Is it possible to build if the columnar foundation has been pulled out? In winter, the foundation moves, why, what to do? Ways to check the foundation of a house

Construction of the foundation- the most important and responsible stage of building a house. The reliability and durability of a building are determined by the choice of foundation type and its parameters, as well as the quality of workmanship. Mistakes made can lead the house to disrepair already at the stage of its construction.

But what to do if the house has already been built, and the builders saved money, hoping for the traditional “maybe”. Most foundation problems arise when building on heaving soils. Soil heaving is a very insidious and powerful phenomenon, which is very difficult to combat after construction is completed. Why is this happening?

If the foundation (strip or pillars) was laid above the freezing depth, then the wet foundation under the support, freezing, expands and squeezes out the structure. This process occurs most actively in the spring on the south side of the house, which freezes at night and warms up during the day. With each passage of the “thawing-freezing” boundary through the lower support platform of the foundation, the latter rises higher and higher. Extrusion forces exceed tens of tons. At the same time, cracks appear in the stone walls. Wooden and panel houses receive noticeable distortions, walls crack, collapse, doors and window sashes do not close. What to do?

Owners of stone houses have several options for improving the performance of their foundation. In places with difficult terrain, it is possible to lower the groundwater level by organizing its drainage using an effective drainage system (Fig. 1). Dry soil is not heaving and “warm”. Considering that in heaving soils with a dusty structure, moisture rises upward, drainage should be located below the freezing depth by 0.5 m. The literature on construction speaks quite well about the technology of creating a drainage system, but it must be borne in mind that this is complex and expensive Job.

You can also take the path of artificially reducing the freezing depth. To do this, add a layer of soil around the house, bringing the depth of the foundation to the freezing depth (Fig. 2). By the way, the visual image of the house will benefit somewhat; it will be on some elevation.

The freezing depth can be increased by replacing part of the soil with a heat-insulating layer, made, for example, in the form of a mixture of expanded clay and coarse sand in a volume ratio of 1.5:1. A layer 20-30 cm thick and about 2 m wide, laid at a depth of 20-40 cm on top of a layer of coarse sand 20-30 cm thick, will insulate the soil and reduce its freezing depth by 60-80 cm. A heat-insulating layer can be made and from polystyrene foam boards 8 cm thick, wrapped in plastic film (Fig. 3). Plates laid at a depth of 20 cm on a layer of coarse sand 20-30 cm thick are a very effective remedy. The width of laying slabs around the house is about 2 m. The gap between the slabs is no more than 5 cm.

A thick layer of snow around the house will also reduce the depth of freezing. If closed for the winter ventilation windows in the basement of the building, then the degree of soil freezing can be somewhat reduced. All options can be combined. Thus, when insulating the soil, it is possible to reduce the depth of the drainage system. Insulating the soil can also be combined with raising its level around the house. Now about light houses (wooden, panel). Heaving phenomena affect them to a greater extent, since such houses themselves are lighter.

Sometimes pillars rise even when they are laid below the freezing depth, if the house turns out to be too light, or too many pillars were installed, which is the same thing. This occurs due to the adhesion of the side surface of the pillars to the ground, if a layer of waterproofing is not laid between them (glassine, roofing felt, polyethylene, bitumen coating, etc.) or the side surface of the pillar is uneven, rough. Then it turns out that the adhesion forces of the soil with the pillars are greater than the weight of the house. By the way, it is for this reason that when laying a conventional columnar foundation, it must be loaded with a house in the same season.

If such a foundation “walks,” then it is necessary to evaluate the real weight of the house and the bearing capacity of the soil. With a large margin of bearing capacity, you can reduce the number of pillars by eliminating some of them from work. To do this, it is enough to dig up extra pillars or destroy their upper part.

Sometimes for wooden and panel houses it is possible to recommend the techniques proposed for stone houses (for example, insulating the soil around the house reduces the adhesion area of frozen soil to the supports). But it is better to replace the previous supports with pillars (Fig. 4), made using TISE technology using the TISE-F foundation drill. How to do it?

First you need to determine where to place the pillars. If the lower crown of the house is “powerful”, then new pillars can be placed near the previous supports at a distance of no more than 1 m. It is also necessary to take into account that the bearing capacity of each such pillar is very high - from 5 to 10 tons, that is, they can be installed less frequently . New supports are installed around the entire perimeter of the house and under its internal walls. After this, the house is raised a few centimeters, leveling pads are installed on the new supports through the waterproofing and then the house is lowered. You can lift the house using a jack and levers. Old supports are removed or their upper part is destroyed.

If the crown of the house is weak and can bear the full load only in the place of existing supports, then on both sides of it at a distance of about 1 m it is necessary to place reliable temporary supports (Fig. 5), which have developed upper and lower surfaces. The house in this place must be raised by 1-2 cm, freeing the old support. Then it should be dug out, and the hole should be filled with soil, thoroughly compacting it. To avoid the house falling off temporary supports, they are replaced sequentially.

To create foundation pillars using TISE technology, you first need to prepare formwork in the form of pipes. Their design depends on the capabilities of the developer, his funds or imagination. The main thing is that they must have a constant cross-section - 500...700 cm2 (square, rectangular or round). The length of the pillars should be taken in such a way that they are buried 30 cm below the freezing line, and from above do not reach the crown of the house by 3-5 cm. Asbestos-cement pipes, boxes welded from steel sheets can be used as formwork (Fig. 6). At the top, they all must have a support crossbar located at ground level.

Before starting to drill an inclined well under a house, it is advisable to first draw a cross-section of the building on a reduced scale. Care should be taken to ensure that the bottom of the hole drilled below the freezing depth is in the middle of the wall and that the drill handle does not rest against the wall. For ease of work, you can make a template marking the distance from the wall to the drilling point and the angle of inclination of the well (Fig. 7).

Having identified the drilling point, they begin to work. After the inclined well is drilled below the freezing depth by 10-15 cm, we begin to expand it to vertically install the formwork of the foundation pillar. To do this, a drill is inserted into the well, the soil is cut with a shovel, and periodically, as the drill storage tank is filled with soil, it is raised to the surface and emptied. The well is expanded until the formwork can be freely placed in it in inclined and vertical positions. The lower part of the well (up to 30 cm from its bottom) is not expanded.

Having installed the plow on the foundation drill, they begin to expand the lower part of the well. First, they work with the drill rod fully extended. In this case, the bottom of the expanded part of the well turns out to be inclined, but it is easier to work. You can level the bottom of the well with the drill in a vertical position, for which you will have to fold the rod a little so that the handle is located under the wall.

Installation of reinforcement and filling the well with concrete is carried out through the formwork, which is located at an angle and rests with its crossbar on two boards laid near the well. As concrete is laid, it must be compacted by bayoneting and tapping on the side wall of the formwork.

Immediately after filling the formwork with concrete, the upper part is shifted, placing the formwork in a vertical position (Fig.). This doesn't require much effort. The concrete in the lower part of the formwork should be further compacted by tapping on its side wall.

Concreting one well must be carried out continuously for 30-40 minutes until the concrete sets. The side gaps around the foundation pillar must be filled with soil, laying it in layers of 10-15 cm, compacting it with a tamper and slightly moistening it. Concrete is poured into the formwork and the upper surface of the foundation column being formed is leveled.

For normal setting of concrete during the first week, it is necessary to periodically moisten it, and to preserve moisture, wrap the top of the column with plastic film. The foundation pillar is loaded no earlier than after three weeks. The part of the wooden formwork protruding above the ground is carefully removed by sawing it off with a hacksaw.

When creating foundation pillars under the internal walls of the house, difficulties will arise: it is impossible to do without opening the floors.

Based on materials from the magazine "DOM"

Today, many developers choose to build a columnar foundation for their home due to its low cost. In addition, such a foundation is built quite quickly - in just 1 day. Such a foundation is considered ideal for the construction of garden and country houses, light bathhouses, and residential buildings made of small timber on non-heaving soil. But there are times when a columnar foundation begins to quickly collapse, fall on its side or bulge. In such conditions, the only method of preventing further subsidence of the foundation is to replace the columnar foundation.

The need to replace the columnar foundation

Many rural houses that were built in the last century have a primitive columnar foundation as their foundation. Such an ancient structure consists of stands made of brick or stone, often quite dilapidated, unreliable and long outdated. They require immediate replacement with a stronger, higher quality and reliable foundation. The most important reason for the destruction of a columnar foundation is settlement, which naturally causes a change in the position of a wooden house, the appearance of cracks in the walls, and jamming of windows and doors.

This process occurs from various physical, mechanical and hydrological changes that take place in the lower soil and reduce its bearing capacity. The foundation actually ceases to perform the tasks assigned to it. Often, changes in soil properties are caused by construction work carried out on personal property. But such problems are not limited to old houses.

And when installing a new house on a columnar foundation, the latter very quickly begins to sag or sag and pull the house along with it. Especially when we are talking about large and heavy timber houses (9 by 9 meters or more) and cottages. In these cases, such a foundation is categorically not recommended, because there is a significant load, and here it is more rational to equip a pile-screw or strip foundation. It is also irrational to build a columnar foundation on heaving soil.

I would like to immediately make a reservation that this is most often not the fault of the craftsmen who carried out the construction. This is due to the phenomenon of soil heaving when it thaws after winter freezing. The ground thaws earlier on the south side of the house, pushing up the southern pillars, which end up on loose, crumbly soil, while the northern pillars stand in place on solid frozen ground.

Even if you dig 2 meters into the ground and pour concrete into asbestos pipes that are resistant to compression and bending, they will not be able to withstand soil heaving. All the same, the level of the columns along the horizon will be disturbed, and the house as a whole will become skewed. In this case, the foundation cannot be repaired and there is no point in trying to align the foundation pillars; you need to remember: if the blocks move at least once, they will change their horizontal position every year after winter, and it must be replaced as soon as possible.

In such cases, the only correct solution is to replace the foundation. This procedure is rightfully considered a radical measure designed to restore the safety and reliability of the house, as well as increase its service life. However, it is worth remembering that it is advisable to replace the foundation for buildings, the structure of which, after replacing the soil, can last for several more decades.

Methods for replacing a columnar foundation

As a rule, replacing a columnar foundation with another takes from 5 to 10 days, and the lifting of a residential building is carried out from below, which allows workers not to dismantle the floor, thus making the work easier. But replacing the base when the internal walls of a residential building are subsiding requires opening the floor covering to correct the defect.

There are several methods for replacing the foundation under a wooden building:

Cosmetic repair is the simplest technique that does not require large financial investments. In this situation, you simply need to cut out the rotten area and insert a suitable wooden element in its place. However, it must be taken into account that with such a partial replacement of the foundation, the integrity of the house is inevitably compromised.
Dismantling the walls is a type of construction work that involves the complete dismantling of the walls, after which the lower crown of the frame is replaced. The method is reliable, but it requires a fair amount of patience and time from the craftsmen to disassemble and reassemble the structure.
Dismantling the foundation. To do this, you will have to remove a layer of 20 centimeters, replace the wooden crowns and then restore the foundation under the house.
Replacing the crowns by lifting the building with a jack is considered the most popular method, according to reviews of replacing a columnar foundation, as it allows you to replace the foundation efficiently and quickly.

Choosing a new foundation for a house

It is important to understand that the procedure for replacing the foundation of a house is a complex process that requires careful preparation. To begin with, it is worth deciding on the design of the future foundation, which will replace the old columnar foundation. There are the following types of foundations that are suitable for wooden houses:

A columnar foundation is a system of pillars that are installed in places of maximum load - the points of intersection of walls. The pillars are made of stone, concrete or brick and are installed at a distance of approximately 1-2 meters. It is adapted to support light residential buildings with wooden, frame or panel walls, which do not create significant loads on the foundation. Despite their simplicity, columnar foundations can be chosen to provide reliable support for a country house or garden house, as well as other outbuildings.
A bored pile foundation is a type of columnar foundation, only asbestos-cement pipes filled with a special mixture are used as load-bearing elements. The design of such a foundation consists of piles and a grillage that connects them. Load-bearing elements are located similarly under the most significant points of the house, for example, in places where main walls intersect and at the corners of the building. A bored pile foundation is considered optimal for buildings on soil with high water levels.
The pile screw foundation is considered the most interesting type of house foundation, as it was originally intended for military purposes. Today, such a foundation is widely used in civil engineering and is valuable because you can use it on any terrain, even on uneven terrain with differences in height. In addition, the low cost of replacing a columnar foundation with a screw pile foundation and the possibility of repeated use of screw piles are additional advantages of such a foundation. The disadvantage is hiring special equipment.
The strip foundation allows you to build heavy houses and at the same time ensures high reliability and security of the house. The most popular shallow strip foundation can be monolithic or prefabricated. Prefabricated structures are made of concrete based on formwork, monolithic ones are made of reinforced concrete blocks and concrete.

Replacing a columnar foundation with your own hands

Of course, you can replace the old columnar foundation yourself, but you must be confident in your own abilities. In this case, you will need the information presented below, as it allows you to navigate the issue of replacing the foundation and control the situation.

Preparatory work

Despite the creation of a reliable foundation and the correct calculations when laying it, sometimes small cracks appear on the facade of a residential building, window sills, plinth and other horizontal lines are bent. This indicates subsidence of the house under the columnar foundation and requires immediate replacement of the foundation.

However, before starting work, you need to make sure that the deformation of the base has already stopped. To do this, install plaster beacons across the crack on a surface moistened with water. Observe these beacons for two weeks: if cracks do not form on them, then the deformation of the house is over, and you can safely begin replacing the columnar foundation with your own hands.

You can raise a house without special construction equipment; you just need to use hydraulic jacks, which are capable of developing sufficient force that allows you to lift a load weighing 10 tons. In their absence, it is not advisable to think about purchasing such equipment, since this equipment can be rented at any railway depot.

You will also need a steel crowbar, a sledgehammer, wedges - tools that are mostly needed to dismantle the old foundation. To create temporary supports, you can use massive beams, logs, bricks, as well as boards of various thicknesses that act as spacers. As a platform for installing a jack, you can use beams and boards knocked into a shield, or any durable material.

To evenly transfer the force from the jack rod to the lower crowns of the house, you will need to cut a steel plate that is at least 5 millimeters thick. If you have to work with a columnar base with a fence, then the latter will have to be disassembled before starting work. Also, at the preparation stage, it is recommended to remove all heavy things and furniture from the house and dismantle the floors.

Raising a wooden house

Raise the building using jacks. They are usually installed on both sides of the house at a distance of 0.5 meters from its corners. Jacks allow you to evenly lift the house, otherwise the logs of the lower frame will sag during uneven lifting, which will lead to their separation and subsequent breakage. The jack should be installed in places where the wood is not damaged by rot.

Remember that it is necessary to install shims in the form of steel plates so that the force is correctly transferred to the logs from the jack rod. Instead of metal plates, you can use pieces of wood. The jacks are fixed on a pre-prepared support platform; if necessary, they need to be buried in the ground to give it maximum stability.

The number of pieces of logs that are used to construct temporary supports depends on the chosen technology for raising the house. If you plan to raise the entire building at once, then the number of temporary supports should be twice the number of foundation pillars. The support is assembled from pieces of logs, like an ordinary well

The height of the supports should be 10-15 centimeters greater than the difference in distance from the soil surface to the height of the jack, because when the house is raised, the supports will settle and be pressed into the ground. If possible, raise the house on both sides simultaneously, evenly, no more than 1.5-2 centimeters at a time. The result obtained is immediately fixed with temporary supports.

If you find kinks in the lower crowns as a result of lifting the house, you should install additional jacks. At this stage, it is recommended to control the process so that the house does not move to the side, because its center of gravity will change when lifted.

The wall must be raised to a height of at least 6 centimeters, the rotted extensions must be removed and the structure lowered onto scraps of beams that are placed on temporary supports. Between the logs and beams, tow is laid, which is treated with an antiseptic, in a width that is equal to double the thickness of the beam. 10 centimeters of brick and gravel are poured under the proposed base tape.

Once you have raised the house to a sufficient height and it is securely supported with temporary supports, you can begin to dismantle the old columnar foundation. You need to break rubble and brickwork using chisels, a crowbar and other tools that are easy to use. Old pillars are dug or pulled out of the ground, swinging them in different directions. Some of the materials that have retained their quality indicators can be used to form a new base.

Construction of a new foundation

Let's consider replacing a columnar foundation with a shallow strip foundation, which is best suited for one-story houses. As the name suggests, this type of foundation is considered a cross between a non-recessed and a solid recessed strip foundation. It consists of monolithic strips of reinforced concrete that run along the perimeter of a residential building and in places where load-bearing walls will subsequently be located.

Now let's talk about the advantages of a shallow strip foundation:

A strip shallow foundation is an economical solution. If you compare this foundation with buried types of foundation, it will cost you two to three times less.
A shallow foundation requires less work than the construction of a deep foundation. This includes modest excavation work and the ease of arranging formwork. Therefore, the time required to replace the foundation is significantly reduced.
A shallow foundation of a strip type allows, in contrast to non-buried foundations, to make a small basement in a residential building, and it is also less susceptible to heaving phenomena.

The construction of a new foundation should begin with excavation work: dig a trench, the depth of which must necessarily exceed the depth at which the base of the old foundation was located. A U-shaped trench is dug - this is necessary to form a frame with reinforcement to combine all sections of the foundation into one rigid structure.

If it is planned to erect new buildings adjacent to the house, then it is necessary to dig a trench based on the design documentation. Place a sand cushion at the bottom of the trench. Then they begin to manufacture and install the formwork. The easiest way to make it is from boards that are planed on one side. They are easily assembled into shields of the required size. In this case, the cost of replacing a columnar foundation will be lower. To install them, spacers and support stakes are used, which need to be driven in around the perimeter of the trench.

Carefully check the correct vertical and horizontal position of each shield. Then you need to waterproof the internal parts of the formwork with roofing felt or other material and begin reinforcing the new shallow foundation. For this purpose, steel reinforcing bars are used, which have a diameter of approximately 14-16 millimeters. The rods are tied into a frame using smooth rods with a cross-section of 8-10 millimeters.

At this stage, it is very important to maintain the distance from the longitudinal rods to the future surface of the strip foundation. Usually it is taken equal to 5 centimeters - this is enough to provide reliable protection of the metal from corrosion. When the frame is ready, you can fill the formwork with concrete. At the same time, avoid the formation of air voids in the solution, so compact the solution every 200 millimeters.

The formwork can be removed 3 days after pouring the concrete. Then the upper and side parts of the foundation should be waterproofed with roofing felt or mastic. Fill the sinuses with sand and protect them from the outside with a blind area. After the concrete has acquired sufficient strength (about two weeks), you need to lay boards on the first element of the strip foundation, on which temporary supports should be installed.

New foundation load

After installing the new foundation, you can begin loading it. Proceed according to the scheme for replacing the columnar foundation - simultaneously with two jacks or with each of them sequentially. Raise the corner of the building until the wedges are free, carefully pull them out, then gradually release the jacks, lowering each corner of the building onto the new waterproofing foundation.

When loading a new foundation, monitor the elevations of the top of the foundation and, if necessary, use antiseptic-impregnated wood spacers or corrosion-protected metal elements if, after applying the load, the top elevation is lower than required. Or trim the lower crown if it turns out that the top mark is higher than necessary.

Thus, if you find that the old columnar foundation has begun to collapse, cracks have appeared on the base of the house, and the building itself has begun to slant on one side, you should immediately replace the old foundation. You can choose the type of new foundation from several options - a columnar foundation similar to the old one, a bored pile foundation, a screw pile foundation or a strip foundation. But it is preferable to equip a shallow strip foundation.

The foundation subsided: what to do in this case and how to save the house from destruction?

In order to repair the foundation of an old house, it must be raised using jacks: automobile, hydraulic and mechanical.

Restoring sagging corners and supporting walls is a task that requires a lot of effort and experience. There are several methods, which depend on the types of foundations and materials from which the buildings are made. The situation with cracked walls due to sagging foundations most often occurs with old houses built in areas of deep freezing of the soil, in swampy areas. The foundation may sag if, when building a house, you chose a type of foundation that does not suit the given area. Usually the question of how to fix a foundation that has sunk arises when buying an old house or receiving an inheritance.

Problems with subsiding foundations arise due to the action of groundwater, which literally washes away the soil from under the foundation, which leads to its subsidence. Under the influence of high humidity, the monolith loses its strength characteristics and begins to collapse.

Columnar foundation and its restoration

Columnar foundations were often built from red brick, which is very hygroscopic and deteriorates over time. You can often observe that the supports of the foundation of the house have sunk into the ground over time, the crowns of the house have become excessively moist, and the house itself has become warped. This leads to cracks and jamming of doors and windows. Depending on the degree of destruction of the columnar foundation, the supports are restored or replaced. Typically, columnar concrete supports under the house, the crown of which is located above the ground surface, are replaced.

To make a replacement column from concrete, formwork is made with a cross-section of 20 to 30 cm. It must be equipped with a support beam in the upper part. The depth of the hole should be made with the calculation of a deepening of 30 cm above the depth of soil freezing. The hole is made with a drill so that the support can first pass at an acute angle and then fall into place. After installing the post, the hole is filled up, carefully tamped every 10 cm, and tapped for better soil settlement. You can install the supports using a jack. The column is ready for use 2 weeks after pouring the solution.

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Strip foundation and wooden house

The strip foundation is restored depending on the material from which the house is made. If the house is wooden, then it can be raised with jacks and completely sagged. To do this, a monolithic belt is poured, connecting the old and new monolith into a single whole. First, preparatory work is carried out:

remove furniture and belongings;
disassemble the stove;
The floors are removed, leaving only the walls and roof.

The house will be lifted using jacks: automobile, mechanical, hydraulic. With a columnar foundation, platforms of 0.5x0.5 m are prepared, on which jacks are installed. With linear, they usually knock out the bricks of the base or hammer out the monolith in order to bring the jack under the house. When lifting a house, the force of the jack must be transmitted through a steel plate with a thickness of at least 5 mm.

To prevent the house from falling apart due to movement and lifting, each log is secured vertically with nailed boards, which create additional rigidity. Raising the house occurs in several stages. At each of them, the house is raised only 1.5 cm. After each lift, the position is additionally fixed with timber supports, and the house is checked for damage. The process of raising a house to the required height takes a long time and requires caution in everything. After raising the house to the required height, it is firmly secured and work begins to update the foundation.

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Replacing the bottom crown of a wooden house

Repair work to restore the sagging foundation of an old wooden house also requires replacing the lower crowns. As a rule, a settled foundation leads to the development of wood destruction due to strong moisture. To do this, 2 layers of roofing material are laid on the foundation. Old crowns are removed and replaced with new ones impregnated with antifungal compounds. Then the house is lowered on one side and raised on the other, repeating all the steps.

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Features of repairing a linear foundation without raising the house

A brick or stone house cannot be lifted and requires a careful professional approach.

If the monolith is cracked in several places and this does not lead to a violation of the integrity of the building, and the cracks that appear do not increase in size, then they are rubbed down with cement mortar. If the house is deformed, then it is carried out completely or partially, or it is strengthened - it all depends on the degree of damage.

To fix a damaged section of a monolithic strip, first dig a trench, the length of which should not exceed 2 m. If the damaged section is larger, then first repair one part of the foundation, wait until the concrete stands, and only then continue. In the old foundation, holes are drilled horizontally, 60 cm long, vertically in 3-4 rows. The diameter of the drill is 2-3 mm smaller than the diameter of the reinforcement used.

This is necessary to fully strengthen the rods after installation. They are driven in to form the reinforcement tape frame. Afterwards, horizontal reinforcement is welded using welding, the voids, previously cleaned and washed of dirt, are filled with thick concrete, and a plaster mesh with large cells is installed. Afterwards, the formwork is placed and poured to a height of up to 0.5 m and the required thickness of at least 15 cm.

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Repair of the foundation of a slag-filled house

The main goal of repairing the settled foundation of a stone, brick or slag house is preventive action aimed at preventing further shrinkage of the weakened foundation. carried out through the creation of a monolithic enclosing and reinforcing belt - an overlay - on the inside and outside. This allows you to correct subsidence of the base, which leads to through cracks in the ceiling, walls, and corners of the building.

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Procedure

Strengthening should be done as follows:

dig a trench around the perimeter 40-50 cm wide, at an angle of 35°. The base of the foundation is not disturbed;
the monolith cleared of dirt is cleaned of dirt, old plaster, and destroyed parts of the foundation and base are removed;
the surface is treated with a deep penetration primer;
drill the entire foundation every 60-120 cm horizontally and in 3-4 rows in height;
drive in reinforcement 2 mm larger than the drill, total diameter 10-14 mm;
horizontal reinforcement is secured by welding;
fill deep cracks and damaged areas with concrete;
a metal mesh for plastering work with a large cell pitch is attached over the reinforcement;
if the foundation is generally strong and has just begun to settle, it is plastered;
if there is significant destruction and sedimentation, then install the formwork at a distance of 5-15 cm from the foundation and fill it with concrete;
after the concrete has hardened, waterproofing is applied;
The trench is filled in and each layer of 15-20 cm is carefully compacted.

The entire sequence of these actions leads to an increase in the bearing capacity of the foundation.

The foundation is the basis of any structure; the comfort and safety of the people or animals living in the building depends on its reliability. During operation, under the influence of weather conditions, there is a constant shrinkage of the foundation. Shrinkage is a change in the volume and size of the foundation under certain conditions.

Rising waters also affect the shrinkage of the foundation. You cannot know about this in advance, but it is possible to postpone this problem for a while by making a drainage system.

Foundation strengthening technologies

There are a lot of technologies that strengthen the foundation.

These technologies differ, and which ones to use depend on the type of building, structure and soil.

Work to strengthen the foundation is carried out using special equipment.

Local renovation work

In the event that the destruction and shrinkage of the structure began recently, it is possible to do local repair work, that is, seal seams and cracks. To do this, make a small hole in the wall and then widen them.

The next step will be sealing them with cement mortar. If voids have appeared under the foundation due to running water and it has sunk as a result, then it is necessary to fill the voids with cement.

Strengthening a pile-screw foundation

If the soil is loose, and you intend to make a pile or pile-screw foundation, then such a foundation will not be strong at all. Due to use, it may become deformed due to wear and tear of the structure. Also, such a foundation will be unstable due to violation of construction technology or due to poor quality material.

In this case, the strip foundation may shrink, move, or become skewed.

In some cases, there may be delamination of the foundation and destruction, both partial and complete.

In these cases, it is best to completely remove the deformed foundation.

Stopping the foundation shrinkage process

If there is shrinkage, then the most important action should be to stop the shrinkage process.

To record the rate of shrinkage, beacons (paper or plaster) are glued to the crack site. If the shrinkage of the foundation occurs very quickly, then the lighthouses will collapse quickly.

If the beacons break, then pouring the solution must be continued.

The next stage of strengthening begins only after the position of the beacons begins to change.

This design will improve the bearing capacity of the foundation and allow the load to be distributed along a horizontal plane, which will prevent the foundation from sagging.

Method of strengthening columnar foundations.

After two vertical piles have been poured, a pile (made of wood or reinforced concrete) is laid underneath them. This pile will strengthen part of the foundation well.

In the event that the foundation has subsided and it has completely lost its structure or completely collapsed, in this case it is completely replaced.

To remove the load from the old foundation, special wooden supports “chairs” are built, which are placed perpendicular to the foundation tracks.

But if there is such a need, then the foundation is made in several areas at once. True, the work is carried out simultaneously in cases where the distance between the zones is from five to six meters.

Before pouring the foundation and erecting the structure, try to take into account all the nuances so that your house can stand for a long time without destruction.

We hope that this information is useful to you. Good luck!

Any violation of the construction technology of load-bearing structures is fraught with the opening of cracks. In 90% of cases, the cause is the foundation of the house (soil) or the foundation, which can only be strengthened using one of the technologies below.

If the crack on the surface of the wall is horizontal (encircling, local), the foundation has nothing to do with it. The reason most often lies in the sagging of the lintels or rafter system. In the absence of tightening, the hanging rafters try to push the opposite walls apart.

There are several main reasons why the foundation has sunk and cracks have appeared in the house. The main ones are traditionally:

areas under the foundation consisting of subsidence soils - rupture of the foundation tape, change in the geometry of the structure;
swelling forces - uneven loads tear the foundation, walls warp;
violation of construction technologies - low grade of concrete, loading of the foundation to 70% strength, low reinforcement coefficient, corrosion of reinforcement, winter concreting without heating.

If the foundation has lost its integrity, restoration is necessary; in other cases, it is enough to strengthen the base under the sole of the tape in certain areas. There are several technologies for this.

Attention! A crack is a “pointer” that makes it easier to find the boundaries of subsidence or swelling soils. This makes it easier for specialists to localize repair work.

There are inclined and vertical cracks with divergence upward or downward, which most accurately indicate the nature of the deformation:

a vertical crack diverging upward in the middle part of the wall - swelling of this particular area;
vertical gap, divergence downwards - subsidence of soil in the middle of the house;
a similar defect with a divergence downwards is swelling on both sides of the wall due to lateral freezing;
an inclined crack from the corner to the center of the facade - the backfill of the adjacent wall has sagged;
inclined crack from the center to the corner - the shrinkage funnel is located directly under this crack;
cracks converging in the shape of an arch – soil subsidence in the central part of the foundation strip.

A crack on the wall extends upward.

After determining the cause, in any case, you will have to expose the foundation with a trench close to the tape to carry out measures to strengthen the soil, lay drainage, install “bulls”, make a clip and other work.

Soil strengthening

If the foundation has vertical movements on soils with low design resistance to loads from the weight of the building (embankment, peat bog, silty sand), it is necessary to strengthen the foundation using the following technology:

lifting the foundation with jacks - to the design level in compliance with safety measures (partial or complete unloading with supports), meaning the lifting of sagging parts;
drilling holes - for immersing injectors with a diameter of 20 - 40 mm;
filling voids - with liquid glass (silicatization), cement laitance (cementation), synthetic resins (smolization) or hot bitumen (bitumenization).

These substances reduce water permeability, stabilize unstable soils, and increase the design resistance (bearing capacity) of the foundation. The disadvantage of the method is the need to use professional equipment capable of injecting binders under a pressure of 5–10 atmospheres. Other methods are not available to individual developers; they are used by restoration teams for architectural monuments.

Attention! These actions may not be enough, since if the foundation subsides in a separate area, this means its destruction in 70% of cases. Instead of costly dismantling of the building, tape restoration methods are used.

Strengthening the foundation

There are several ways to strengthen the foundation strip depending on the condition of the reinforced concrete structure:

unloading – inserting beams into load-bearing walls to support the masonry;
restoration of bearing capacity - drainage for drainage of ground, soil, surface water, relocation, replacement, protection from mechanical destruction (weathering, corrosion);
increasing the load-bearing capacity - frames made of monolithic concrete, brickwork, reinforced concrete slabs;
hardening - epoxy, polymer resins, cement mortar, and penetrating compounds are introduced into the drilled holes;
special methods - screw piles, pressed piles, “bulls” in the corners, injection of cement mortar into the masonry.

If the foundation has non-through cracks caused by weathering, the surface is plastered or targeted, coated or impregnated with penetrating mixtures. Tarquetting is called pressure (0.4 - 0.6 MPa) spraying with cement laitance with a minimum amount of quartz sand.

To strengthen the prefabricated foundation with a cage, the following technology is used:

strip exposure - a trench along the wall to a depth just below the base;
reinforcement - own frame by analogy with a strip foundation, installation of rods in holes drilled in the foundation, tying them to the frame rods;
formwork - below the blind area or to the entire height of the basement;
concreting - standard laying of the mixture.

After stripping, the upper part of the cages, rising above ground level, is protected from moisture by ebbs.

Attention! Unlike the underlying layer created during the construction of the foundation, non-metallic materials under the expansion (cage) are compacted into the ground without laying geotextiles.

Reinforcing ring around the foundation.

When manufacturing a reinforced concrete cage, the following points should be taken into account:

width – from 15 cm on each side for reinforced concrete, from 20 cm for concrete;
thickness of the underlying layer - from 10 cm of crushed stone or sand;
anchoring with the existing tape - rods with a diameter of 20 mm to a depth of 12-25 cm, rod length 25-40 cm, step 1 - 1.5 m;
reinforcement of the cage - mesh with a cell of 15 x 15 cm for the lower belt, 10 x 10 cm for the upper belt;
concrete – class B10 – B15.

When restoring brick strip foundations, it is necessary to remove crumbled stone. When repairing reinforced concrete structures, the oxide film should be removed from the surface and the roughness should be increased by notching.

If it is not possible to increase the bearing capacity of the soil under the foundation (the thickness of the loose layer is significant), the technology of strengthening the underground structure with piles is used:

short driven ones - pipes with a diameter of 57 - 89 mm with a pointed tip made from their body (analogous to SBC, but without a blade) are driven in next to the foundation and embedded in the cage;
external screws - SHS are immersed around the perimeter, the building is raised, the ends are tied with a metal grillage, the house is lowered onto a new foundation (suitable for wooden houses);
“bulls” - the method is used when settling corners, screw piles are screwed in obliquely on both sides of the corner, a beam (I-beam, channel) is welded onto their heads, on which the corner of the foundation rests.

The advantage of the technology is the unloading of the existing foundation. The piles are guaranteed to penetrate through unstable horizons and rest on a bearing layer with high resistance.

These measures are usually carried out as a complex, since when individual sections settle, the integrity of a monolithic or prefabricated structure is violated. For example, if the foundation partially rests on subsidence soil, the base is first strengthened, after which a reinforced cage is poured. When using screw piles, there is no need to strengthen the foundation, however, after raising the foundation to the design level, it is necessary to fill the voids formed under it with concrete or cement mortar.

Another option for strengthening the foundation with piles.

When the casing is deepened by 0.7 meters or more, standard thermal insulation measures are taken. This is necessary to reduce the pulling forces during swelling:

vertical surface of the frame with high-density polystyrene polystyrene foam + horizontal thermal insulation of the blind area 0.6 - 1.2 m wide at a depth of 0.3 - 0.4 m;
sand, crushed stone in the sinuses of the trench + at the level of the base of the cage;
or crush-sliding thermal insulation - EPS rigidly fixed on the vertical surface of the casing, polyethylene film (attached only in the upper part), polystyrene foam PSB-S without attachment to the casing (pressed to the film with backfill material).

In some cases, it is possible to sufficiently strengthen the foundation in certain areas and strengthen the foundation using one of the indicated methods, but sometimes this may not be enough.

If you have a wooden house, we additionally recommend that you read the article:.

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