We fill the foundation with our own hands

The most common foundation material is reinforced concrete. The design made of a monolith becomes optimal in terms of labor intensity and cost. This method avoids the need for lifting equipment, but requires strict adherence to technology. Do-it-yourself foundation pouring should begin only after a detailed study of the process steps.

The design and construction of the supporting part of the building begins with a study of the characteristics of the soil. There are two options for completing this task:

  • contacting a specialized company that will perform a full-fledged geological study with laboratory tests;
  • independent study using excerpts of pits or manual drilling.

The first option will determine the strength characteristics of the soil most accurately. Before pouring the foundation of a multi-storey building, such an event is carried out without fail. For buildings with a low degree of responsibility and private buildings, you can examine the soil visually using GOST 25100-2011 “Soils. Classification” to determine its type. Based on which group the base belongs to, its approximate strength is assigned. The method does not give high accuracy, but can be used to save money.

Layout of axes and dimensions of the structure

An important stage that affects all other building structures. If you make a mistake in marking the foundation, the distance between the walls will change. This is especially critical if prefabricated elements are used for walls and ceilings. The markup is correctly performed using the following technology:

  1. removal of the fertile soil layer, which is from 30 cm;
  2. designation of the first side of the house (most often marked parallel to the front border of the site or fence);
  3. then mark the points on the first side, which will be the corners of the house;
  4. right angles are built from the marks using the Egyptian triangle method, all the walls and corners of the structure are designated using the same method.

Marking the foundation with the help of cast-offs.

Foundation marking can be done using pegs or a full-fledged cast-off made of vertical posts and horizontal lintels. The elements are installed at a certain distance from the axes of the building so that they do not interfere with work when excavating trenches or excavations. On wooden markings, after completion of earthworks, a thread or cord is fixed, which will indicate the contours of the supporting structure of the house.

It is important to control the following points related to geometry:

  • compliance of the design lengths of the sides with the actual ones;
  • the equality of the diagonals of structures that have a rectangular or square shape in plan (a deviation of not more than 20 mm is allowed), the coincidence of the diagonals indicates that all the angles of the rectangle are 90 °.

Soil excavation and cushion laying

The most difficult earthworks are if the foundation is poured with your own hands using tape technology. In order to dig a trench or pit yourself (if there is a basement), in this case, sufficiently large penetrations into the ground will be required. In this case, the following recommendations should be observed:

  • The width of the trench is assigned more than the width of the foundation by 0.8-1 meter to provide access to the structure during waterproofing and insulation.
  • It is important to correctly unfasten the walls of the pit or trench. If you miss this moment, the performance of pouring work can become dangerous to life and health. This is especially true when constructing buried foundations. The maximum height of a trench with vertical walls without reinforcement depends on the type of soil. More details are provided in the table below.
  • It is also important to take into account the angle of internal friction of the soil (natural repose). When constructing an angle equal to this value from the bottom of the pit, the minimum distance is obtained at which it is allowed to install massive equipment or store materials.

After excavating a pit or trenches, the need for backfilling under the sole is considered. According to SP 50-101-2004, it can be made from sand (medium or coarse), sand and gravel mixture or gravel. Before pouring the foundation, it is worth laying the backfill in the following cases:

  • deepening below freezing with heaving soil;
  • the presence of a bulk layer (it is replaced with a more durable material).

In other cases, there is no urgent need for laying the substrate. In general, the backfill performs two functions:

  • leveling the base under the sole of the foundation;
  • prevents the rise of capillary moisture to the structure.

This element is necessary to remove excess moisture from the supporting part of the house. It is carried out even at a low level of groundwater to prevent trouble when liquid rises in the spring or with high rainfall. Work on laying drainage pipes should be carried out with the following recommendations:

  • deepening relative to the base of the foundation by 30-50 cm;
  • the distance from the foundation of the house is not more than 1 m;
  • the slope of the pipes in one direction is taken equal to 3-4 degrees so that the liquid moves by gravity;
  • to prevent silting, crushed stone laid around pipes is wrapped with a layer of geotextile with an overlap of 30 cm.

Formwork

Formwork for pouring concrete according to GOST R 52085-2003 is classified according to the following criteria:

  • design;
  • materials;
  • turnover (the possibility of reuse);
  • possibility of use at different ambient temperatures;
  • impact on the concrete mix.

In addition, the mold for pouring can be removable and. One of the most common removable options is wooden, of the non-removable ones, polystyrene foam is most often used. It is also possible to manufacture from materials such as metal, plastic, foam concrete, moisture-resistant plywood.

When installing the formwork, it is required to control:

  • accuracy of geometric dimensions and installation;
  • shield stability;
  • tightness (seams no more than 2 mm).

Laying of reinforcement is necessary to increase the ability of the structure to resist bending loading. Reinforcement of tape and columnar bases is performed with spatial frames. Grids are used for the plate. With a structure thickness of more than 150 mm, the grids are laid in two layers. The following are the main recommendations for reinforcement:

  • calculation for a private house can be performed in a simplified form, assigning the total area of ​​​​the rods depending on the cross section of the structure, the minimum diameters differ for different types and sizes of the foundation, so this issue requires separate consideration;
  • for the manufacture of frames and meshes, reinforcement of a strength class of at least A400 can be used, but the use of A500 and higher rods is not economically justified;
  • it is important to observe protective layers of concrete, in general it is worth remembering the following numbers: foundations without concrete preparation - 70 mm, with concrete preparation - 40 mm;
  • reinforcement should be provided in the corners, usually the step of the transverse horizontal and vertical reinforcement is halved, and the main reinforcement is also reinforced with P or L-shaped clamps.

After the formwork and reinforcing cage are installed, they begin to fill with concrete mix. As recommendations on how to properly fill the foundation under the house, the following can be given:

  • Filling is performed in one step. Breaks are allowed only during the setting period of the mortar, which depends on the type of binder and weather conditions. On average, a break is allowed for 1-2 hours.
  • It is best to work at a temperature of 20 ° C. At lower values, the period of strength development of the material increases. When the temperature rises to 30°C, the performance of concrete may deteriorate. It is important that during pouring there is no dry weather, since high-quality pouring requires an air humidity of about 80%. Also, do not do work in the rain, if it started during the production process, use plastic wrap. It is laid immediately after pouring.
  • The formwork is filled in such a way that 2-5 cm remain from the upper edge of its shields to the mortar level.
  • Liquid concrete is poured by moving the mixer from point to point. Pour from one point followed by manual movement reduces the quality of the material.
  • The concrete mixture must not be dropped from a height of more than 2m.
  • After pouring, a thorough compaction of the solution is carried out using internal vibrators. Such a tool provides a seal to a depth equal to 1.25 of the tip length. It is recommended to first pour the mixture into the formwork to a height of 60 cm, then compact it and pour another 60 cm. The operation is repeated until the design mark is reached. It is important that all stages occur before the end of setting of the previous layer.

Concrete care and formwork removal

Recommendations on how to properly pour the foundation under the house are not limited to laying the mixture. It will take an average of 28 days to complete the grade strength process. During the first weeks of construction, maintenance will be required to prevent cracks from appearing on the surface. Its first stage is covering with plastic wrap, tarpaulin or burlap, which will not allow moisture to evaporate too quickly.

  • in the daytime, humidification is carried out every 2-3 hours;
  • during the night it is enough to perform the operation 1-2 times.

Formwork according to SP 70.13330 can only be removed after the concrete has gained 70% strength. When justified, it is allowed to perform work at 50% of the brand value. The time taken for this process depends on the outside temperature. Concrete on a normally hardening binder gains the required strength at a temperature of 20°C in 5-7 days, at 10°C in 28 days, and at lower temperatures the process slows down significantly.

Read more about stripping.

backfilling

In the manufacture of a strip or column foundation, less often a slab foundation, it is required to backfill the sinuses of the pit or trench after removing the formwork. It is important to observe the following principles:

  • the beginning of work is carried out only after the soil reaches the optimum moisture content;
  • for backfilling, soil is used that is denser and with better strength characteristics compared to the extracted one (coarse-grained sand is often used);
  • the work is carried out in layers, the maximum thickness of the material at each stage is 30 cm;
  • each layer must be compacted before laying the next;
  • backfill material should not contain foreign components, organic inclusions.

Compliance with the technology at all stages of pouring concrete will allow you to get a reliable and durable structure that will last for many years.

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