The corner of a brick house sank, how to fix it

Narrative plan:

Introduction;
Causes of foundation subsidence;
How to avoid foundation subsidence;
Stopping the subsidence process.

The foundation is a solid foundation for any structure. Its reliability directly affects the safety and comfort of building occupants.

During operation, a process of shrinkage constantly occurs under the influence of environmental factors and weather conditions.

Shrinkage is a change in the size and volume of a house support structure under certain conditions. It leads to the appearance of wall cracks, distortion of door and window openings, subsidence of building corners, and destruction of some structural elements.

Without action, this process can lead to the destruction of the structure over time.

How and with what can you strengthen the foundation if there is a crack in the wall

The slightest deviation from the technological requirements for the construction of load-bearing foundations contributes to the formation of cracks. Almost always, the problem lies in the foundation of the structure, which can be secured using one of the available methods. But when the crack runs horizontally, the foundation has nothing to do with it. Today we will look at options on how to strengthen the foundation if there is a crack in the wall.

Causes of cracks

Imagine that after pouring the foundation and erecting the walls, vertical cracks appeared on the surface of the latter. Their formation can be explained by one of three reasons:

If you have poured a foundation and cracks appear in it, the foundation is restored. In other situations, strengthening the soil composition will be a sufficient measure.

To determine the nature of the damage and identify the causes of the formation of normal cracks, it is recommended to study their shapes and directions:

Harmful influence of external factors

In addition to structural violations and failure to comply with all required steps, damage to the foundation slab is possible after exposure to certain natural factors.

Most often, such cracks can occur at the end of the winter period due to soil movements during freezing and thawing.

Physically, this can be explained quite simply: the soil either expands, causing heaving, or decreases in volume.

Thus, “pushing out” and deformation of the base of the building occurs. This is a very common cause of cracks along the perimeter of the entire structure.

If a brand of concrete with a high degree of hygroscopicity was used when pouring, then it is possible that water will be “drawn” into the pores of the slab, which will cause an increase in volume when frozen.

This is followed by internal breaks and cracks when warm weather sets in.

The wear and tear of the laid foundation can also be an important factor.

Watching the cracks

Foundation cracks are:

In terms of dimensional parameters, they are classified into small, large and through cracks.

Horizontally directed faults are the consequences of mistakes made in the work. They do not pose a danger to the overall stability of the structure; they are sealed during the process of plastering the facade.

Large cracks directed diagonally and ordinary cracks in the base are considered dangerous.

Microcracks in the foundation, the parameters of which barely exceed 1 mm, are formed for various reasons. They do not pose a danger, but they should be sealed, since moisture and low temperatures can turn hairline cracks in the foundation into wide cracks, beginning the process of gradual destruction of concrete in this area.

So, what should you do if the foundation of your house is cracked? Experts recommend organizing monitoring to monitor changes in the size of the gap. The process of determining the nature of crack expansion occurs as follows:

If cracks in the foundation of a brick or block house continue to increase, or a through-cut fault is discovered, work should be immediately organized to restore the integrity of the foundation.

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Let's consider a situation when the foundation begins to sag near the house. This leads to the appearance of vertical and horizontal cracks in the walls, window and door openings are distorted, the corners of the house begin to sag, and some elements of the foundation itself are destroyed. If you don't take immediate action, the house may simply collapse.

Causes of foundation flooding

The answer to the question: "What should I do if I'm lowering the foundation?" Typically you should look for when you inherit an old house or buy a dilapidated building. Often the foundations hang in old houses built on wetlands or in areas where there is a lot of freezing. Another reason. the choice of base does not correspond to the characteristics of the area.

Hydrological and physical-mechanical processes can occur in the lower layers of the soil, which leads to a decrease in its bearing capacity. Sometimes changes in soil properties are caused by construction work taking place near your home.

Soil strengthening

What should you do if the foundation of your house bursts?

In the case of vertical displacements of the foundation on soil with a low resistance to load effects from the mass of the structure, you should strengthen the foundation using a certain technology:

All of the above substances can reduce moisture permeability, strengthen unstable soil areas, and increase the design resistance of the foundation.

The disadvantage of this method is the need to use special equipment that injects the binder component under a pressure of five to ten atmospheres.

Other methods are not available to private owners; they are used by construction crews when restoring architectural monuments.

Unfortunately, the listed strengthening measures may not be enough, because subsidence of the foundation in a certain area in most cases means its destruction. In these cases, the foundation strip will have to be restored.

Execution of brick cladding

Brick blocks are applicable to buildings located on a pile or strip base. Work must begin with preparation - clean the product from dirt, prime it, putty the cracks and crevices, and, if possible, add additional insulation. Experts advise organizing a blind area that will protect the foot from moisture.

Brick laying along beacons for foundations on screw piles

Activities that include the arrangement of ventilation lines and communications can be carried out independently:

Weld a 120x120 mm corner around the perimeter. Beacons are installed strictly along a line, which is marked with an elastic cord or pencil.
Treat the sole with a mixture with a corrosion protection effect.
Lay out the first row of cladding, keeping the seam width to 5 mm.
In the second row, leave ventilation trenches for ½ brick block.
The subsequent laying should be carried out according to the scheme of the 1st row.
Reinforce the corner parts and connect them by welding.

When facing in order, the corners are raised, and then the entire surface of the base. It is obligatory to bandage half of the brick and cover the border with galvanizing. For a binder solution per 1 m2 you will need 30 kg of concrete mixture, the number of bricks is 51 pieces.

Methods for sealing cracks

Let's figure out how to fix cracks in the foundation. The method of performing the work is determined taking into account the type of materials used to construct the external walls of the facility. If a crack has formed in the foundation of a wooden house, then the work is carried out according to the same scheme; for stone and block structures, the technology for repairing cracks in the foundation will be different:

How are simple cracks in the foundation repaired after pouring? The algorithm of actions is as follows:

What structures can be lifted

For major repairs, only one-story buildings of the following types are raised: made of wooden beams;
from rounded and other logs; panel wooden houses. Structures made from timber or hardwood, such as larch and oak, last for quite a long time. There are still houses built before the revolution, which are over 100 years old and have retained their almost original appearance.

Modern wooden buildings are not so durable. The reason for this is the quality of the timber, which became especially susceptible to various diseases after the beginning of the “atomic era” and the ongoing testing of nuclear bombs.

In this regard, wooden structures must be thoroughly inspected every 15 - 20 years to identify signs of rot and the appearance of fungus; the lower crowns of wooden houses are especially often affected by this.

Foundation strengthening methods

How to strengthen the foundation if there is a crack along the wall? Let's look at the options that are used most often.

Strengthening the strip base

Strengthening it is resorted to in cases where repair work has not produced a positive effect, and cracks in the foundation exceed the permissible dimensions.

Suppose the strip foundation cracked under the weight of a wooden frame. In this case, the following actions are performed:

The strip base, freed from the load, can now be repaired in the most convenient way.

How to repair a cracked foundation if a house made of aerated concrete or brick stone stands on it? Raising the walls without damaging them will be quite difficult. Therefore, the cracks that appear are closed and fixed with special metal belts.

If the foundation of a new house bursts, steel tires are applied to the damaged areas:

The option of strengthening the foundation strip of an old house with a reinforced concrete layer is distinguished by its reliability:

After filling from above, the repaired breach will receive an additional supporting surface that will absorb part of the load.

A similar method is used to seal thread-like cracks on a FBS base.

We repair the pile foundation

Cracks in structures erected on pile-grillage foundations appear due to subsidence of the support posts. The problem is eliminated by erecting a strip base, with the help of which the structure in the problem area is strengthened. So, if the TISE foundation is cracked, you will need:

Some people use this technology to repair slab foundations if the base slab is cracked or the floor is subsiding.

Signs of Problems

There are several such signs and they can be seen almost with the naked eye. Namely: partial or complete violation of the foundation of the house; deepening the foundation into the ground; subsidence of the building in one of the corners; large distortion of windows and doors, as well as the tilt of the building.

After inspection and identification of many additional works, a decision is made to raise the house. At the same time, they create a plan according to which they purchase the necessary building materials and tools. In addition, the following activities are planned for major repairs:

replacement of rotten building crowns;
preventing further subsidence;
alignment of the distortion of the entire box around the perimeter;
treating wood with chemicals to prevent rotting;
complete or partial replacement of the foundation.

Such grandiose work is carried out within 1 - 2 weeks, involving the entire family and several invited specialists.

Causes of foundation deformation

If the foundation is deformed, then it is necessary to find out the reasons for this deformation and then look for solutions to restore it.

If measures to repair the foundation are not taken in time, then its further restoration will be very difficult. And if the case is very complex, then recovery will be completely impossible.

In the event that the foundation has subsided due to the fact that it is being washed away by groundwater, then it is necessary to pump it out from the problem areas.

If the foundation collapses due to the fact that during the construction of the foundation there was uneven drying of the concrete or its uneven distribution.

In this case, it is necessary to strengthen the foundation with a metal frame and then fill it with concrete. In this case, the concrete used is the same grade that was used when pouring the foundation itself.

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

Before laying a foundation, you need to find out what kind of soil you have, finding out its strength and composition. To prevent the ground from sinking under the foundation, it is necessary to pour cement under the foundation that will be.

Another factor for destruction is the choice of low-quality materials for the construction of the building.

A common factor for the destruction of the foundation is its saturation with moisture. Once the moisture freezes, the foundation is subjected to heavy loads and its structure eventually collapses.

In order to avoid subsidence of the foundation during construction, it is necessary to control its moisture resistance. Very often the negative influence of moisture manifests itself in swellings and cracks on the surface of the base. They can tell you about the presence of moisture on the surface of the foundation and also about poor maintenance before the construction of the building begins.

If you discover these unpleasant findings, you need to immediately start eliminating them, otherwise this will lead to problems with the foundation in the future. First you need to clean the damaged areas and treat them with mastic.

General information

Before determining the complexity of the work and proceeding with its implementation, it is necessary to inspect the building.

Foundation problems are indicated by signs such as:

Presence of cracks in the walls;
Warping of the house;
Subsidence of the building can be either complete or partial, for example, touching one corner.

Type of repair	Peculiarities
Partial	If the foundation has only slightly sunk into the ground or a separate part of it has become unusable, you should think about how to raise a rickety wooden house and “build up” the sagging section of the foundation.
Capital	Necessary if the base is severely damaged.

Below we will take a closer look at both repair options.

Foundation strengthening technologies

There are a lot of technologies that strengthen the foundation.

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, crack, or become skewed.

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

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.

Preparing to lift the building

Before lifting the house, it is necessary to carry out actions to ensure ease of lifting and further repairs. This is done to protect against sudden and unexpected destruction of the structure. The following must be done:

dismantle the outgoing sewer pipes;
disconnect the power line;
turn off the gas pipeline (if any);
cut off the heating pipes from the boiler and disassemble the chimney;
remove all furniture;
remove all doors and windows from the boxes;
reject or cut down interfering trees and bushes.

In many houses, the floor is built on joists that have their own columnar foundation. The walls of this building are connected to the floor only by baseboards, which will also have to be removed. In addition, the upper crowns on which the rafters are attached must be well connected to each other with reliable 50 mm thick blocks or bars so that the roof does not move apart. You also need to separate the veranda attached to the wall.

When everything is ready, choose suitable jacks for wooden houses. For ordinary standard buildings with a total area of 60 to 100 sq. meters, hydraulic jacks with a lifting capacity of 5 - 10 tons are quite suitable. You need at least 2 of them. Drivers of heavy-duty trucks always have such lifts.

Prepare wooden pallets with a thickness of at least 50 - 80 mm, on which jacks for lifting and steel plates for the heads of these devices will be installed. There should be a small depression in the center to prevent the jack from slipping.

How to fix a sagging foundation

They ask us:
Good
afternoon, tell me what to do correctly in this situation:

Near the house there is a veranda made of white brick (strip foundation). The building is not large, 3 by 4 meters and 3 meters high.

After a snowy winter, melt water approached one side and this side began to sink. I received the following advice: make a trench on the sagging side 50-70 cm wide and approximately the same depth, take reinforcement 12 cm thick and 50 cm long and drive it 25-30 cm at the bottom into the old foundation in 2 rows at a distance of 70-90 cm and fill the trench and ends of concrete reinforcement protruding from the old foundation.

Is it right to do this? Will there be any effect from strengthening the foundation this way? Is everything correct in this advice or can something be done differently than I described. And how should concrete be poured to the ground level or to the level of the plinth, which rises almost 60 cm above ground level, I would not want to pour an extra half meter of concrete.

We answer:

I will answer from the end: no, that’s not correct, such “amplification” will have practically no effect. With the same success, you can pour a similar “beam” of concrete in a neighboring garden. If you reinforce it with a side bench (that’s what it’s called), you need to insert a whole cantilever structure made of metal beams into the body of the foundation. Reinforcement, and even with such a step, will not give any effect. The foundation will sag safely, and the only thing the constructed mass will do is an additional load on the already subsiding soil.

In each specific case, you need to look at what the existing foundation is and only after studying the situation make a decision. There are many options for strengthening foundations, and which one is suitable in your case should be decided by a specialist after an on-site inspection. In the vast majority of cases, advice from non-professionals is money wasted. And it’s good if the situation doesn’t get worse.

Only the lower part of the foundation “works”—the base of the foundation, resting on the ground. The wider it is, the higher the bearing capacity of the foundation. Therefore, to strengthen the foundations in such a case (as an option), dig a trench to the very bottom, to the base, and then dig under the base in separate sections. This is done in separate sections, usually no more than a meter in length, so as not to cause settlement of the entire structure of the house.

The excavation is carried out, if possible, at least half the width under the sole, and going downwards by at least 300 mm. It is best to carry out such work from both sides - from the street and from the room, in this case the pillow will be brought under the entire supporting part, but it is not always possible to do this (it is necessary to dismantle the floors, remove a significant amount of soil, etc.).

After the excavation is completed, reinforcing bars are placed in it, from AIII reinforcement with a diameter of 14-16 mm, in increments of 15-20 cm. The rods are located across the axis of the foundation. After installing the reinforcing mesh, the formwork is installed so that its height is at least twice the height of the slab being poured. We pour the concrete, vibrating it carefully so that the space dug out under the foundation is filled as completely as possible. We get a kind of half-clip covering the foundation from below (if similar work is done from the premises, then the tunnels are closed and the clip is completed, in the form of an inverted letter “P”).

If the foundation is made of piece materials, bentonite or rubble stone, it is necessary to make a protective jacket of concrete; in this case, in fact, holes are drilled in the foundation with a hammer drill into which anchors made of 10-12 mm reinforcement are inserted. In this case, a repair compound, or at least cement, is injected into the holes with a construction syringe. a solution prepared using non-shrink cement with the addition of PVA emulsion or another plasticizer. The anchor spacing is at least 250 mm, both horizontally and vertically.

Then the formwork is arranged and concrete is poured, usually 250-300 mm thick. You can read more about foundation repair here.

Be sure to take measures to drain melt and rain water. Also, make a blind area around the building, at least 80 cm wide, made of concrete or asphalt concrete, with a slope from the house of at least 3-5%.

Good afternoon. Part of the supports of a columnar foundation of a light frame building 6x6 meters has sank. How can you strengthen the sagging elements and bring a new support base into the level of the structure of the lower support rim of the beam? Thanks in advance for any suggestions.

Hello. I can’t advise much, but the situation is similar. A small country house, approximately the same size, with a columnar brick foundation. It sags constantly, every year or two you have to jack it up and put up the pillars, at the same time somehow deepening them, that is, increasing them in height. But all this still doesn’t help, I’m planning to make a shallow shallow foundation in the near future. Making a foundation for an existing building is not an easy job, but it can be jacked up in parts and poured in parts; I will use rubble concrete.

Major renovation

Lifting the house

First, let's look at how to raise a wooden house and pour the foundation if the old foundation has completely fallen into disrepair. For this operation you will need at least two jacks with a lifting capacity of 5 tons.

It is best to use hydraulic equipment. Of course, renting it is more expensive, however, the work in this case will be significantly simplified and speeded up.

Scheme for raising a house with a jack

So, the instructions for performing this operation are as follows:

First of all, the corners are supported. You should start from the most sagging side. However, before installing the jack, it is necessary to concrete the areas on which it will be installed, or lay concrete slabs.
Next, the house is lifted. This must be done slowly, carefully monitoring the distortion.

After raising the wall by more than 1-2 cm, it is necessary to install supports, which can be used as wooden blocks. Supports should be placed on a hard, durable surface, just like jacks. The step between them should be about 30 cm.

If one of the jacks fails, the house will settle on the supports.

According to the same scheme, the building rises along the entire perimeter until it reaches the required level.

In the photo - making a strip foundation under a wooden house

After raising the house, you can build a new foundation. Most often, this operation is performed in segments no more than 1.5 - 2 meters wide.

The work is performed in the following sequence:

First of all, it is necessary to dismantle the corner of the old foundation.
Next, you should prepare the soil - fill in a sand-crushed stone bed and fill in the footing (a bed of thin cement mortar).
Then you need to make a reinforcing frame, which significantly increases the load-bearing capacity of the base.
The next step is to install the formwork. The structure must be securely fastened.
Next, you need to prepare a cement mortar from one part M400 cement, three parts sand and five parts gravel.
The prepared solution should be poured into the formwork and compacted.
After the concrete has completely hardened and gained brand strength, waterproofing should be laid on top of the foundation, and then the house can be carefully lowered.

According to this scheme, a wooden house is raised onto the foundation along the entire perimeter. It should be noted that the base can also be made of brick or rubble stone, however, such a structure will be less durable.

Partial foundation repair

Partial renovation

Now let's look at how to raise the foundation of a wooden house with your own hands if it has sagged. This procedure involves “building up” the foundation and depends on the level of subsidence, as well as the material from which the foundation is made.

Often you can raise the foundation by laying timber or placing bricks under the house. You can also pour concrete under the logs after installing the formwork.

Often home specialists are interested in how to raise a sagging corner of a wooden house if it is in poor condition and there is a possibility of its destruction? There are several options for solving this problem.

Replacement of the lower crown of the house

Most often, openings for jacks are cut out in the lower rims with a saw. In this case, it is necessary to use at least two jacks. As a result, the emphasis is on strong, non-rotten logs or beams.

If the lower rims do not change, logs of suitable size are installed in place of the cut openings. In this case, the joints are sealed with mineral wool, tow or other insulation.

There is also another way to raise the corner of a wooden house that has rotted. In this case, the frame is assembled and placed on jacks. Thanks to the frame, the structure is lifted evenly.

Lifting a wooden house using a frame

Here, perhaps, are all the main points of lifting wooden houses to repair the foundation or lower crowns. It should be noted that many construction companies are engaged in such work, however, the price for the services of specialists is quite high.

Therefore, in many cases it is more advisable to do the work yourself. The main thing is to do repairs in a timely manner, which will significantly extend the life of the building.

Tags: do, sag, angle

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The corner of the house is sinking (photo)

The house is around the 50s of the 20th century. There is no design documentation, of course. We only know that it is adobe, lined with brick. Recently, the corner began to sag catastrophically quickly. (When it rains, water from the drainpipe is discharged far beyond the limits - nozzles are not shown in the photo.) Please advise what to do. And what to do with the cracks temporarily, because... Repairs are expected to be done in the spring.

Are the valiant construction companies from Rostov building houses higher up the slope by any chance?

Digging and pouring concrete. It's all from water. Water from the drain gets into the cracks of the blind area, etc. It was necessary to put a gutter on the ground and point it away from the house.

Mikhalych wrote: It’s all because of the water. Water from the drain gets into the cracks of the blind area, etc. It was necessary to put a gutter on the ground and point it away from the house.

gluck911 wrote: During rain, water from the drainpipe is discharged far beyond - the nozzle is not shown in the photo

Stan wrote: taken far beyond

Far is an “extensible” concept. How much? Doesn't it rain in this area? What is the foundation? What kind of soil? In any case, because of the water. If not high water, then groundwater is close. Houses don't just fall apart. Good luck!

Mikhalych wrote: If not high water, then groundwater is close. Houses don't just fall apart.

This may lead to a different approach to solving the problem: if the house was standing before and suddenly the corner began to sag, this is not necessarily wastewater or groundwater, there may be piles nearby; groundwater doesn’t just rise, and if it does, then we’re not talking about saving one corner of the house, but the entire house. Anything concrete can be said only after examination by specialists.

Recommendations for developers

Preventive measures taken at the stage of building a house will help you avoid troubles. Let's try to give some advice that is not related to difficult tasks. Firstly, in no case should you neglect hydrogeological surveys or carry them out yourself, hoping for a successful development of events rather than common sense. It is possible to save in this matter, but most often such frugality later turns out to be too costly. Secondly, it is necessary to strictly follow the technology for preparing the base and laying the foundation. The desire to experience material benefit in this case always leads to problems during operation. In particular, it is strictly prohibited:

use concrete of lower grades than required by the project;
mix or order the solution long before installation;
lay reinforcement of inappropriate diameters or thinner frame meshes.

The base must be compacted thoroughly. This rule applies to both the sand cushion and the backfilling of a trench or pit.

Thirdly, do not forget about waterproofing and drainage base. At this stage, a responsible attitude towards the work being carried out is required. If necessary, reservoir or ring drainage should be performed, which will help reduce the groundwater level. Fourthly, it is recommended to lay all communications before pouring the foundation. Installation of a water supply or sewerage system after the construction of an underground structure will lead to the destruction of its solidity. It is necessary to think through the entry and exit points of the pipes in advance, marking them in the design documentation.

Over the entire area of a columnar or strip foundation, it is necessary to dig a ditch with a width of twenty to thirty-five centimeters.
Boards are laid at the bottom of the trench along the edge that is on the outside. These boards will act as formwork.
Between the elements, metal pins are driven into the foundation and a metal mesh is attached to them.
Thus, we will get something like reinforcement that is poured with concrete.

How to strengthen a cracked foundation

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.

Complete replacement of the base

The foundation of a house is replaced when it is no longer possible to strengthen and restore it.
The whole process is labor-intensive and long. To do this, you need to dig a trench along the entire foundation strip up to 2 m deep, remove the old structure and pour a new foundation. To prevent this method of strengthening, it is necessary to monitor the structure. If cracks or distortions of windows or doors occur, carry out restoration measures. As you can see, strengthening the foundation can be done on your own, the main thing is to carry out the work step by step, taking into account the technology and the characteristics of the damage that has occurred.

Possible amplification options

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

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:

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.

If you have poured a foundation and built a house recently, we recommend reading the article: Why does the foundation crack after pouring?

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:

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.

Video description

Pouring the foundation

Now let's move directly to the question - how to add a foundation to an old wooden house. The first thing to do is to form the grips. These are sections of the foundation that are built in areas where jacks were installed. Their length is 1 m, and at the corners of the house 1 m on each side. Accordingly, formwork is made for them, taking into account the height of the future structure. As well as a reinforcing frame made of steel reinforcement.

Grip in the form of a box made of boards Source freemanzone.com

The reinforcing frame is laid first, and then the formwork is built around it. It is made in the form of a box, that is, closed on four sides around the perimeter. After which the structure is poured with concrete and compacted with an internal vibrator. This process is mandatory because air always remains in the concrete mixture, which, after the material hardens, turns into pores and cavities. The latter reduce the strength and load-bearing capacity of reinforced concrete structures.

As for the concrete mortar, it is a classic mixture of one part cement, two parts sand and four parts crushed stone. All this is mixed with water until a homogeneous liquid structure is obtained. In this case, a thick mass is not needed, because pouring it into the formwork through the gap between it and the house will be difficult. Yes, and it will be difficult to compact.

The grips will remain in the formwork for 7 days, after which the wooden panels are removed. But it’s better to lower the house after 28 days. During this time, the poured concrete will reach its brand strength. You will have to lower it using jacks, which are installed next to the filled grips. Temporary supports are dismantled.

Pouring concrete mortar into the formwork installed under the house Source stroyka37.com

Next, holes are made in the sides of the foundation sections into which several reinforcement bars are driven. You can approach this matter differently - leave the ends of the reinforcing belt of the grips protruding from the formwork. The reinforced frame of the remaining sections of the foundation structure will be connected to them. That is, it is necessary to ensure that parts of the foundation become at least partially monolithic.

The next stage is the installation of the reinforcing frame and the formation of formwork between the grips. These are boards or boards that are installed between poured and finished areas. The ends of the latter will perform formwork from the end sides. All that remains is to pour the concrete and compact it. After 7 days, the formwork is dismantled.