Construction begins with the project. Even small structures are recommended to be pre-sketched on paper so that you can clearly see the proportions and estimate the consumption of materials. For serious buildings you need design estimates made by professionals, but when constructing a private house, cottage, fence or garage, you can get by with online calculators or turnkey solutions. The most important issue in the construction of structures is the construction of a reliable foundation, and therefore the question of how to calculate the amount of concrete on the foundation is of paramount importance.
Calculating concrete on the foundation is not difficult if there is certainty with the size and type of structure. The type of foundation and its dimensions should be determined by an experienced builder, based on the characteristics of the building under construction, the type of soil and the depth of freezing in the area.
Tape
The most popular basis for the construction of a private house is considered a strip foundation. It is a kind of closed tape made of concrete, passing under all the bearing walls of the building.
How to calculate how many cubes of concrete are needed on the foundation? Calculators that help determine the flow of cement-sand mortar for pouring are available on many sites with a construction topic, one of which is presented at the end of this material. To calculate the volume in cubic meters, you need to know the linear dimensions of the structure: height, width and total length of the base.
Concreting of the tape base occurs by pouring the finished cement-sand mixture into a wooden formwork with a pre-installed reinforcing mesh. Large fractions (gravel, crushed stone) are added to the solution to acquire higher strength characteristics of the foundation.
The dimensions of the base depend on the dimensions of the building that you plan to erect. Typically, the width of the foundation tape has a size of at least 300 mm, the height of the ground part - from 400 mm, and the depth can reach 1500-2500 mm depending on the presence of groundwater, the depth of freezing and the desire to equip the basement. Strip foundations are not recommended for installation on heaving soils if the formwork is deepened less than the freezing depth.
For the middle strip, when erecting small private houses and baths, it is enough to perform a burial within 1500 mm with a height of the ground part up to 400 mm.
The length of the foundation will be equal to the total length of all the outer walls, including the inner supporting wall, under which the base is also installed. As a result, having received all the required values, it is possible to calculate the volume of concrete for the foundation. In this case, a calculator may not be necessary - just multiply all the indicators in meters and get the desired number in cubic meters.
The calculation formula looks like this:
V = h * b * lwhere:
- V is the volume of solution in m3;
- h is the height in m;
- b is the width in m;
- l is the length of the tape in m
For example, for a building measuring 6x6 m and one internal load-bearing wall, with a foundation height of 2 m and a width of 0.4 m, the volume of mortar for pouring will be: V = 2 * 0.4 * 30 = 24 m3. With the same width and height of the foundation, for a 10x10 house with two load-bearing internal walls, the calculation will look like this: V = 2 * 0.4 * 60 = 48 m3.
This calculation allows you to calculate the almost exact cubic capacity of the mortar, but it should be remembered that part of the concrete is lost during transportation, as well as during loose formwork, part of the concrete mortar can leak out, but there is an additional internal volume occupied by the reinforcing cage. Therefore, it will be correct to introduce a correction factor in the direction of increasing the calculated value by 2%.
As a result, we obtain a more accurate formula for calculating the volume of concrete for a strip foundation:
V = h * b * l + 0.02 * (h * b * l)
The resulting value is rounded to the nearest integer. For our examples, the refined calculation will look like this: for a 6x6 house V = 24 + 0.02 * 24 = 24.48 (25) m3for home 10x10 V = 48 + 0.02 * 48 = 48.96 (49) m3.
Tiled
The slab foundation is a solid monolithic base under a building spot. For its use, concrete grade not lower than M100 is used. The volume of this monolith is calculated quite simply - it is enough to multiply the length, width and height of the plate.
Pouring mortar from cement and sand with the addition of large fractions for a monolithic slab is made to a height of at least 100 mm. Thus, for a slab 100 mm thick, the following volumes of concrete are obtained:
- for home 10x8 - 8 m3;
- for home 9x9 - 8.1 m3;
- for the house 18x8 - 14.4 m3.
This calculation is suitable for completely flat plates, but to give the base higher strength characteristics, additional stiffeners are often arranged in the form of trapezoidal longitudinal beams. Therefore, the correct calculation of the tile foundation should also include the volume of pouring of stiffeners.
How to count concrete cubes on a foundation? Online calculators will help you perform these calculations for free, you can refer to special tables, well, or to independently calculate the required volume of concrete is not difficult.
The volume of stiffeners must be added to the already obtained volume of the slab, for which the trapezoid area formula is used. The volume of the slab foundation with stiffeners is found as follows:
- Calculate the volume of your plate: V = h * b * l.
- Find the area of the trapezoid: S = h1 * (a + c) / 2where h1 is the height of the trapezoid rib, and c are the lengths of the trapezoid bases.
- Find the volume of the stiffeners and multiply by the number of ribs: V1 = S * l * nwhere n is the number of stiffeners.
- The resulting volumes are added up and get the total volume of the required concrete: Vtotal = V + V1.
Usually the reinforcement is placed at the bottom of the base in increments of 3000 mm. They can be performed both exclusively longitudinal amplifiers, and with intersection, forming squares. Typically, the ratio of the wide part of the trapezoid of the stiffener refers to the narrow part directed downward, as 1.5: 1. To calculate the slab foundation, volume adjustment is also provided with an error coefficient of 2%.
Columnar
This type of foundation is a kind of pile field, only the supporting pillars are not clogged with piling, but are poured into prepared pits. Column foundation allows you to get a reliable foundation with minimal material consumption. The posts can have a round and square cross-section, they are placed along the perimeter of the building spot and at the joints of the walls.
The depth of the columnar foundation usually exceeds the freezing depth for a given area, and the surface part has a height of 400-500 mm. The building structure can be installed directly on the support pillars, but most often a grillage is installed around the perimeter, which connects the pillars into a single whole.
To calculate the volume of concrete required for pouring the column foundation, it is necessary to know the length of the column, its cross-sectional area and the number of columns. If a grillage is provided, its linear dimensions will be required; calculation of grillage volume is carried out in the same way as in the case with a strip foundation.
To calculate the volume of columns with a square or rectangular section, you need to use the following formula:
V = a * b * l * nwhere a and b are the sides of the cross section of the column, l is the length of the column, n is the number of columns in the foundation.
To calculate the volume of concrete for pouring pillars with a circular cross section, you need a formula for finding the area of a circle: S = 3.14 * R * Rwhere R is the radius. We get the formula for calculating the volume of columns with a circular cross section:
V = S * L * n
To obtain the total volume of concrete required to fill the pillars and grillage, it is necessary to add the already obtained indicators, not forgetting the error coefficient of 2%.