determined by the lowest point (the largest number is taken).
We need to know the volume in order to select the components that need to be purchased. So be guided by the following:
- The construction documentation indicates that to prepare one cubic meter of cement composition, 490 kg of binder is required. Leveling the floor is allowed using a dry compound of a grade not lower than M400. Moreover, the higher the grade, the more sand you can add;
- By multiplying the cubic capacity and the original unit - 490, we will get a figure that explains how much binder to buy. It is better to make a purchase with a small reserve, but not too significant, because the remains of the dry composition are difficult to store; if moisture gets into the packaging, the cement hardens and becomes unsuitable for further use;
- There is sand in the leveling solution. It is used with Portland cement in a ratio of 3:1. That is, if we take one bucket of binder, we should take 3 buckets of sand. Thus, we multiply the above derived indicator by 3, we obtain the required volume fraction. concrete calculation
Important! There is water in the cement mortar. But we do not take it into account. It does not affect the cubic capacity of the finished composition, because it fills the voids formed between grains of the binder composition and grains of sand. Process water cannot be used for preparation, as it will reduce the strength of the finished mixture. The water must be clean, without foreign impurities.
We erect a fence for our own site
If you decide to build a fence, do it using metal pipes sunk into a hole filled with concrete; here you also need to carry out the appropriate calculations to determine the volume fraction of the components.
When figuring out how to calculate how much concrete is needed in a hole, we will initially determine its capacity. It has the shape of a cylinder, so you will need to multiply the height of the hole and the S section (radius multiplied by a constant value of 3.14). This way we will find out the cubic capacity that will be required to fill the recess. But keep in mind that there will be a metal pipe inside it. Its volume lowered into the hole is calculated using the same formula, only the length of the deepened part of the pipe is taken as the height. Now we subtract the smaller one from the larger indicator, obtaining the figure we are interested in. There was no need to carry out particularly complex calculations. Now you can purchase materials, plan and carry out work. concrete calculation
Try to be very responsible when choosing dry mixtures, because the quality factor of the frozen site depends on their quality. Pay attention to the brand of binder, which becomes the main criterion when purchasing, and to the presence of plasticizers, water repellents, and other components and additives that improve performance characteristics.
Remember that the concrete solution is prepared using sand. Only the ratio of components differs. The less disintegrant, the stronger the hardened base. Buy bulk baking powder of the middle fraction, ensuring its good adhesion with other components.
When building a foundation, it is important to correctly calculate the amount of concrete mixture that will be used for construction. Moreover, in in this case a variety of factors are taken into account, ranging from the chosen foundation design, the conditions of its construction, temperature and humidity levels, the depth of groundwater and much more. To find out how much concrete will be needed for work, special formulas should be used.
Calculation formulas for pile foundations
A columnar foundation is considered one of the simplest to manufacture; it consists of pipes (or piles) that are immersed in the soil and then poured. The method of constructing a pile foundation is used for heaving, complex soils, for lightweight buildings, frame houses, bathhouses. The formula for is as follows:
- S = 3.14*r 2, where S is the area of the covered surface for one column, r is the radius of the pile;
- V = H*n, where V is the volume of concrete to be poured, H is the height of each pillar for the foundation, n is the number of pillars.
That is, for a pillar with a diameter of 20 cm and a height of 2 m, 0.0628 cubic meters of concrete will be required. All that remains is to multiply this value by the number of support pillars and the calculation is ready.
In some cases, it is necessary to calculate the volume of mass required for the construction of square support pillars. In this case, a different formula will be used, where the width is multiplied by the length (for rectangular posts) or the value of one side is raised to the square power (for a square section). Therefore, carefully select formulas and do not use the first one you come across, so as not to make a mistake and get completely different results.
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Volume of concrete for strip base
Strip foundations today are one of the most popular foundation options in country house construction. It is suitable for the construction of single and two-story houses, garages, baths, is characterized by ease of construction.
All these indicators are simply multiplied together.
The formula for calculating the number of cubes of concrete will look like this:
- V = S*L, where V is the total volume of concrete, L is the length for the foundation strip, S is the area for the cross-section of the strip;
- to obtain the value of the cross-sectional area, you simply need to multiply the width of the tape by its height (with a uniform cross-section).
For example, with a tape length of 28 m and a cross-section of 0.16 m², the volume can be calculated as follows:
V = 28*0.16=4.48 cubic meters.
But it is also possible that the section of the tape will be non-uniform, for example: at a length of 8 m - 0.2 m², at a length of 12 m - 0.16 m². In this case, the formula takes the following form:
V = 12*0.16+8*0.2+8*0.25=5.52 cubic meters of concrete.
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Slab foundation: how to calculate cubic capacity without errors?
To calculate the volume for a slab base made of reinforced concrete, it is necessary to use completely different formulas. This type of foundation is used on floating, complex soils, if there is no plan for a basement or if the slab acts as a foundation for the floor of a living space. It is this type of foundation that places the least load on the soil, but the rigidity is quite high. When constructing such a foundation, special reinforcing bars are used, which must be taken into account when deciding how much concrete will be required for construction.
To find out the cubic capacity of the mixture you will have to use the formula:
- S is the total area of the entire slab, it is calculated by multiplying the length by the width);
- H is the thickness of the slab.
For a slab with a length of 10 m, a width of 5 m and a height of 0.15 m, the amount of concrete will be:
V = 10*5*0.15=7.5 cubic meters.
The volume for stiffeners, that is, reinforcement, is calculated separately:
V 1 = 0.12, V 2 = 0.15, V 3 = 0.12, V 4 = 0.15 m²
V = 7.5+0.15++0.12+0.15+0.12=8.04 cubic meters of concrete.
In order to avoid overuse of materials and downtime due to shortages during the construction stage, it is important to calculate the cubic capacity of the foundation in advance. Having understood general principle techniques, this work will not be difficult to perform with any base configuration.
General provisions
For calculations, it is enough to use formulas from a school mathematics course and some techniques that simplify calculations in order to quickly obtain the necessary data. Calculations can be carried out using the calculated data available in the design documentation for the future structure or using the finished formwork. The second method is more accurate.
When using reinforced concrete, some part of the volume will be occupied metal structures. The calculation can be carried out in a similar way, the error will be insignificant.
To simplify calculations, foundations of complex geometry are divided into simpler constituent figures, and their volume is represented as the sum of the volumes of these simple figures.
With complex foundation geometry, you can apply the geometric trapezoidal rule: measure the width of the base at the bottom and at the surface. The arithmetic mean between them is used in further calculations.
Slab foundation
Using calculators
Instead of “manual” calculations, many people use special calculator programs. After entering the basic parameters of the future foundation, the program produces detailed results, including not only the cubic capacity of concrete, but also the recommended parameters of the foundation, as well as other necessary data. This method is optimal in the absence of preliminary engineering calculations.
Calculation of slab foundation
Calculations will be somewhat more complicated if there are stiffeners. Such amplifiers can have a rectangular or trapezoidal cross-section and are also calculated according to the parallelepiped rule (LxWxH), and in the second case the trapezoid rule mentioned above is applied.
Calculation example
If, based on the results of measuring the installed formwork, the length, width and height of the base are 10, 5 and 0.15 m, respectively, then the volume (or cubic capacity) of the foundation will be 10x5x0.15 = 7.5 cubic meters. m.
Let us assume that such a slab has four stiffeners - two longitudinal and two transverse, respectively, with volumes of 0.12 and 0.15 cubic meters. m. In this case, the volume of stiffeners is added to the volume of the foundation parallelepiped. The final result will look like the sum of 7.5 + 2x0.12 + 2x0.15 = 8.04 cubic meters. m.
Depending on the configuration of the base, the stiffeners can be the same or different (longitudinal and transverse) in size.
Slab foundation with stiffeners.
Calculation of strip foundation
The area of a strip foundation can be calculated as the difference between the areas of rectangles (or more complex shapes) calculated along the outer and inner contours. To make it clearer: the strip foundation plan consists of two figures identical in shape, but differing in size, one inside the other. The difference between the areas will become the required area of the base. To calculate the cubic capacity of concrete, it remains to multiply the resulting area of the tape by its height.
When calculating a strip foundation, it is important to remember that the volume of concrete for the internal foundations must be added to the calculated cubic capacity of the main strip load-bearing structures, if any are provided for by the project.
Calculation example
Tape width – 0.4 m,
The sides of the outer rectangle formed strip foundation, - 6 and 7 m.
The total length of the tape is 2x6+2x7= 26 m.
Sectional area 0.4x0.8=0.32 sq. m.
The cubic capacity of the strip base is 26x0.32 = 8.32 cubic meters. m.
Strip foundation
Pile foundation calculation
A pile foundation is a complex of cylindrical supports, the volume of each of which is calculated as the product of the area of the base-circle (PI multiplied by the square of the radius) and the height. PI=3.14. Having calculated the volume of one support, the total cubic capacity of concrete is calculated by multiplying the resulting volume by the design number of piles.
Calculation example
If the diameter of each support is 20 cm, then its radius in meters is 0.1.
Sectional area S=0.0628 sq. m.
If the height of the pillar is 2 m, the volume of each support will be 2x0.0628 = 0.1256 cubic meters. m.
It remains to multiply the volume of one support by the number of piles.
Pile foundation.
Calculation of a bored foundation with a monolithic grillage
This type of foundation can be considered the most complex from a geometric point of view. However, when the structure is broken down into simpler figures, the calculation becomes as simple as the techniques used in other cases. The grillage slab is a parallelepiped and a complex of cylindrical columns. Examples of calculations of cylinders and parallelepipeds are described above.
Rice. 5. Bored foundation with a monolithic grillage.
Bored foundation with a monolithic grillage.
Calculation of material requirements
After calculating the cubic capacity, another important task is set - to calculate the consumption of concrete. Theoretically, the need for the materials that make up the mortar may differ. The calculation is influenced by the grade of concrete and the nuances of the object (type of soil, load on the foundation from walls, roofing, etc.). That is why many people prefer to use calculator programs, which, as a rule, perform complete calculations. In practice, universal concrete is suitable for almost any private housing construction project (residential, commercial, fence, etc.), the preparation of which requires the following materials:
By multiplying these numbers by the total cubic capacity of the foundation, we obtain the required amount of materials for construction.
In order to avoid overuse of materials and downtime due to shortages during the construction stage, it is important to calculate the cubic capacity of the foundation in advance. Having understood the general principle of the technique, it will not be difficult to perform this work with any base configuration.
To accurately determine the time for completing concreting work and the amount of material consumed, calculations should be carried out, this will help online calculator calculating the volume of concrete.
The concrete volume calculator will independently calculate for you the required amount of solution, providing the most accurate numbers. Consumption is taken into account in cubic meters.
Calculate the volume of concrete for the foundation slab or screed
The calculator below produces calculation of concrete for slab foundation in accordance with building codes and regulations. To calculate a slab foundation, you need to know the area and thickness of the slab, because a slab is an ordinary rectangular parallelepiped.
A slab foundation is a closed reinforced concrete solid monolithic slab that is laid under the entire area of the house, thereby distributing the load along the entire length.
Enter your data in the fields for calculation:
Correctly calculating the cubic capacity of concrete in this case is much more difficult: we must multiply the length of the structure, which includes the perimeter from the outside and the length of all partitions between rooms, by its height and width (provided that the foundation strip has the same cross-section along its entire length).
It is imperative to take into account the depth of groundwater, landscape, soil and other factors when calculating the height of the foundation.
The foundation calculator will help you independently calculate the required volume of concrete for pouring the foundation, and will also calculate the amount of formwork and reinforcement. It is worth noting that the “Foundation height” parameter includes both the depth of the underground part and the height of the above-ground part.
If your interior partitions are not represented by a load-bearing type structure, then a lighter foundation layer is used under them, which has its own geometric parameters, and you need to calculate the foundation for the partitions separately in a calculator, and then summarize the data obtained.
Foundation calculation
Before you start building a house, the first thing you should do is familiarize yourself with the composition of the soil, since both the choice of foundation type and the costs associated with the construction process depend on the quality of the soil.
The next step is to calculate the foundation, namely to calculate the permanent load from the house itself, and the temporary load from wind and snow cover, in order to determine whether the soil will withstand the load from the house and the foundation.
Then you can start calculating the volume of concrete for the foundation. To do this, the length of the structure should be, and this includes both the perimeter from the outside and the length of absolutely all partitions between rooms, multiplied by its height and width, but provided that the foundation strip has the same cross-section along its entire length.
Concrete volume V=L*A*B , Where
L - Foundation length
A - Foundation height
B - Foundation width
If you are planning to prepare concrete yourself, then you should know that concrete is most often prepared from cement grades M 500 and M 400 using sand and crushed stone. When calculating the proportions of concrete, many factors should be taken into account, such as fractions of crushed stone and sand, their density, and the required qualities of concrete. The table “Concrete proportions” shows average data.
When calculating reinforcement for foundation reinforcement, it is worth knowing that longitudinal bars bear the load, and therefore ribbed reinforcement is used for them, mainly 10-12 mm, and vertical and transverse bars are made from smooth and thin reinforcement, since they do not carry loads.
To quickly calculate the volume of concrete for pouring the foundation, as well as all the necessary building materials, you can use our foundation calculator located above.
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