What is the best foundation for a two-story house, calculation of depth and its thickness

The foundation in construction is the basis for a strong and durable house, resistant to weather and seismic conditions. The durability of the entire structure depends on the features of its execution, materials and quality of materials. Further, various types of foundations will be considered, recommendations regarding installation calculations, depth and width. Recommendations will be given, thanks to which the client can decide which type of foundation is right for him.

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Foundation construction options

Foundations may differ in the materials used for their construction, in depth, as well as in the method of execution. It is by the way of execution that their types are divided:

• Columnar the type is almost universal, it justifies itself well, as a basis for any panel houses or townhouses. The installation of the pillars takes place in special pre-drilled holes, which are made around the entire perimeter of the building. The distance between the supports is calculated individually. For supports, natural materials such as logs, natural stone and artificial components (pipes or reinforced concrete stepsons) are used.
  

  Columnar foundation device

• The pile foundation differs from the columnar in the length of the elements and in the principle of operation. In a columnar house, the mass of the house falls on the sole, and in the pile, on the side surface. The pile is good in that it allows you to exclude deformation of various parts of the building due to the uniform distribution of the load of the entire structure, and this prevents its deformation. Such a foundation can be of two types: hanging or retaining.
  

  Types of pile foundation

  In the first type, piles are driven directly into the ground, where the load is concentrated: corners, intersections of walls. The length of such piles can be several meters. This is due to the fact that the main load is transmitted by the lateral part of the support.
  2. The retaining type of foundation should be installed at a shallow depth, but at shorter intervals than the hanging one.
  Whether it is worth making a pile foundation for a two-story house is determined by several parameters. The main parameter is the type of soil, the second is the material of the house.

• Strip foundation - the most convenient type for the construction of small houses. For its installation, a block type of bookmark or a solid concrete tape is used. This design is simple and non-destructive. Basic blocks can be filled or lightweight (hollow), depending on the requirements of the entire structure. Its advantage is that houses made of aerated concrete built on such a foundation are durable and resistant to soil movement. In addition, the strip foundation can be installed at a minimum depth, which makes the construction independent of geodetic indicators.
  

  Strip foundation and its device

• The monolithic slab is earthquake resistant. This is a solid platform with a large area, the height of which is calculated relative to the conditions of the terrain of the future construction. This type of foundation is the most resistant to soil displacement and the most expensive in terms of concrete consumption.
  

  Monolithic base device

The choice of a specific type of foundation for a two-story house depends on the wishes of the client, the characteristics of the area and the architectural plan. But at the same time, there are recommendations regarding the choice of the best option, in terms of durability, ease of installation and budget saving.

Which is better

The optimal choice of the foundation for low-rise construction consists in a detailed analysis of many indicators of the object, as well as the characteristics of the area where the house will be installed.

Pile and columnar structures are used for construction, but have not proven themselves sufficiently in terms of practicality and durability. A monolithic slab is relevant for the construction of both one-story and two-story houses, which are built on landslide soils or in zones of movement of the earth's crust.

In areas with stable seismic activity, the monoplite is a very costly method. Practice shows that tape technology is the best choice for a two-story brick house. And the installation of foam block houses on a strip foundation is also gaining great popularity, since it has a number of advantages:

• resistance to various deformations (cracks, breaks, shedding);
• ease of installation and ease of maintenance;
• high indicators of bearing capacity and operation;
• variety of layouts.

The listed advantages are possible only if the installation technology is observed.

Foundation calculation

Calculations are made according to certain formulas, the material and features of the house are taken into account, as well as a number of geodetic factors. The dimensions of the foundation for a house made of brick, cinder block or concrete will differ, since the masses of materials are different and exert different pressure on the ground.

To calculate the area of ​​the base, you need to know the total mass of the house. In the table, the specific gravity of building materials

Simple calculation

Without taking into account additional individual features, the depth of the foundation installation can be calculated using the standard formula, where 0.8 meters must be multiplied by the number of floors expected - a total of 1.6 meters.

The thickness of the foundation in the classic version is equal to the estimated thickness of the bearing walls plus 15 cm.However, it is worth knowing some parameters that can change this indicator:

• looseness of the soil;
• sole area;
• the total mass of the structure.

Foundation thickness depending on soil and number of storeys

Accurate calculation

For a more accurate calculation of its depth, you need to know:

• Type of soil (sandy, clay, sandy loam).
  

  Soil density

• Soil freezing point. It is necessary to know it so that deep freezing of loose and moisture-filled soil does not destroy the base. However, if the building is being built on fairly dry land or slightly loose soil, this indicator does not matter.
  

  The depth of soil freezing in some regions

• Height of aquifers. In a situation where the aquifer is located close, its depth should be minimal, for the purpose of waterproofing.
• Accommodation in the house.

The depth of freezing of the soil of your zone is taken as a basis. To this value, add 150 mm if the house is wooden or 350 mm when it is brick.

Let's first calculate the depth of a one-story house. We take the depth of freezing in the Moscow region with fine sand soil. It is 1.34 m.The house will be brick, therefore we add another 35 cm and we get 1.69 m.

There is a relationship between the depth of the foundation and the room temperature. This dependence is expressed in coefficients and is shown in the table. According to it, the higher the temperature in the house, the less deep it needs to be done.

Dependence of the room temperature and the depth of the foundation device

We will have a floor on logs on the ground with a temperature of at least 20. This gives 1.69 * 0.6≈1 meter. It is enough to deepen the foundation by 1 meter.

Now for the two-story. The mass of the house will be almost 2 times more, so it must be stronger. According to the rule written above, the depth should be 1.6 meters. And this is below the freezing point, which is fine.

Installation of strip foundation

When choosing a basis for a two-story house, it is recommended to take into account the complexity of the installation and material costs. The most convenient, economical and durable option is the belt type.Before installation, it is necessary to calculate the width of the base, as well as the thickness, which directly depends on the material used. The smallest width is for reinforced concrete, then for concrete, and the widest base must be made for natural stone, due to the weight of the material.

The deepening depends on the type of material of the future structure and the correlation with the freezing point of the soil. The height of the foundation varies according to the individual needs of the customer and his preferences. If there is a threat of flooding, naturally the height should be increased.

There are standard standards suggesting a height of 35–40 cm for wood, and 20 cm for brick and aerated concrete. In addition, it is recommended to add another 10 cm to the height of the snow cover, which is most typical for the construction site.

The main stages of the strip foundation installation:

• a preliminary drawing is drawn up;
• marking and digging of trenches is carried out;
• laying the pillow, moistening it, and tamping;
• reinforcement is done;
• formwork device;
  

  Elements of the formwork strip foundation with dimensions

• pouring concrete;
• drying.

Reinforcement is the main stage in the strip base, since it is the reinforcement frame that creates a strong structure. Usually, rods with a diameter of 12-16 mm are used. The spacing between the rods is about 30 cm and may vary depending on the individual parameters of the building.

Filling must be carried out in one or at most two stages in order to maintain the solidity of the structure. With manual mixing or using a private mixer, this is difficult to achieve, so it is better to resort to factory concrete. After final casting, a high level of insulation must be ensured. The pillow can be made of sand, gravel, mixtures thereof or concrete, which justifies the density of the soil.

Errors in the construction of foundations

Mistakes made during construction can lead to the complete destruction of the building. For those who want to strengthen the foundation on their own, seek to save money or want to hire a team of specialists, while not understanding anything about construction, the most common mistakes when pouring the base will be listed below.

Choosing construction according to a standard design, the customer usually saves time and money on the development of unique drawings. But at the same time, keep in mind that there is no data on the type of soil, its freezing, the horizon of the groundwater. All indicators are directly related to the installation depth of the main structure, which must be calculated immediately. This is the first technically possible mistake, and the following unsuccessful construction ideas are also possible:

• Saving on material. Usually leads to the rapid appearance of cracks, after which the entire foundation will begin to crumble. A cheap brand of concrete for the foundation of a two-story house is not suitable, since the base made of it, having collapsed, entails the destruction of the walls and the entire structure.
• Wall masonry and installation of any supporting structures earlier than 4 weeks after the foundation is poured. Without waiting for the concrete to fully set, the construction of the entire box of the house takes place on a movable base, which ultimately leads to its destruction literally immediately after the end of construction.
• Lay a concrete tape around the entire perimeter of the same width and thickness without taking into account the internal features of the house. This creates an uneven load, and, accordingly, different shrinkage at different points in the building. The thickness at each specific point should be calculated depending on the thickness of the walls, their location and purpose in the supporting structure.
  

  Mistakes in the construction of the foundation affect the house

• The use of shields from unsuitable boards for formwork leads to the fact that liquid flows from the concrete through the cracks. Subsequently, this leads to stratification of concrete, a decrease in its strength and further destruction of the house.
• Replacing the factory fill with a manual batch is time-consuming and the fabric itself becomes heterogeneous. A solid foundation requires a one-step pouring, which ensures its homogeneity and increases its strength. The appearance of air voids, which leads to the destruction of the foundation, is due to poor tamping of the concrete mixture.
• Reinforcement and piles are the supporting frame for the foundation, therefore, its thickness, grade and metal must be selected in accordance with the requirements of the architectural project, without saving.

A common mistake in construction is a careless attitude to the season and climatic conditions. In winter, it is imperative to use specialized plasticizers (anti-freezing), and in summer, cover the concrete with polyethylene and moisten it with water twice a day in order to maintain the strength of the material.

Work in construction can be done independently, for complex tasks, professional mixing of the solution and calculations, you should contact the professionals. The base must be made of the highest quality materials, in the required quantities. Savings are possible in decoration or design, and so that the house does not collapse, maximum attention must be paid to the installation of the foundation.