The soils where the construction of the building is carried out can be divided into several main types. One of the most common soils is considered to be soils with a high clay content, which are not entirely favorable for construction.
The fact is that clay is quickly eroded by water, and therefore the foundation on such soil can behave unpredictably. But what if the construction of a house is allowed only on this site? To build a beautiful and durable house on such soil, you need not only to know the type and structure of the soil, but also to choose the exact foundation.
Soil features
Clay is a fairly plastic soil that deforms under the influence of water. Its plasticity depends on the composition of the soil, since different types of clay have their own plasticity. Being practically on the surface, the clay soil is easily eroded by melt, rainwater, exposing the foundation.
Therefore, before construction, it is recommended to determine what type of soil in your area. To do this, analyze the condition of the soil in selected areas, determine the depth of groundwater, establish the level of soil freezing. Basically, the soil at the site is heterogeneous, the clay goes in layers, mixing with the sand. The conclusion about which foundation is better to choose should be taken taking into account all the ready-made data.
This check is best done in the spring, when the groundwater rises to its highest level. Having received samples from several sites, you will have an idea of what the structure of the soil is, its moisture.
Foundation selection
Construction work on such soil is carried out quite rarely, but what to do if there is no way out. On such soil, the foundation must have the highest resistance to deformation.
Tape
The best option for clayey soil will be a columnar foundation, the most popular is the pile type. Although this is an inexpensive option, its strength is quite high:
- the difficulty lies in the fact that rather deep drilling under the piles may be required. But this will be a guarantee of the reliability and durability of the entire structure;
- in the selected area, holes with a diameter of more than twenty centimeters and a depth below the freezing point should be drilled. Gravel is poured to the bottom; special drainage can be used. Then a pipe is installed, which is poured with good quality concrete. It should be tamped in layers. A reinforced frame is required, for which it is better to use metal rods. The step of fixing the tables should not be more than two meters;
- with such a foundation, damage to any structure as a result of soil movement is excluded.
If you are starting to build a house, the main type of work you need to do is to lay the foundation. Here you may encounter a number of urgent problems. One of them is soil type. One of the most difficult types of soil on the site for construction is clay soil. Clay belongs to the heaving category of soil, so the foundation on clay must meet certain requirements.
The thing is that clay can lose its original shape, being washed out by water. And in winter it can expand. How to be? What is the best foundation for this type of soil? You will find answers to these and other questions in this article.
Clay soil types
To begin with, consider the varieties of such soil. It is divided into groups, depending on the percentage of clay in the composition. There are three groups of clay soil:
- Clay - in such a soil, the soil content is in the range of 30% or more.
- Loam - in it the percentage of clay is equal to 10% of the total composition.
- Sandy loam contains the smallest amount of clay in the composition, which ranges from 5 to 10%.
Depending on the type of soil, the foundation for the house is also chosen. How to do it? Let's look at suitable options for clay soil, which will fulfill their main purpose without problems.
Choosing the right foundation on clay soil
In fact, on such soil you can arrange almost any type of foundation, it all comes down to your capabilities and site characteristics. Regardless of which type of foundation you choose, backfilling is mandatory. The work consists in digging a trench under the foundation and forming a cushion of sand and rubble. This significantly increases the cost of construction, but only there it is possible to provide a reliable foundation.
Note! It is especially important to do this in those regions where winters are cold and long.
The main criteria that determine the choice of the base are clay content and the level of soil freezing. In the event that the water in the soil is above the freezing point, a drainage trench is additionally constructed to drain the liquid. The foundation for a house on clay soil can be of the following types:
- strip foundation;
- pile foundation;
- shallow slab foundation.
Let's look at the features of the device of these types, as well as their pros and cons of each base.
Strip foundation on clay soil
Ideal for home on sandy loam, with little clay inclusions. In some cases, loamy soil is also suitable, only it is important that the groundwater is not close to the surface. The base will look like a monolithic strip reinforced concrete structure that copies all load-bearing walls. If you want to build a cellar or garage in the house, then this is the only possible option.
How is the foundation construction process carried out?
Foundation advantages:
- well withstands loads and has a high bearing capacity;
- long service life, from 75 to 150 years;
- the presence of a basement floor, garage or cellar.
Flaws:
- large labor costs;
- high cost;
- it is allowed to make a deeply buried version for sandy loam and loamy soil.
Slab foundation
An excellent option if we talk about clay soil. In this case, the mass of the structure is evenly distributed on the concrete base, and in the event of erosion or displacement of the soil, the entire slab will be displaced, and not a separate part of it.
In this case, you can use the shallow version. But, the slab should be installed on a pillow, based on sand and stone, as in the first option. The depth of the trench is equal to the thickness of the slab, plus an additional 30 or 40 cm. The base is covered with sand and poured with concrete. Formwork is made around the entire perimeter of the base, from the inside it is sheathed with waterproofing. Reinforcement mesh is installed inside. The entire ground part is poured with concrete mortar at a time.
Foundation advantages:
- high resistance to erosion of clay soil, subsidence and seismic activity;
- long service life, up to 150 years;
- during construction work, you can change the layout of the building, without any significant changes to the base.
Flaws:
- high cost of materials and land works;
- there is no way to build a basement or garage under the house;
- labor intensity.
Pile foundation on clay soil
It is considered the best option for this type of soil. You can choose from a pile or pile-strip base. Depending on the size of the piles, you can reach the depth at which hard ground is laid. It will not be subject to erosion and freezing, which will create the perfect base for the house.
When calculating the pile foundation, a certain load is planned for each pillar, which it will withstand. Taking into account the load and the burial depth, you can choose different types of piles:
- Screw piles.
- Driven products.
- Bored (at shallow depth).
How is the process carried out? In selected places, iron screw products are screwed in thanks to special levers with their own hands. If we are talking about driven piles, then they are installed using special equipment. As for bored products, they are reinforced concrete supports, which are created immediately on the site. To begin with, a well is drilled, liquid is pumped out of it, and a sand cushion is arranged. A pipe is placed in the hole, which will be reinforced and filled with concrete. Difficulty can arise when pouring deep pipes.
The piles are mounted in one row along the perimeter of the building under the load-bearing walls. In the case of a massive building, the piles are mounted in the form of a field, in uniform rows. A reinforced concrete beam (grillage) is installed on top of them, which connects the foundation into one whole. It distributes the load evenly over the entire ground. You can see this in the picture.
Foundation advantages:
- long service life, equal to 200 years;
- excellent ability to withstand heavy loads and deformations;
- low cost of work;
- piles can be used more than once;
- installation is carried out regardless of the season.
Flaws:
- there is no way to create a basement;
- in some cases, you cannot do without special equipment;
- some parts can corrode.
Conclusion
It is clear that no one wants to choose clay for the foundation. But, this is not a disaster, as there is a solution. It is enough to adhere to the tips mentioned in this article. We warn you in advance that you cannot save on such construction, since in the future you may encounter a number of problems that will cost tens of times more.
The foundation on clay, 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 characteristics of the soil on which the house rests have a great influence on the reliability of the structure.
Therefore, it is extremely important at the design stage to choose the best option for the foundation, corresponding to the geological structure of the building site. This article will help private builders who are going to build a house on clay: which one is best for such a case?
The main problems when building a foundation on clay soils is the likelihood of subsidence, breakage and swelling of the base of the building. This can happen under the influence of too much pressure on the foundation, or due to insufficient depth of its laying.
In the zone of particular risk are houses whose walls are built of lightweight building materials - foam blocks, for example (). The heaving forces in clays can be balanced only by the heavy above-ground part - brick, stone or reinforced concrete.
Types of clay soils
Clay soils include:
- sandy loam;
- loam;
- clay.
Clay is a collection of small (up to 0.01 mm) particles with a small admixture of sand and dust. It is characterized by flowability and high plasticity. It is possible to 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 and heavy. Loams are prone to frost heaving, so the construction conditions on them are classified as difficult.
The sandy loam contains no more than 5 percent clay. These soils have another name - quicksands, 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 way out, pile structures with a crushed stone base are chosen.
Choosing the type of foundation
When building a foundation on clay soil, regardless of the type chosen, the main rule must be followed: the width of the base should be 25 percent or more larger than the upper part of the structure (). A pillow made of sand and gravel (or crushed stone) is mandatory.
Strip foundation
Clay strip foundations are suitable for heavy buildings and light timber structures ().
But if, in the first case, a buried structure is set up, the bottom of which is below the freezing line, then in the second case, preference should be given to a shallow foundation: on clay soil, the light aboveground part cannot become a counterweight to 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 uniformity of the layers throughout the construction site.
Only in this case, uneven deformations during heaving of the soil will not threaten the structure.
Slab foundation
Clay slab foundations 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. With any movement of the soil, the slab moves with it, maintaining the uniformity of the load.
The slab is poured practically 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 sole of such a foundation has a maximum area, even the 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 being built on sandy loam and other types of clay soils. Pile fields are arranged under buildings of a large area: under the walls, supports are installed in the form of rows, and under the columns - with bushes.
When choosing the type of foundation on clay soil with a high level of groundwater, 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 should be carried out with a widening downward.
Screw piles have proven themselves well - structures equipped with screw blades in their lower part). When the screw is screwed in, the density of the soil around the support is maintained - the blades do not loosen the soil, but cut off individual layers. The design depth of the screw is below the aquifer and the freezing point.
Scheme of the pile - screw foundation on clay soil. 
Conclusion
The construction of a foundation on clayey soils is a complex business, but quite feasible. The main thing is to know all the advantages and disadvantages of such soils and use the former correctly, avoiding the latter.
Video about what clay is dangerous for the foundation.
If the construction site is located on clay soil, it is necessary to familiarize yourself with the nuances of soil masses and their characteristics. For this, a preliminary analysis of the soil, its bearing capacity, the depth of the aquifer, the freezing point, etc. is carried out. But it is worth considering the types of clay soil, so that the construction of the foundation of the house is not too expensive.
Soil types
To determine “clay”, the soil must contain at least 30% of this material, loam is 10% of clay, and sandy loam contains 5-10% of clay. There are types of glacial and alluvial clay. The glacial is distinguished by a very high density and excellent bearing capacity, which is revealed only in deep layers. Alluvial clay is a plastic soil, so it is better to completely abandon construction work on such a site or equip the structure on piles.
Nuances of foundation construction technologies, types of bases
When starting the construction of the foundation of a house on clay, it is important to remember that the soil does not tolerate water, therefore it is important to conduct geological surveys. For example, maybe, in your case, clay layers alternate with sand layers, and you will have to take into account the depth of each layer. Performing work on your own, you can determine this fact by digging pits, the depth of which depends on what depth the type of foundation being built will be.
Important! While maintaining the heterogeneity of the soil, it is better to use crushed stone or sand filling, taking into account the moisture content of the layers. And with a high level of groundwater discharge, it is better to give preference to the pile foundation.
Shallow foundation on clayey soils
The design makes one think about the low bearing capacity and low strength of the clay soil. To avoid the danger of cracking and distortion of the foundation of the house, it is better to use a reinforced concrete slab, which is ideal for this type of soil composition.
A floating foundation is also allowed, the strength of which does not depend in any way on the intensity of soil erosion. The slab is poured independently using concrete of especially strong grades. But you can take a finished slab, additionally reinforced. The depth of the bookmark will depend on the weight of the house. And for the installation of the slab, you will need a foundation pit with a cushion of gravel and sand.
Advice! The high price of the project is considered a disadvantage of arranging such a foundation.
Strip foundation
Only a recessed strip foundation is allowed. Construction begins with digging a trench above the freezing point. Then the bottom is covered with gravel, sand and it is important to consider the depth of the trench in order to equip the correct thickness of the pad. Then, on top of the sand, a layer of insulating material (polyethylene) is lined, which reduces the force of pressure from the weight of the house on the foundation on clay soil. When arranging the strip base, before pouring the concrete composition into the trench, it is necessary to mount the reinforcement connected to each other.
Advice! Arrangement of the tape base is justified in cases where it is necessary to have a basement of a house being built on heterogeneous soils. And if the construction is carried out on heaving soils, it is worth giving preference to the foundation on a monolithic slab or piles.
Pros of a tape base on clay:
- Possibility of arranging a basement or basement;
- High structural strength;
- Long service life without loss of quality characteristics;
- Providing a reliable foundation for the building.
- High cost of work;
- The need to consume a large amount of material;
- Labor intensity.
Pile foundation on clay
This type of base is considered to be especially popular due to the provision of sufficient strength and stability to the entire structure. At the same time, the type of pile supports is large, which allows you to choose the most suitable elements for homogeneous clay and heterogeneous soils.
Important! When deepening piles, it is necessary to reach dense layers that are not subject to freezing, displacement due to filling with aquifers. The immobility of these layers will protect the base, and therefore the structure, from all destructive factors.
Experts recommend the construction of a pile foundation on clay by means of driven or screw piles, choosing from which type is more economical and practical. But in some cases, bored piles for a house are acceptable, the installation of which requires drilling holes, pumping water, reinforcement and concreting. At an increased cost, this method guarantees exceptional base strength.
Pluses of a pile foundation:
- Increased durability for a long time;
- Resistance to heavy weight loads;
- Ideal for unstable soil masses.
Flaws:
- The threat of exposure to corrosion (processing of piles with special compounds will help to minimize the threat);
- The need for additional costs;
- The absence of a basement room, or the obligatory performance of labor-intensive and costly work.
Columnar base on clay
If you plan to build a wooden house without a basement on clay, this option is better than any other. Therefore, when choosing what kind of foundation will be, it is worth paying attention to the least costly way of arranging the foundation. The technology is simple, you need to dig in the pillars with a step of at least 1 meter, and the base can be pre-fired piles made of oak or pine wood. The pile holes cannot be higher than the freezing point of the soil, but must fall below at least 2 meters.
Pros of Columnar Bases:
- Affordable price;
- Efficiency of installation and the ability to carry out work with your own hands;
- The use of a small amount and range of materials.
- Short service life;
- Low bearing capacity, for buildings of large mass it is better to choose a different base;
- Cannot be used on moving ground.
Considering all the features, you can always choose which foundation is more suitable for arrangement on a construction site in terms of strength, efficiency and speed of construction. However, considering these factors, one cannot ignore the mass of the structure, the water content of the soil, the number of storeys of the building and other characteristics that affect the operation and durability of the house.
The most crucial moment in the construction process is the choice of the foundation. The most problematic for building a house is considered to be clay soil. The building, both from a bar and from a log, is lightweight, therefore, several base options are possible. Which one to choose, reviews from experienced developers can help, but it is very important to heed professional advice.
What soil is considered clayey
According to its parameters, clay soil in different areas can be very different from each other. In fact, this term can cover both clay and loam and sandy loam. Consequently, the construction of a house from a log or a bar, according to all the rules, should begin with an accurate determination of the composition of the soil, the percentage of clay in it.
Loose clay post requires a special approach to the choice of the foundation
Pure clay is extremely rare, usually this term means soil with 30% of its content. In the presence of 10% clay, this is already loam, and from 5 to 10% - sandy loam. The clay itself can be of two types: glacial and alluvial. In the first case, with a sufficient depth of occurrence, the bearing capacity is large, and the soil is able to withstand even a concrete foundation. When glacial clay is the top layer, it is very malleable. Alluvial clay, with its even greater plasticity, is the most difficult option. Under load, it can float and cracks appear on the foundation and walls of the house.
Attention! It is necessary to determine the composition of the soil at different points of the site by drilling pits to the same depth at which you intend to arrange the foundation. The structure can be very heterogeneous. When deciding on the type of foundation to be erected, one should proceed from the depth of the clay layers.
Foundation selection
Wood is not a very heavy material, therefore, lumber or log walls create little pressure on the base, and this is an advantage when building a house on clay soil. In any case, the foundation must be laid correctly, otherwise, due to the heaving inherent in clay, the building may turn out to be skewed after winter frosts. Currently, many masters upload videos of their work to the network from which you can also get a lot of useful information.
A competent approach to laying the foundation is the key to a strong and reliable home for decades
Experts believe that the best constructive solution for a wooden house is to use piles when constructing a foundation. Other options are also possible:
- tape, allowing you to arrange a basement under a log house;
- slab;
- combinations of solutions of these foundations.
To dwell on one, consider each.
A trench for this type of foundation must be dug in such a way that its bottom is below the level at which the groundwater is located. Having completed this work, you can erect a foundation strip:
1. Fill the bottom with gravel 10-15 cm, then sand. The thickness of the last layer depends on the height of the trench walls - the higher they are, the more sand you need to fill up.
2. Lay the waterproofing on the walls using roofing felt or plastic wrap.
3. Pour concrete - 3-5 cm. Let it harden.
4. Install the formwork on the hardened base so that the future walls are 10 centimeters narrower than the foundation.
5. Form a reinforcing frame by tying the reinforcement into meshes.
6. The concrete is poured in pieces, approximately 17 cm, and each layer is tamped. The concrete is completely hardened for 28 days, then the formwork is removed and a waterproofing compound is applied to the base by coating or spraying.
Laying strip foundations on clay soil
If everything is calculated and done correctly, then heaving soil is not terrible for such a base, but it will cost a lot. In the northern regions, digging will have to be deep, sometimes up to 1.5 m, and this implies the use of construction equipment and the delivery of large quantities of the same rubble, sand, cement and metal for reinforcement. Experts allow the construction of this type of foundation only on loam or sandy loam.
Advice. To increase stability and reduce the impact of the soil on the structure during its expansion, the base of the foundation is made 1/3 wider than the rest of it.
"Floating" plate
This is the name of a slab foundation, which implies the presence of a reinforced concrete slab under the entire area of the structure, located at a depth that depends on the weight of the house. The base with a uniformly distributed load from the building, in the event of ground movements, will not be displaced in parts, but completely, therefore, deformation does not threaten the building.
The concrete slab is laid not on the ground, but on a previously arranged gravel-sand substrate. As in the case of the tape base, it is necessary to dig a trench, fill up crushed stone, sand. The depth should exceed the thickness of the slab by an average of 35 cm. When the groundwater is high, it is also necessary to drain it by installing a drainage system.
The slab foundation is laborious to install, but it can last for more than a century.
Such a foundation will last a long time - up to 150 years, but the technology is complex, the installation itself is laborious, you cannot do without heavy equipment, a lot of materials will be needed. A single foundation can cost more than a house. And if you have to build a basement, then you will need to carry out a number of additional work, which will further increase the cost of construction.
Pile foundation
The pile foundation is considered by professionals to be the most reliable for clay soil. The foundation is created by selecting the length of the piles so that they rest on solid, stationary soil. More often than others, metal piles are used - driven or screw.
A pile foundation is considered the most reliable solution for a house on clay soil, but this design does not imply a basement
For the installation of driven piles, you need to involve special machines, and screw piles can be screwed in on your own, having one or two assistants. Screw piles can be installed at different depths, which is convenient if the soil on the site chosen for construction has a different structure or noticeable slopes. The stages of work for the construction of such a foundation are as follows:
- According to the drawing, the number of piles is calculated, the load on each element is checked, the area is cleaned and the markings are made. Be sure to provide supports under the outer, load-bearing walls. A "bush" of piles is arranged under the columns.
- Start with a corner pile. They are screwed in with a svaykruk or a lever, constantly checking the verticality.
- The floor is marked, marks are made at this level on the piles and the excess is removed with a grinder.
- To strengthen the piles, their body is poured with concrete, but if the house made of timber or logs is small, then this operation can be dispensed with.
- To tie the foundation in one piece, a wooden beam or channel is laid on the piles. For wooden buildings, timber is most often used as a strapping, but on the piles there should be heads with fastening holes.
This design is durable, resists deformation well, and is the least expensive. The main disadvantage is called the impossibility of arranging a basement. More details about this method of editing can be found in the video from competent masters.
It is impossible to unequivocally give advice on the foundation for a log house or a lumber erected on clay soil. To do this, you need to know the percentage of the clay component, the level of freezing, the occurrence of the water layer, and the weight of the building. The main thing is to study the composition of the soil, then you can make a competent decision about the type of foundation.
Video: Building a foundation for a house from a bar
