Calculation of the foundation pit and excavation algorithm

The foundation of a house is usually somewhat deep into the ground, so to lay the foundation, you need to remove some layers of soil. As a result of this work, a pit or a trench is obtained, depending on what purpose was pursued. In this article we will tell you how to calculate and correctly dig a foundation pit for different types of foundations.

Types of strip foundation

Before proceeding with the construction of such a foundation, it is necessary to carefully consider its features and varieties. This will allow you to choose the right foundation for the construction of a particular structure. This will also make it possible to carry out all the necessary work correctly. A strip foundation is not just one way to make a foundation for a house; there are several types:

Solid cast

A monolithic or solid strip foundation is constructed directly at the construction site. To begin with, formwork is constructed into which a reinforced belt is laid along its entire length. After this, concrete is poured.

The base is a closed monolithic contour made of reinforced concrete. Thanks to this, you can create a solid frame that is suitable for any soil, including unstable ones. On such a foundation you can easily build a country house or a stone fence.

Among the advantages of this design are ease of construction and reliability. In this case, the base can have a different shape. As for the disadvantages, there is a large mass of the monolithic structure.

Solid strip foundation - concrete is poured in one go into the prepared formworkSource sazhaemvsadu.ru

Made

Ready-made reinforced concrete blocks are used to construct the foundation. They are used to lay out a tape of the desired shape directly on the site. They are held together using cement mortar. They are optimally suited for the construction of low-rise buildings. It is quite easy to purchase ready-made blocks, since many factories are engaged in their production.

Among the advantages, it is worth highlighting the ease of assembly, which can significantly save time on foundation construction. But, at the same time, prefabricated structures have some disadvantages. The non-solid structure and the need to attract heavy construction equipment reduces the popularity of this type of strip foundation.

A prefabricated strip foundation is assembled from ready-made slabs, and the joints between them are sealed. Source kinozavr.info

Shallow foundation

This type of foundation is mainly used in the construction of light buildings. So, these can be frame houses and structures made of timber and logs. The peculiarity of this foundation is that it is located slightly above the soil freezing level. Therefore, it is often used on less problematic soils.

Shallow structures can easily withstand soil heaving that occurs in winter

During construction, special attention is paid to waterproofing and thermal insulation. This will protect the base from the negative effects of the environment.

The advantages of a shallow foundation include its low construction cost. At the same time, there is no need for complex earthworks. It has several disadvantages. First of all, it is worth noting that this design cannot be used on all types of soil and for the construction of not all structures.

The design of a shallow foundation is standard - it is simply buried into the ground no more than 50-70 centimeters. Source novostroika93.ru

Deep strip foundation

The construction of a strip foundation of this type is carried out below the freezing level of the soil. This makes it possible to distribute the load from the future structure onto a stable layer of soil. Due to this, deep foundations are used for the construction of multi-story buildings that have significant weight.

The advantage of this design is that they are suitable for the construction of heavy structures. It is also possible to equip the basement and basement. Of course, arranging the foundation will require significant physical and material costs. This is especially true for excavation work.

A deep strip foundation is buried below the soil freezing level - this can be 1.7-2.2 meters or lower, depending on the region. Source diagnostika.spb.ru

Pit for the basement. Written by an excavator operator

This is exactly what a FORUMHOUSE member with the nickname chichic called his topic on the portal, where he shares his knowledge on digging pits.

chichic

I have been doing earthworks for a very long time. He started back in 1991 as a bulldozer driver. Since 1995 I have been working on an excavator. I work on a full rotation machine. During this time, he accumulated vast experience in digging pits for cottages. One day a friend approached me with a request to help dig a pit for the basement floor. At first I wanted to write to him how to do it correctly by email, but then I decided to post everything on the portal. I think it will be useful to many.

First, a little theory. According to Yuri, you need to dig a pit for the basement using a full-rotary excavator .

Option with a conventional backhoe loader, the so-called. “jisibishka”, or the old “Belarus” is worse, because this technique is best suited for digging trenches.

Among the advantages of the JCB, we note the compactness of the machine and the ability to drive under its own power over a small area.

An experienced excavator operator can dig a medium-sized pit in 8 hours, i.e. for one work shift. To save on labor costs, it is better to look for a private owner who has his own excavator, or negotiate with an excavator operator who works outside of working hours.

Option: ordering an excavator from an organization specializing in this work will most likely cost more, because in the chain customer-digger-excavator-excavator operator there are too many extra “mouths” - intermediaries - managers and executives. In addition, the excavator operator from the company is interested in doing the work not in one, but in two shifts, and the developer will not be able to catch an experienced person deliberately slowing down the digging process. And this is again a waste of time and money.

So, the first rule of digging a pit is to not be lazy and look through friends and acquaintances for those who have already built in the village, an experienced excavator operator with his own machine. Such a person will not have to explain how to dig a pit, but only need to be told what needs to be dug.

chichic

When I arrive at a site, the first thing I do is listen to the customer, and then I walk around the place and take a closer look. And even after looking at the digging site, I cannot always say how I will dig the pit. But I definitely say where I will start and where I will end. If the customer begins to doubt my qualifications, then I tell him that there are a dozen methods of digging in his area, and once I start, I will choose the most optimal one.

Rule two: the developer should not walk around the site and teach the excavator operator how to work. If you are not sure of his experience, look for someone else. The responsibility of the developer is to estimate the sequence of work on the site . The list of these works in general (since much depends on the method of constructing the house and the selected building materials) includes:

1. Choose a place for storing soil and a location for earth dumps so that they do not interfere with construction.
2. Choose a place where construction equipment will arrive - trucks, a concrete mixer, a crane, etc.
3. Select the exact location where the building materials will be stored. So that it does not turn out that unloaded floor slabs, bricks, aerated concrete, wood on rafters, etc. you will have to move it again, because... the crane cannot approach the “box” of the house because of the piles of earth.

The developer must think ahead and plan the course of the entire construction, and not let everything take its course.

Having chosen an excavator, we look for and negotiate with truck drivers for removing soil. Practice shows that the best option is KamAZ. The vehicle has good cross-country ability, does not get stuck on a country road after the first rain, can handle overload well, and most importantly, there are many such trucks. KrAZs and Urals are too slow. ZIL has a small load capacity and body volume, and this means extra mileage for the vehicle.

It is also necessary to decide in advance what kind of soil and where it will be transported or stored on the site. For example, chernozem should not be wasted, and it can be carefully moved to a corner of the plot. The bulk of the soil, and depending on the composition of the soil, this can be loam, sand, clay, etc., is either removed or used for backfilling or subsequent leveling of the site.

Important: you should not level and fill the site with soil removed from the pit at the same time as digging a pit for the base and subsequent construction of the “box” of the house. The fact is that such soil cannot be properly compacted right away. Multi-ton equipment - mixers with concrete, trucks with reinforced concrete panels, blocks - will become bogged down and stuck on the site, especially if there is even a little rain. As a result, the territory of the site will be gouged with wheels, and it will turn into a “tank track,” which will significantly complicate and increase the cost of construction.

Backfilling and final leveling of the site is best done after the “box” of the cottage has been erected and no work is planned, except for finishing work associated with the entry of heavy construction equipment into the territory.

We also remind you that backfilling of the foundation sinuses must be done either with native (excavated) soil, or with imported soil that has the same or greater water-resistant capacity.

If you follow the principle “everyone does this” and fill the sinuses, for example, with sand, and there is good dense clay around the foundation, then it turns out that water will constantly begin to collect in the sand, it will get wet, you will get a “pool”, and this, in turn, , will negatively affect the soil foundation.

Beginner builders often have a question about how to carefully cut off black soil on a site. According to chichic, it is better to do this with a front loader.

With such a machine, this work is done quickly, accurately, the top soil layer, which will be useful to us, will immediately be moved where the developer needs it, and the place for digging the pit will be as level as a table. This is necessary for the next most important stage - marking the foundation and foundation.

Step-by-step action plan

It is recommended to dig a hole with three or four people - this way the work goes faster. After preparing all the tools, workers should have a plan.

Step-by-step sequence of actions when performing excavation work:

1. Marking.
   A preliminary plan must be drawn up on paper or electronic media. It needs to be moved to the ground. To do this, control the position and dimensions of the hole using a geodetic level. The dimensions are checked along the axes and diagonals - they should not deviate from the norm by more than 2 cm in any direction. If there is no level, use the Pythagorean theorem and the point of intersection of two curves. To mark the depth, use a measuring rod with marked marks. Pegs are installed at the corner points, and a cord is pulled between them.
2. Removing the top layer. To remove the fertile layer of soil, first cut off bushes and uproot trees. To determine the volume of the fertile layer, multiply the length and width of the pit on top by the thickness of the plant layer. This layer is removed using garden and bayonet shovels.
3. Excavation and soil removal. During digging, personal protective equipment is used - gloves and goggles, special suits. First, safe areas for excavation are formed, and as development progresses, space is made available for normal movement of labor.
4. Export of rock. The soil is loaded into large buckets using a shovel and removed from the mining site. Later it can be removed using special equipment.
5. Alignment of walls and bottom. Compaction of the base must occur with proper humidity. Soil that is too dry will take a long time to compact. Too wet soil will interfere with the compaction procedure. Sandy soils are compacted by vibration; compaction is suitable for manual leveling. The process is carried out by lowering a heavy tamping plate to the bottom of the pit.

How much fill is needed?

This figure schematically shows the volumes of the recesses, which are enclosed in prisms with side “a” and various marks at the four corners h1,2,3,4.

In this case, marks with a “-” sign refer to the execution of the embankment, and “+” - to the foundation pit. The total volume of the selected soil is determined as a result of adding the volumes of individual prisms located on the site.

When there is uneven ground cover with closed horizontal lines, the triangular prism method is used. In this case, the amount of work is calculated by dividing rectangles or squares diagonally into triangles. With this method, sufficient accuracy in processing the results is obtained.

After the construction of the pit, there are various unfilled cavities in its walls, as well as entry/exit routes, which must be filled with soil with a backfill volume of V backfill.

It is established using the formula: the difference between the volume of excavation V total and the deep part V cap.

V backfill = V total - V cap.

In the case when structures protrude up to 1 m above the ground plane with soil filling around, the volume of such filling is V fill.

Calculated as the volume of a pyramid with a truncated vertex V truncated. minus the poured volume V dump. by height h of the fill:

V obs = V truncated — V backfill.

Over buildings located in a pit and having ceilings, for example, underground tanks or tanks for liquefied gas, an embankment is placed on top of them.

Its volume is calculated as the volume of a pyramid having a truncated vertex V truncated. minus the volume of the object that will be filled. The total volume of the soil layer stored in reserve on the excavation bar must contain the volume of soil for backfilling the sinuses, backfilling structures and making an embankment above them. The excess layer of earth is transported outside the construction site.

Time for work

Beginning builders often think about what time is best to carry out work on digging a pit. There is only one obvious fact on the surface - this should not be done in winter, since digging frozen ground is extremely difficult. However, this does not mean that all other seasons of the year are suitable for work.

A good specialist will answer that there are two suitable seasons: summer and autumn. This type of work cannot be carried out in the spring. At this time of year, the processes of thawing of the earth begin, resulting in the release of a large amount of water that will need to be pumped out. Consequently, additional costs will be required for specialized equipment.

The autumn season is not entirely suitable for this activity. You can only work in its first, warm part. In late autumn, frosts already begin, the soil behaves unstable - it freezes at night and thaws during the day. This can leave an imprint on the progress and quality of work.

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

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

When is the best time to do the work?

Let's figure out when it is recommended to dig a foundation pit.

Before you start preparing a hole or trench for the foundation, it is recommended to clarify several important parameters:

• expected load effects;
• features of soil composition, soil freezing point;
• the amount of precipitation that falls during the year and the presence of ground moisture.

Having this information, you can determine to what depth to dig the foundation for the house.

So, when is it allowed to start digging a foundation pit? Experienced builders recommend the summer and autumn seasons (the first half of it) for this work, when the soil is soft and excavation for the foundation is easy.

Preparing a trench for a strip foundation or a pit for a pile foundation is possible in winter and spring; there are no strict prohibitions for these seasons. You just need to take into account that the implementation will be complicated, and the cost of the work will increase by one and a half to two times.

Preparation and calculation

Before starting work on digging a pit, 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 a building: the dimensions of the foundation must be 40 cm greater than the width and length of the facade, since a foundation is also required for the facade finishing. Therefore, you need to add another 20 cm to the size on each side.

As already mentioned, the size of the pit also depends on the depth, since in cross section the pit should have the shape of a trapezoid. This is due to safety precautions. The walls (when excavating soil from a pit) must have slopes. The dimensions of the house, increased by 40 centimeters, will be projected only onto 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 proportion with the walls sloping at 45 degrees. This is done in order to protect the walls from soil shedding.

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

To determine the area of ​​the sole, it is recommended to divide the pre-calculated load by a certain soil value and the level of its permissible load (this data is obtained through an examination). Once the size of the foundation pit has been calculated, you can begin digging it.

The process of digging a pit is divided into several conventional stages of work.

• Prepare the area for the foundation, remove 40 centimeters of the top layer of soil.
• Pump out moisture, if it has formed, remove excess water from the area.
• Remove the soil (to the depth calculated earlier). If the pit is deeper than 125 centimeters, special support beams are installed to prevent the earth from sliding along the walls.
• They arrange steps in the pit if the soil depth is approximately 500 centimeters (it is better to entrust the calculation of the step depth to an experienced specialist).

Calculation

First of all, calculations are performed to determine the parameters of the width and length of the foundation, which depend primarily on the dimensions of the future object. At the same stage, the depth of the trench for a strip or other type of foundation and the level of the base are specified.

In such actions, one requirement is met - the length and width of the foundation for a house or other object must exceed the corresponding dimensions of the structure by forty centimeters in order to finish the facade. It turns out. That each side increases by twenty centimeters.

It has already been noted that the dimensions of the pit also depend on its depth. In the process of digging a foundation pit, the walls must have slopes.

The zero cycle looks like this: the dimensional values ​​of the pit of a private house must correspond to the same parameters of the object, increased by the depth value.

To clarify the area of ​​the reinforced concrete base, the installed load is divided by the soil value and the permitted load.

Why do you need to clean the bottom?

Cleaning the bottom of the pit is necessary to level the earthen surface to create a flat and solid platform on which the foundation structures will be placed. At this stage, elevation differences in the earthen foundation and places of excessively loose soil, where deep subsidence of the soil is possible during compaction, are eliminated.

Mechanized excavation by earthmoving machines is constantly monitored by levels. When 100 - 200 mm remains to the design mark, soil excavation by machinery is stopped. Subsequently, the foundation is prepared by reworking the soil and cleaning the bottom to the design mark, manually or mechanized with the use of special construction equipment.

What technologies can be used to produce?

Cleaning of the excavation pit is carried out manually or mechanized: with bulldozers, levelers, excavators or scraper machines. The choice of method for planning the bottom of the excavation depends on the following factors:

Dimensions of the pit and the volume of the proposed excavation. In small areas with a small amount of uncollected soil, it is best to use manual cleaning. In this case, they begin to finish cleaning the base along one of the main axes, gradually moving along the pit

During work, it is important to focus on the control mark marked on the wooden peg. For the simplest control of stripping the base to the design horizon, it is recommended to stretch a steel wire or a strong polyester thread between two opposite pegs. Using a construction tape measure, measure the stripping depth every 1–2 meters.

In this way, the bottom is cleaned manually by one person. When performing work by two or three workers, the site is divided into equal adjacent areas and the base is cleaned layer by layer. For large areas and significant volumes of excavation of uncollected soil, it is recommended to use a mechanized method for completing the earth masses.

The tightness of the pit. If the horizontal platform of the earthen foundation of a building is located on a complex terrain, is in contact with other buildings, structures or particularly valuable architectural monuments, cleaning is carried out exclusively by hand.

Soil category. On soft soils, the leveling of the earthen foundation is carried out using bulldozers and mini-bulldozers. During the work, the bulldozer moves from the extreme slope in a spiral, moving towards the center line of the excavation from the earthen slope. The movement of the mechanism is forward-shuttle, with alternating working forward and reverse idle. Type of foundation and depth of its foundation. If the project provides for the installation of a monolithic slab foundation placed over the entire area of ​​the pit, a mechanized method of leveling with a bulldozer or a light excavator with a straight shovel is excellent for clearing it. Wide trenches prepared for strip foundations are cleared manually or with an excavator, constantly monitoring the level of soil cutting to the design level marks. Excavations for columnar foundations are usually cleared manually; the mechanized method is practically not used.

Basic layout options

All necessary dimensions for calculating work on the preparation of holes, trenches and embankments are established in the course of simple steps. To simplify the calculation, the volume of the future pit is divided into separate sections of standard length from 100 to 200 m.

First, the cubic capacity of the soil is determined for each site, and then the results are added up . Next, a methodology for carrying out the work is adopted, taking into account the need to remove or store the earth at the site for backfilling. The following formulas and calculation algorithms are most often used.

Calculation formula for a polygon with slopes

For this configuration of pits, the upper F1 and lower F2 areas are first determined, dividing them into several regular figures. Taking into account the indicators of the excavation depth H, the middle line is found and the average area F of the excavation is determined on it.

The total volume of the excavation with the polygon configuration and slopes is determined using the following calculation formula:

Vboiler = N/6*(F1 + F2 + 4Fmedium), where:

F1/F2/Fcp - top, bottom and middle of the excavation area m2.

To correctly determine the volume, you will also need to add the cubic capacity of the entry/exit trench routes:

Vtotal = Vcat. + nVexit + nVentrance, where:

1. Vcat. — net volume of excavation only, m3;
2. Ventry/Vexit — volume of entry/exit routes, m3;
3. n is the number of entry/exit routes.

From the total volume of the excavation, the cubic capacity of the cut vegetation cover is determined, which is usually done with a bulldozer, and the cubic capacity of removing the shortfall at the bottom of the excavation, developed by an excavator, so as not to disturb the integrity and strength of the soil at the base of the foundation.

With vertical walls on a flat area

The simplest method is excavation on a flat/planned area , shaped like a rectangle with vertical walls of equal size.

In this case, the formula by which the calculation must be made will look like:

V = L x B x H, where:

1. V—volume value, m3;
2. F - area size, m2;
3. B—width indicator, m;
4. H—actual height, m;
5. L is the length of the section, m.

For example, to excavate a simple rectangular section with dimensions:

• B =10 m;
• L = 6 m;
• H =2 m;
• volume of excavation (V) = 320 m3;
• plan area (F) = 160 m2;

The calculation will look like this:

• V = 10 x 16 x 2 = 320 m3;
• F = L x B = 10 x 16 = 160 m2.

With vertical walls having different vertex marks

Very often, when developing a pit, its corners have different levels, as a result of which a special formula has to be used.

For example, if the pit has a regular rectangular shape with 4 different vertices:

1. B =5 m;
2. L=10 m;
3. H1=2 m;
4. H2=3 m;
5. H3= 2 m;
6. H4 =4 m.
7. Volume of excavation work: (V) = 137.5 m3.
8. Area (F) = 50 m2.

We calculate:

V = B x L x ( H1 + H2 + H3 + H4 )/4 = 5 x 10 x ( 2 + 3 + 2 + 4 )/4 = 137.5 m3.;

F = B x L = 5 x 10 = 50 m2.

With slopes on planned terrain

The dimensions of width B main and length L main at the base are determined by the dimensions of the structure, taking into account the gap between it and the bottom of the slope of more than 3 m. The dimensions at the top of the pit are calculated taking into account the steepness of the slopes. It depends on the slope coefficient.

This indicator can be calculated by dividing the height of the excavation to the slope, the formula looks like this:

m = H/Wotk.

For example, for a notch having the characteristics:

• Width at the base of the excavation (Bosn), 4 m;
• length of the excavation base (Lobas), 6 m;
• height (H), 2 m;
• selected soil: loam;
• coefficient m = 0.5.

1. Bup = H * m + Bosn + H * m = 2 * 0.5 + 4 + 2 * 0.5 = 6 m.
2. V = (Bon + Bup) / 2 * H * Lbasn = (4 + 6) / 2 * 2 * 6 = 60 m3.
3. The volume of the trench will be equal to (V) = 60 m3.
4. F = (Bottom + Top) / 2 x H = (4 + 6) / 2 x 2 = 10 m2.
5. Sectional area: (F) = 10 m2.

Similarly, for a square-shaped recess, the formula will look like:

Vк = H /3 x (Fbasic + Ftop) + (Fbasic x Ftop) x 0.5).

For a pit with a polygon configuration:

Vк = H /6 x ( Fbas + Ftop + 4 Fav ), where Fav is the cross-sectional area at the average height, m2.

These formulas can be used to determine the volume of not wide excavations less than 15 m . They will be able to go deeper with a dragline, which will be located on the surface of the earth.

If the width is large, soil operations are performed with an excavator at the bottom, with the “straight shovel” option; in this case, the volume for arranging the entrances must be added to the cubic capacity of the excavation.

A pit with a circular cross-section and slopes

For pits with a circular cross-section with slopes, the cubic capacity of the excavation is calculated using the formula for an inverted truncated cone.

In a truncated cone, R and r are the upper and lower radii, respectively.

For example, for a round well with slopes:

• Width of the lower base D1=2r, 3 m;
• upper diameter D2= 2R, 5 m;
• pit height (H), 3 m;

Formula for calculating volume:

V = 3.14 x ( (D1 + D2) / 2 )2 / 4 * H = 3.14 x ( (3 + 5) / 2 )2 / 4 x 3 = 37.699 m3

The volume of the pit will be equal to: V = 37.699 m3

Pits for objects that have both cylindrical and conical parts, for example, settling tanks and digesters, are usually built in groups. They are dug into the ground in 2 stages:

1. first, a general rectangular recess is organized up to the installation mark of the cylindrical components;
2. Afterwards, a recess is made for the conical elements, therefore, the calculation of the volume of soil sampling is carried out in 2 stages.

Features of constructing a pit for a slab foundation

To construct a pit intended for the construction of a slab foundation, a rectangular hole is dug. The dimensions of the pit correspond to the overall parameters of the façade of the building. This rule is relevant when constructing shallow foundations. In other cases, the dimensions of the pit increase.

Work procedure:

1. A layer of fertile soil is removed from the surface to a depth of 30 cm. This soil can be effectively used in the future. In the future, sprouted plants can destroy the concrete foundation.
2. Marks corresponding to the dimensions of the slab plus its height are applied to a flat and clean surface.
3. Along the marked boundaries, the first excavation of soil is carried out to a depth of 0.5 m. This must be done from the center of the pit, gradually moving to the edges.
4. After excavating the first layer, they move on to the second, retreating 0.25 m from the previous boundaries on each side. Step depth 0.5 m.
5. Work continues until the bottom of the foundation slab is reached.

Calculation errors and solutions

Correctly calculating soil volumes is quite labor-intensive and complex work, since many factors must be taken into account.

If the designer makes even the smallest mistake, the entire process of preparing the pit will go wrong, with a violation of technology and an overestimation of construction costs. An improperly prepared pit can lead to disruptions during the construction of the foundation, and therefore pose a danger to the reliability of the facility.

When performing calculations, specialists are guided by the technological map, in compliance with the following construction standards:

1. The cubic capacity of the land is established according to design materials, taking into account the classification of soil by type and group.
2. The location of moist soils is taken into account. These include layers located below the groundwater level and above. For example, for coarse and fine sands 0.3 m higher, for sandy loams by 0.5 m, clays and loess soils by 1.0 m.
3. The groundwater level is established using the well with the highest elevation.
4. In order to correctly determine the volume of excavation development, it is recommended to first draw up a diagram with the dimensions of the plan and sections of the excavations.
5. If the amount of cutting of plant soil is calculated separately, the depth of the excavation is reduced by the thickness of the cutting layer.

For life support objects, modern calculations of soil volume are performed on the basis of geodetic surveys with a total station and calculated using the AutoCad Civil 3d software package, which is capable of providing high accuracy calculations.

In order to perform accurate calculations, you will need to go through the following steps:

1. 
   Accurately carry out topographic survey of the initial configuration.

2. Formation of a digital model of the territory and the designed pit.
3. Cartogram calculation.
4. Passing the desk stage. At the same time, engineers using licensed software process data and draw up technical documentation.
5. The design axes of the object are carried out and the parameters of the slopes are set.
6. Temporary access roads are being constructed.
7. Determine the layout of soil in dumps.
8. Control of pit height marks.

Video description

The construction of a pit for a slab foundation is described in the following video:

Additional work during excavation: artificial foundations and compaction. backfilling

Soil that has not been dug to the required level with an excavator is simply removed with your own hands, but in case of digging, an artificial foundation (cushion) is required.

We arrange the cushion from incompressible soils: pour construction sand, crushed stone, sand and gravel mixture to the required height in layers of 25-30 cm, compacting it with a tamper or spilling it with water.

Advice

. To check the quality of crushed stone compaction, you can lay another piece on the compacted layer and tamp it again. If the compaction is sufficient, the stone will collapse, if not, it will be pressed in.

Backfill compaction

You can strengthen the surface of the bottom of pits and trenches by pouring a thin layer of crushed stone and “driving” it into the ground with a tamper.

For backfilling, after installation of structures, we use loam and sandy loam, compacting them layer by layer. In this case (as a rule) no water spilling is carried out.

Choosing the time of year to dig a pit or trench

Experts recommend planning the development of soil for the foundation in the summer or autumn. At this time, the soil is as soft as possible and lends itself to digging.

In winter, foundation construction is impossible due to frozen soil. If you plan work for a given period, their cost increases several times. Also, constructing a trench or pit in winter becomes more difficult due to the need to complete the laying of foundation blocks or pouring a monolithic structure as soon as possible. They should not freeze, which will negatively affect their load-bearing capacity.

Also in winter, it is important to immediately provide for the process of removing excess soil. Otherwise it will freeze and it will be very difficult to remove it.

Slope fastening technology

Fastening pit slopes
Collapse of pit walls can be caused by various factors: precipitation, low density and high soil moisture, vibration. To prevent collapse, the walls of the pits are strengthened. The method depends on the excavation depth and geodetic data of the site. The walls are fenced around the perimeter with the following materials:

• pipes;
• tongue and groove of various types (Larsen, flat);
• piles;
• rolled metal;
• reinforced concrete structures.

Sheet piling is more economical than constructing a concrete structure. Metal fencing is quicker to construct and can be dismantled and reused. A common option is to install pipes. They are hammered around the perimeter with a diesel hammer or a hydraulic hammer installation.

When strengthening pits with pipes, if necessary, they are filled with boards (so that the soil does not spill out). When using lumber, fewer metal products are required; part of the walls is covered with boards. In narrow trenches, the sheet pile is strengthened with spacers. Larsen sheet pile creates an airtight barrier and is recommended when there is a threat of groundwater flooding.

For small houses or outbuildings that require a shallow foundation, you can build a trench yourself. Buildings with several floors and a basement require complex calculations and large-scale work at the stage of soil development. It is better to contact specialists who know how to dig pits correctly.

Video description

The features of excavation work in winter are described in detail in the following video:

It is also undesirable to dig a foundation in the spring. During this period, the soil is oversaturated with moisture from melted snow, and the groundwater level rises significantly. To cope with this problem, it is necessary to additionally use equipment to pump out the liquid.

It is also not recommended to start excavation work in late autumn. At this time, regular frosts are observed, which leads to freezing of the top layer of soil.

Marking and reference to terrain

We determined what needs to be done and how to excavate the soil, with what mechanisms and tools. Now let’s determine where to do the work: dig a trench, holes or a foundation pit.

To do this you will need wooden pegs, a hammer and a tape measure at least 30 meters long.

Two people need to take measurements. First, we mark all the axes of the future building with paired pegs, then, using them as a basis, we mark the edges of the soil sampling sites.

Advice

. The exact lines of the edges of the excavation pit for the excavator can be marked by filling them with light sand

The depth of the pit is measured in one of two ways:

• from the existing ground level;
• from a point (benchmark) with known coordinates and height.

The first method has a significant error and is suitable for simple structures that do not use existing or planned communications and (or) structures.

The second method is used for structures where precise height reference is needed to calculate the slopes of sewerage systems, calculate connections to existing structures, utility networks, etc.

The depth is constantly monitored during soil development: first roughly, using a rod or tape measure, and when approaching the mark, precisely, using a level.

Important

! Make the axes stand out further from the pit to avoid damage: drive a “U” shaped structure of two stakes and a board into the ground, two pieces for each axis. Mark the axis line using a nail that is not driven in completely. By pulling the thread, you will always receive a standard for breaking down and controlling the work.

Briefly about the main thing

Before digging a trench or pit to construct a foundation, you must first perform all the calculations. Their parameters depend on the characteristics of the soil, the depth of soil freezing and the level of load from the load-bearing structures of the building.

To carry out excavation work, you can use an excavator or dig everything by hand. The choice of method depends on the volume of soil excavation, the need to load it for further removal and other nuances.

When constructing a pit for a foundation slab, soil development is carried out in stages. The soil is dug out layer by layer, taking into account recommendations for strengthening the walls.

Types of pits

Having decided to start constructing a trench for the foundation, you should clearly understand what type of pit is needed. This condition depends on the type of foundation structure specified for pouring by the design plan and drawings.

There are certain parameters according to which foundation pits are divided into several categories related to the presence or absence of the following conditions:

• slopes and their quantity;
• corner fastenings;
• vertically inclined walls.

There is one more condition that determines what the hole for the foundation is called - a pit or a trench.

To install a strip foundation, a trench is dug around the entire perimeter and at the locations where the internal load-bearing walls are installed. When pouring a foundation slab, the minimum dimensions of the pit must correspond to the area of ​​the building under construction.

If someone does not know how to dig a foundation for a house with their own hands, here is a list of priority excavation work:

• the type of soil composition is determined and its examination is carried out;
• the technical parameters of the structure are clarified in order to determine the maximum load on the base;

• the depth of a pit or trench is calculated;
• The climatic conditions of the region are being clarified to identify seasonal soil movements.

Features of the pit device

Digging a pit with an excavator

Few people know that a feature of dug soil is that it increases its volume by 30-40%. In this regard, when digging a pit with an excavator, it is necessary to organize uninterrupted work to remove excess soil, and also leave a certain part for filling the constructed foundation.

As for the shape and size of the pit, these indicators are directly dependent on the type of foundation chosen. So, in the case of making a slab foundation, you should equip a recess with a clear rectangular shape. When making a foundation using strip technology, it is necessary to construct a foundation pit in the form of a trench, and in the case of constructing a columnar foundation, in the form of pits or wells.

Depth

The height of the future pit is calculated based on two important quality indicators of the soil: the freezing level and the groundwater boundary. An important point when arranging the foundation is the location of the foundation 40-50 cm below the identified soil freezing line.

The groundwater boundary must be at a distance of at least 50 cm from the foundation being developed. Otherwise, you will need to carry out additional work to install foundation waterproofing and a drainage system to drain excess water, which will significantly complicate construction and increase costs.

Side dimensions

When digging a pit, it is important to take into account that its length and width depend on the size of the future structure and the depth of the foundation being built. Everything is simple with the dimensions of the building - the length and width of the base must exceed the declared parameters of the structure being built by 40-50 cm, 20-25 cm on each side

This distance is necessary for the subsequent placement of the facing layer, which must also be supported and not suspended.

In accordance with safety regulations, it is necessary to pay attention to making a pit in the shape of an inverted trapezoid, the slopes of which will subsequently be protected from unintentional shedding or sliding of the soil. The lower point of the slope of the pit is considered to be a base increased by 40-50 cm, and to calculate the upper one, it is necessary to measure a segment equal to the depth of the foundation in the opposite direction from the house at the zero ground level

The end result should be an isosceles triangle with two internal angles of 45º

The lower point of the slope of the pit is considered to be a base increased by 40-50 cm, and to calculate the upper one, it is necessary to measure a segment equal to the depth of the foundation in the opposite direction from the house at zero ground level. The end result should be an isosceles triangle with two internal angles of 45º.

Digging features for different types of foundations

There are certain requirements for foundation pits for buildings. They must comply with the size and load of the house, building codes, and not change the established parameters and shape. To complete the last point, you must follow the digging technology. According to the standards, the size of the steps and the slope angle are selected, and the walls of the pit are fastened. Features of the development depend on the type of foundation of the house.

Tape

The foundation pit for the strip foundation is dug in the form of a trench. The design of slopes depends on the type of soil. On clay soil, the formation of vertical walls is allowed. In deep trenches with wet or sandy-gravel soil, slopes are arranged with different inclination angles - from 45 to 63°. When calculating the width, the need to install formwork holding reinforced concrete is taken into account. An additional 50 cm is allowed; the maximum size is not standardized.

Pegs are driven in at the corners of the perimeter of the house and at the intersection of the internal walls and markings are made. The width of the trench is indicated by two parallel lines. Excavation begins from the highest angle, following the outlined perimeter line. During the digging process, the depth is controlled by milestones.

If necessary, a tape trench is secured against shedding from wooden panels, boards, and slate. Spacers are installed between opposite edges for reliability. After the foundation hardens, the shields are dismantled. Part of the soil is not removed, but is left for backfilling. It is better to use sand. After digging, the bottom of the trench is compacted under the backfill.

Monolithic

Soil compaction with a vibrating plate.
Due to the large volume of excavation work, a foundation pit for a house with a monolithic slab foundation is dug using an excavator. If the depth is 40-50 cm, then you can dig manually. The soil is removed in parts, each layer is 50 cm, gradually forming steps of 25 cm in size. The soil is removed starting from the center. Then the site is leveled and the next layer is started.

Drainage pipes are laid along the perimeter of the pit, below the general level. This is a necessary measure for wet soils. Development is carried out taking into account the characteristics of the soil:

• The sand compacts well and holds the load, but crumbles when digging. It will be necessary to form slopes and strengthen the side walls.
• Clay and loam swell in winter as a result of freezing moisture. A competent calculation is required when arranging a slab foundation on such soil.

After the technician’s work, the bottom is leveled manually. Often it is necessary to carry out additional excavation of soil in a layer of up to 10 cm. After leveling the bottom, backfill with clean sand. The layer is spilled with water and compacted.

Columnar

A hole for a columnar foundation
You can dig the ground for a columnar foundation yourself. The work begins with clearing the site from the top layer of soil and marking the ground. You will need to draw a diagram of the perimeter of the house, in the form of two parallel cords. Places for holes for poles are marked in corners and on spans in increments of 1.6-2.5 m.

To do the work manually you will need:

• shovels (bayonet and shovel);
• pickaxe or crowbar;
• wheelbarrow for removing soil.

Pits up to 1 m deep can be dug with vertical walls; as the depth increases, slopes are built so that the soil does not crumble. The width of the pits is 20-40 cm larger than the size of the pillars in each direction. This distance is necessary for installing the formwork. Depth is calculated according to general rules.

How to calculate the cost of constructing a pit?

When constructing pits, building materials are practically not used. Accordingly, costs will be completely determined by the amount of payment for work and rental of special equipment, if it is used. It all depends on the area, since the construction market in each region has its own prices. In addition, there may be various factors specific to a particular one, which can affect the cost of work towards higher prices. This:

• Difficult landscape. If the site is located in a forest, there will be costs associated with clearing it of trees and root systems. If the area is swampy, land reclamation will have to be carried out, and this also requires serious expenses.
• The characteristics of the soil often make the construction of a pit more labor-intensive and, therefore, more expensive. So, when working on sandy soils, be sure to specially secure the walls when digging a pit. Groundwater, the horizon of which is too close to the surface, also complicates and increases the cost of work.
• The main factor determining the cost of work is the size of the pit and its type
• The total amount of expenses is influenced by the costs of delivering a team of hired workers, as well as rented equipment and special equipment to the location of the event.

Arranging a foundation pit, despite its apparent simplicity, is a very important stage of the entire construction. The size of subsequent expenses largely depends on its quality and accuracy of execution.

When and how to dig a pit

There are only two suitable times of year for this:

• autumn;
• summer.

Of course, everything depends on the climate, but in winter the soil freezes too much and it is difficult to work. In the spring, the soil begins to thaw, and excess water will have to be disposed of during the process. All this is possible, but a little expensive. You will have to exceed the original estimate by about double.

Ideal weather for this type of work: dry, sunny, warm. Light rain can be ignored, but a prolonged downpour lasting several weeks is worth taking into account and postponing trench digging.

You can prepare the excavation for the foundation yourself or use the services of specialists or rent equipment. In any case, the correctness of execution is verified against the standards of the “Building Codes and Rules” governing construction. Compliance with them will save you from further problems, both with the house itself and with local authorities, since violations become the object of their close attention.

Calculator for calculating the pit and the volume of excavation work

Enter the dimensions in m:

Instructions for the pit excavation calculator

We present to you an online calculator that calculates and determines the volume of excavation work for a pit.

All parameters are indicated in meters

The whole process includes digging a pit for the foundation of a house, sewer system for a cottage, a reservoir or swimming pool, water supply or drainage for a villa.

During preparation and production, the main stage is the correct assessment of the amount of excavated soil.

Design and cost of earthworks

A full assessment will consist of digging a hole and removing the volume of soil removed. It is recommended to carefully plan where the fertile layers of soil will be moved, which can be used for a personal plot. Infertile soil can be used to fill the foundation, plan a garden, vegetable garden, or simply take it outside. You should find in advance the places where the excavated or waste soil will be transported.

Important! During the digging process, the price per 1 m³ of soil may increase with increasing trench depth. Thus, the cost from the surface of the earth up to 1 meter deep, and deeper often doubles

Soil removal is often an additional expense. In order to avoid unforeseen waste, all stages and their costs should be discussed in advance with the contractor.

Before installing the formwork for pouring the foundation, it is necessary to take into account the size of the pit.

Call a technician or dig it yourself?

Before deciding which way to dig a hole, let's consider the advantages and disadvantages of each method.

If the process is carried out manually, then you will get a neat and precisely sized hole.

If the volumes of land are relatively small and with available labor, then the final price of manual work will be much cheaper than when renting special equipment or an excavator. This method also makes it easier to control the geometry and parameters of the future trench for the foundation.

If you plan to dig up a large volume of soil, then in terms of productivity and in order to save time, it would be preferable to order an excavator. But in any case, the choice is yours.

First, we carry out markings for the future foundation pit. The best way to do this is to use pegs that need to be stuck around the perimeter of the area and connected with a thin colored cord, marking the location of the work. To control the geometry of the future pit, it will be necessary to measure two diagonals, which must coincide.

This method is not professional and is best suited for relatively flat plots of land.

If you need a more accurate marking of the planned excavation work, then it is best to use the following method.

At a short distance from the pit, you will need to dig in wooden posts or metal rods in groups of 2 pieces (castoffs). On these posts the boards will be fixed in a horizontal position, onto which we pull the cords. Try to fix the boards relative to each other at the same level.

By moving the cords, you can achieve perfect markings. The remaining cast-offs can be used when installing the formwork under the strip foundation.

If you have a laser level, theodolite, or level, they will make your work much easier.

Perform geometry control

To get an exact angle of 90° we use a tricky method. We take a triangle whose sides have a ratio of 3:4:5 meters with one angle of 90°. On one side we set aside 3 meters from the corner, and on the other side 4 meters, while the distance between these points should be 5 meters.

If you plan to go very deep or there is weak soil in the work area, then first of all it is necessary to ensure safety. It is best to make the trench walls with a slight slope, which will prevent the soil from collapsing.

To control the bottom and walls, you can use a level and slats of sufficient length.

How to correctly mark a pit for digging a plinth

Having chosen the exact location for the foundation pit of the future house and departing the required distances from the neighbor’s fence (3 m), the “red line” (5 m), we proceed to marking the digging site. To do this, all work is divided into a number of sequential steps.

1. The outer corners of the foundation and the axes are set out using temporary wooden pegs. Don’t forget to check the geometry of the foundation and check its diagonals.

2. We make a 2-meter extension of the external corners with reinforcement pegs, about 0.5 m long, driving it into the ground. To see these places, we put plastic bottles with the neck down on the fittings.

Important: The pit is dug wider than the foundation, at least 1 m in each direction . This is necessary so that it is convenient for builders to work in the pit - installing formwork, insulating the basement, etc.

vehcy FORUMHOUSE user

They dug a crooked pit for me, and the meter was not maintained everywhere from the base wall to the ground. There is only 40 cm left in one place. I will say that when working in such a cramped “nook”, it is very difficult to properly waterproof and insulate the basement walls.

3. Find the “horizon”. To do this, stakes (posts) about 2 m high are driven into the corners of the site, approximately 1 m from the fence, so that you can freely stand behind the stake. The stakes should not be shaken by the wind. At a height of about 1500 mm, a planed board with a section of 5x50 cm, painted with white paint, is nailed horizontally to one post. Now you need to either hire specialists with a level to “shoot the horizon”, or do it yourself, using, for example, a laser level, and a receiver or “old-fashioned” - a long hydraulic level. The point is that the nailed board is a reference point, then 3 more marker boards are nailed along it to the remaining pillars according to the level. Those. Regardless of the unevenness of the site, we need to obtain a virtual horizontal plane from which we can read and control the depth of digging the pit.

4. The so-called "visor".

chichic

Where the corner of the house is (preferably the one higher than the others), we temporarily drive in a stick about 2 meters high. We go behind one of the pillars and look at the “horizon” from our mark to the opposite one. An assistant on your command (higher or lower) nails a horizontal plank onto a stick. Three tablets: the one from which you are looking; the one on the opposite side and the one on the stick at the corner of the house should be on the same horizontal line. We approach this stick and measure the distance to the ground. For example, it turned out to be 1.5 m. That is. we found the distance from the “horizon” line to the ground. We remove the stick. Next, we calculate the distance from the ground to the bottom of the pit. For example, taking into account all the layers (crushed stone, concrete base, etc.) and the concrete base, the result is 2 m. We add 1.5 + 2 = 3.5 m.

Now let’s take a block 3.5 m long, if there is no such thing, knock it out of two and, having measured the distance of 3.5 m on it, nail it perpendicular to a 5x50 cm board. The sight is ready. Now, when digging a pit, an assistant lowers the sight to the bottom of the pit. The developer, “aiming” from one mark to another, sees a dug or underdig and “talks” about this with gestures to the excavator operator, i.e. either dig deeper or take higher.

Measurements should be taken every 1.5-2 meters to prevent digging and loosening of hard, compacted continental soil. It is also necessary to prepare a ladder in advance so that the assistant can go down into the pit. Soil loosened with a bucket should not be left at the bottom of the pit. It must be carefully cut with shovels and removed. Digging the base of a pit of 10-15 centimeters or more automatically leads to an increase in the cost of the entire estimate. Because instead of the same height of the plinth (planned according to the project), it will have to be increased to compensate for the difference, and this will be additional costs for building materials.

For clarity, we present a pit marking diagram, top view.

• The blue rectangle is the outer contour of the foundation base.
• Black dots are temporary pegs. To check diagonals and axes.
• Green lines are diagonals.
• The blue line is the dimensions of the pit along the base of the foundation with an indentation of + 1 m.
• The purple dots are a guideline for the excavator operator to follow when digging a pit.
• The yellow line is the outer contour of the pit, dug taking into account the “collapse prism”.
• Red dots are permanent extensions of the foundation axes. Pegs with plastic bottles.

Important: to mark the perimeter of the foundation for the excavator operator, i.e. visual boundaries along which you need to dig, instead of driving a series of pegs or stretching a fishing line between them (purple dots in the figure above), it will still be torn by a bucket, you can do the following. We stretch the lace and scatter along it (this straight line), for example, alabaster, sand, i.e. we make a white or yellow path. Or we take a can of white paint and spray the aerosol directly on the ground, drawing a line along the lace. Then the rope is removed, and a drawn perimeter of the foundation remains on the ground, clearly visible to the excavator operator.

Important: the excavator is located at a distance from the pit, taking into account the so-called "collapse prisms". This is a volume of soil (slope) that is located at the edge of the pit and is prone to sliding when the frictional forces that hold the soil from shifting are exceeded.

Thus, the walls of the pit (depending on the type of soil and the depth of the excavation) are not dug strictly vertically, but at a certain angle. The excavator should also not stand on the edge of the pit, because... there is a possibility that the slope, due to the mass of the equipment, will collapse down along with it.

The standards for slope steepness are prescribed in SNiP 12-03-99. For a “cheat sheet”, you can use the data from the following table.

If there are several types of soil at the excavation site, then the steepness of the slope is selected according to the weakest type of soil. If the pit depth is more than 5 m, a set of measures should be taken to strengthen the soil - erection of retaining walls, etc.

Planning our possibilities

Do not leave the pit until next year - this may reduce its strength

Before starting any construction, it is necessary to carefully plan the entire course of work. To do this, you need to know how to carry out the work correctly and in what sequence. The most common mistake is soaking the pit or installing a strip foundation without a house.

Sometimes, a foundation pit is dug ahead of time, and the construction of the foundation itself is postponed until next year. This is usually done to save time, so that you can start pouring the foundation in early spring into a dug trench, without waiting for the soil to completely thaw. Such actions can lead to a decrease in the strength and load-bearing characteristics of the foundation. The full cycle of work on installing a strip foundation, from digging a trench to backfilling, should be completed in one season as quickly as possible. To learn how to prepare a foundation pit, watch this video:

Sometimes there are situations in which, after installing a concrete foundation, construction is frozen for several years. If the object is properly preserved, losses will be minimal.

But more often, due to improper preservation, the foundation rises as a result of frost heaving of the soil.

When designing, the mass of the entire house is taken into account, so the lightness of the concrete base is not designed for heaving forces. In such a situation, physical damage to the foundation is quite likely.

When planning to build a house, calculate your strengths and capabilities.

When starting to implement the question of how to dig a foundation manually, you need to be sure that the construction work on at least the first floor of the building will be completed this season.

Preparatory process

At first glance, it may seem that digging a foundation pit is not difficult. However, in order to complete all the work correctly, it is necessary to carry out a number of additional actions:

Preparing the soil for digging a pit

• Soil analysis allows you to determine its condition at the planned construction site.
• Assessing the future structure helps to study the dimensions of the house, its planned weight and the expected load on the soil.
• Study of climate in the region and seasonal ground movements.

The results obtained will help you choose the optimal type of foundation to determine the parameters of the future pit.

Preparatory activities

Preparing the site for digging a pit

Development of a foundation pit includes the following steps:

• drawing up diagrams and drawings of excavation work on the site (qualitative analysis of the soil for its composition and density, determining the level of groundwater);
• clearing the area for construction from old communications, buildings, debris and other obstacles (in the case of existing communication systems, it is necessary to coordinate their relocation);
• performing geo-survey of the site and marking.

Having finished carrying out these types of work, you can begin to directly dig the pit. The presented construction procedure is carried out both manually and through the use of special equipment.

Of course, the first method will significantly save money, but it greatly affects the installation time. Fast shipment, removal of excess soil, combined with high-quality soil leveling, significantly simplify the procedure for preparing a pit, so it is most rational not to skimp on this issue and use the services of special equipment.

Prices for development and device services

When preparing estimates, they take into account the type and characteristics of the planned construction project, as well as the size of the foundation and clarify the question of whether the foundation pit will be placed on the entire site or only on its individual sections.

In addition, when drawing up estimates, the following are taken into account:

1. The method of carrying out the work is manual or mechanical.
2. Types of mechanisms and machines used.
3. Land movement plan and transportation distance.
4. Stage of securing the walls.
5. Presence of groundwater and location of surface water bodies.
6. Soil parameters.

An example of an estimate can be downloaded here.

Approximate cost for development, backfilling, removal:

An example of calculating prices for excavation:

• Excavation perimeter, 52 m.
• Excavation area, 160 m2.
• Excavation depth, 3 m.
• The ratio of depth to slope length is 1:2.
• The cost of digging is 200 rubles per cubic meter (1 m3).
• Transportation cost, 450 rub./m3.
• Soil sampling volume, 948.00 m3.
• Cost of work. 189600 rub.
• The cost of transporting soil is 426,600 rubles.

Execution of work on the construction of pits

This process is divided into certain stages:

• on the site allocated for the construction of the building, a check is carried out for the passage of communication lines, the diagrams of which can be clarified with local administrative authorities. If such systems are available, you will have to obtain written approval for the procedure for performing excavation work from the organizations servicing this site;
• a site is being prepared for the construction of a private house or other structure, the fertile composition of the soil is removed to a depth of forty centimeters;

• water is pumped out and a drainage ditch is installed;
• Excavation work is being carried out. If the depth of the pit for a monolithic or other foundation exceeds 1.25 m, support beams are installed to prevent the soil from crumbling, and steps are arranged.

Under strip foundation

If you have to build a foundation pit for a strip foundation for a garage or other building, it looks like a buried trench, its dimensions allowing for the installation of formwork panels.

The dimensions are determined as follows: the length and width parameters increase by thirty to forty centimeters, the width of the trench is equal to the sum of the same value of the walls and a gap of fifty centimeters for the installation of shields.

First, the boundaries of the future foundation on the ground surface are determined, and the highest angle is determined. After this, you are allowed to dig using a shovel or tractor and periodically checking the depth with stakes.

The soil is poured nearby so that there is something to cover the backfill and drainage system.

Slab

Step-by-step instructions for installing such a foundation in a rammed pit are as follows:

with a slight recess, the dimensions correspond to the façade parameters of the object. If a slab foundation with insulation to a great depth is to be poured, sum up the dimensions of the load-bearing walls of the building and the height of the foundation;

the soil is developed gradually, in the first layers of fifty centimeters with a gradual decrease in their thickness. As a result, steps are formed on the walls. By the way, if someone doesn’t know how to dig a foundation on a slope, use this technology.

This type of foundation is convenient to pour for standard buildings - a house 8 by 8 or a house 10 by 10 m. It is an ideal solution for the construction of three-story buildings; it is a solid reinforced concrete structure that has almost no shrinkage and is not afraid of heaving of the soil composition.

For strip base

The most common type of foundation is strip foundation. It consists of an iron frame installed along the load-bearing walls and filled with concrete. This design is not very expensive compared to others, and at the same time is almost universal for all types of terrain (except for those where groundwater is too close to the surface).

Such a foundation could be:

• shallow - 0.5-1.5 meters;

• recessed - from 1.5 meters.

Accordingly, the dimensions of the pit, as well as its appearance and operating procedure, depend on the specific type of strip base, which will be discussed in detail below. But we will not ignore others: slab and columnar.

What are the advantages and disadvantages

A monolithic strip of concrete, on which the load-bearing walls of the building are then laid - this is a strip foundation.

Such a base can be installed on various types of soil. The exception would be, perhaps, peat and unstable clay soils. Buildings of any weight are erected on the foundation, adjusting the width and height of the trench. The base is recommended for use in the following cases:

1. When constructing residential buildings and utility structures from materials whose total mass will be impressive. For example, load-bearing walls made of slag concrete, concrete, brick, etc.
2. During the construction of basement buildings, with a basement floor, and an underground garage.
3. When a house with heavy floors, several floors or an attic is being built.
4. Strip foundations are indispensable in those regions and areas where the soil generally has a heterogeneous structure.

Let's get acquainted with all the pros and cons of the tape structure. This will allow you to understand how the foundation will behave during further operation of the building.

Advantages

• The strip base can withstand the same loads as a foundation poured using a monolithic method.
• Preparatory work for pouring concrete is simple and is usually done on your own.
• When a strip foundation is built according to all the rules, it has a long service life. The rules imply making accurate calculations of the tape, using waterproofing, thermal insulation, laying a sand cushion, etc.
• Among the types of tape base, you can choose a variety that is suitable in terms of technological characteristics and finances.
• The tape foundation is cheaper than a monolithic base. In terms of strength qualities, it competes with a monolithic foundation.
• Thanks to the strip base and an insulating cushion made of several layers, it is possible to better thermally insulate the floors in your home.

Albeit a little, but there are also disadvantages :

• It cannot be installed on some types of soil. For example, do not use on weak and unstable clay soils.
• The technology for filling the tape with concrete involves pouring the entire thickness of the base in one go. It is difficult to make such an amount of concrete mortar yourself. We have to buy concrete from construction organizations.
• Although the preparatory work for pouring concrete is not complicated, it is labor-intensive and takes quite a lot of time. It is difficult to dig a trench alone and prepare it for filling with mortar. Helpers needed.

As you can see, the strip base has more advantages than disadvantages.