How to calculate the foundation for the house: weight, dimensions, markings

How to calculate the foundation for the house

The question of how to calculate the foundation for the house,It should be solved at the design stage. The main objective is to determine the load on the foundation and the soil, and the support of the foundation area. Total load includes permanent and temporary load. To include a constant weight of the building structure (walls, foundations, roofs), and operational loads (the amount of people staying in the room, furniture, equipment). load variables - wind loads and snow.


  • Constant elements that transmit the load foundation
  • We consider the weight and dimensions of the base
  • Determining the amount of concrete

Calculation of the foundation includes the definition of the areahis bearing and weight, allowing to calculate the load on the foundation and the house that will stand the ground. For professional designers importance are precise calculations of the future structure of the weight and volume of the construction materials used. For self-construction works to produce enough approximate calculation of the house foundation. The calculation assumes a uniform load distribution from the house across the square.

Constant elements that transmit the load foundation

To determine the loading on the foundation elements emit list giving load. These include:

  • directly to the very foundation;
  • base, including finishing;
  • walls, interior partitions finished;
  • ceiling with trim;
  • roof;
  • stairs and floors, supported by the foundation;
  • soil above the foundation sole (important for some types of foundation).

Due to the average reference data, the proportion of building materials (SNIP II-3-79), we determine the approximate weight of the house and the load on the foundation.

The proportion of some materials

The share of construction materials

Thus it is necessary to take the largest shareto provide a small margin. The share of building materials Y (kg / m3) is multiplied by the volume of structures V (m3) is obtained as a result of the weight of the structure P (kg).

Further, the resulting ratio is multiplied by the weight load of reliability. The average value of this ratio are presented in the table.

Reliability factor used in the calculation of the foundation

safety factor

Operating (utility), the load is determined with a margin, calculated as the product of the total area of ​​the house and the amount of 180 kg / m2.

Furthermore constant load induced weighthome time necessary to calculate the load. Snow load is determined by the product of the area of ​​the roof on the weight of the snow cover, depending on the area of ​​construction.

Snow load to calculate the foundation for the house

snow load

We consider the weight and dimensions of the base

To calculate the total load on the ground, it is necessary to weight the house with the main elements of added weight of the foundation. Please identify foundation dimensionsThe amount of which depends on the planned construction materials for the manufacture of penetration. The presence of a sketch or a foundation scheme is a prerequisite to simplify calculations.

Recommended values ​​foundation depth depending on the type of soil are given in the table below:

The depth of the foundation

Depth of laying the foundation

The thickness of the foundation is also dependent on the value of defined soil categories. Usually it is not less than 350 mm.

foundation dimensions

The dimensions of the foundation for buildings with basement

On the basis of these values ​​we calculate the weightfoundation, for which the amount is multiplied by the specific gravity. For further calculations, the main indicator will be the width of the foot of the basement. That it affects the specific ground pressure.

The total amount of all the indicators: weight construction elements, operational load, snow load is the weight of the house, which affects the foundation. Specific pressure on the sole ground of the foundation is determined by dividing the total weight of the house on the foot of the basement area, the figure was designated P (measured in t / m2).

For each type of soil determined the value of the bearing capacity without precipitation, this figure is called - the estimated ground resistance R (t / m2).

Indicators calculated resistance of clayey soils

Design strength of clayey soils

Estimated sands resistance

The design resistance of sandy soils

The main condition of the foundation operationIt lies in the fact that the value of the specific load on the plantar primer must be smaller than the calculated resistance. In other words, P <R. If the requirement is met, it shows the correctness of the calculations.

Important! The design resistance must be greater than the specific pressure by 15-20%, it is necessary to create a reserve of strength and compensate for small inaccuracies in the calculations.

If the load on the ground is too large,You need to change the dimensions of the foundation, increasing its reference area. To strip foundation - to increase the width of the tape to the columnar - to increase the diameter of the pillars and their number. If you change the settings in the mandatory need to recalculate the weight and the foundation load to the ground.

Determining the amount of concrete

Making the foundation for the house payment, innecessarily need to have a project. It is not necessary for it to be carried out professionally. Independently developed by the construction plan could greatly facilitate complex calculations and to determine the required amount of concrete.

Type of foundation is the main indicator for determining the amount of concrete to fill.

For example, to calculate the amount of concrete forfoundation slab requires the following indicators - the thickness of the plate and its area, the presence of ribs and their parameters. Strip foundation requires knowledge about the value of penetration, the width of the tape and its total length. In the case of the pier foundation necessary to become familiar with the height of the pillars and their number.

The process of construction of the foundation - one of the mostcritical stages of construction home. This is the foundation house, upon which all the supporting structures. Properly carried out the calculations are the basis for the longevity of the building and help avoid serious mistakes in carrying out the construction work. This technique is already in the design phase allows you to reliably determine the main parameters of the future foundation.

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