The foundation is one of the main elements of any structure. The service life of the entire structure depends on how reliable it is. This is especially important on unstable lands, in particular on heaving – mobile soils, which are considered dangerous both for the foundation and for the entire structure as a whole. Experts say that a strip monolithic foundation can cope with the loads.

Shallow strip foundation on heaving soils: features and advantages

This is the name of a structure made of a monolithic concrete strip reinforced with metal rods, made to fit all load-bearing walls around the perimeter of the building. Shallow strip foundation on heaving soils used for the construction of light structures, so its maximum height does not exceed 1.5 m.

The main advantages of a shallow foundation are:

1. Easy to do.
2. Low cost.
3. The ability to complete work without involving serious construction equipment.
4. Strength. The base can support the weight of small buildings - frame structures, houses, baths.
5. The ability to use available materials and apply the most appropriate technologies in work. For example, create a structure made of brick, concrete blocks, or make a monolithic base by filling prepared forms with concrete.
6. If necessary, it is possible to build an insulated semi-basement.

It has a shallow foundation for the house and its disadvantages. This is insufficient strength. But this problem can be solved: sand filling and drainage can be arranged. This reduces the load on the soil and, accordingly, increases the strength of the building foundation.

The disadvantages include the fact that it is impossible to build foundations for buildings on frozen ground. It is unacceptable to leave a shallow foundation unloaded during the winter. Because of this, it is necessary to speed up the work on pouring the structure and erecting walls.

Preparations for strip foundations and manual soil modification

The construction of a strip foundation begins with the preparation of the territory. It's about about geodetic breakdown. This process consists of several stages:

1. Cleaning the area. It is necessary to remove everything that will interfere with construction.
2. Finding the main landmarks. In geodesy, these are axes or lines, which will serve as a guide for the structure being built.
3. Performing geodetic work - correct calculation of angles. Each angle should be 90 degrees. Accurate adherence to this indicator will help to avoid skewing of the building, which can reduce its performance characteristics.
4. Completion geodetic works- marking using construction cords and pegs - they are only baited immediately, and not driven into the ground. After marking, you need to check everything again and only then securely secure the pegs and begin excavating the soil for the strip foundation.

Working with soil

Soil development is the preparation of a trench. The depth of the trench for the strip foundation depends on the material that will be used to build the structure, while the height of the part buried in the ground ranges from 50 to 70 cm.

You can dig a trench using an excavator. Especially if you have to work on heavy soils consisting of wet clay, it is very difficult to work with it manually. When performing delicate work, it is better to dig by hand, but if possible, it is advisable to dig the entire pit by hand: thanks to this, the soil will maintain its structure intact and the likelihood of a collapse will be reduced. In addition, a manually dug trench under a strip foundation comes out much neater, which greatly facilitates further work.

If you have to build a foundation on marshy soil, it is best to work in the fall or early summer, when the ground contains a minimum of moisture.

How deep should you dig if a new structure is being built on the site of an old one? The base of such a structure under construction must necessarily be 5-7% deeper than the base of the old building. If you have to level the surface of the earth in a problem area with unpredictable heterogeneous soil, a protective cushion is made. To do this, the prepared trench is covered with sand. The height of the sand cushion after compaction should be at least 30-40 cm - this will protect the structure from deformation.

Foundation on sandy soil It is little susceptible to heaving, since it practically does not retain moisture. Therefore, there is no need to equip a cushion of sand, but in order to ensure the strength of the foundation of the building, it is necessary to make a cushion of crushed stone at the bottom of the prepared pits.

Concrete preparation

This is the name of a layer made of crushed stone or “lean” concrete. It is laid under a shallow foundation. The main purpose of concrete preparation:

1. Prevent the loss of concrete milk.
2. Help achieve the desired concrete condition.
3. Distribute the load on the soil more evenly.
4. Facilitate the production of reinforcement base for the foundation.

Concrete preparation is made from cement grade M400 or M300.

How to build a strip base on clay?

The foundation of a house on clay soils can be built in three ways:

1. Completely fill the prepared trench with a sand and gravel cushion, the surface of which, after compaction, should be level with the ground. The main thing here is tamping. Each layer (15-20 cm thick) is watered and thoroughly compacted. Then a concrete base is made. If the soil is good and dense, this option is quite acceptable.
2. The next option for arranging the foundation of a house on clay soils involves filling sand and gravel only up to half the height of the trench. After this, a row of bricks is placed on top, formwork is made from edged boards impregnated with an antiseptic and covered with tar, the formwork is filled with concrete and then waterproofing is done from roofing felt.
3. Preparation for a strip foundation according to the third option is suitable if the soil is dense and moist. We dig a trench for the tape, make formwork from slate, fastening it overlapping, and fill it to the middle with sand, compact it, fill it with gravel, compact it again, and then pour concrete, each layer of which is 15-17 cm. To compact the solution, you need it compact until cement laitance appears on its surface.

Features of construction on other types of soil

It is much more difficult to build a foundation on loam than on clay: loamy soil is heaving and difficult to work with. Reinforcement must be used to create rigidity and reliability. If possible, you can replace the loamy soil with sand.

If construction is carried out on sandy loam or dusty sand, it is necessary to ensure that the load on the foundation is reduced by heaving forces. To do this, increase the size of the area of ​​the base of the house, building it in the form of a trapezoid, with slopes to the upper part.

It is no less difficult to build a foundation on bulk soil, since it has an uneven structure and density. Such soil can be of both natural origin and artificial, for example, when there is a steepness in the area and it needs to be eliminated. The solution is to compact the soil with special equipment and continue construction works.

To build a foundation on peat soil, it is necessary to install piles and install the strip foundation of the building on them: there is no weaker or more reliable soil than peaty soil.

Waterproofing works

This stage is the most important and difficult: waterproofing should protect the strip non-buried foundation as much as possible from moisture penetration. The choice of material depends on the type of waterproofing:

1. Horizontal. For its production, roll materials are used (for example, roofing felt, polyethylene film).
2. Vertical. There are two types - non-pressure and counter-pressure. A non-pressure trench is a trench filled with clay and then compacted, which is dug around the perimeter. To prevent moisture from retaining in the clay, it is poured cement mortar and install a storm gutter. To make anti-pressure waterproofing, plaster, paint, various lubricating mixtures and other materials are used - they are applied to the insulated surface.

Application of reinforcement

The following types of reinforcement can serve as reinforcing elements:

1. Longitudinal. The diameter of the product is 12 mm, the surface is ribbed.
2. Transverse. The diameter of the product is 10 mm, the surface is smooth.
3. Vertical. Dimensions and surface are the same as transverse reinforcement.

First, the posts are assembled from vertical elements, then the frame is assembled together in the trench, fastening the structure with special crochet hooks.

Installation of floors for strip foundations

The arrangement of the floor depends on the preferences of the owners and future operating conditions. There are several methods that can be used to install floors in homes with shallow foundations.

The easiest way is to cover the base with a slab, which will be the base of the floor. In this case, it is imperative to take care of creating ventilation, especially if the building is being erected in a very wet or swampy area. If this is not done, the concrete slab will begin to deteriorate over time from moisture, especially if the building is located in swamps. Ventilation holes are made in the foundation, and since it is not high, the holes can be filled with snow in winter, which is unacceptable.

Therefore, it is best to install floors on the ground. Beginners are usually interested in what is the right thing to do: build the walls and roof, and then work on the floor, or vice versa - first lay the floor on the base, and then build the walls? Both options are acceptable, so everyone chooses the one that suits them.

The construction of the floor begins with leveling the soil:

The earth, taken out of the trench and placed in the inner perimeter, is leveled and compacted, watering it several times with water every 2-3 hours.

1. Add a layer (at least 10 cm) of expanded clay or crushed stone.
2. Pour a rough concrete screed. Its thickness is about 7-8 cm. To do this, the crushed stone is covered with plastic film and the solution is poured. But you can fill the crushed stone with liquid sand-cement mortar and not use the film.
3. A hydro-vapor barrier is carried out - bitumen is applied to the hardened solution, roofing material or PET film is placed (in 2 layers).
4. A vapor barrier layer is installed. To create it, you can use mineral wool, foam glass, polystyrene foam or any other material.
5. Pour a clean cement screed with a thickness of 5 cm. For its reinforcement, a welded metal mesh is used.
6. The finishing floor covering is being installed. Tiles, linoleum, floor boards, laminate, parquet, etc. can be used as floor coverings.

Shallow strip foundations are often used in the construction of light houses: wooden, brick, gas and foam concrete. The choice of this type of foundation is due to cost and time savings compared to depths below the soil freezing level.

If the technology is followed, the reliability of such a shallow foundation will not be affected and the building will stand for a long time. Read more about how to calculate and correctly pour a shallow strip foundation further in our article.

What is such a foundation?

This type of foundation is a cross between conventional buried and non-buried strip foundations. When the soil heaves, the shallow foundation strip will rise and fall along with the house during the changing seasons.

The foundation is not destroyed. To achieve this effect, it is necessary to strictly follow the technology during construction. When deviating from the standards, there is a high probability of foundation cracking.

Advantages:

• ease of implementation;
• low cost of work;
• can be built without the use of technology;
• sufficient strength for small houses or buildings (dachas, garages, bathhouses).

This type of foundation cannot be laid on frozen ground during the winter months, nor can it be left unloaded during the winter.

The period from pouring the foundation to the completion of the construction of walls in the middle zone climate is approximately 4-5 months.

Material of manufacture

The easiest way to build a shallow foundation is to pour a monolithic concrete base. There are other options: this type of foundation can be made of either brick or concrete blocks.

Reinforced concrete

The most popular and durable material for foundation construction. It is obtained by combining concrete mixture and reinforcement. Installing an additional metal mesh around the perimeter adds strength to the foundation.

Rubble concrete

It is a mixture of cement mortar, sand and large stones.

This material is only suitable for foundations built on light soils - sandy, for example, or for laying on rocky rocks or gravel.

Brick

Quite rarely, strip foundations are made of brick. This technology is used exclusively in dry climates where there is minimal precipitation and there is no groundwater.

Foundation calculation

The calculation of a shallow strip foundation consists of an analysis of the degree of soil heaving and the bearing capacity of the soil. Based on these data, the thickness of the pillow, the dimensions of the foundation, its height and thickness are determined.

The area of ​​the future building, the number of floors, and the layout of residential and non-residential premises are taken into account.

The presence of basement or semi-basement premises and the type of material from which the foundation will be built are taken into account.

The above-ground part should not be larger than the underground part of the foundation. In this case, it can be as much smaller as underground.

Most often, the depth of laying a monolithic foundation is 45-50 cm.

Features of construction on heaving soils

The most common reason for this phenomenon is seasonal temperature changes. The soil also consists of moisture, which freezes in winter. This causes shifts in the soil - heaving.

Heaving can be caused by groundwater, and in this case the soil begins to sag.

The construction of a shallow strip foundation on heaving soils is an ideal option for this type of soil.

A shallow foundation, as a rule, is made on cushions of sand, gravel, and crushed stone. They are not subject to heaving.

Due to its rigidity and stability, this type of foundation reliably protects the building from destruction.

Laying depth

How to calculate the depth of a shallow strip foundation?

This depends on the following factors:

• soil freezing depth;
• height of groundwater;
• the degree of its heaving.

The closer the groundwater is to the surface, the greater the depth the soil freezes, the more it will shift. This means that the strip foundation will have to be laid at a greater depth.

Minimum depth of strip foundations:

Do-it-yourself shallow strip foundation

Many people prefer this type of foundation also because almost anyone can build a shallow strip foundation with their own hands. This does not require special skills or construction experience.

It is better to lay the foundation in the spring. This will give him the opportunity to gain strength in order to have time to build walls during the summer period.

The main thing is to make the right calculations.

It is enough to carefully carry out all stages of work in this sequence:

1. After marking, you need to lay a trench to a depth of up to 70 cm. The trench is made to a width of 300 mm.
2. Its walls must be made strictly vertical.
3. The bottom of the trench is covered with geotextile, which allows water to pass through and prevents soil particles from mixing with sand.
4. The edges of the fabric are raised above the sand filling being performed.
5. The bottom of the trench is covered with coarse sand - over geotextiles.
6. Each sand layer is spilled with water, then thoroughly compacted. On sandy soils, it is enough to lay 20 cm of sand; on clay soils, the layer of filling should be half a meter.
7. Formwork made of boards is installed, which serves as a continuation of the walls of the trench. The boards are fastened with nails.
8. WITH inside formworks mark the level of pouring concrete.
9. Reinforcing bars are laid. Metal rods are attached to a reinforcement grid using a special binding wire. If the foundation height is more than 30 cm, several layers of reinforcement will be required.
10. The formwork is filled with concrete. The first layer is evenly distributed over the formwork, removing air voids with a rod. The next portion of concrete is poured only after the previous one has set. The last layer is leveled according to the markings, smoothed and sprinkled with dry cement for a more durable setting of the upper part of the foundation. This prevents cracks from occurring.
11. Concrete matures within 28 days. The foundation must be covered with film to prevent rapid evaporation of water and to avoid the appearance of cracks.
12. The construction of walls for the construction of light types of buildings can begin in about 2 weeks.
13. If the house is made of brick, masonry cannot begin until the concrete has matured.

Foundation insulation

The shallow, insulated strip foundation has greater strength and heat-insulating properties. Polystyrene boards are used to insulate the foundation on the outside.

Plates are used with a thickness of 5 cm. They are fixed to the side surface, then laid horizontally on a drainage pad.

At the corners of the foundation, a thermal insulation layer must be about 8 cm thick. The polystyrene foam is usually covered with a special membrane on top, then soil is added and a blind area is made.

The insulation of a shallow strip foundation prevents it from freezing in the coldest winters.

Construction of a foundation from foundation wall blocks

For low-rise construction They use a shallow strip foundation made of FBS blocks. Such foundations are called prefabricated foundations.

The size of the foundation blocks is selected depending on the thickness of the walls.

The algorithm for constructing a prefabricated foundation looks like this:

• special blocks are laid on the prepared base - foundation pads;
• FBS blocks are installed on them, which are fastened with cement mortar. A metal mesh is placed between the blocks as a reinforcing element;
• the upper part of the foundation is leveled with cement mortar. Waterproofing is carried out on top - roofing material is laid on bitumen mastic in two layers. Waterproofing must be carried out along the entire perimeter of the building, along the outside of the foundation.
• after backfill foundation walls, approximately 50 - 80 cm wide, a blind area is made around the entire structure. It is most often made of concrete.

The advantage of prefabricated foundations is the speed of their construction. A short period of time is required from laying the foundation until the start of laying the walls.

But, unlike monolithic strip foundations, they are more expensive and have less strength. To complete them, it is necessary to use construction equipment.

Video about the construction of a shallow foundation

Building a foundation is an important component of building a strong and reliable house. If the required area at the border of the seasons is deformed due to excess groundwater, then a foundation for heaving soils, which is able to ignore the pressure of soil and ice, will help to secure the structure and protect it from destruction and flooding.

The location of a house does not always fall on an ideal terrain, and an incorrectly selected foundation can lead to serious problems with housing Source domostroy-region.ru

Heaving soils and construction features

Soil masses that expand under the influence of low temperatures and have a destructive effect on building structure elements are classified as heaving soils. Sandy loam, loose clay and highly porous soils that are capable of retaining moisture are subject to heaving processes.

Before proceeding with the construction of the foundation, it is necessary to conduct research on the upper layers of the surface. According to the GOST description guidelines, 5 types of soil are distinguished:

non-heaving - coarse soils, pebbles, gravel, coarse and medium sand, well-filtering liquids;

slightly heaving soils - elevated and hilly places that are well moistened by precipitation;

medium-heaving – slightly hilly places with long slopes, where moisture occurs by high water and precipitation;

highly heaving - wetlands in which the situation is aggravated by the influx of groundwater;

excessively heaving - soils of fluid plasticity and consistency, which are in a watered state due to the low density of the soil layers.

The table shows the parameters of the degree of soil heaving, but in reality, it is better to entrust the calculation of these indicators to a professional Source kamtehnopark.ru

In the process of determining measures to prevent deformation, the corresponding coefficient is calculated.

Calculation of heaving intensity in the area

Calculation of heaving intensity is carried out to design the stability forces of foundations and neutralize their effects. This indicator is determined using the formula:

E = (H – h) / h, where

E – degree of heaving;

H – level of freezing at low temperatures;

h – soil level before freezing.

Therefore, to calculate it, it is necessary to carry out appropriate measurements in winter and summer.

Anti-heaving measures

To combat heaving forces, it is planned to implement measures of the following nature:

complete replacement of the heaving layer on the proposed site is a labor-intensive process that requires digging pits of considerable size, searching for and compacting the brought soil;

construction of a foundation below the freezing layer in order to relieve the load on the base;

insulation of the structure in the freezing area will require laying insulation along the entire perimeter and to the depth of the construction of the base of the structure;

organization of drainage is carried out by constructing a drainage system with laying gravel, sand and a perforated pipe treated with geotextile into the trench.

Installation diagram of a perforated channel for groundwater drainage Source el.decorexpro.com

Heaving soils - choosing a foundation

For the construction of load-bearing structures of any building on moving soils, the following types of foundations can be considered:

The organization of an expensive slab base will be effective for brick or heavy wooden structures that occupy large areas. It is predominantly of regular square or rectangular shape, but if necessary, complex perimeter figures are also designed;

Source keysdom.ru

Pile - screw or reinforced concrete. Here, too, you need to know exactly the depth of freezing of the soil in order to place the piles below this mark. Effective for the construction of small buildings in marshy and watery areas. A special reinforcement frame is constructed on the surface of the piles, which is filled with composite mortar just below soil level.

Columnar. It is used only for light and ultra-light commercial buildings, has a shallow depth and is not considered as a foundation for a residential building.

Concrete strip foundation buried below the frozen soil level.

Less expensive and in demand is a shallow or non-buried strip foundation on heaving soils. It must be used very thoughtfully, having previously calculated all the loads in order to eliminate the influence of heaving forces.

Strip foundation is the most familiar option for many, which “takes root” on many types of soil. Source pinterest.com

The type of base chosen will depend on the size and shape of the building, the arsenal of equipment used, as well as the financial capabilities of the customer.

Modern TIS technologies involve the use of support-column elements connected by a grillage. To organize such construction, special equipment and electricity are not used, it is possible to hide communications and minimize the slope of the construction site. A similar technique is relevant for frame, stone or brick construction.

Slab reinforced concrete load-bearing structures, which are effective for arranging a low base and are applicable in the case of a simple building structure, can also resist freezing.

The use of a strip foundation involves the installation of a construction reinforcing strip along the perimeter of the building and in the area of ​​construction of load-bearing walls. Such developments are less expensive, however, they are superior in reliability to the above options.

On our website you can find contacts construction companies who offer foundation design and repair services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Online foundation calculator

To find out the approximate cost of foundations various types, use the following calculator:

Types, features and advantages of strip foundations

Strip foundations made of rubble concrete, rubble, and less often brickwork– a fairly popular technology for reliable construction.

A non-buried strip foundation is applicable for high loads and is even more capable of ensuring the stability of small-sized frame and wooden foundations.

A mandatory stage of work for a strip foundation is formwork Source mastrerkon.ru

However, such a foundation on heaving soils with a high groundwater level and excessively swelling soils requires replacing the foundation with piles. But when exposed to uneven loads, it is better to give preference to the first option.

The simple technology of constructing strip foundations and the ability to use them on any soil greatly facilitates construction work. You also don’t have to worry about using specialized equipment and machinery, which allows you to as soon as possible and cope with the assigned tasks with minimal costs.

In this case, the construction of houses is carried out on a sand cushion using the following types of strip foundation:

a monolithic reaming installed directly on the ground surface eliminates the impact of tangential forces, and the vertical impact can be leveled due to reinforcement with a monolithic contour;

prefabricated monolithic model of the 20/60 series, representing the installation of a complex of reinforced concrete blocks on a reinforced solid base;

monolithic base series 20/60 with reinforcement and treatment with a composite building mixture;

monolithic reinforced base, which is characterized by an increased support area and allows you to create a reliable foundation.

A combined column-strip foundation is often used Source martand.ru

By expanding the tape, using insulation and drainage, you can increase the capabilities of the listed types of foundations.

Shallow strip base will require more earthworks, the use of formwork and significant hardening time. But the resulting safety margin will be enough for a hundred years. This foundation option has the following advantages:

reliable in operation;

suitable for any base configuration;

there are no difficulties with the installation and construction of buildings;

It is characterized by high resistance to external influences.

When the soil freezes deeply, additional volumes of building materials will be required to build a reliable foundation. However, this is the only way you can cope with uneven shrinkage during the construction of low-rise buildings, massive buildings, basements, ground floors, as well as low-rise construction.

Video description

One option to avoid problems with soils is a strip foundation. More details in the video:

Construction of a strip foundation on heaving soils

A shallow strip foundation on heaving soils requires the organization of a special cushion of sand or gravel. It is also necessary to provide waterproofing. For this purpose, hydrophobic admixtures are added to concrete compositions. In the process of arranging such foundations, protective measures are taken to prevent exposure to cold:

for a cushion up to 0.5 m thick, a non-heaving material is poured under the base, and in order to prevent siltation, an additional layer of geotextile is laid;

at the level of the base, drainage is installed with the laying of a special pipe at a slope;

waterproofing and insulation on the vertical layers of the foundation is carried out using extruded polystyrene foam, liquid polyurethane and the construction of an outer layer of polystyrene foam;

You should also take care of storm drainage, which will help neutralize the passage of water flows near load-bearing structures.

Source homerenovates.com

Preparatory work

Before starting work, the geometric parameters and dimensions of the building are determined, as well as the selection of materials. The amount of concrete is determined based on its density and dimensions of supporting structures.

The calculation includes the length of the structure along the perimeter and the area of ​​its internal partitions. In this case, the depth of foundation construction is determined based on the characteristics of the soil, consumables and the number of storeys of the building. It should be taken into account that the location of moisture should be 50 cm lower from the base of the base, otherwise there is a high probability of deformation.

Upon completion of the design work, the dimensions from the paper are transferred to the area, and the correct placement of the marks is checked. The designated area is cleared of debris and the top layer of soil is removed.

Source mybesedka.ru

Laying work

A shallow and shallow foundation on heaving soil must be built in accordance with the following requirements:

digging trenches is carried out taking into account the width of the base, formwork, insulation, waterproofing and decor;

the surface of the pillow is lined with a waterproof barrier, and the side surfaces of the supporting structures are treated with a waterproofing material - film or roofing felt;

compaction of the pillow material is carried out by wetting the layers of material with water; pour a sand pillow 20-30 cm thick;

installation of formwork is carried out from available materials - plywood, edged boards, the elements of which need to be fastened together;

the steel reinforcing belt is strengthened along and across the base by tying it with special wire;

the belt is filled with a concrete seal in one step from a height of no more than 0.5 m;

it is possible to lay a second layer of reinforcing belt.

Approximately this “pie” should be the result after pouring a shallow foundation Source stroy-dom-pravilno.ru

Scope of application of strip foundations

The easiest way to deal with heaving soils is to arrange pile foundation below the freezing mark. If it is impossible to carry out such construction alternative solution– shallow foundations, which will require significantly smaller volumes of building mixtures, amounts of reinforcement and labor costs.

It is effective to use shallow burial technology when groundwater is located at a depth of more than 1.5 m. Ribbon structures on steep slopes, where lateral pressure must be taken into account, make it possible to compensate for the uneven impact of soil movement in the longitudinal and cross sections.

The foundation on heaving soils is suitable for the construction of frame and timber buildings, the use of foam concrete and aerated concrete materials. If it is necessary to construct a shallow foundation or build powerful structures on soft soils, strip foundations are a priority. Such construction methods are applicable for clayey and sandy loam soils, loose rocks, as well as water-saturated surface layers.

Source domastroim.ru

To build a strong and reliable foundation, pay attention to the following nuances:

work on the construction of load-bearing structures is carried out in the summer before the onset of cold weather; if construction is stopped, the facility needs conservation;

in the case of using a shallow strip foundation, it is necessary to construct load-bearing structures like a frame, which will allow seasonal loads to be evenly distributed;

to add additional rigidity to the structure, the strip foundation can be combined with bored piles;

for insulation it is necessary to select dense polystyrene foam of a special grade PSB, intended specifically for insulation;

Waterproofing with roofing felt is done by gluing it overlapping onto hot mastic and additionally lubricating the seam joints.

Video description

Video on how to avoid problems with a house on heaving soils:

Conclusion

A competent choice of foundation type and adherence to construction technology will allow you to build reliable buildings and structures. Despite the problem of frost heaving, the design and construction of buildings can be carried out anywhere in the world.

Heaving soil is not the best the best option for construction, since it is associated with the need to solve a number of problems, in particular, neutralizing winter, that is, movements that can be dangerous for the foundation and the structure as a whole. That is why experts recommend making it, which copes well with loads without being subject to uneven shrinkage and destruction. One of the popular ones is, which is relatively easy to perform; such a base is suitable for almost any structure.

For a strip shallow foundation, it is necessary to dig a pit 50-70 cm deep and lay waterproofing in the form of roofing felt on the side slopes.

Foundation installation on heaving soil

The construction of a foundation on heaving soils is undesirable because the heaving force can be large and can easily lift entire buildings. That is why it is so important to choose the right type of foundation, and during its construction to follow a number of measures to reduce this negative phenomenon.

One option is to replace it with sand up to the freezing point. This method is the most reliable, but its cost is high and it is not always advisable. Another option is to use foundations that lie at a depth below the freezing point. These are columnar and pile structures. Heaving forces do not apply to them, but the construction of such foundations can be very costly, that is, not entirely profitable.

The third option is, which, along with high strength, also ensures the stability of the house. It successfully resists heaving and does not give strong and dangerous shrinkages. Most often this is a shallow shallow foundation made of monolithic reinforced concrete.

Such a shallow foundation is placed on sandy base, which is covered with a layer of waterproofing, the walls of the trench are reliably protected using special materials. Recommended in concrete mortar When mixing, add water-repellent additives that increase the stability of the material. After constructing the foundation, you need to worry about creating a drainage system that effectively removes excess moisture from the structure. To build a base, in addition to the concrete itself, reinforcement should be made of a strip of metal rods with a diameter of 12 mm, and their number will be slightly larger than for a conventional strip base.

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Foundation options for heaving soil

When carrying out construction on heaving soils, not every type of foundation can be used. The most optimal solution– use a non-buried or shallow foundation that perfectly resists soil heaving during frosty months.

Among similar shallow foundations on heaving soils, the tape type is especially popular, which provides the necessary reliability and durability, and its construction is extremely simple and the cost is not so high.

Columnar foundation on heaving soils it is used when the supports can be installed below the freezing point.

This allows you to save financial resources for the construction of the foundation, maintaining high reliability.

Such a foundation is placed if the site has loam, soils with close moisture, damp and swampy areas.

For the device in this case, metal pipes with a cement-sand protective composition, reinforced concrete supports, asbestos-cement pipes, into which the concrete mixture is poured, are used.

For construction on heaving soils, a pile version of the foundation can also be used, which, however, is not so popular. The fact is that its construction requires the use of special construction equipment, and this is an extra financial expense. This option is used only when the soil freezes to a depth of one and a half meters.

To make a structure on heaving soils from piles, materials such as concrete, reinforced concrete, and wood are used, which successfully resist heaving. Among the types that can be used, screw, cast-in-place, reinforced concrete simple and cast-in-place piles are recommended. Required condition When carrying out work on constructing a foundation of this type on heaving soils, it is important to have an excellent drainage system.

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Shallow strip foundation

For heaving soil, it is a monolithic concrete strip with reinforcement in the form of a belt of metal rods. To properly install such a foundation for a house on heaving soils, several simple conditions must be met.

The initial stage differs little from the construction of the most ordinary foundation. You should dig a pit, the depth of which will be from 70 to 50 cm. After this, you will need to lay waterproofing material on the side slopes, which is usually ordinary roofing felt or plastic film.

Next, the pit on heaving soils must be filled with sand in layers, the thickness of each will be 20-30 cm. After filling, each sand layer is compacted. Next, a layer in the form of waterproofing is placed on the sand, reinforcing metal rods with a diameter of 12 cm are installed. Such reinforcement will have two separate belts, each of which will have five rods and jumpers.

At the last stage, the shallow foundation is poured using concrete mixture. The top layer of reinforcement is laid directly on the wet mixture (this is a feature that a non-buried foundation has for heaving soil). When connecting reinforcement elements, you cannot use a welding machine - only knitting wire, which provides higher strength and reliability.

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Uneven shrinkage of structures on heaving soils

Construction on heaving soils is dangerous because during the first winter period shrinkage and deformation of the foundation are possible. Among the frequently encountered ones it is necessary to note:

• camber/sag: occurs due to uneven shrinkage. In this case, the most dangerous thing is the bending, which affects the condition of the roof and the stretching of the building area;
• shear: occurs due to the subsidence of one part of the building and the rise of another. The most dangerous zone is the middle one, where the walls of the foundation and the structure itself begin to crack;
• tilt: observed due to the rigidity of the structure for buildings with a relatively high height, but for the construction of which a shallow foundation was used;
• distortion is a consequence of uneven shrinkage in individual small areas under the building;
• horizontal displacement occurs at the foundations, individual sections of which are literally pushed out and moved during heaving.

Why do such uneven shrinkages occur on heaving soils? The fact is that when the soil freezes, the moisture contained in it freezes, its volume increases, and the soil begins to swell. The soil layers begin to rise, and if the construction was carried out without taking such features into account, the structure begins to deform and cracks appear on it.

As a result, traces of destruction appear on the walls of the building.

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To reduce such consequences, it is recommended to build on heaving soils using materials such as foam blocks, wood, brick, and concrete.

Calculation for a shallow foundation

• An example of calculating shallow foundations on heaving soils should be given. For example, a one-story house is being built with the following dimensions:
• height – 4 meters;
• width – 5 meters;

length – 10 meters.

The structure includes two load-bearing internal walls, each 4 m high and 3 m long. The floor does not rest on the foundation and is filled with concrete. The base will have the shape of a tape with a base width of 40 cm and a depth of 70 cm. The foundation is made of reinforced concrete, for which reinforcement with a diameter of 12 mm is used. The frame will have two belts, each of which consists of five rods, jumpers with a length of 25 cm. Such jumpers are placed in increments of 50 cm.

• To find out the mass that the strip foundation will have, you need to determine the following values:
• geometric dimensions of the structure;

density of the building material used.

Geometric dimensions are quite easy to find out. So, the length of the foundation is equal to the perimeter of the future building, that is, you just need to calculate the sum of its sides:

10+10+5+5+3+3=36 meters.

The strip foundation will be poured not only under the external facade walls, but also under the internal load-bearing walls, so they are also taken into account.

Now you can find the volume based on the fact that the height of the tape is 70 cm and the width is 40:

V=36×0.4-0.7=10.08 cubic meters.

But this is the total volume from which the reinforcement must be subtracted to find out the amount of concrete. Knowing that the strip foundation has two belts of five rods with ligation, calculate the length for each:

The length of all belts will be equal to:

2×(9×2+4×2+2.5×2)=62 m.

Each belt has five rods, which means their total length is: 62×5=310 m.

Now determine the length of the required jumpers for reinforcement:

9/0.5+1=19 pcs.,

One of the most important tasks in the construction of almost any building is the choice of the appropriate type and installation of the foundation. When choosing a foundation, it is necessary to take into account heaving and other properties of the soil. Heaving soils expand and rise during freezing.

If you use a non-buried foundation on heaving soils, this will save time, money and labor costs.

Because of this, the foundation and the structure itself can become deformed and collapse. To avoid these unpleasant moments, the foundation is constructed at a depth below the freezing level, however, when constructing a lightweight building, this option will be impractical and very expensive. In view of this, as an alternative, in most cases a non-buried foundation is installed.

What can a non-buried foundation look like?

Once you understand how to install a shallow foundation on heaving soils, you will be able to handle this work yourself. During the installation process, all parts of the structure are combined into a single base. Thanks to it, it will ensure equalization of deformations and uniform distribution of load along the entire perimeter of a non-buried foundation on heaving soils. The foundation can be strip or columnar. Tape base is a single frame. In the case of a columnar support, the structural elements are fixed using steel beams or monolithic grillages.

When installing a non-buried foundation on heaving soils, there is a possibility of a slight rise in the foundation.

Deviations must not exceed the maximum permissible design values. They are determined according to the type of construction and used building materials. It is very important to ensure that the non-buried foundation on heaving soils is so rigid that it can normally withstand the deformations that occur during soil freezing.

If the installation of a non-buried foundation on heaving soils is carried out in accordance with the technology, then a building on such a support will be used no worse than a building on a buried foundation.

Using a non-buried foundation on heaving soils allows you to reduce money, time and labor costs.

The foundation is built using the following tools:

• construction thread;
• level;
• hammer drill;
• shovels;
• construction wheelbarrow;
• concrete mixers;
• hammer;
• measuring tape.

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Preparing for the construction of a columnar non-buried base

Before you start installing a columnar foundation, you need to prepare construction site and make markings. Clear the construction site of debris. It is important that it has a slight slope for the drainage of melt and rainwater. The slope can be in any direction, except north. After preliminary preparation of the site, marking is carried out. To do this you will need the following:

• linen cord;
• roulette;
• triangle with right angle;
• pegs 0.5 m long;
• level.

Level the site and remove the plant layer of soil. The finished base should be 10 cm wider than the building. Start marking from the inner contour. It is necessary to set the first corner of the building and hammer in a peg. Take the triangle and determine the size of the outside of the base. On the one hand, this size should be equal to the length of the transverse wall, on the other - the longitudinal wall. Where the axes intersect, hammer in the 2nd and 3rd pegs. Using the same principle, measure all other corners of the building.

After this you will need to install the cast-off. At this stage, posts are installed near the driven pegs, and boards are fixed to them. They need to be mounted at the floor level of the future building, but no higher than 150 cm from the ground level.

Don't forget about axial dimensions. They need to be applied to the upper edge of the cast-off, hammer in the nails and tighten the cord. Pull the clothesline over the driven pegs. Do this from all sides of the future building.

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How to pour a columnar foundation?

Column foundations, among other things, have become very popular due to their high strength and ease of construction. In addition to these advantages, a columnar foundation also has its disadvantages. They must not be forgotten when constructing the foundation. It is impossible for the area to have large differences in elevation and high groundwater levels. Construction on moving soils is permissible, but if possible, it is recommended to make a strip foundation. Another advantage of a columnar base is its relatively low cost.

This type of foundation consists of many supports that are installed in the most important points buildings, namely:

• under load-bearing elements;
• at the intersection of walls;
• at the corners of the building.

The foundation is built in strict accordance with the plan, drawings and project documentation future building. Only if these important conditions strong columnar foundations are obtained.

When choosing supports, be guided by the expected load on the foundation. To do this, you will need to know the approximate weight of the finished building, the number of people staying inside at the same time, the presence of heavy equipment and furniture, etc. Based on these factors, the material for making the pillars and their quantity are selected. The columnar foundation must be poured before frost begins. It is forbidden to leave it without load during cold weather, because... by spring it will be deformed, and you will be forced to redo everything.

The foundation is built using the following materials:

• supports (made of reinforced concrete, brick or concrete);
• boards for formwork;
• fittings;
• cement;
• crushed stones;
• sand

The formwork is made from boards 2 cm thick. It will be lightweight and cheaper when compared to chipboard and metal plates. Assemble shields from boards. Assemble boxes from them. Install the finished boxes into a previously prepared hole in the ground. These holes are created in the places where the support pillars will be installed. Wet the inside of the boxes with water. There should be quite a lot of water. It will prevent the absorption of moisture from the concrete and will greatly facilitate the dismantling of the formwork after the filling has dried.

The columnar foundation is reinforced with rods with a diameter of 14 mm. They must be placed in the box so that their edges do not reach the wall of the box by about 0.5 cm. The longitudinal reinforcement should have a diameter of 6 mm. It needs to be welded to horizontal rods in increments of about 30-40 cm. Longitudinal rods should be 50 cm longer than the box. In the future, the grillage frame will be attached to them. Once this frame is ready, excess reinforcement can be easily removed.

Finally, the concrete solution is poured. It must be poured in layers 25-40 cm thick and must be treated with a vibrator to prevent the formation of air pockets. This is very important because... air pockets will significantly weaken the overall strength of the foundation. If possible, fill in 1 time. Pour a layer of concrete, break it with a vibrator, and so on until the end. If you take a break even for 1 day, a seam will appear at the junction of the layers, reducing the bearing capacity of the base.