How to dig a foundation pit?

The foundation is the base on which the whole building rests. That is why it is necessary to take very seriously his device. It is necessary to get advice from professionals, make a large number of calculations, check and analyze everything. Often, in order to save money, people carry out the digging of the pit by themselves, but in such cases it is important to understand what and how to do.

Digging - this is what ends the device pit. But this process takes its origin from the calculations that go into the preparatory stage. It includes the search for special vehicles, the purchase of the necessary tools, clothing and equipment, the selection of a team of workers (if necessary).At each stage, it is necessary to pay great attention to the quality of work performed, as the reliability and safety of the structure depends on it.

Novice builders often think about what time is best to carry out work on digging a pit. On the surface there is only one obvious fact - in the winter it is not worth doing, as it is extremely difficult to dig the frozen ground. However, this does not mean that all other seasons are suitable for work.

A good specialist will answer that there are two suitable seasons: summer and autumn. It is impossible to carry out work of this kind in the spring. At this time of year, the process of thawing of the earth begins, as a result of which a large amount of water is released, which must be pumped out. Consequently, additional costs for specialized equipment will be required.

The fall season is not fully suitable for this activity. You can work only in its first, warm part. Late autumn frost begins, the soil is unstable - it freezes at night and thaws during the day. It can leave a mark on the course and quality of work.

Of course, it is impossible to prohibit unequivocally digging a pit in the cold season. If there is an overwhelming need for its urgent creation, it is possible. However, it is necessary to take into account that this “pleasure” will cost you one and a half to two times more expensive.

If you want to make a pit under the basement or under the foundation of an ordinary house with your own hands, first of all, you need to prepare a drawing and a plan of work.

Before starting work, you need to clearly define what type of pit you need to dig. It depends on the type of foundation.

There are several parameters that must be considered when dividing the trenches into separate categories:

• the presence or absence of slopes, their number;
• the presence or absence of corner mounts;
• the presence or absence of vertical sloping walls;
• trench or pit (this aspect is determined by the type of foundation - slab or tape).

If you are building a tape-type foundation, then you need to dig a pit-trench along the perimeter, as well as in the places where the bearing walls will be located.

Here is a list of earthworks to be carried out first:

• determine what type of soil is on the site, to conduct an examination (this is necessary for planning the depth of the foundation);
• explore the technical characteristics of the building to determine the load on the foundation (all the specifics affecting the weight, up to the roofing materials) are taken into account;
• calculate the depth of the pit (this type of calculation is best trusted by professionals);
• analyze the category and state of the climate characteristic of this band in order to identify seasonal ground movements.

Before starting the excavation of the excavation, it is necessary to calculate its length and width. Of course, they depend on the parameters of the building itself (its length and width), as well as on the depth of the base of the structure. There is a rule for determining the size of the building: the dimensions of the foundation must be 40 cm more than the width and length of the facade, since a foundation is also needed for the facade decoration. Therefore, it is necessary on each side to add another 20 cm to the size.

As already mentioned, the size of the pit also depends on the depth, as in the cross-section the pit should have the shape of a trapezium. This is due to safety. The walls (when excavating from the excavation) should have slopes. The dimensions of the house increased by 40 centimeters will be projected only on the lower part of the pit. In this case, the top must exceed these dimensions by an amount equal to the depth of the sole. This will help ensure a 45-degree proportion to the walls. This is done in order to protect the walls from the shedding of the soil.

The zero level will look like this: the size of the pit (length and width) will be equal to the size of the house (respectively, length and width), increased by the size of the depth of the pit. The dimensions of the pit at the level of the sole will be the same as the parameters of the facade, increased by 40 centimeters. If the sole is buried by 0.5 m, you can not adhere to this rule, since then the walls of the pit will be vertical.

To determine the footprint area, it is recommended to divide the pre-calculated load by a certain value of the soil and the level of its permissible load (these data are obtained by conducting an examination).After the size of the foundation pit has been calculated, it will be possible to start digging it up.

The process of digging the pit is divided into several conditional stages of work.

• Prepare a site for the foundation, remove 40 centimeters of topsoil.
• Pumped out moisture, if it was formed, divert excess water from the site.
• Remove the ground (to a depth calculated previously). If the pit is deeper than 125 centimeters, special support bars are installed to prevent the land from sliding on the walls.
• Arranged in the pit steps if the soil depth is approximately 500 centimeters (it is better to entrust the calculation of the depth steps to an experienced specialist).

If the planned construction of the foundation of the tape type, the pit will be a trench buried in the ground, which provides for the formwork in its inner part. The dimensions are calculated according to the following scheme: the dimensions of the house (length and width) increase by 0.3-0.4 meters. The width of the trench itself is the sum of the width of the walls and the gap of 0.5 meters with the expectation of the construction of the formwork.It is important to know that the size of the trench must be at least one meter (the fact that the minimum tape is 0.4 meters is taken into account).

First, outlines the dimensions of the future excavation on the ground, after removing the layer of soil, amounting to 20-30 centimeters, for leveling. Choose the highest angle and begin to dig (manually or with an excavator), going deep into the soil around the perimeter and controlling the depth with the help of milestones.

For this type of foundation other rules apply.

• In the case of small penetration, its parameters are equal to the length and width of the facade of the building. In the case of significant penetration - the sum of the length (width) of the facade and the height of the foundation.
• The development takes place in steps: the soil is removed in layers of 0.5 meters. Each of the layers has smaller dimensions than the previous one. As a result, on the walls should get a height of 0.5 meters and a width of 25 centimeters.
• Manual labor is not used here; digging is done with special equipment.

The first stage is to remove the 30-centimeter layer of soil. Then on the surface cause the size of the pit. Along these boundaries make the initial excavation depth of 0.5 meters. At the same time, the soil is removed from the central part to the edges.

From the first layer they go to the next one, reducing the boundary by 25 centimeters, and so on to the bottom of the pit. Extracted soil sorted on the sand and the rest. Sand is left for bedding.

In this case, make a small trench (up to 0.5 meters) along the borders of the facade. At the bottom create pits for mounting pillars. They begin to remove the soil from the site by 20–30 centimeters, mark the edges, tear off a trench of 0.5 meters over them, make holes at the bottom. By means of milestones depth is controlled in a standard way.

First of all, the construction of the excavation must be carried out in strict accordance with the legal regulations laid down in the SNiP.They regulate the norms of the size of the pits for specific types of soil, etc. Also, any work that is carried out when creating the pit, must be accompanied by strict adherence to safety regulations and technologically correct methods.

It’s better to trust this kind of work to professionals who have the appropriate training., education, experience and (not least) documents that give them the right to produce relevant work. But, unfortunately, life makes its own adjustments. Indisputable is the fact that the independent implementation of construction works can save significant amounts for the budget.

However, this situation has a downside. With an independent construction of the pit, there is a great risk of making mistakes that may be irreparable. It is good, if it will pour out only in the spoiled material, the spent money and bad mood. But improper construction work is a process that can pose a direct danger to the life and health of people. Therefore, if you are not confident in your abilities, refer to the team of professionals.

To learn how to dig a foundation pit, see the following video.