Strip foundation on a swampy area. Do-it-yourself foundation on swampy soil

Construction on marshy soils can be compared to an extreme sport due to the unpredictability of the results. The main problem of a house on swampy soil is the very poor bearing capacity of the soil and excess moisture. It is possible to build in such conditions only using a guaranteed effective and stable foundation. Not all options for foundation structures will be able to hold the building in a stable position for a long time.

Which foundation is best to use in swampy areas?

In each specific case, the choice of a specific foundation scheme depends on the condition of the soil, the level of groundwater and the types of soil in a particular area. Therefore, before making a decision, it is necessary to conduct exploration and assessment of the nature of the soil, sources of groundwater that flood the area, and the depth of solid rock layers.

Advice! If you can qualitatively assess why a given area is flooded and how to deal with the causes of flooding, you can reduce the cost of a foundation in a swamp several times.

Depending on the results of the study, you can choose the most optimal option for the foundation for the house:

Strip foundation with enhanced drainage and deep drainage. Although experts do not recommend using strip foundation systems for waterlogged areas, it can be used for a certain type of soil in a swamp. For example, for soil with a large amount of coarse river sand, with deep aquifers and the absence of natural springs and springs on the surface in close proximity to the building;
Pile foundation on bored or concrete supports. When building in a swamp, such a construction of a foundation block is often the only correct and reliable option if the soil gets wet to the point of a watery porridge. In this case, the piles are driven to the level of hard layers under the bottom of the swamp;
Floating or slab foundation can be used on very viscous and dense soils in the absence of flooding of the area with flood and rain water.

When choosing a specific scheme, it is advisable to perform full deep drainage and drying of a small area of soil of several square meters. By digging a hole one and a half meters deep, you can try to get an idea of the soil of the swamp on which you plan to build a house.

Which foundation in a swamp will be most effective?

The main problem in the construction of any buildings is not the technical or technological issues of arranging foundation systems in areas where swampy soil dominates, but the huge costs associated with a large amount of additional work and the need to ensure effective drainage from the basement parts of the foundation. A strip foundation may seem like the cheapest option, but not every swamp can build one.

Strip foundation for a house in a swamp

The construction of a foundation in the form of a strip in terms of the volume of materials used and the amount of work will be the cheapest from the list above. If the results of a study of soil geology show the presence of coarse-grained sand layers up to one and a half meters deep, it is quite possible to get by with the construction of a classic strip foundation. Most often, this situation arises if the owners of the future building choose an area for construction in the floodplain of a river, in a lowland, where swampy and waterlogged soil is associated with the presence of a river.

The construction of a strip foundation in such a swamp is possible only if the following measures are taken:

The site must be equipped with a very powerful drainage system using hydraulic barriers to prevent the penetration of water from nearby areas;
The foundation for a house on the site is installed in the highest place, taking into account the possible direction of rain flow;
Highly efficient drainage system for soil adjacent to the foundation.

Before starting work on building a foundation in a swamp, it is very important to make sure that there are no underground springs, of which, as a rule, there may be a lot in such an area. If reconnaissance confirms their presence, it is better to abandon the use of this type of structure in the swamp in favor of other options.

Pile foundation in a swamp - the optimal solution for heavy houses

If you are planning to build a solid brick house with an attic, you will need to use foundation systems with maximum load-bearing capacity. For a swamp, this is the pile version of the foundation. The essence of the design of such a foundation in a swamp is to install the required number of concrete or bored piles resting on solid layers of rocky soil under the bottom of the swamp. The cost of such a foundation block for a swamp will be many times higher than the previous option. Unlike strip schemes, which can support relatively small frame-type houses in a swamp, a pile version of the foundation for a house in a swamp can easily support a brick building of several floors for many years.

In this case, to build the foundation you will have to use special equipment with which you can drill and fill bored piles. Doing this amount of work manually is quite difficult. The depth to which the pile support is installed can reach 5-7 meters, which is determined by the geology of the swamp.

If hard soil layers are located at a relatively shallow depth of 2-3 meters, screw piles can be used. They are much cheaper, and in some cases you can even install them yourself. As a preventive measure, the top layers of soil to a depth of 60-70 cm are often removed, road geotextiles are laid and backfilled with a sand-crushed stone mixture. The upper heads of the piles are connected by a powerful grillage or a steel frame made of paired channels No. 200.

If the swampy area has a top layer of hard soil, which is often found on peat bogs and lake remains, it makes sense to use it as it is simpler and more accessible to make with your own hands.

Slab foundation for a small house

The advantages of a foundation system in the form of a continuous monolithic slab include enormous rigidity and strength. Such a foundation structure will not float up and will not tilt, even if the water level of the swamp rises. A good slab foundation is suitable for frame, aerated concrete, foam concrete houses that require special measures to ensure frame rigidity.

The cost of building a slab foundation in a swamp will cost you 20-25% less than the pile version. If we compare the construction of a foundation system on pile supports and a slab version in ordinary dry soil conditions, then the cost of the slab will be as much as 40% more than the pile system.

The slab construction technology will require digging a pit 60-70 cm deep, filling it with a layer of sand and a layer of crushed stone, laying film waterproofing and installing panel formwork around the perimeter of the pit. For a slab foundation structure in a swamp, in addition to high-quality waterproofing, it will be necessary to lay more powerful steel reinforcement. Most often, reinforcement with 12 mm rods is used with the installation of lintels and crossbars. The base and top of the slab must be insulated with expanded polystyrene or foam glass.

Building a house in a swampy area is not as simple as it might seem at first glance - the soil in such areas is oversaturated with moisture, and the presence of small and solid soil particles in it leads to the formation of quicksand, which are characterized by their instability. And that's not all, such soil is significantly susceptible to heaving, and with the onset of heat, erosion by groundwater. It is these nuances that need to be foreseen when approaching the question of how to build a foundation in a swamp? This will be discussed in this article, in which, together with the website, we will talk about the most suitable foundations for such soil and the features of their manufacture.

How to make a foundation in a swamp photo

How to make a foundation in a swamp: floating monolithic slab technology

This is the easiest foundation to make and is best suited for wetlands where the groundwater level is very high. Its essence is to create an independent floating concrete slab, the task of which is to uniformly distribute the load from the building over the entire soil area. A solid monolithic slab, perhaps even equipped with stiffening ribs, perfectly resists soil heaving, quicksand, and many other features of such soils. The disadvantages of such foundations for a house include the need for a flat area - on a sloping wetland, the slab will simply slide down, and it is not a fact that during such a movement it will remain intact. Also, as a disadvantage, it should be noted the huge amount of necessary concrete and reinforcement, which undoubtedly affects the cost of such a foundation.

Making a foundation with your own hands in a swamp is quite simple. To begin with, in those places where it is planned to erect walls, trenches are dug with a depth of 0.5 m and a width of 800 mm at the top and 600 mm at the bottom. It turns out to be a kind of cone, the task of which is to increase the plane of contact between the foundation and the soil, which leads to a more correct distribution of the load. In addition, these same trenches will play a role in the so-called foundation stiffeners, which will increase the load on the foundation of the house. If we are talking about a relatively lightweight house structure, then stiffeners can be abandoned altogether.

Slab foundation in a swamp photo

Then everything is standard - first, a 200 mm layer of compacting sand is filled, which is covered with geotextile material on top. A concrete preparation 100 mm thick is poured on top, roll waterproofing is laid on it, and only after that they begin to pour the main concrete pad. Its production involves the use of M300 concrete and a huge amount of reinforcement, which is tied into a powerful three-dimensional frame. It should be noted that the base slab cannot be thinner than 300mm - in general, this parameter is calculated based on the characteristics of the wetland.

You need to understand that this type of foundation is not suitable for all types of buildings - if we talk about heavy ones, then here you need to pay attention to the thickness of the upper peat bog, which forms in wetlands. If its thickness is small (up to 1 m), then it is removed and a base is erected on denser soil located under a layer of peat. If the depth of the peat bog is 2 m or more, then the foundation is additionally strengthened with piles. But, most likely, this is not for you, since we are probably talking about building a light wooden house or a building made of - for such houses a standard floating cushion without additional stiffeners and installation of piles is quite suitable.

How to pour a foundation with your own hands in a swamp photo

What kind of foundation to make in a swamp: pile foundation

There are three types of piles that can be used to build a foundation in marshy areas, and all of them allow you to build a house on them that is quite heavy. Even high-rise buildings are installed with the help of piles, the mass of which can be said to be enormous.

Driven reinforced concrete piles are familiar to everyone who deals with construction in one way or another. They are driven using a special machine, which drives the piles until they reach the rocks - thus, it turns out that the foundation is not installed on swampy soil, but on a solid rock foundation.

Also, one should not exclude such advantages as ease of installation (in fact, such supports can be screwed in with the efforts of two pairs of male hands), the ability to expand them by welding a piece of pipe, transportation anywhere without the use of special equipment and, of course, their reliability and durability .

Foundation on screw piles in a swamp photo

Such piles are coated with a special composition that prevents corrosion, and their screw, which is used to immerse the pile into the soil, compacts the soil to such an extent that the piles cannot be unscrewed back without special equipment. The only drawback of such piles is the much smaller loads that they can withstand. In principle, this issue can be resolved by installing additional supports, but in such a situation the price of a foundation on screw supports will exceed the cost of a slab foundation.

As you can see, building a foundation in a swamp is not very difficult. There are, of course, some nuances, but if you carefully study the chosen technology from “A” to “Z,” then problems will not arise either during the construction process or later, during the operation of the house.

Building a foundation is always associated with difficulties and serious financial costs. In some cases, home owners pay up to a quarter of the cost of the entire house construction for the foundation. And yet, you should never skimp on the foundation. Still, it bears the load from the entire structure. So any attempt to save on quality can lead to the most dire consequences.

Example of a finished monolithic foundation

However, in some cases, building a foundation causes even more problems than usual. Of course, we are talking about a foundation on swampy soil. This soil has a number of disadvantages. Firstly, this is a low load-bearing capacity - under significant loads, the soil simply gives way and the structure fails.

Secondly, there are seasonal fluctuations in ground level. This most often happens in the spring, when due to the melting of large amounts of snow, the groundwater level rises significantly.
In this regard, special requirements are imposed on the foundation in swamps. Not everyone can answer them.

It is a number of soil imperfections that make many people think seriously - what kind of foundation in a swampy area will best solve all the problems? After all, if the foundation was chosen incorrectly, after the ground level changes, the building may simply be destroyed.

An example of a monolithic foundation in a swampy area

In addition, after a few years, the building may simply begin to sink underground from its own gravity. Therefore, solving this problem should be approached as seriously and responsibly as possible.

Fortunately, today there are several options for solving this problem. Yes, you can decide for yourself which swamp foundation best suits your requirements and financial capabilities.

. This is an excellent solution if you need to complete the foundation in the shortest possible time. The main elements are piles - reinforced concrete or bored. Using special equipment, they are laid to a great depth - most often about 10-12 meters, but in areas with particularly difficult types of soil this depth can reach 20 and even 25 meters! Having gone to such a depth, the pile simply pierces the marshy layer of soil, resting on a solid foundation.
Pile foundation installation diagram
This makes the foundation and the entire structure of the house completely immune to seasonal fluctuations in soil level - the base acts as a support for the piles, the level of which does not change depending on the season or precipitation. It is important that all the work can be completed in two to three days. The installation cost is relatively low. Such a foundation can be installed both in summer and winter. Pile foundations in swamps have proven themselves to be excellent - reliable, durable and unpretentious, they have collected thousands of positive reviews from different parts of our country.
. The most expensive and difficult to manufacture. And yet, in the northern, swampy regions of our country, it is monolithic or most often used in the construction of private and multi-storey houses. It consists of one huge, monolithic slab, buried to the level of soil freezing.
One of the options for a monolithic foundation
Even if the soil around you is very heaving, this in no way affects the reliability and safety of your foundation. The large weight of the slab (tens of tons!) eliminates the possibility of raising the foundation, which could lead to the destruction of the house. High strength allows a monolithic foundation to withstand enormous loads of compression, bending and tension without harm. Therefore, it is most often used during construction in marshy areas of our country, despite its high cost.
Shallow foundation. It occupies a niche between pile and monolithic foundations, both in terms of cost and construction time. Such a foundation in the swamp has also proven itself well.
Schematic diagram of a shallow foundation
However, it is worth considering that a shallow foundation is only suitable for - or. The fact is that the relatively small thickness of the foundation does not allow it to withstand significant compressive loads. At the same time, it perfectly resists loads from soil heaving. Since it is also monolithic, under heavy loads from the soil, it simply rises or falls slightly, like the entire house built on it. This, combined with low cost and speed of production, makes this type of foundation quite popular in swamps.

As you can see, people who decide to build a house even on problematic, swampy soil have quite a large choice. However, some of them do not want to spend extra money, preferring to build a foundation in the swamp with their own hands. Is it possible?

Which foundation is easier to build with your own hands?

Many of our compatriots prefer to carry out construction of any complexity with their own hands. First of all, because it makes it possible to save a lot of money. Of course, cases where they need to build a foundation in a swamp are no exception. So it will be useful to consider the possibility of building different types of foundations on your own.

First, let's look at the pile foundation. Alas, it is almost impossible to build it on your own, without the involvement of specialists. The fact is that only specialists have information about the thickness of the marshy layer in a certain area. In addition, they have heavy equipment at their disposal, which allows them to easily and quickly screw in piles to a depth of 10-20 meters.

Therefore, you should not even try to cope with this work yourself. Fortunately, this does not apply to monolithic and shallow foundations. In this case, the work can easily be done on your own, which will reduce construction costs several times. And even though you will need to rent a concrete mixer and, possibly, use the services of a bulldozer, the savings will be quite significant.

Construction of a monolithic foundation yourself

So, you have decided to build a monolithic foundation. Where does it all begin?
Of course, from markings on the ground. For construction, it is best to choose the second half of summer - at this time the groundwater level is close to the minimum, rains are relatively rare, and warm air will allow the concrete to harden in the shortest possible time, without the use of special construction additives, which are quite expensive.

You can start building a foundation only when you already have a ready-made house project.

In this case, you know exactly what the dimensions of the building will be and, accordingly, the dimensions of the foundation. It is desirable that the foundation protrudes beyond the perimeter of the house on all sides by 30-50 centimeters.
Using pegs and a nylon cord, you need to mark the specific place where the foundation will be located.

This is how the area for the foundation is marked

Now you need to remove the soil to a depth of 1-1.5 meters. The specific level of the foundation depends on the depth of soil freezing; this indicator can be obtained from any construction company.

Of course, when carrying out excavation work, many tens of cubic meters of earth will have to be removed. It is simply impossible to carry out such a volume of work manually with a shovel. Therefore, a smart move would be to rent an excavator and truck to remove all or part of the soil. Yes, you will have to pay a considerable amount. But you will save several weeks of continuous work.

The bottom of the resulting pit must be filled with crushed stone and distributed evenly. The thickness of the crushed stone layer should be 20-30 centimeters. After this comes the same layer of sand, which is also carefully distributed and compacted.

This stage should never be skipped.

The sand-crushed stone cushion allows you to solve several problems at once:

uniform distribution of the load from the foundation and the house over the load-bearing soil;
reducing the effect of heaving in the winter season;
rapid removal of moisture after precipitation or melting snow from the foundation.

When the sand-crushed stone cushion is ready, reliable waterproofing must be laid on top of it. Roofing material is best suited for this. Yes, it is significantly more expensive than regular construction polyethylene. But it is more durable and efficient, and is also able to withstand significant tensile loads without tearing.

Sheets of roofing felt should not only cover the entire bottom of the pit, but also the walls to a height of at least 30-50 centimeters. The purpose of waterproofing in this case is twofold. On the one hand, the roofing material layer does not allow groundwater to come into contact with the concrete before it gains sufficient strength.

On the other hand, the possibility that “concrete milk” will be absorbed into the soil is excluded, as a result of which the strength of the monolithic foundation will be reduced.

The next stage is preparing the frame from reinforcement. To do this you will need fittings and binding wire or a welding machine. A frame of appropriate dimensions is constructed from reinforcement - it must cover the entire volume of the future foundation, thereby allowing the concrete to withstand significant bending and tensile loads.

Installation of the frame can be done manually, but in this case the work will take quite a lot of time.

Therefore, it is better to use a special knitting gun or welding machine - you will save at least one working day.

When creating a frame, take into account the fact that the reinforcement should be not only at the bottom of the foundation, but also at the top. The walls of the pit need to be covered with formwork - ordinary thin tin or plywood will do.

An example of formwork installation for a monolithic foundation

The main thing is to ensure reliable isolation of liquid concrete from the ground, from which it can draw water.
After this it is the turn of concrete. It is best to use concrete grade M400 or M500 for this. Yes, you will have to overpay at least several thousand rubles. But you will be sure that the foundation will be able to withstand enormous loads without the slightest harm to itself and, accordingly, to the house that will be built on it.

It is worth remembering that to pour the foundation you will need tens of tons of concrete. So, it makes sense to spend money and rent a concrete mixer. In this case, you can get a large amount of concrete in a short time. You should not pour concrete in several stages when the bottom layer has already set - the foundation will not turn out to be monolithic, and even small cracks in its structure will lead to its technical characteristics being significantly reduced.

When the pit is filled with concrete, it must be compacted using special equipment - constant vibration allows you to fill any cracks with concrete and get rid of air bubbles in the foundation structure. Such bubbles can significantly reduce the strength of concrete.

After compacting the concrete, you need to leave it for three to four weeks so that it sets and gains sufficient strength. Setting times depend on many factors - air humidity, ambient temperature, foundation thickness and others.

Be that as it may, after a month you will receive a monolithic foundation that can easily serve you for many decades, withstanding any type of load and without losing its original strength.

That's all. Now you not only know which foundation is best suited for building houses in marshy areas, but also, if necessary, you can do all the required work yourself.

Never drying out swampy soil with moisture-loving vegetation that can be systematically moistened is not the most favorable place to build a house frame. The close location of groundwater creates seasonal fluctuations in soil, especially during spring warming. Modern construction technologies can solve the problem of how to organize a foundation in a swamp so that it can withstand the load of a house.

Soil analysis

What does swampy land represent? This is an area with a porous structure, which is 90% water. The remaining percentage is formed by chaotically located particles of minerals - peat, sand, clay. The unsystematic order of occurrence of rocks does not allow calculating the load on the soil.
Soil studies on the site will help identify the following characteristics of the area:

type of soil mass;
groundwater volume;
freezing depth;
distance of the aquifer from the surface.

The data obtained make it possible to determine the physical properties of the layers, their thickness and depth, and to characterize changes in the soil over the past few years. Based on geological expertise, you can choose which foundation to build in marshy areas.

How to explore the soil yourself?

It is not advisable for summer residents to delve into the details of geodetic surveys. Private developers need to take a number of simple measures:

selection of earthen material from four wells. The drilling depth is 5 m for wooden structures, 8 m for large stone buildings. It is better to probe the surface in the spring, when it contains the maximum amount of moisture.
Mechanical analysis is carried out by taking a small piece of earth. It rolls out in your hands and bends into a ring. A disintegrated element indicates sandstone, an unstable element indicates loam, a dense element indicates clay;
inspection of vegetation. On excessively moist marshy soils, wild rosemary, blueberries, sedge, cloudberries, horsetail and other crops are present.

Research and determination of soil type include determining changes in groundwater level.

When does the groundwater level change in a swamp?

The volume of groundwater varies throughout the year. During the thaw period, their number increases significantly. The lowest groundwater level was recorded in winter. A high aquifer imposes restrictions on building a frame in a swampy area. A moisture concentration of 2 meters or less poses a threat of flooding of trenches, pits, and the appearance of mold in the house or basement. A clear operating algorithm will help minimize the impact of springs on the life of the foundation.

Pile frame

A base designed for wetlands. Supporting elements are piles that are driven into the soil. A pile foundation in a swamp allows you to solve the problem of heaving, instability of the top layer of the earth, and allows you to smooth out the unevenness and slope of the territory.
Advantages of the structure:

low-cost, non-labor-intensive process (in 2 days you can build a supporting structure);
mounting the frame reduces the amount of earthwork: garbage removal, digging a pit, concreting;
the ability to choose building materials for piles: wood, steel, reinforced concrete;
increased strength, long service life.

It is rational to use a pile foundation in swampy, unstable terrain with a high groundwater level. There are several limitations to consider when choosing a support structure:

weak bearing capacity in horizontally moving soil;
additional financial costs for the arrangement of the basement (filling voids).

The average depth of a well pit is 10-15 m. To mount a pile frame at a high groundwater level, use pillars at least 25 m long. The piles must be driven in until they fit tightly to the ground.

Work algorithm for constructing a foundation on piles

Construction work is permissible at any time of the year.

We treat the tongues with an antiseptic to prevent the development of corrosion.
We plunge the piles into the ground: we screw in the driven ones, and for the screw ones we use a special lever.
Cut off the excess protruding part.
We fill hollow pipes with cement.
Using an electric welding machine, we mount the support platforms on the cut parts of the piles.
We treat the surface with a waterproofing solution.
We connect the structure along the heads with a horizontal grillage.

High speed of construction and resistance to soil vibrations make it possible to increase the service life of the structure.

Slab foundation

The structure is widely used for the construction of a monolithic stone building. Concrete slabs are resistant to temperature changes and loads.
The problem of high groundwater levels is solved with the help of a sand and gravel cushion located at the base of a monolithic slab, buried to the level of soil freezing. Rocks allow spring flows below their location, which prevents deformation. The sequence of technological steps will allow you to create a solid slab foundation in the swamp.

We prepare the wetland, clear it of vegetation and debris.
We drill holes in the corners of the future structure.
We drain the trench. For groundwater levels up to 2 meters from the surface, use pumps; from 2 meters and below, limit yourself to the drainage system.
We will strengthen the bottom of the pit with an embankment of sand and gravel. This will protect the foundation from the effects of groundwater. We form roofing felt flooring on top.
We make formwork from lumber.
We install reinforcement made of metal rods along the entire perimeter of the form-building structure.
We fill the trenches with concrete mixture in several approaches. The thickness of each layer should not exceed 0.2 m.
Dismantle the concrete form after the solution has dried (it will take several days).
We treat the vertical and horizontal surfaces of the frame with waterproofing mastic.

A foundation in a swamp made of monolithic slabs is an expensive type of construction. Changes in soil heaving will not affect the reliability and strength of the frame. Therefore, slab foundations are mainly used for marshy areas.

Tape base

A shallow foundation for a house is suitable for the construction of small frame structures made of wood. The peculiarity of the type of supporting structure is that the depth of the masonry is higher than the freezing level of the soil. When arranging the feed, you need to take into account a number of nuances:

The role of the drainage system is performed by a cushion of sand and gravel.
When the soil heaves, the reinforced frame rises slightly, but the use of monolithic technology allows it to maintain its shape and prevent the appearance of cracks.
At the design stage, soil characteristics should be determined. This will allow you to calculate the effect of loads on the future construction and determine the safety margin.
The sequence and technique of performing the work of arranging a foundation, which is located in a swampy area and is relevant in case of high groundwater loss, is identical to laying a deep-depth tape - digging a pit, forming a cushion, constructing formwork, reinforcement and layer-by-layer pouring of cement mortar.
It is advisable to install a channel for water drainage along the entire perimeter of the foundation at a distance of 1.5 - 3.00 m.

Ease of installation and low cost make the tape popular as a foundation on marshy soil.
Dampness and moisture have a destructive effect on the frame. It is difficult to predict how soil density will change over time. To avoid the effects of swelling of the ground, use waterproofing systems. When choosing the type of foundation that will be located in soft, swampy terrain, focus on the climatic conditions of the area, the type of structure and the budget.

The construction of buildings on swampy and heaving soils can be carried out only after a thorough study of the condition and types of soil layers in a specifically selected area, determining the depth of groundwater and the correct choice of foundation design.

Designs used

Which foundation is better in swampy areas? For low-rise individual buildings in wetlands and heaving soils, two types of house foundation structures are used:

on concrete, screw or bored piles with a load-bearing grillage;
“floating” slab foundation in the absence of flooding.

On soils with shallow water depths, the construction of small one-story buildings is allowed if there is a drainage system.

In each individual case, the correct choice of design and materials used for this is determined on the basis of geodetic and geophysical research. Their result should be data on the characteristics of soils on the site, the possibility of flooding and the groundwater level (GWL) at the time of their maximum rise, as well as information on the depth of hard and dense soil layers.

A geological study of a building site can cost you from 30 to 50 thousand rubles, which may seem like an unnecessary expense. However, it is not.

Conducting a thorough site survey will increase the reliability of the building under construction and significantly reduce future operating costs.

You can reduce survey costs if you purchase a test drilling pile and screw it into the ground in several places to obtain data on the depth of the dense bearing layer. You will know that a dense layer has been achieved by the changed physical load on the control lever when twisting the metal pile.

When conducting independent geological surveys, it is advisable to arrange a deep drainage with water drainage over several square meters, and then dig a pit there with a depth of up to 1.5 meters. This way you can get a more complete picture of the condition and composition of the soil.

Pile foundation

For a massive residential building made of brick or with a pitched roof and attic, it should be supported by dense load-bearing layers of soil. When constructing two-story buildings, such a system is economically justified because it has the best load-bearing capacity.

SVF plan.

The fundamental design of a foundation in a swampy area for a residential building should be based on standard calculations and installation of the required number of concrete, bored or screw piles. Connected by a grillage into a single supporting system, they will ensure reliable support of the entire building structure on solid layers located below the bottom of the swamp.

The cost of a foundation on swampy soil using concrete piles will be significantly higher than that of strip and “floating” slab systems, since special construction equipment will have to be used to complete the work. But, depending on the type and number of installed piles, such a scheme will be able to withstand the weight of a two- or three-story brick residential building without subsidence for many years.

If the depth of the hard soil does not exceed three meters, then metal screw piles can be used to construct the foundation.

Their use reduces the cost of the foundation, but reduces the load-bearing capacity of the structure. In addition, their use is limited by the installation depth.

The material for the load-bearing walls of a residential building on a screw pile foundation will have to be hollow brick or wood, with additional external insulation made of foam plastic. At the same time, using screw piles, you can make a foundation in a swamp with your own hands, without inviting contractors for this.

To install screw piles in a wetland, the top layer of soil over the entire building area, with the addition of 0.5 meters to each external axis, must be removed to a depth of 50-60 cm. After this, install the piles, screwing them in according to the design scheme. Cover the bottom with geotextile and fill it with crushed stone-sand mixture not below ground level.

Slab "floating" foundation

In cases where the layer of relatively hard soil on the surface is more than 0.8 meters, and the depth to the bottom of the swamp does not exceed 2.5 meters, it becomes possible to construct a foundation in the form. This type of soil can be found on old peat bogs, dry lakes and swamps.

The main advantages of such a support system include the high strength and rigidity of the load-bearing concrete slab, which will not tilt and is movable in the presence of heaving soils. In winter, when the ground freezes, it will simply rise with it, without causing any damage to the building structures.

The cost of installing a “floating” monolithic slab is 20-30% cheaper than pile systems while maintaining the same durability and reliability.

A slab is a simpler and less expensive foundation for a small frame-type residential building, as well as from light and wooden building materials. It is also possible to make such a foundation on a not very swampy area yourself. To do this you need:

dig a pit in the ground, deepened by 0.5-0.7 meters and 1 meter larger in size than the perimeter of the building;
dig a trench around the perimeter, deepening it 0.5 meters below the bottom of the pit;
lay horizontal drainage system pipes at the bottom of the trench, observing the necessary slopes for water drainage;
connect the system to drainage wells;
pour and compact a layer of crushed stone-sand mixture 0.2-0.3 meters thick at the bottom of the pit;
cover it with geotextile so that the throughput of the material is directed downward;
pour a layer of medium-fraction crushed stone onto the canvas and compact it to a height not lower than ground level;
install formwork for pouring monolithic concrete with a layer thickness of 30-40 cm;
make two meshes of reinforcement with a diameter of 12 mm, linking between them vertical posts made of rods with a diameter of 8-10 mm;
pour concrete into the formwork and compact it with a manual submersible rack vibrator or vibrating plate.

Construction work on the construction of walls on such a foundation for a house in a swamp can begin no earlier than six months later. This holding time is necessary so that the lower layers of soil can compact under their own weight.

It should be noted that the “floating” slab must be waterproofed and polystyrene foam at the ends, along with the installation of an insulated blind area around the entire house. This will reduce the heat loss of the building into the ground and ensure the durability of the structures.

Shallow strip foundation

It is the most low-budget option for private development. Such a foundation for a house in swampy areas is used when the groundwater level is high, if as a result of geological research it has been established that sand layers with a depth of at least 1.5 meters are located closer to the surface and the freezing depth does not exceed 1 meter. If at least one of these conditions is not met, then it is better to abandon such a foundation structure immediately.

MZLF scheme.

A similar soil structure can be found in floodplains, lowlands, near dry lakes and swamps. In such places, soil moisture and swampiness are no longer determined by the high level of groundwater and swampiness, but by the presence of reservoirs.

To successfully complete the construction of a house on a shallow strip foundation, it is possible subject to the following conditions:

the house is being built on the highest point of the site;
the area, especially near the building, is equipped with a drainage system;
before starting construction, it is necessary to accurately determine the water level in the ground not only under the building site, but also in the adjacent territory;
calculate the weight load on the foundation under the house and determine its required dimensions and cross-section of the reinforcement.

All such measures lead to a general increase in construction costs, and therefore you should first calculate everything and make sure that the savings on the strip structure will not be eaten up by the costs of drainage, wells and additional landscaping.

Foundation drainage.

If you have problems with geological surveys and it is difficult to determine the type of foundation you need, then simply check the depth of the groundwater level. To do this, dig a vertical hole to a depth of a meter and if no water is found, then choose a “floating” slab foundation. It is cheaper than the pile type and is not much inferior to it in terms of reliability. And you can do it yourself, without involving contractors from a construction company.

But first consult with an on-site specialist