Which foundation to choose if the groundwater level is high. Which foundation to choose if groundwater is close? Foundation high groundwater level

Swampy terrain is a fairly common occurrence. The presence of moisture in the soil close to the surface can be a real problem, leading to premature destruction of the building. To avoid this, it is necessary to correctly design and build a foundation at a high groundwater level (GWL).

One of the main enemies of any building structure is liquid. In most cases, problems arise with moisture in a vapor state and are easily solved by installing a vapor barrier. But when building foundations, you can encounter not just the liquid phase of the substance, but also pressure water, which can cause much more trouble.

There are three most common problems if the groundwater level on the site is located close to the ground surface:

• the emergence of frost heaving forces;
• moistening the material and reducing its characteristics;
• destruction of foundations when exposed to aggressive groundwater.

Frost heaving

The phenomenon itself occurs unnoticed; only the consequences float to the surface: vertical or inclined cracks. Depending on the material of the walls, destruction can affect not only the foundations, but also the overlying structures of the house.

The reason for the occurrence of frost heaving lies in the unique property of water. All substances on the planet decrease in volume as the temperature decreases, but this rule does not apply to H2O. This liquid, when converted to ice, expands noticeably, leading to excessive pressure under the building.

The pressure is distributed unevenly. In the center of the structure the soil is heated, and at the edges the temperature is slightly lower. Therefore, the outer parts of the foundation will rise more strongly during frost heaving, and uneven deformation will lead to the appearance of cracks.

Scheme of exposure and consequences of frost heaving.

For such a situation to arise, the simultaneous presence of two components will be required:

• moisture in the soil (for example, high groundwater level in the area);
• temperature below zero (in winter).

To prevent the possibility of damage, it is enough to get rid of at least one factor.

Excessive moisture

Most often, the foundation is made of concrete. This material has a certain frost resistance, which shows the maximum number of freezing and thawing cycles. Limitation of cycles is also associated with the expansion of water when it freezes.

If the GWL is located close to the ground, the foundation concrete becomes excessively wet, and its internal structure is subject to severe “loosening.” Excess moisture penetrates into the pores of the material. In winter it freezes, causing increased pressure in the concrete. In the spring, thawing occurs and the pressure decreases. Such constant changes ultimately lead to a decrease in strength and destruction.

Excessive moisture is also dangerous because it destroys the surface of the foundation, gradually washing away particles of material.

Aggressive environment

Such soils and the moisture in them have a negative chemical and physical effect on building materials. We are talking about corrosion of concrete and metal. For cement stone, three types of phenomena are distinguished:

1. leaching of minerals from cement (most often occurs under the influence of carbon dioxide groundwater);
2. damage caused by acids or alkalis;
3. chemical reactions that cause crystallization processes in the pores of concrete during which internal pressure increases.

Consequences of concrete corrosion.

The aggressiveness of groundwater to metal is considered separately. It is not so dangerous, since when pouring monolithic structures, a protective concrete layer is provided. Requirements for materials, the need for protection and its choice are regulated by SNiP 2.03.11-85.

What to do if the groundwater level is located close to the surface

Before starting construction on the site, it is necessary to perform geological studies and determine the location of moisture. You can do this yourself using hole fragments or hand drilling. To correctly determine the groundwater level, you will need to dig up the ground 50 cm below the expected level of the base of the foundation.

Depending on which of the above problems you need protection from, choose the method of carrying out the work. In most cases, you will need to consider more than one consequence. For example, frost heaving and destruction of the surface from excessive moisture.

Methods to combat frost heaving

The construction of a foundation at high groundwater levels will be successful if the following protective measures are taken:

• partial or complete replacement of soil;

Advice! Replacing the soil layer is a labor-intensive and costly undertaking. It is recommended to consider it if there are other reasons. For example, soil strength is a significant reason for replacement. It is better to remove very fine sands and unreliable foundations from the site, and instead fill them with coarse or medium sand, which does not retain moisture at the surface and is classified as a conditionally non-heaving soil.

A backfill of coarse sand or crushed stone not only reduces the likelihood of heaving, it strengthens and levels the soil before making foundations. In some cases, it is enough to make a bedding 30-50 cm thick, but sometimes you will have to use more material. In practice, there have been cases when crushed stone literally sank into the ground. In this case, you need to sprinkle it until the base becomes strong.

Important! Building supports located above the frost depth will require thermal insulation. It would be correct to carry out a set of measures, including thermal insulation, drainage (water disposal) and proper designation of the sole mark.

Protection against waterlogging

Even if you properly protect the foundation from frost heaving in winter, there is a possibility of rising moisture in the spring. To prevent problems in this case, it is worth taking additional protective measures:

The device for waterproofing the foundation when groundwater is located close to the surface includes vertical and horizontal protection. Vertical can be done using bitumen mastic or adhesive materials. In the presence of pressure water, the option of installing a caisson with metal waterproofing or erecting brick walls is considered.

Horizontal insulation is made of two layers of rolled material (roofing felt, linocrom, waterproofing, etc.). Designed for prefabricated monolithic foundations at a level just below the basement floor.

If moisture in the soil is located close, the grade of concrete for frost resistance and moisture resistance is of great importance. To construct a foundation with a high groundwater level, you need a material with a water resistance of at least W8 - W10. It is recommended to assign a frost resistance grade of at least F100 - F150.

To protect against aggressive environments, paint, varnish, lining and facing materials, impregnations and water-repellent compounds are used. The choice is made taking into account the composition of groundwater and the degree of its mineralization.

In conclusion, it is worth saying that installing a foundation with a high groundwater level requires careful preparation. All protection measures must be considered as a whole: bedding, waterproofing, insulation, drainage. In general, the following recommendations can be made for choosing a design solution:

• GWL below 1.5 m - shallow tape or slab;
• below 0.5 m - ;
• above 0.5 m - piles (the easiest and cheapest are screw piles).

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Good afternoon.

I will try to answer all your questions to the maximum. It is very correct that you are trying to delve into and understand all the technology. We work for such people.

1. On the base. That means we didn't understand each other. What is described in this question is true, but for a strip foundation. But it is precisely on the basis of these rules that we recommend that you make a platform from a slab (stand) of 1.5-2 m, since this law also applies to a slab. This is exactly what happened according to calculations. Only not according to the elementary ones, but on the condition that the slab is 30 cm thick and on an unstable solid base, with all the introductory information that you gave us. We don’t publish the calculation itself, but I can write to you briefly what happened:

I calculated the approximate load of the entire house, it turned out to be approximately 200,000 kg, that is, 200 tons. According to the standards, I took 416 kg per m2 load per 1 m2 (this load is according to the standards for unstable foundations). And then I calculated that if your slab is 30 cm thick, then its load bearing area should be approximately 480 m2. You understand that it is impossible to fill such a slab, almost 500 m2, that is, the minimum allowable value of the indentation and the start of construction of the base is 1.5-2 m. This is what I said earlier.

With the same values ​​and inputs, it turned out that if the slab is 1 m thick, then 125 m2 is enough to support it, since your area is a little larger, we give you approximately the normal thickness for the slab, equal to 60 cm, and it is well reinforced. The designer will be able to calculate the reinforcement correctly. In this case, you can start building the base either without retreating at all, or by retreating 10-20 cm.

But I can immediately say that I recently came across a detailed design for a house a little larger than yours and on stable loams, with low GW, but even there 5 tons of reinforcement of different classes from diameter 8 to 28 were laid. Yes, there is a 30 cm slab, but it so reinforced that it’s hard to believe that this even happens. People approached it wisely, checked the geology and they were allowed to make the slab, the designers calculated it. This is a very good foundation in initially good conditions.

2. By filling the site. If you simply level the area and the house will not be placed there, then fill it up, it will compact over time (7-10 years), you can fill it with any soil or construction waste, but not black soil or soaked clays. I'm talking about the corner of the plot.

But in the pit, remember, this is very important. Before construction begins (concrete pouring), you should not touch the foundation pit at all: neither dig nor add sand or crushed stone. This is due to the fact that after the winter your sand will turn into such a dirty, unrecognizable wet substance that any builder will tell you to take it out of the pit and dry it before pouring the foundation. The same thing will happen to the pit itself, the soil will simply become soaked from hot water and snow, the frost will destroy the ground and you will need to dig and clean up this mess again. Therefore, do not touch the foundation pit at all until summer, then lower the hot water level if there is water there and begin work.

3. Regarding the depth of placement. Read the rules here. An insulated blind area is a relatively new invention and you won’t find anything about it in the standards. But we can assure you from experience that it partially retains heat at extremely low temperatures (in Kyiv it can be very cold, down to -30, we ourselves live not far from you and know what it is), accordingly, a warm blind area partially saves you from freezing of the soil. By the way, it allows you to reduce the foundation depth by only 200 mm from the design one. What I do in your case, I allow you to lay the slab at 60 cm, and not at 90 cm; backfilling and drainage are not considered in the design laying depth. I hope I explain clearly.

4. Svarog allowed me to comment on his answers, since we are colleagues and have already discussed everything about your house. Yes, he said that the slab is possible in your case, but this is only subject to geology and good design miscalculation. The shape of the house definitely needs to be changed to rectangular; it is better to insulate the slab from the top (as you write). But you are wrong in one statement: “that the smaller the size of the slab (of the house), the more reliable the foundation will be.” This is not true. He meant that the lighter the house, the more reliable the foundation. Your house is too heavy for such difficult conditions, it needs to be lightened as much as possible. Use frame construction or remove 1st floor. And the risk is precisely that we cannot say exactly what the house will most likely suffer from. It can tilt, crack the foundation (and in this case you know that the entire structure dies), deformations and cracks. Anything can happen. That is why we are concerned about your efforts so that they are not unjustified.

5. On stilts. It's a shame that you think so, but it's your right. There are big doubts about the cost. And if there is a small passage, then in our practice in our region, people manage to screw in piles with a small drilling rig (a drilling machine that digs wells; they are small in size and are transported on trucks). Builders are like that.

6. People have learned to build their houses everywhere, on water, in the desert, and in the snow, but we don’t know how practical this is in your case. You understand that slab foundations and pile foundations are specialized foundations. They are built in cases where conventional types of foundations are not suitable, and in most cases for special-purpose objects, but not a private house. This is a forced measure that is expensive and unjustified. The fact is that this flooded area may manifest itself unpredictably in the future. The level of HS has recently (over the last 17-20 years) increased very strongly throughout the former USSR. People are tormented and constantly write to us about what to do with a house that has existed for 50 years and has never seen water. And you initially want to build on water. Your swamp is not drained, it really exists, but so far only in a dormant state with a slight rise in the water level. I am in no way trying to persuade you or scare you, I am only warning you. All my colleagues agreed on one opinion: it is not worth building on water. But this is our opinion, you don’t have to listen to us.

7. According to the brand of concrete. You also have aggressive waters, and it’s good that at least someone is doing geology. Even if this geology is neighboring, it makes it clear that you have an aggressive environment with sulfate activity. Sulfate resistance of concrete is its ability to withstand the overly aggressive and extremely destructive effects of liquid sulfate media for a long time. The molecular volume of ettringite increases the existing volume of the initial phases. This causes small microscopic cracks to appear in the concrete, which then become large cracks. Sulfate-resistant concrete is resistant to this kind of influence. Such concrete is not used often and its price differs from the price of ordinary concrete (more expensive).

• Sulfate-resistant concrete is obtained from the most common average cement, but only when mixing this mixture are special modifying additives intended for concrete added to it.
• In addition to additives, you can use types of sulfate-resistant cement specially designed for this purpose when mixing concrete.
• Substances such as superplasticizers, plasticizers and air-entraining additives help to significantly and significantly increase the sulfate resistance of concrete.

That is, you need moisture-resistant concrete of grade W6 with modifying additives. Hence the conclusion that making a 60 cm slab will be very expensive.

Your geology is necessary to find out if there are quicksands or any other surprises, since you correctly say that even in one area you have different soils, they can be different even by 1 m2.

Ask.

Often, when starting construction on a summer cottage, a problem arises associated with a high groundwater level (GWL). GWL are layers of water that lie close to the surface. Their level directly depends on the season. It usually increases greatly in spring and autumn, when snow melts or heavy rains occur. The construction of a foundation at a high groundwater level is also made difficult by the presence of clay in the soil. In this situation, there is no question of a cellar.
However, a foundation can be laid if the groundwater level is high if you follow the recommendations and technological process.

The influence of groundwater on the foundation

When groundwater is high, the foundation is more affected by salts and substances dissolved in it. It is they who react with concrete and gradually destroy it. As a result, the base gradually loosens and delaminates. Visually, cracks, plaque, yellowish spots, fungus appear, and when you are close, you can smell dampness.
Problems begin to arise already in the process of digging trenches or pits. Rising water softens the bottom, washes away the soil, significantly worsening its physical condition, making it unable to withstand the pressure of concrete. In such a situation, drainage should be done immediately.

How to determine groundwater level

In river valleys, water meadows, and lowlands, they are visible to the naked eye. In the spring, the water stays there for a very long time; in the summer, having gone a couple of feet deeper, the soil will be wet.
When starting work, you can contact the organizations involved in these issues; if there are none, then you can do everything on your own:

• in the immediate vicinity of the proposed foundation, make a pit, or preferably two in different places, about 3 meters deep, the recommended width is 1 m, but this value is not important and depends largely on the size of the one who will dig;
• cover it with something to prevent precipitation from entering;
• After about a day, the pits are opened and the water level is measured;
• if the bottom is dry or the depth reaches below 2 m, then the GWL is low or moderate. In this case, there is no need to resort to any additional protective measures.

If the water level is higher than two meters, then you will have to install drainage and take care of waterproofing.

Foundations for soils with high groundwater level

Let's consider what kind of foundation is needed for a house if groundwater is close.

• On screw piles. Most suitable for wetlands, foundations on water and those in areas of constant flooding. In some cases it can be used as foundations on bulk soils. Installs quite quickly. A significant disadvantage is that it is not able to take high loads.
• Slab. In this case, there is no need for deep laying. This structure must be placed on a bed of sand and crushed stone and insulated with plastic film or roofing felt. Otherwise, a crack may occur. In terms of price, it is not economical.
• Brick. This foundation is good because even winter soil movements do not have a significant impact. When working with brick, you will have to take care of good waterproofing, and the presence of a high-quality blind area will protect it from precipitation. A negative feature of such a foundation is its high cost, both financially and in terms of effort and time.
• A floating foundation is a strip foundation that is resistant to soil heaving. It is the most acceptable in country house construction. It does not go very deep, so it can withstand the load of not very heavy buildings.

Water disposal when laying trenches and pits

At the stage of digging foundation pits or trenches, it happens that the water level rises so quickly that carrying out the activities is difficult or impossible. To do this, it is necessary to drain the building area. For this purpose, special drainage pumps or motor pumps are used.
The water should be pumped out until the removal of soil particles to the surface begins. If this starts, stop pumping.
Plastic sewer pipes with a diameter of 110 mm are used for drainage. Through them, the liquid will flow by gravity into wells or reservoirs prepared in advance for this purpose, or into drainage ditches reinforced with shields to avoid soil collapse.
Ideally, the groundwater level should be 200 - 400 mm below the construction site level.

Drainage system equipment

If groundwater is close, then drainage is not a luxury, but one of the main guarantees of the strength and durability of both the foundation and the structure as a whole.
Its device will require the following materials:

• sand;
• crushed stone;
• geotextiles;
• drains (drainage pipes).

For foundations with high groundwater levels, circular drainage is advisable. First, a trench about 400 mm wide is dug. The depth is calculated individually: the ditch should be at the level of the base, or preferably 200 - 300 mm lower.
It is recommended to carry out installation at a distance of no more than 20 m at a time, but with regard to a country house, outbuildings, bathhouses, garages - this wish is most likely conditional. We must proceed from their real circumstances.
Sand is poured into the bottom and compacted thoroughly. The thickness should be 200 mm. To prevent siltation, geotextiles are laid on the sand.
The next layer is crushed stone (gravel). Its thickness is also 200 mm. The choice of crushed stone is not the least important. It is advisable to purchase washed. If not, you will have to sift at least. When liquid gets in, contaminated material impairs drainage: particles of dust, sand, and earth in the water reduce the space between the crushed stone.

The gravel bed is covered with geotextiles, the pieces of which should overlap from 150 to 300 mm.
The next stage is laying the drains. Perforation in factory pipes is located on one side. This is used to lay it on geotextiles. To save money, you can make drains yourself. Holes are drilled in a regular plastic sewer pipe, the optimal diameter of which is 5 mm. The distance between holes is no more than 10 mm.
When the pipeline installation is completed, it is covered with geotextiles and backfilled. A layer of sand of at least 200 mm, gravel (crushed stone) - 150-200 mm. The trench is filled to the top with previously excavated soil.
If the drainage system is of good quality, practically no water will get under the foundation.

Construction of a strip floating foundation

Let's look at how to make a foundation. To build a good house, if the groundwater level allows, a medium-depth type is chosen.

• A trench is dug 700-800 mm deep and wide enough for the installation of formwork and its subsequent dismantling.
• The bottom is covered with waterproofing material.
• The formwork is installed and strengthened, which is insulated with film on the inside.
• A sand cushion 200 mm thick is poured and compacted.
• The next layer is gravel or crushed stone. The thickness is the same or 5-10 mm thinner.
• The pillow should be isolated from the concrete. Ruberoid and polyethylene film are used.
• A frame is constructed from Ø12 mm reinforcement and installed in the formwork.
• The solution is poured. Please ensure that the concrete strip is continuous. This will help create a durable monolith. There is no need to rush, you need to fill it in layers. Each is pierced with reinforcement to force out excess air and compact the concrete. When one layer has set sufficiently, you need to pour the next one.

To prevent the concrete from drying out, it must be watered daily and covered with film at night.
After the concrete has completely hardened, the formwork is removed and waterproofing is done with bitumen.

Monolithic slab foundation on a floating cushion

To drain swampy soils and level the terrain, bulk soil is used. If a person does it on his own, that’s one thing. But if you buy a plot where this work was carried out several years ago, it’s completely different.
The essence of the problem is that such soil does not have a uniform structure and is not properly compacted, as a result of which foundations on such soils can shrink unevenly. And if the groundwater level is still high, then problems cannot be avoided.
For these types of soils, a number of foundations can be used:

• screw piles, but only if they go into the “mother” established soil. An examination is being carried out to find out. Do not forget that screw piles are not designed for heavy structures;
• for the strip base, qualitative analysis is also needed;
• Although a monolithic slab is an expensive undertaking, it is most suitable for foundations on bulk soils and at high groundwater levels.

Stages of building a foundation on a floating cushion

• A pit of a given size is dug. You can do it yourself, or you can use special equipment.
• The bottom is carefully compacted. Here it is better to use a vibrating plate - a device that allows you to quickly and efficiently compact the soil.
• Sand is used for the floating cushion. It is filled in layers, each of which is compacted. The thickness of the pillow should be at least half a meter.
• The pillow is covered with geotextile (another waterproof material).
• A layer of crushed stone 150-200 mm thick is poured.
• Roofing felt is laid on top of the crushed stone.
• The formwork is formed and inserted inside. It is carefully strengthened from the outside.
• A reinforcing mesh with cells 200×200 mm is welded. For it, reinforcement with a diameter of 12 mm is taken. There is a single rule here: the bottom row does not reach the sole by 50 mm, the top row by 50-70 mm. Vertical rods are cut based on the thickness of the slab, and are arranged in a checkerboard pattern.
• To pour concrete, it is better to use a mixer to do it during the day.

Then everything follows the standard scheme: the slab is periodically moistened and protected from precipitation. When the solution is completely dry, the formwork is dismantled and the slab is treated with a waterproofing mixture.
The foundation built in this way will stand without fear of flooding and swelling of the soil. This is the most expensive option, but in this case it is the most suitable.
Your own home requires both costs and the right attitude to the construction process. As a result, it will delight you for many years.

It very rarely happens that a development site has ideal conditions. Many owners of private plots are upset when they discover that soil water runs close to the surface of the earth on their territory. Clay deposits in the ground can complicate the situation: the future structure will have to withstand a significant load caused by frost heaving. However, you should not get upset and rush to sell the “troubled” plot. Thanks to special construction technologies, it is possible to build a foundation at a high groundwater level, allowing to minimize all unfavorable factors.

Influence of soil waters on the basis

For concrete foundations, not only the groundwater itself is particularly dangerous, but also the various chemical compounds it contains, for example, saline solutions. All these components affect the monolith, provoking its destruction. Professional builders call the complex of such substances “cement bacillus.”

Signs of the influence of the “cement bacillus” on the basis:

• Delamination of the monolith;
• The appearance of a light, loose coating on the foundation, similar to gypsum;
• The appearance of fungus and mold;
• The appearance of fuzzy spots of a yellowish tint;
• Unpleasant damp smell emanating from concrete.

When soil water runs close to each other, difficulties in foundation construction arise even at the stage of excavation, the bottom of which becomes loose due to erosion. The bearing force of the soil decreases several times. If the base is built directly on the soil, shrinkage and erosion of the structure cannot be avoided. That is why, before building a foundation, it is necessary to properly equip a drainage system that collects and drains water into a special well.

Do not forget that suffusion (erosion of the soil composition and leaching of minerals from it) has a particularly negative effect on the foundation of a house when the groundwater level is high. This process is fraught with a weakening of the bearing capacity of the soil, therefore, to protect the base, a preliminary set of works should be carried out to drain the territory. Ignoring drainage work will lead to the fact that the master will fail in laying even a very light structure.

Types of Suitable Bases

First, you need to decide on the type of foundation that is suitable for an area with high groundwater levels. Most often, in private country construction, craftsmen give preference to:

• Floating bases;
• Pile foundations with grillage;
• Tape structures.

The most correct solution in this situation is to install a slab base - a floating slab. This type of foundation was developed for construction in areas characterized by weak, unstable soils and high groundwater. The foundation is a solid platform made of concrete, reinforced with reinforcing bars.

The main advantage of the design is the uniform distribution of the load from the building onto the soil. In addition, the foundation is not afraid of seasonal heaving, since it “floats” with the soil (hence the name).

However, this type of foundation also has disadvantages:

• The possibility of using the base is limited depending on the slope of the building site. If the slope exceeds 5 degrees, the use of the slab is prohibited;
• Impossibility of constructing a basement.

A pile foundation, also known as a grillage foundation, is used quite often when the groundwater level is high. It has an affordable price, and is very stable even on “capricious” soils - wetlands and peat bogs.

The supports are arranged below the freezing point of the soil - until they adhere to stable and dense layers of earth. The problem of uneven shrinkage of piles and weight distribution is solved by a grillage - a solid rigid structure that runs along the perimeter of the house and connects the supports to each other.

Another advantage of this type of base is the minimum excavation work. However, sticking to TISE, the master will need to drain each hand-drilled well in advance.

The pile-grillage structure has negative aspects:

• Impossibility of laying a basement (as with the construction of a slab foundation);
• Inability to support massive structures. It is advisable to arrange the basis for frame and wooden houses.

Another significant drawback is that the base is irrational to use in areas where stable soil layers lie very deep.

As for the tape option: in this situation, experts recommend abandoning its device. Unfortunately, many masters ignore professional advice. A shallow strip base is allowed to be erected only if there is a distance of at least 1 m between groundwater and the surface of the earth.

Technology of laying a slab foundation

Laying a foundation with a high groundwater level is labor-intensive work, but it is possible to cope with it. As mentioned earlier, a monolithic base in this situation is the best option. It is the technology of its construction that should be considered in more detail:

• After completing the installation of the ring drainage system, a pit of a suitable size is dug according to the project. The base must stand exclusively on dense soil, so the bottom of the pit is compacted using a vibrating plate;
• Sand is poured into the bottom of the pit to form a “floating” cushion. The minimum thickness of the finished layer should be 0.5 m. Do not forget that you should not pour out the entire volume of sand at once - the work is done gradually (layer-by-layer). Each new layer of raw material is additionally compacted;
• Waterproofing is laid on the pillow - geotextile or other waterproof material. Completing this step will prevent shallow soil from subsiding;
• Next, crushed stone is poured (layer thickness should be 0.2 m). The material is compacted similarly to sand;
• Another layer of waterproofing (roofing felt) is laid;
• The formwork is assembled from wood or plywood. Its height should correspond to the dimensions of the future slab (the normal height of the foundation above ground level is 0.4 m), plus 5-10 cm. The formwork is installed inside the pit. On the front side it is reinforced with supports;
• Next, a reinforcing mesh is made from two rows of rods D The mesh size of the metal skeleton is 20x20 cm. The vertical rods are arranged in a checkerboard pattern. The length of such rods varies depending on the height of the base;
• The finished mesh is installed in the formwork. The distance between the lower part of the base sole and the frame is 5 cm. The distance between the concrete surface and the mesh is 7 cm;
• If you do the pouring yourself, do not rush and pour all the concrete solution into the formwork. The best option would be layer-by-layer laying of the mixture (each new layer is poured after the previous one has set);
• Since the material requires careful compaction, each layer of mortar laid (until it sets) should be pierced with a steel rod. This will avoid the occurrence of air gaps in the thickness of the concrete;
• The concrete is leveled and covered with polyethylene.

After the material has fully matured (on average 28 days), you can begin dismantling the formwork. The side surfaces of the base are coated with bitumen mastic or other waterproofing. The upper surface of the base is covered with roofing felt, which will protect the lower frame of the building from moisture.

Solutions for foundation contact with water:

In the video, experts will tell you how to avoid problems when laying a foundation when groundwater is higher than normal:

Samara is located on the banks of one of the world's largest rivers, and groundwater lies under the city at a relatively shallow depth. It is their proximity that threatens the foundation of the house with dampness, the appearance of fungus and mold. The danger lies not only in moisture, but also in chemical compounds dissolved in these waters. Their prolonged exposure - which is inevitable if the foundation comes into contact with a network of underground rivers - leads to corrosion of the building material.

Such prolonged destructive soaking sooner or later entails more global consequences - the house sags, as if “falling” into the ground. That is why many projects of houses and cottages very often turn out to be “unviable” (Samara, of course, is no exception). Neglecting such a small detail leads to fatal consequences.

What to do if the groundwater level in your area is high? Sell ​​the land and run away? Such drastic measures will not be necessary! But you will have to give up the basement space. And in this case, you can choose one of two types of foundation:

1. Support-columnar- laid under “lightweight” wooden and foam block walls and is incredibly cheap;

2. Tape(represents a concrete strip running under each load-bearing wall) - suitable for heavy building structures, since the weight of the building is distributed evenly over such a base.

What to do if the foundation pit is already completely prepared for construction, and water suddenly appears at the bottom? There are two options here:

1. install a system for automatically pumping out and removing excess moisture;

2. ensure the outflow of water by constructing ditches along the perimeter of the building (excess water from the pit will rush to where the ground pressure is less).

These are just some recommendations for overcoming the groundwater problem. The solution is individual in each case. If you are lucky enough to find a good specialist, he, focusing on the characteristics of the soil on your site, will advise you something. All that remains is to find him. Well, everything is simple here. Type “samara cottage design” into a search engine and begin monitoring offers on the regional construction market.