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Which clay foundation is best for a house? Which clay foundation to choose? Which foundations are suitable for clay?

The foundation is the basis on which the service life of any building largely depends - anyone who has been involved in the construction of their own home knows this. The estimated cost of the foundation is approximately 30% of the total construction estimate. Therefore, there is no need to try to save money on building the foundation for a house - this will result in serious problems in the future. The quality of the foundation does not always depend on the quality of the building materials; the soil on which the structure is built also matters. For example, pouring a foundation on chernozem is a technology that is fundamentally different from the process of constructing a foundation on clay soil. This article will discuss how to build a foundation on clay according to all the rules.

It doesn’t matter whether you want to build a greenhouse, a bathhouse or a two-story house - in all cases the soil will be the same. Of course, you can save a little here if you use sawdust or sand instead of building materials such as gravel or crushed stone. But be on your guard - do not forget about the insidiousness of clay, and build a foundation on clay soil in accordance with all building rules.

Despite the fact that clay is the most difficult type of soil for construction, we will help you figure it out.

Building a foundation on clay is not an easy task, you will be able to understand all the nuances after reading this article.

Surely, even without expert advice, you understand perfectly well that the likelihood of breaking, swelling and subsidence of the main structure are the main problems when building a foundation on clay. This can happen due to insufficient foundation depth, or if too much pressure is applied to the foundation. Similar problems arise with the foundation of a house on clay if small stone was used during its construction or the walls were built from foam blocks.

If you want to avoid such problems, then you should choose the right type of foundation for the future structure. The blocks can be folded back immediately, because you will need to mount a reinforcing frame, which will act as a connecting element. In addition, it is better to make the bottom of the base wider than the top. If there are concerns about the pressure of freezing soil, then coat the foundation with machine oil or use PVC film. When the thaw begins, the film will not let water through to the base. Insulating the top layer of the earth will also not hurt; for this you can use expanded clay or crushed stone.

Types of Clay Soil

Clay soil is different everywhere and, depending on its characteristics, there are three types of clay soil: clay, loam and sandy loam. Therefore, before you start making a foundation on clay, determine the properties of the soil in your area.

Clay

This substance consists of very small particles, the size of which does not exceed 0.01 mm. There are additives of sand and dust. Such soil is suitable for use as a foundation only if it is relatively homogeneous in composition, and also if the freezing point of the soil is located significantly above the groundwater layer. Clay soil is characterized by high flowability and plasticity.

In such conditions, building a foundation on clay should only be done with the help of professional builders and very carefully. You should not try to do this yourself, as you do not have the necessary skill and knowledge.

Loam

Loam is sand with clay admixtures. Usually its presence does not exceed a third of the total volume of soil. There are three types of loam depending on the amount of clay it contains: light, medium and heavy loam. In the table of building materials, loam occupies a place between clay and sand, in addition, it has high heaving rates.

Sandy loam

In such soils, the admixture of clay is quite small - no more than 10 percent. Such areas are often called quicksand - they can move under the influence of groundwater. Almost nothing can be built on such soil. But if a hopeless situation arises and you have to build anyway, then you should use a pile foundation; The base for the piles is made of crushed stone.

Selection of foundation structure

You have already determined the type of soil on your site, found out the depth of groundwater and the depth of soil freezing. Now it's time to choose a base. There are two possible options in this case: a strip foundation on clay or a pile foundation. If the soil is more or less homogeneous, then a strip foundation is installed, while a pile foundation is used if there are stones in the soil.

Your future structure will also influence the choice of foundation type, for example, if your house is built from foam block or brick, then a strip foundation is the best option. This choice is due to the serious load that will be placed on the base.

If you have to build a barn or a summer greenhouse, where the loads are insignificant, then the use of a pile foundation would be quite justified - it can provide a sufficient degree of monumentality to the structure.

Tips for building a foundation on clay soil

You must be able to take advantage of the benefits of clay, despite its disadvantages. A clay foundation can withstand a very heavy load if the groundwater is deep enough. The result is a very strong supporting structure, on which you can also save money.

If the groundwater is not far from the surface of the earth, then it is better to immediately choose a pile foundation and not waste time calculating the cost of the “tape”. Although a foundation on piles will be a little more expensive, it will be reliable and of high quality.

Whatever type of base you use, the first step is to take care of a bed of crushed stone, sand or gravel. Remember that the bottom of a clay foundation should be at least 25 percent wider than the top. Thanks to this, your home will be saved from subsidence and deformation.

The process of creating a foundation on clay

For greater clarity, we will give an example that reveals an approximate technology for constructing a foundation for a bathhouse on clay. It will be built from timber. The following is an instruction in which everything is described step by step:

Marking is carried out for the base;
Trenches are being dug. You should dig until you reach at least half a meter below the fertile layer. The trenches should be at least three times wider than the proposed foundation;
The formwork structure is being installed. The formwork can be metal or wood - it depends on the material at hand. There is no fundamental difference in using metal or wood;
The cement mixture is being prepared. Compliance with the technological chain is not at all necessary in our case, this means that you can use straw or sawdust as additional elements;
The solution is poured into the formwork structure. After which it is compacted with a hoe or shovel;
You should wait until the cement mixture dries;
If the solution has completely hardened, then the formwork is dismantled;
Now the foundation on clay is subjected to heat treatment. The base is covered with firewood, and then it is set on fire. We can say that the finished product is fired in order to give it greater strength. You can cover the trenches with metal sheets during firing, this will increase the quality of firing;
You should wait until the wood burns completely, then you need to fill the trenches. The process of constructing a foundation on clay has been completed. As you can see, it is quite possible to build a foundation on clay soil with your own hands, without the help of workers.

Conclusion

Building a supporting structure for a wooden house on clay is not such a difficult process if you approach it wisely and carefully. However, we should not forget about the specificity of this type of soil. You need to skillfully take advantage of the advantages of such soil and avoid its disadvantages.

Clay foundation, which one is better to use? This question arises before the developer when it is discovered that there is clay soil on his site. The strength of the foundation depends not only on the quality of building materials. The reliability of the structure is greatly influenced by the characteristics of the soil on which the house rests.

Therefore, it is extremely important at the design stage to select the optimal foundation option that corresponds to the geological structure of the development site. This article will help private builders who are going to build a house on clay: which one is better for this case?

The main problems when building a foundation on clay soils are the likelihood of subsidence, breaking and swelling of the building's foundation. This can happen under the influence of too much pressure on the foundation, or due to insufficient depth of its foundation.

At particular risk are houses whose walls are built from lightweight building materials - foam blocks, for example (). Heaving forces in clays can only be balanced by a heavy above-ground part - brick, stone or reinforced concrete.

Types of clay soils

Clay soils include:

sandy loam;
loams;
clay.

Clay is a collection of small (up to 0.01 mm) particles with a small admixture of sand and dust. Characterized by flowability and high plasticity. You can build on clay if the soil is homogeneous and the groundwater is deep. But in any case, such a case is not at all suitable for independent construction.

Loam contains up to 10% clay. Depending on its specific volume, the soil can be light, medium or heavy. Loams are prone to frost heaving, so construction conditions on them are classified as difficult.

Sandy loam contains no more than 5 percent clay. These soils have another name - quicksand, as they have great mobility under the influence of groundwater. It is undesirable to build a foundation on sandy loam soils, but if there is no other choice, choose pile structures with a crushed stone base.

Choosing a foundation type

When building a foundation on clay soil, regardless of the type chosen, the main rule must be followed: the width of the base must be 25 percent or more greater than the upper part of the structure (). A cushion of sand and gravel (or crushed stone) is required.

Strip foundation

A clay strip foundation is suitable for heavy buildings and light wooden buildings ().

But if in the first case a buried structure is being built, the bottom of which is below the freezing line, then in the second, preference should be given to a shallow foundation: on clay soil, the light above-ground part will not be able to counterbalance the heaving forces.

Monolithic tape is used only if the groundwater is below the soil freezing line. On loamy soils, a foundation of this type can be built if geological exploration has confirmed the uniform occurrence of layers throughout the construction site.

Only in this case, uneven deformations during soil heaving will not threaten the structure.

Slab foundation

Slab foundations on clay are the most reliable, but also the most expensive). Therefore, they are practiced only in the case of the construction of luxurious mansions.

Another name for this type of foundation on clay soil is floating. During any movement of the soil, the slab moves with it, maintaining the uniformity of the load.

The slab is poured almost on the surface of the earth. But buried slabs are also practiced - in houses with basements. In this case, the walls of the underground part of the house and the slab form a single monolithic structure.

If you need to build a foundation on loam, there is no better solution than a monolithic slab (). Since the base of such a foundation has a maximum area, even a calculated soil resistance of 1 kg/cm2 is sufficient to ensure the stability of the structure.

Pile foundations

With the help of piles, a foundation is built on sandy loam and other types of clay soils. Pile fields are arranged for large buildings: supports are installed in rows under walls, and in bushes under columns.

When choosing the type of foundation on clay soil with a high groundwater level, the most correct solution is to build a house on piles (). In this case, it is necessary to adhere to the basic rule - the support must be made with a widening downwards.

Screw piles have proven themselves well - structures equipped with screw blades in their lower part). When screwing in the screw, the density of the soil around the support is maintained - the blades do not loosen the soil, but cut individual layers. The calculated installation depth of the screw is below the aquifer and freezing point.

Scheme of a pile-screw foundation on clay soil.

Conclusion

Laying a foundation on clay soils is a difficult task, but quite feasible. The main thing is to know all the advantages and disadvantages of such soils and wisely use the former, avoiding the latter.

Video about the dangers of clay for foundations.

You can easily and simply build a house only on paper. In fact, construction is a very important and responsible process in which each stage requires a lot of attention, effort and time. When constructing a residential building, the correct choice of foundation is of great importance. The strength and durability of the entire structure depends on this.

Before choosing the type of foundation for a house, it is necessary to carefully study and analyze the soil at the construction site. Based on the research carried out, the bearing capacity of the foundation is calculated. In most regions of Russia, clay soil predominates, therefore, it is necessary to talk in more detail about the features of building a foundation on this type of soil.

Characteristics of clay soil and its types

In order for the structure to be reliable and durable, it is necessary to decide in three directions:

What can be built on clay soil.
What materials to use for construction.
Which foundation is better to choose?

To answer these questions, you should familiarize yourself with the types of clay soils and their characteristics.

Soil rocks are very rare in their pure form; in most cases they contain various impurities. In the case of clay soil, the admixture is mainly sand. Depending on its quantity, clay soil is divided into the following types:

Clay. In such soil rock, the pure clay mass is more than 30 percent. The soil is classified as heaving soil due to the ability of clay to retain water. When it freezes, the soil expands, which always causes the destruction of the foundation. In addition, under the influence of groundwater, clay is quickly washed away, which leads to the formation of voids and subsidence of the foundation.
Loams contain from 10 to 30 percent pure clay. Such soil can also be called unreliable, since its behavior changes under the influence of certain factors. Construction on such a site is possible only if the soil is strengthened.
Sandy loam– soil containing no more than 5 percent clay. It is also one of the problematic soils, as it changes its characteristics under the influence of groundwater. If there is a need to build a house on such a site, then it is best to use a pile foundation.

When studying clay soils, you should pay attention that clay can be red and blue. The first type contains a large amount of sand, which promotes moisture conduction. Because of this, the soil can change its properties and collapse. Blue clay is more durable and less susceptible to destruction, since it practically does not allow moisture to pass through. However, there may be a large accumulation of water on its surface.

Glacial and alluvial clays are also distinguished. If the glacial layers lie deep enough, then a concrete foundation can be built on them without fear. Alluvial or river clay is found in lowlands and near water bodies and is characterized by high plasticity. In such areas of the house it is better not to build a foundation; in extreme cases, you can make a pile foundation.

Features of building a foundation on clay soil

Almost any foundation for a house can be built on clay soils, taking into account the characteristics of a particular site and the capabilities of the developer.

When choosing a foundation, consider the following:

The type of clay soil on the site.
Soil freezing depth and groundwater level.

In any case, the construction of the foundation should begin with the following actions:

Excavation of soil under the entire area of the foundation and leveling of the base.
Backfilling the area with sand or crushed stone.

Construction of a strip foundation on clay soil

A foundation in the form of a concrete strip requires a lot of effort and time, but such a foundation can withstand the load of a massive structure even on clay soil.

The construction of the strip foundation is carried out using a certain technology, taking into account the characteristics of clay soil.

Site marking

Excavation

To lay the strip base, you need to dig a trench. The base of the foundation should be located just below the freezing level of the soil; it is better to make the trench much wider in width. In this case, you should take into account the thickness of the formwork and backfilling with sand to protect the foundation in case of freezing and expansion of the clay soil.

Creation of formwork and reinforcing belt

For formwork, support pillars are used, which are driven into the ground or installed during the process of pouring the concrete pad. Sufficiently thick boards are sewn onto the supports (we previously looked at). For greater strength of the formwork structure, the opposite walls are connected by jumpers made of wooden blocks, and supports are installed on the inside.

Pouring concrete solution

For a strip foundation, high-strength concrete should be used; most often it is prepared from the appropriate grade of cement, sand and crushed stone. All materials are taken in a certain proportion, mixed and diluted with water to the desired consistency (also read the article about). During the pouring process, concrete is supplied in small portions, each layer is compacted or pierced with a metal rod. This is necessary to remove voids from the concrete mass.

Construction of a pile-screw foundation on clay soil

Steel screw piles are very popular because they can be used to build a strong and reliable foundation on any type of soil. The technology for constructing such a foundation is as follows:

Calculate the required number of piles. At the same time, it is taken into account that supports should be located at each corner of the house, at the intersection of internal and external load-bearing walls and along long walls with a pitch of at least 2 meters.
Foreign objects and large vegetation are removed from the site and the top fertile layer is removed. Then mark the places where the piles will be installed.
Now they begin to screw in the piles, for which they use a lever or a special mechanism. During the dive, the verticality of the support is constantly checked using a building level. The piles are screwed to a depth below the level of groundwater and soil freezing; if the length is insufficient, the pile can be increased. Read also.
When all the supports are installed, the tops of the piles are leveled to the same level.
To give greater strength, concrete mortar is poured inside each pile.

It is worth noting that piles are possible, but they are possible.

Foundation on piles made of asbestos-cement pipes

Very often, asbestos-cement pipes are used for the construction of pile foundations on clay soils. This option is considered the least expensive and at the same time stable on problematic soils.

Construction work is carried out in a certain order:

The installation locations for pile supports are marked, taking into account that they should be at the corners of the building, at the intersection of load-bearing walls and every 2 meters along the length of the walls.
Wells with a diameter of 20-30 cm are drilled under each support. The depth depends on the level of soil freezing.
The bottom of each recess is covered with crushed stone and compacted.
An asbestos-cement pipe is lowered into the well, a reinforcing frame made of metal rods is installed inside and filled with concrete mortar.

You can read more about this type of construction in our article about.

Foundation on clay soil is a complex task that requires certain knowledge and experience. However, even such difficult processes can be performed independently, subject to technology and expert recommendations.

Before you start building a foundation on clay, you need to know all the features of clay soil.

What you need to know about clay soil

Clay is a finely dispersed composition of particles that have the ability to absorb and retain moisture. Such soil has the property of heaving. When the soil freezes, it increases significantly in volume and can push the foundation of the house upward. The clay foundation is subject to erosion by melt and rain water, which can have a destructive effect on the foundation on clay.

Clay soils have several types:

clay soil includes 30% or more pure clay;
sandy loam – sandy loam contains about 5% clay;
loam contains up to 10% clay.

One type of clay soil is sandy loam

Using the method of test drilling, the structure of the soil layers is determined. They drill a hole in the ground to the depth of the foundation of the house. To avoid errors in the analysis of the sample, it is better to contact the regional department of architecture at the location where the construction master plan is linked and obtain a copy of the vertical survey.

From this document it will become known about the qualitative composition of the soil, the level of groundwater and the depth of soil freezing. In most of the country, excluding the regions of the Far North, the depth of soil freezing reaches an average of 0.8 m. In the north, this figure reaches 2.4 m.

If the groundwater position is above the freezing level, artificial drainage of the clay soil will be required. For this purpose, drainage ditches and wastewater outlets are constructed.

If the type of soil does not allow drainage of the foundation, then the foundation on clay will have to be built on piles.

Which foundation to choose

Pile foundation on clay

Before building a house, you need to carefully study the characteristics of the foundation and choose the right type of clay foundation.

On clay soil, three types of building support bases are applicable:

strip foundation on clay;
strip-pile;
monolithic slab;
pilewort.

Strip foundation

The foundation is only made deep. A trench under the tape is dug to a depth below the soil freezing level. At its bottom there is a cushion made of two layers of sand and crushed stone. The trench must be wider than the foundation so that it is possible to install the formwork without interference. Then roofing felt or polymer film is laid. The waterproofing coating will block the path of moisture penetration to the foundation structure.

The height of the formwork should be higher than the top surface of the concrete. The edges of the waterproofing material are raised to the same height.

The reinforcement frame is mounted nearby on the site, then its elements are lowered into the formwork. Sections of the frame are connected with knitting wire and form a single structure of reinforcement.

In cross section, the foundation of the house is a trapezoid. The bottom base will be one third wider than the top surface. This type of construction gives high stability and increases resistance to heaving of clay soil.

The concrete mixture is poured continuously. This will prevent the concrete from delaminating as it hardens. As liquid concrete enters the formwork space, it is compacted with a vibrator or available tools (shovel, wooden hand tamper).

To build a basement, a pit is dug. Foundation walls are made to the height of the basement.

Monolithic slab

Monolithic reinforced slab is the most expensive option for supporting a house. It is made from concrete grade no lower than 300. The depth of the foundation slab depends not only on the freezing of the soil and groundwater, but also on the total weight of the structure.

The reinforced concrete monolith creates the effect of a floating slab. This gives independence from any shifts in the clayey base.

Work on the installation of a sand and gravel cushion, waterproofing, formwork, reinforcement and concrete pouring is carried out in the same way as during the construction of a strip foundation.

Strip-pile foundation

Shallow foundations are erected for light wooden houses and for brickwork. A trench under the monolithic tape is dug 50 - 70 cm below the groundwater level.

To enhance reliability and load-bearing capacity, shufta-type support piles are installed every 2 meters below the soil freezing level. After removing the formwork, all cavities are filled with compacted sand. Watch the video on how to build a strip foundation on clay.

Pilewort

At the design points, piles are driven until they reach dense layers of soil. In some cases, due to special conditions of the soil, pile bushes are made (piles from one point diverge downwards in different directions) or hanging piles are installed (posts are driven in at an angle, ensuring stability due to lateral friction against the soil base).

The upper ends of the piles are tied either with a metal profile or with reinforced concrete beams or slabs. The most reliable and durable option for supporting a house is a grillage made of a monolithic slab on piles.

Clay foundation

Clay is suitable for building a foundation for a greenhouse

Clay foundations are used for light buildings (greenhouses, sheds, utility rooms). In places where clay soils are available, the foundation is made of clay. The clay soil is mixed with water, adding sawdust, sand or any available filler. A shallow trench is dug and formwork is installed. Then a continuous strip is formed from the resulting mixture in the formwork space along the entire perimeter of the future building.

The cross-sectional dimensions of a clay foundation are selected based on the type of structures resting on it. After the clay has dried, the formwork is removed. Firewood is laid out around the resulting structure and lit. In the process of burning wood, the clay foundation is fired. As a result, a strong support for light buildings is obtained.

Building foundations on clay soil is a very important task. When something happens to the upper building structures, it requires local repairs. And an incorrectly laid foundation can “destroy” the entire house.

If the developer is not confident in his knowledge and experience in constructing structures of this type, then it is better to turn to specialists.

A foundation on clay causes many difficulties during construction, especially when groundwater is close to the ground. Clays saturated with water are record holders for the strength of frost heaving. Foundations and all other underground structures on clay are affected by these forces, causing serious deformations, cracks, failures and destruction. Of course, mostly in cases where a clay foundation is designed with errors and without taking into account the influence of foundation soils.

Frost heaving of clays

Permafrost science is a branch of engineering geology and a very serious science, which, among other things, develops special methods for studying the characteristics of frozen soils and methods for high-quality construction on these extremely difficult soils.

Wet clay freezes in a rather complex way. The clay does not freeze as a whole at once, since it has pores, although you won’t notice it visually. First, water in large pores becomes ice and cements soil particles, as a result of which weak clay turns into rocky soil, which can only be mined with a pickaxe, or even with explosives. The increase in volume during freezing is about 9%. It is clear that in the spring this rock will turn into mud.

But the matter does not end with the freezing of water in the pores of the soil, since during the long winter there is a process of constant increase in the moisture content of the clay, due to the suction of groundwater from the lower horizon. And if the ground level is high and this water is nearby, the frozen soil can absorb so much of it that it forms entire layers of ice, and at the same time increases its volume so much that it can easily and simply lift a house, swell asphalt concrete road surfaces, deform railway tracks and the airfield runway etc. Tens of centimeters of heaving in winter is not uncommon.

And in the spring, the result of this phenomenon, called frost heaving, is obvious - the liquid melted soil becomes mud, the asphalt is destroyed, there are holes and potholes on the road, buildings have subsided, and the foundation has cracked. And repairs often won’t help.

Another “interesting” phenomenon is that frozen water-saturated soil tends to freeze with the foundation, including the pile, as with any underground structure. The pressure from frozen soil that arises in this case is so great that it breaks the piles. These forces act tangentially on the vertical surfaces of foundation walls, both destroying and pushing buildings out of the ground. One of the effective means to prevent all this is to arrange vertical waterproofing of the foundation using rolled materials; this will significantly reduce adhesion and force the frozen soil to “slide” along the surface, while the tangential forces of heaving will be largely leveled out.

But professional builders and road workers not only have a lot of troubles from the process of frost heaving, but they fight it quite effectively. There are different methods, sometimes using chemistry. But on your site, the best method of combating abyss is a simple remedy - drainage. If you managed to drain the water by arranging an effective drainage system, then heaving either will not occur or will be much weaker.

But before you fight, you need to recognize the enemy by sight. To build a permanent house on clay soil, geological research and design calculations are needed. Contacting a design organization in this case will be a practical solution, and construction in compliance with technology and according to a project carried out by specialists will save you from unpleasant surprises in the future.

In the case when a bathhouse, garage or small house is being built, it is possible to make a high-quality foundation on clay soil yourself, having studied the issue technically and being guided by building regulations.

Determination of soil characteristics

First you need to decide on some characteristics of the soil on your site:

The content of clay particles in the soil
Soil moisture
Soil freezing depth (SFD) for a given area
Groundwater level (GWL)

Many people don’t need to be taught how to visually determine the composition of the soil; everyone who deals with the soil has a good understanding of what kind of soil is under their feet.

If you take a lump of wet soil in your hand, knead it and try to roll it into a sausage or make a “cord”, the sand will simply crumble, loam or “greasy” sandy loam will first roll into a sausage, but will quickly crack and fall apart into pieces. But if a whole and elastic “sausage” is rolled in the palm of your hand, it is clear that this is clay. That is, you have a soil foundation for construction of particular complexity.

Humidity can also be estimated without laboratory methods, although not in exact percentages. If you leave a lump of clay soil in the air and it takes hours to dry, the clay is wet. It is this kind of clay that can cause strong seasonal heaving and movement.

The groundwater level of the site is determined if there is a well. If not, you can determine it when drilling a well or pit. Information can also be obtained from neighbors, because during construction they often dig wells and drill wells.

Soil freezing depth

The depth of soil freezing is reference data; it is included in construction regulations, classified by construction area.

Table with standard freezing depth

City	Standard freezing depth for loams and clays	Standard freezing depth for dusty and fine sands	Standard freezing depth for large and medium sands	Standard freezing depth for coarse soils
Moscow	1,35	1,64	1,76	2,00
Dmitrov	1,38	1,68	1,80	2,04
Kashira	1,40	1,70	1,83	2,07
Vladimir	1,44	1,75	1,87	2,12
Tver	1,37	1,67	1,79	2,03
Kaluga	1,34	1,63	1,75	1,98
Tula	1,34	1,63	1,75	1,98
Ryazan	1,41	1,72	1,84	2,09
Yaroslavl	1,38	1,80	1,93	2,19
Vologda	1,50	1,82	1,95	2,21
Nizhny Novgorod	1,49	1,81	1,94	2,20
Saint Petersburg	1,16	1,41	1,51	1,71
Novgorod	1,22	1,49	1,60	1,82

Choosing the type of foundation on clay

The choice of type of foundation on clay depends on both the depth of freezing and the height of groundwater passage.

Shallow strip foundation on clay

If the groundwater level is much lower than the freezing depth, then the choice for a small structure is MZLF - a shallow monolithic strip. There are several features:

The section of the tape should be taken in the form of a trapezoid resting on a wide base, or a T-shaped widening of the sole of the tape should be made. These measures will lead to an increase in the area of the foundation base, and as a result, to a decrease in the specific force on the foundation from the soil.

A cushion is required under the foundation - at least 40 cm of coarse sand, compacted layer by layer, in layers up to 10 cm. The cushion can be made of crushed stone or a sand-gravel mixture. The main thing is that this foundation will drain, that is, it will remove water from the foundation. Another function of the pillow is that it acts as a shock absorber.

External vertical waterproofing of the foundation is mandatory, and it must be done using high-strength roll waterproofing materials. By creating a sliding surface, waterproofing will weaken the adhesion of frozen soil to the foundation walls and will not allow clay to stick to the foundation. As a result, the frozen clay, which has increased in volume, will move with its mass separately from the foundation wall, without causing it to shift, rise and collapse. Insulating the foundation is also a rational measure. Of course, if a heated basement is being built, insulation is done in any case.

The blind area around the building, which contains an insulating layer as part of the “pie,” significantly reduces the effect of frost heaving forces on the foundation.

Monolithic floating slab on clay

The second case, when groundwater passes close to the surface, is more complicated. In this case, it is possible to choose a base in the form of a reinforced monolithic floating slab.

This foundation will eliminate the problem of the influence of heaving and seasonal movements on the building, since by its design it is designed not to fight with the foundation soil, but to move with it, like a boat on the surface of the water. That is why this base is called “floating”. One serious disadvantage is that this foundation is the most expensive.

Pile foundation with widening on clay

Another possible type of foundation is a pile foundation with widening. Bored piles are buried to a considerable depth, below freezing of the soil, and in addition, they are not made with a constant cross-section, but with a “heel”. The widening at the end of the pile prevents the forces of frost heaving from pushing it out of the ground. One of the technologies for constructing piles with widening, TISE technology, is used by many private builders.

The pile-screw foundation has also earned the respect of private builders. The technology of creating a reliable foundation at relatively low material costs and time is becoming increasingly popular. Piles, made of seamless steel pipes with a certain wall thickness, which have undergone anti-corrosion treatment both inside and outside the pipe, have helical blades at the ends. These blades make it possible not only to drill a pile into the ground, even frozen ground, but also perform the task of widening the base of the pile. The internal cavities of screw piles are filled with concrete to prevent metal corrosion.

One of the effective measures to combat heaving remains drainage and water reduction on the site - that is, the installation of a drainage system.