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How to determine the depth of laying the foundation

How to determine the depth of laying the foundation

There are such unpleasant cases where the wallshouses suddenly cracks occur, which, in spite of all attempts to patch up their becoming wider and wider every year. If you are going to build a house and do not want to be in the position of the owner of the structure collapsing, you need a very responsible approach to the device foundation.

Its depth bookmark refers to the most important parameters that determine the service life of the building.

You will need

  • - access to the Internet-
  • - Calculator.



Identify normative depth of freezing of soils inthe place where going to lay the foundation, using a schematic map of soil freezing depth. It can be found on the building site.


Based on the normative values ​​of depthsoil freezing, compute the calculated depth of freezing, depending on the operating conditions of the building (heating mode). It is defined by the formula Df = k * Dfn, wherein:

  • Df - estimated depth promerzaniya-
  • Dfn - standard depth promerzaniya-
  • Kn - coefficient taking into account the conditions of the thermal regime of the building (taken from SNiP2.02.01-83).


Determine the type of soil at the site of construction. To do this, dig a hole at the site, which will lay the foundation, and take soil samples. On exposure to the foundation soils are divided into several groups. First - it rocks, gravelly sands of medium and large size, coarse rock with sand filling. The second group of silt and fine sand. Third - sandy loam. Finally, the fourth group - clay, loam, coarse rock with silty-clay filler. The same grounds may have different turnover rates, which also affect the condition of the foundation.

The type of soil can be determined to be kneaded in the hands of histhe sample and roll the cord from it. Try to give the ring-shaped cord. If it turned out a whole - in your hands the clay if divided into several fragments - loam, if the ring when minimized crumbled into small pieces - sandy loam. If you have difficulty in determining the type of soil yourself, contact a specialist.


Determine the level of standing water table. For this section of the well drilled to a depth of 2.5-3 m and immerse the metal or plastic pipe to the well not to swim the ground. Check the water level in the different seasons. Captures two values ​​level - deeper than 2 meters of depth of freezing and at least 2 meters.


Based on these results (of Df, the level of groundwater, soil type) determine the desired value of the foundation depth (Table 2 SNiP2.02.01-83).

In that case, if the groundwater level is higher than 2 meters from the calculated level of freezing, the depth of the foundation is taken not less than the calculated depth of freezing (at least Df).

If the water level is less than 2 meters from the level of Df, foundation depth should be assumed as follows:

  • if the ground are large, medium or gravelly sands - 0.5 metra-
  • If the soil is silty and fine sandy loams and sands - not less than 0.5 metrov-
  • with loam, clay, coarse soils with silty-clay aggregate - at least 0,5Df.

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