Replacing part of the foundation under a wooden house. Repairing the foundation of a wooden house. Conditions for partial and major repairs

Wooden houses built in the middle or even at the beginning of the last century serve the current generation of owners well. But there is no escape from the ravages of time - the age of the buildings, which have witnessed an entire era, shines through the warped windows and doors, sagging foundations, and leaning walls. However, there is no need to rush into plans for new construction. Very often, a dilapidated foundation is to blame for the unsightly appearance of a wooden house. Its renovation will provide the building with a second youth, and perhaps your grandchildren will also live in it.

Factors that indicate the need for foundation repair or replacement

Before starting restoration work, it is necessary to understand why the foundation was destroyed, how serious the damage is, and also determine how the damaged building can be reconstructed.

Brick foundation that requires complete replacement

Causes of damage to the foundations of wooden houses

To prevent a similar problem in the future, it is necessary to understand the factors that lead to the destruction of the foundation. And this happens for several reasons:

geological and hydrological changes that lead to subsidence or displacement of the soil under the building;
violation of construction technology and use of low-quality materials;
absence or improper operation of the drainage system;
time factor - even high-quality materials lose their performance properties over the years;
weighting of the structure due to additional superstructures.

It is quite simple to determine whether the house is currently subsiding or whether the foundation has found new support points. To do this, beacons made of plasterboard or paper are installed in the busiest places. Their damage indicates that the process of destruction continues.

What are the types of deformations?

The second thing that needs to be done during the research process is to determine the degree of destruction. The complexity of restoration work depends on this factor. Conventionally, 4 types of deformations can be distinguished:

Small defects that manifest themselves in the peeling of the foundation finishing. As a rule, the strength of the foundation does not suffer from this, and problems can be eliminated without any problems.
Peeling of plaster, as well as small cracks, are easily removable defects
Moderate damage, indicated by cracks in the base that appear as a result of its displacement. To reveal how much the foundation subsidence is progressing, a layer of putty is applied to the problem area. A crack that appears at the slightest deformation can tell about the rate of deformation, as well as its nature and direction of displacement.
Cracks whose propagation has stopped at the initial stage can be sealed with mortar
Significant or catastrophic damage resulting from significant subsidence, displacement, or failure of the foundation. They are revealed in the violation of the geometry of the walls, the appearance of large gaps between the crowns, and the warping of windows and doors. Problems of this kind lead to the impossibility of operation or complete destruction of the house, so urgent reinforcement or replacement is necessary.
If deformation of the foundation can lead to complete destruction of the building, repair work should begin immediately
Unavoidable consequences. If the moment is missed, then repairing the house will most likely be unprofitable. In this case, a decision is made to demolish the building and build new housing.

After carefully analyzing the nature and extent of destruction, a decision is made on how to reconstruct the foundation. If deformations can be eliminated and prevented in the future, then the foundation can be strengthened. Otherwise, it will need to be completely replaced.

In some cases, it is not practical to renovate a house - it is easier to build a new one

Strengthening or replacing the foundation may be required not only when it is destroyed. Reconstruction is also carried out in cases where there is a need to build a superstructure on the house, and the existing foundation is not designed for increased load.

How to repair the foundation of a wooden house yourself

Several types of foundations are used in the construction of wooden houses, so we will select the most common cases and consider the most effective and popular restoration methods.

Repair of strip foundations

Small single cracks that appeared due to sedimentary changes in the soil under the house can be repaired with mortar (provided that the process has stopped and the base of the building has found new support points). To do this, the foundation is dug to the entire depth of the defects, the cracks are cleaned and filled with a sand-cement mixture.

Strip foundations are often used in the construction of wooden houses

Serious damage requires thorough restoration work. Most often, a new reinforced concrete structure is erected next to the old foundation strip, which is combined with the existing foundation using grooves and rods. Due to the fact that the repair structure is built on a stable cushion, as well as due to the redistribution of the load over a large area, it is possible to completely stop the deformation processes and return the foundation to its former solidity.

A groove (colloquial groove) is a recess, groove or groove in a monolithic concrete base, which is intended for laying cables and other utilities, as well as embedding reinforcement elements in order to strengthen or combine reinforced concrete structures.

Repair of uniformly subsiding strip foundation

In the case when the subsidence of the house occurs evenly along the entire perimeter, work to strengthen the strip foundation is carried out in the following order:

A trench is dug along the perimeter of the building, which covers the old foundation to its entire depth. The width of the pit is chosen so that it is possible to work comfortably. In addition, it is necessary to take into account the increase in the thickness of the foundation during restoration activities.
If the subsidence is caused by miscalculations in the design or mistakes made during the construction of the foundation, then the supporting structure is built taking into account previous mistakes. Perhaps the building began to sag due to the high groundwater level, which was not taken into account at the stage of its construction. In this case, the bottom of the repair trench should be below the freezing point of the soil.
Thoroughly clean the concrete surface from soil residues. Remove crumbling fragments of brick or rubble masonry.
The bottom of the pit is carefully compacted and covered with a layer of crushed stone 10–15 cm thick.
Holes are drilled in the old foundation to install the rods. It is best if the reinforcement fits into the holes made with a slight interference.
Strip foundation repair technology
Individual boreholes (in a checkerboard pattern) are drilled to expand their entrance hole to a diameter of 100 mm to a depth of 100–150 mm. During the process of pouring the foundation, concrete will fill these voids, combining both structures into one.
Create a reinforcement belt. To do this, the driven rods are welded to a three-dimensional reinforcement grid.
To strengthen a reinforced concrete base, it is best to use not welding, but connecting rods using knitting wire. Such fastening is much easier and faster to make, and its elasticity will avoid damage and displacement of the reinforced belt during concrete pouring.
Formwork is installed along the outer contour of the trench, for which any suitable lumber is used - boards, bars, wooden panels, etc. Before pouring concrete, the walls of the structure are covered with plastic film.
It is best to pour concrete gradually - in sections 1.5–2 m long. This will allow the solution to better penetrate into the grooves and fill all the voids and defective areas of the old foundation. To do this, a shield is made, which is installed across the formwork.
After the structure is filled and the concrete has set, the timber structure is removed and the foundation is waterproofed.
The remaining space is filled with soil. Of course, you should add soil gradually, adding a new portion of soil only after the previous layer has been thoroughly compacted.
The repaired foundation will extend the life of the old wooden house

To drain water from the foundation, a concrete blind area is made around the house. If the site suffers from excess moisture, then the base of the building is protected with drainage, which can be installed in parallel with the repair work.

Repair of individual sections of the foundation strip

If individual corners or small areas of the foundation are damaged, spot repairs can be done. It is performed in the following sequence:

If inspection of the base reveals its weakening along the entire perimeter, then the structure can be strengthened using a narrow (15–20 cm) encircling reinforced concrete clip. It is concreted using an anchor bond to the foundation, using reinforcement and formwork.

Replacing an old foundation with your own hands

If the foundation is destroyed or has sunk so much that it cannot cope with the functions assigned to it, then it is completely replaced. The log house does not weigh that much, so it is quite possible to do without a truck crane. To raise the walls to the required height, hydraulic jacks with a force of 5–10 tons and supports from logs or metal structures are used.

To avoid mistakes during repairs, work is carried out in stages.

Determine the weight of the building. To do this, the total cubic capacity of the log house is multiplied by the specific density of the wood from which the house is built. Based on the calculations, a decision is made about what lifting mechanisms will be needed and their quantity is determined.
You can lift a small, light house without jacks at all, if you use a pole - a long pole with a cross-section of at least 80x80 mm. One of its edges is placed under the corner of the building and rested on a round deck, and the second is used as a lever.
To reduce pressure on the foundation, bulky items and equipment are removed from the house. In some cases, the floor and stoves are even dismantled. Naturally, if the heating devices are installed on separate bases, then there is no need to disassemble them.
Using wooden beams and boards, window and door openings are carefully strengthened. This will prevent distortion during the lifting of the building.
A wide trench is dug around the perimeter of the house. It will provide access to the foundation and provide convenience when replacing it.
The old rubble or brickwork of the base is dismantled in small sections 0.3–0.5 m long - jacks will be installed in these openings. For small houses, it is enough to place lifting mechanisms only in the corners, while massive buildings will require additional supports in the middle of each wall.
To distribute the load on the jacks, you can use a powerful angle or channel
Install jacks. To prevent subsidence of lifting mechanisms, they must rest on a solid, reliable foundation. Plates made of thick steel or pieces of springs from a heavy truck, which are placed under the lower crown, will help to avoid damage to the log house.
Slowly and carefully they raise the house. It is important that all corners rise as evenly as possible. To protect yourself in case of insufficient load-carrying capacity of the jacks or their displacement, wooden wedges are inserted between the lower rims and the foundation cushion. Spacers should be increased every 15–20 mm.
When lifting a wooden house, the main force falls on the lower crowns. To prevent them from sagging, the logs are tied together with a steel hoop or reinforced with boards and bars.
Next to the jacks, as well as in other accessible places, temporary supports made of channel bars or powerful steel angles are placed under the frame - they will help unload the old foundation.
Any suitable materials can be used as temporary safety supports.
The house is lowered, after which they begin to dismantle the damaged foundation. At the same time, you should not save money and dismantle only the damaged areas - a partial replacement will not significantly reduce the cost of repairs as it will weaken the new foundation.
Dismantling the old strip base
Having reached the ground, it is excavated to a depth of 15–20 cm and a sand-crushed stone layer is created. The pillow is thoroughly spilled with water and compacted.
Construct corner and intermediate supports. They can be metal, reinforced concrete, stone or brick columns.
Reinforcement is installed and formwork is arranged. The wooden structure is made in such a way that it can combine the reinforced concrete base with the previously installed columns. To avoid leakage of the solution, the inside of the formwork is covered with plastic film.
The formwork for the new strip foundation is constructed according to all the rules - with reinforcement and protection against leakage of cement laitance
Concrete is poured into the established form. The solution is compacted by bayoneting, using a vibrating screed or manual tamper.
After the concrete has completely set, the formwork is removed and the structure is left open for another one or two days for the solution to dry completely.
Several layers of waterproofing are applied to the concrete surface, and the top of the foundation is covered with roofing felt. This material will prevent the spread of moisture from the base to the lower crown.
The gap between the foundation and the side wall of the trench is filled with soil, which is thoroughly compacted.
Slowly and evenly lower the house onto the new foundation.
On a new foundation, a wooden house will stand for many more decades

After completion of the repair work, a blind area is built around the house and the surface part of the foundation is lined.

Features of leveling a skewed base

If uneven shrinkage is observed, and the foundation tape has sagged and skewed, then a jack or a wagon is also used to repair and level it. The first thing they do in this case is to determine whether the deformation processes have stopped or whether the subsidence of the foundation continues. For this purpose, the already known beacon method is used. Based on the experiment, a decision is made on the repair method:

with strengthening the foundation using additional reinforced concrete tape;
increasing the sagging part of the base to a new height.

In order to restore the straightness of the surface in the first case, a trench is dug on both sides of the sagging corner. Its length should be such as to cover areas where the upper part of the foundation has deviations from the horizontal. After this, the building is raised to a height of 15–20 mm above its original position, after which a repair foundation is installed next to the problem area.

You can level the foundation using brick or stone masonry

Leveling “horizontally” is carried out using brickwork and is regulated by a layer of mortar, into which pieces of steel reinforcement, crushed stone, etc. are laid. The repair is completed with waterproofing work, after which the trench is filled up and the house is lowered into place.

If the shrinkage processes have stopped, then there is no need to dig a pit. The building must be raised and the surface of the sagging section of the foundation must be brought to zero. For alignment, use the method discussed above.

Repair of columnar or pile foundations

Owners of wooden houses installed on a columnar foundation may eventually encounter certain problems:

the tilt of individual pillars due to heaving of the soil, and, as a consequence, the tilt of the building towards the defective columns;
subsidence of supports, which led to skewed walls or excessively close location of the lower crowns to the soil.

Such problems require strengthening the foundation and replacing individual supports. One of the most effective and at the same time simplest methods is the installation of bored piles.

Foundation repair scheme using bored piles

The house is raised according to the method described above (to restore the strip foundation) and rigidly fixed in order to relieve the load on the support columns. The defective pillar is dug up and removed. After this, the pit is expanded to dimensions of 400x400 mm (for columns with a diameter of 200 mm), deepened 0.3–0.5 m below the base of the old support and prepared for installation of a new pile:

An intact, skewed column can be straightened. To do this, a tunnel is made from the side opposite to the direction of inclination, the pile is installed vertically, and the space around it is filled with concrete.

What can you do to avoid future damage?

The reliability and durability of the foundation depend not only on its design and compliance with climatic conditions and soil characteristics, but also on proper hydro- and thermal insulation.

The cause of most problems associated with foundation subsidence are errors associated with choosing the depth of its underground part. Foundations whose base is below the soil freezing level require restoration or restoration work much less often than shallow foundations. At the same time, certain types of soil (for example, peat) require reclamation measures or the excavation of unsuitable earthen soil and subsequent replacement with imported soil.

An important detail on which the safety of the foundation depends is proper waterproofing. Since the foundation is affected not only by wet soil, but also by atmospheric influences, the waterproofing system must be ensured by:

wide blind area;
vertical and horizontal waterproofing;
effective drainage.

For wooden houses without basements, only horizontal protection against moisture penetrating into the wood will be sufficient.

High-quality waterproofing will protect the foundation from the damaging effects of moisture

For these purposes, Bicroelast, Akvaizol, Bipol and other rolled materials are used, which are laid between the foundation and the lower crowns. Waterproofing is laid in 2-3 layers along the edge of the foundation.

Vertical waterproofing prevents moisture from penetrating into the basement of a wooden house. It is applied both to the outer surface of the foundation and on both sides. In this case, insulation work is carried out in several ways:

installation of roll or film materials on a layer of mastic;
coating the surface with a bitumen-rubber or bitumen-polymer mixture;
installing geotextile membranes or arranging waterproof locks using bentonite clay panels;
applying penetrating cement-polymer compositions.

Special attention is paid to the drainage system - it should ensure water drainage no closer than 2–3 m from the extreme point of the foundation.

If the walls of the basement suffer from excessive moisture and fungi, then in addition to waterproofing, the base of the building is also insulated. For this purpose, special waterproof boards are used, which are glued to a layer of bitumen mastic and then sealed with plastic protective materials.

When choosing adhesive compositions for installing thermal insulation boards, you must ensure that they do not contain acetone or other chemical solvents.

Video: how to repair the foundation of a wooden house

In conclusion, I would like to remind you that work related to strengthening and replacing the foundation is particularly complex and risky. At all stages of construction, safety regulations must be observed and repair technology must be adhered to. Only in this case can you count on the fact that restoration measures will take place without unpleasant incidents and will give the wooden house a new life.

You can determine whether a foundation needs repairs by taking just one look at it. The fact that the days of the foundation of the house are already numbered is indicated by the skew of the building, cracks on the walls and subsidence of the house. It is impossible to insure a building against such deformations, because over time the foundation materials deteriorate. Therefore, one day the time comes when the owners of a wooden house have to decide what type of repair to do - partial or complete.

Conditions for partial and major repairs

In order to find out the extent of damage to the foundation and determine the necessary measures to restore it, you need to carefully study the current state of the foundation and identify characteristic defects that may affect the strength and integrity of the building or its individual elements.

If cracks appear on the foundation, then you need to think about the need to repair it.

The foundation is restored in fragments if it has sunk lower but has not begun to collapse. Complete repairs are resorted to when cracks and other damage are detected.

The decision on what basis to replace a completely damaged structure is made taking into account the type of soil, the terrain and the type of foundation originally created.

If the foundation of the house has sunk into the ground, it’s time to repair it

With a strip base, they often proceed as follows: the destroyed areas are dismantled and the structure is reinforced along the entire perimeter. In case of serious damage to the foundation strip, it is decided to completely replace it.

If there are serious defects in the strip foundation of a house, it makes sense to think about its complete replacement.

Repair of a columnar foundation is almost always carried out completely: all the old supports of the building are replaced with new ones. To do this, the house is raised to the height of the pillars using jacks. New reliable supports are fixed on reinforced concrete “pillows”.

The columnar foundation is most often completely replaced with a new one

A wood foundation that has already been slightly damaged by fungus is usually replaced with a strip or columnar structure. To do this, the building is raised to a certain level and concrete blocks or bricks are placed under it.

Strengthening the foundation of a wooden house

When repairing the foundation, it makes sense to immediately strengthen it. This can be done if you are confident in the stability of the soil, which is below the foundation level of your house. Strengthening the structure under the building may also be required in the case where it is planned to add another floor to the house, but there is a suspicion that the previously installed foundation will not withstand the increased load.

You can strengthen the foundation in two ways, depending on the load it has to withstand.

Instructions for strengthening the strip structure

To make the foundation more durable, perform the following work:

A trench is dug along the perimeter of the base. The hole must be wide, otherwise it will be inconvenient to work. In addition, we must take into account that the new foundation will become stronger.
The soil is removed from the excavated foundation. To do this, use a metal brush.
The trench must be wide enough to make it comfortable to work in.
Holes are made in the old base with a drill. It is important that their diameter exceeds the thickness of the purchased reinforcing bars by no more than 1 mm. In this case, the metal elements will be installed securely and without gaps.
Reinforcement rods are inserted into the drilled holes using a hammer. They will help connect the new foundation to the old one.
Reinforcing bars are driven into the drilled holes, to which the vertical grid is attached.
Further metal elements are welded to the hammered rods, forming a reinforced belt. It is better to solder the reinforcement with already installed rods only in a few places. For the most part, it is wiser to tie metal elements with wire to avoid deformation of the reinforcing belt during pouring and hardening of concrete.
The reinforcement cage will firmly connect the old foundation with the reinforcing concrete structure
The formwork is installed and filled with concrete. After waiting for the solution to harden, the structure of the boards is dismantled. The new foundation is not touched for several days so that it becomes even stronger.
Formwork is installed around the reinforcement cage and concrete is poured into it. After the reinforcing layer has hardened, the formwork is removed
The created base is covered with waterproofing material. An asphalt strip is created around the foundation at an angle.

Thanks to the reinforcement, the weight of a wooden building is distributed over a larger area. This method allows you to stop subsidence and destruction of the house.

Video: how to strengthen a strip foundation

Replacing the foundation under a timber building

The method for replacing the base depends on its type.

Replacement of strip foundation

Overhaul of the base in the form of a tape is carried out in stages:

In order to reduce pressure on the foundation, furniture is removed from the house, floors are dismantled, and the stove is dismantled. Only heating equipment located on a separate concrete platform is not subject to dismantling.
The building is raised slightly. If the house is small, then its level in relation to the ground is changed using a kind of lever for lifting weights - a beam measuring 8x8 cm, placed at the corner of the building. A log will serve as a support for it. For heavy construction, it is better to choose thicker lumber. The wooden structure is raised by applying pressure to the timber.
The house is raised on jacks and temporary supports are placed under it.
A trench is dug around the house or only in areas where the wooden building needs to be raised.
A jack is placed under the old foundation. There may be several mechanisms for raising a building. The number of jacks is determined by their load capacity and the weight of the house. The mechanisms can only be installed in areas where there is no damage.
Using a jack, the house is slowly raised to the desired level. It is important that it rises evenly above the ground. Since there is a risk of unsuccessful installation of the jack, it is advisable to play it safe - place wooden wedges between the structure and the base pad.
The house is raised evenly on several jacks. For insurance, wooden blocks are placed under the load-bearing beams.
The lower crown of the raised wooden structure is tightened with a steel hoop or hammered with strong boards. This technique will protect the overloaded lower beams of the house from damage.
The house is freed from its former foundation right up to the surface of the earth. If you are not ready to spend a lot on repairing the base, then you can partially disassemble the structure - remove only the damaged areas.
A hammer drill is used to destroy the old foundation.
A cushion of sand-cement mixture is made under the reconstructed base of the house. Supports made of concrete or bricks are placed at the corners of the building. Instead, you can use piles. Thanks to the installation of supports, the size of which must correspond to the height of the foundation being constructed, in the future the foundation will be able to withstand increased pressure.
Construct a reinforcing belt necessary to strengthen the base. Elements of a metal structure are connected not by welding, but by wire.
Formwork is made from boards. The finished structure is filled with concrete mortar.
Formwork with a reinforcing frame inside is reinforced with side supports and filled with concrete
After 3 days, the concrete hardens, so the formwork is removed, but no further work is carried out yet, waiting for the foundation to strengthen.
A few days after dismantling the formwork, the new base is covered with a waterproofing sheet, for example, roofing felt.
A few days after the formwork is removed, the foundation is covered with waterproofing material
The house is lowered, acting as slowly as during the raising of the building. The front side of the base is covered with waterproofing and facing materials. A blind area is made around the house, which will not allow rainwater to seep into the foundation.

Video: how to repair a strip concrete base

Repair of support pillars

To replace a columnar foundation, proceed as follows:

If it is necessary to replace just a few pillars, they act differently: they make tunnels in the area where they are located, and pipes are immersed in them and filled with concrete. Old supports are dismantled after the solution has hardened.

Video: replacing a columnar foundation with your own hands

Converting a rubble or brick foundation into a monolith

Since the brick foundation is characterized by increased fragility, it is more advisable to replace it with a concrete foundation.

To build a concrete foundation in place of a brick or rubble foundation, perform the following steps:

Video: brick foundation repair

Repairing the foundation of a wooden house with your own hands

The wooden foundation is mainly made of pine or larch. A wooden structure always requires complete replacement, since over time it becomes completely covered with fungus and rots. Replacing old elements of such a base with new ones is carried out as follows:

The damaged foundation of a dilapidated wooden house can be put in order. To do this, you need to obtain the necessary knowledge and choose a repair or replacement technology. You can do the reconstruction of the foundation of a house yourself, if you have the desire and at least a little experience in construction work.

Wooden houses, built several decades ago, are now being reborn thanks to the development of construction technologies and the emergence of new finishing materials. If such a house is made of high-quality wooden material, properly processed and well built, it has a chance for a long and happy life. Repairing and replacing the foundation will help extend the life of a wooden house.

Often used in the construction of wooden houses pile foundation. It suffers most from deformation under the influence of an aggressive external environment. Deviations in the construction technology of such a foundation lead to distortion of the entire structure. Also, the foundation may suffer if the necessary waterproofing work has not been completed. Soil subsidence, groundwater and melt water lead to deterioration of materials, resulting in distortions of openings, cracks in finishing and walls.

What to consider when replacing the foundation

If your home is showing signs that your foundation needs repairs, you need to take immediate action. Repairs can be carried out in several ways:

Cosmetic The method is the least expensive, but also not reliable enough. If a small part of the wooden base is rotten, it is cut out and replaced with new material. With this method, there is a danger of the wall skewing.
You can replace the foundation dismantling the walls. Very reliable, but quite labor-intensive.
The work can be completed by removing approximately 20 cm of soil, then updating the crowns and repairing the foundation.
Most Popular method using jacks. At the same time, the house is raised, construction work is carried out quickly and to the required extent.

When starting work on repairing the foundation, you need to make sure that the house itself is in good condition and will last for a long time; plan waterproofing work to avoid destruction of the new foundation.

Types of foundation for a wooden house

Tape with base- the most reliable option. Suitable for heavy houses, very resistant to the destructive influences of the external environment. It is divided into monolithic and prefabricated. Monolithic is erected using concrete poured into formwork. Prefabricated is a structure made of concrete and reinforced concrete blocks.
The foundation on screw piles will facilitate work on uneven areas. The building material is quite affordable, and can also be reused. But it cannot be used on unstable soils.
Columnar used in the construction of light structures made of wood, panels and frame houses. Load-bearing pillars made of brick, stone or concrete are installed in corners and where walls intersect. In this case, the distance between them is from 1 to 2 meters. A type of columnar foundation is a bored pile foundation made of asbestos-cement pipes. It is also used for soils with high groundwater levels.

Pile and column structures require in strict compliance installation technology, otherwise there is a high probability that the supporting pillars will begin to collapse.

The main stages of work to replace the foundation under a wooden house

A complete foundation replacement is carried out in four stage: raising the house, destroying the old foundation, installing a new one and lowering the house onto the new foundation.

Lifting the house

To raise a wooden house you will need at least four jack with a lifting capacity of 10 tons. It is advisable to have one more in reserve. One person will work on each jack. A flat platform with a solid base and sides measuring about 50 cm is equipped for the jack. To prevent the jacks from slipping, the platforms can be buried in the ground. Places are equipped along the long walls of the house, retreating at least half a meter from the corners. To prevent the jack rod from pressing through the wood on the lower crown, a metal plate about 5 mm thick is used for laying.

Before lifting it is necessary make the house as light as possible, remove all the furniture and things from it, and, if possible, dismantle the floors.

Prepare material for temporary supports. They will be bricks, timber, logs, wooden blocks.

Jacks are placed in prepared places. design lift at the same time, resting against the logs of the lower crown. A one-time rise should not exceed 2 cm. It should be taken into account that if the synchronization of the rise is disturbed, a difference of one centimeter at the bottom gives a distortion at the height of the ridge of several centimeters. Temporary supports are placed, then the house is raised another 1.5-2 cm. So, in steps, they reach a lifting height of 10-15 cm and securely fix the house on the temporary support. Support elements are installed at all four corners and at the intersections of the walls.

If the bottom log finds significant bend, it is necessary to use an additional jack at the bending point.

To remove structures made from cement mortar or rubble materials, use wooden wedges. They are driven with a sledgehammer into the vertical and horizontal seams of the foundation. A hammer drill, a crowbar, a chisel, and a shovel will also come in handy. The materials resulting from the dismantling of the old base may be useful in subsequent work.

Strip foundation device

Installation of the base is carried out alternately for each side of the house. Taking into account the depth of soil freezing, a trench is dug. On average, its depth is 60−80 cm. In profile, the trench has a U-shape for removing and tying reinforcement that strengthens the concrete base of the new foundation.

At this stage, if it is necessary to increase the area of the house, the installation of a foundation for new extensions is provided.

A layer of sand and gravel is poured into the bottom of the trench. Next, reinforcement is knitted from a rod with a diameter of 12-18 mm; curved rods are used in the corners to create a single structure. After installing the wooden formwork, the prepared structure is poured with concrete. After the final hardening of the concrete solution, after about two weeks, temporary supports are installed on the new foundation and the base is installed on the other side of the house.

You can organize the work process differently. In this case, first corner posts are poured, and after they harden, the entire foundation strip is installed. The house rests on temporary supports at the corners.

When pouring the foundation, openings are provided for the operation of jacks during the stage of lowering the house. After completion of the work, they are laid with bricks.

Conduct audit of lower crown logs and floor joists, replace if necessary. Next, the foundation and wooden structures are waterproofed. The resulting voids are filled with earth.

Upon completion of all work and the final hardening of the concrete, the building is lowered onto a new foundation, acting smoothly and carefully.

Construction of foundations on modern screw piles

After raising the house and strengthening it on temporary supports under the foundation I-beams are installed, cut to the size of the base with a tolerance of 5−7 cm for attaching piles. Beams are used to create a grillage and are installed under the external and load-bearing walls of the building.

To construct the entire foundation you need 8-10 screw piles. They are twisted in pairs at a distance of 30-40 cm from the wall of the house so that they are support for beams. When performing work, a building level is used for control. After installation, the internal space of the pile is filled with concrete to give strength. Then a cap is welded onto the top of the pile, onto which the grillage channel is attached. After installation is completed, the old structure is destroyed. The wooden base of the house is evenly lowered onto the new pile foundation.

Replacement technology with a new one columnar foundation about the same. Instead of installing piles, holes are drilled for pillars and supports made of concrete, brick or reinforced concrete are installed.

When replacing an old foundation, it is necessary to take into account that such work is classified as highly complex and can pose a danger to the performers. You need to soberly assess your strengths, avoid haste and inaccuracies, and observe safety precautions for construction work.

Houses built of wood several decades ago, thanks to modern construction technologies, have the right to a new life. Especially if such a building requires replacement of the foundation.

Often the reasons for the need for such work are:

Natural shifts and subsidence of soil;
Illiterate execution of any excavation work on the site, which leads to a violation of the integrity of the foundation of the house;
Ignoring waterproofing work when installing the initial foundation;
Violation of construction technologies;
Wear and tear of the initially created foundation over time, especially if it was a pile frame (in this case, the metal undergoes changes over the course of 4-5 decades and may lose its integrity).

Important: a clear sign that a house needs to replace its foundation is the appearance and enlargement of cracks in the outer part of the foundation, cracks on one of the walls of the house, and door jambs and window frames moving away from their “home” places.

Methods for performing repair work

Frame cosmetic update option. In this case, only the damaged part of the base is dismantled and sealed with new building materials. This method of repair, although economical, is still not reliable. After all, internal changes in the foundation design still take place. And in this case, the structure of the house may be completely destroyed over time.
Dismantling the walls and then replacing the base. This is the most time-consuming and expensive repair method. You definitely can’t cope here alone and with your own hands. Not only will you have to invite helpers to dismantle the house, but you will also have to pay them for reassembling the building.
A method of removing the top layer of soil with subsequent renewal of the foundation crowns. Not a particularly popular method, because if you really use it, then it is better to completely replace the frame.
An option for lifting a wooden house using special jacks and completely replacing the foundation with a new one. This method is used more often than others, since it makes it possible to operate a wooden structure for more than a dozen years after repair.

Important: the last repair option takes a minimum of time and is highly effective.

Advice: before deciding to completely replace the foundation of the house, it is better to make sure that such work makes sense at all. That is, a wooden house must be suitable for further living in it; the wooden walls must be intact and not rotten. In addition, for a new foundation it is better to immediately provide a high-quality waterproofing system in order to extend its life to the maximum.

Types of foundations for a wooden house

Work to change the foundation under a wooden house should be carried out only when the building material is completely prepared. And for this you need to decide in advance on the type of frame. So, for wooden buildings the following are often preferred:

Belt prefabricated or monolithic. This type of foundation is good for particularly heavy houses and calm sandy soils with low groundwater levels. The foundation can either be poured into prepared shallow formwork with mandatory reinforcement, or assembled from special concrete blocks.
Pile foundation good if the wooden house has one level, and the terrain of the site or the composition of the soil on it is quite complex. An exception for a pile foundation is soil that is prone to horizontal movement. From the point of view of financial benefits, such a frame for a wooden house is the most economical.
Columnar frame. This type of foundation for a wooden house is suitable if the building is made of lightweight panels or panels. Here the pillars do not need to be deepened too much into the ground. A height of 60-70 cm will be sufficient. In this case, it is important to place the foundation pillars at all corners of the building and under the points of intersection of the walls of the house. The distance from column to column should be in the range of 1-2.5 meters. If the soil on the site has highly located groundwater, then bored piles, which are mounted in asbestos-cement pipes, can be used as pillars.

Important: columnar and pile types of foundations require special care when installing them yourself. Otherwise, non-compliance with construction technologies will lead to vertical misalignment of the columns, which will lead to the burning of the house.

Execution of work: stages

Carrying out the entire repair process consists of four important stages:

Lifting the building using jacks (depending on the length of the walls, you may need from 2 to 10 pieces);
Dismantling of broken or sagging old foundation;
Installation of a new foundation;
Installation of a wooden house in place.

Let's take a closer look at the entire work process.

Lifting the building

To lift the house you need to use jacks, each of which can lift 10 tons of weight. In this case, lifting devices must be placed exclusively along the long walls of the building in such a way that the mechanisms recede 50 cm from the corners of the house. To operate each jack, one master operator will be required.

Under the jacks you need to install a strong support platform (concrete slab) with a section of 50x50. For greater reliability and to eliminate the possibility of the machine slipping, the slab can be slightly deeper into the ground. And so that the metal rod of the lifting device does not damage the wood of the lower crown of the house, you can use a special metal plate-gasket under it.

Important: you need to lift the house only in a lightweight state. That is, if possible, you need to remove everything from it, including furniture and household appliances. If possible, you can dismantle the plumbing and also disassemble the wooden flooring.

Bricks, cinder blocks, wooden logs or chocks can be used as temporary supports for a wooden house.
The house must be raised from all sides at the same time. However, there is no need to rush. A one-time lift of the building should not exceed a height of 2 cm to avoid distortions or collapse of the structure.

Important: it is worth knowing that if the synchronization of the building’s rise is not observed, then with a discrepancy of only 1 cm at the level of the crown of the house at the level of the ridge, this difference will already amount to several cm.

The house is being raised in stages. First, when lifting by 2 cm, it is necessary to place temporary supports and check the level of the building. Then they raise the house again, re-laying temporary supports. Thus, it is necessary to raise the building to a height of 10-15 cm, after which the building is installed on temporary pillars with mandatory dislocation at the intersection of the walls and in the center.

Important: if, when lifting the house, there is a bend in the lower log, then you should use another jack in this place.

Dismantling the old base

You can dismantle the old foundation with your own hands using tools such as a hammer drill, crowbar, chisel, and shovel. At the same time, do not rush to throw away construction waste. It may still be useful. To dismantle an old monolithic or rubble foundation, use the method of driving wedges into all horizontal and longitudinal fill joints.

Installation of a new foundation

Here, the nature of the construction work will depend entirely on the type of new foundation chosen. But it is worth knowing that installation should be carried out alternately for each side of the house.

Tape frame

In this case, a trench is dug around the perimeter of the building for the tape. Here it is worth taking into account the depth of soil freezing, but the optimal depth for central Russia is a strip frame depth of 60-80 cm.

Important: if it is planned to increase the area of the house due to extensions, then it is necessary to form a trench for the foundation for new premises.

The bottom of the trench is well compacted and covered with layers of sand and gravel, 10 cm each. These layers of the cake are also compacted.
After this, formwork and reinforcing mesh are installed in the pit. At the same time, it is worth knowing that the rods at the corners of the foundation must only be bent for tying. It is forbidden to join reinforcement bars one to another in the corners of the house.
Concrete is poured into the formwork with reinforcement and waited for it to dry completely.
After one part of the poured foundation has dried completely, temporary supports are installed on it and the construction of the foundation on the other side of the house begins.

Important: when pouring the foundation, it is worth considering the space for the jack. In this case, it is left unfilled, and after the house is lowered, this part of the foundation is simply laid with bricks.

Upon completion of the work, it is necessary to carefully waterproof the foundation and lower logs of the crown of the house with your own hands. After this, the remaining soil voids must be filled with soil and compacted well.
As soon as the foundation is completely ready, the house is also gradually, synchronously and smoothly lowered into place.

Pile foundation

In this case, from 8 to 10 piles are used to construct the foundation. The works look like this:

I-beams are driven under the already raised house, which will play the role of a grillage. They are located under load-bearing and external walls.
Now the piles are screwed into the ground in pairs at a distance of about 20-30 cm from the outer walls of the building. The level of the piles in the horizontal plane is controlled so that they become supports for the grillage. The piles are controlled vertically by level.
After installing the piles, their internal space can be filled with concrete mortar with your own hands for greater strength.
The top of the excess metal is cut off and a head is welded onto it, on which the grillage will rest.
Upon completion of the work, the old frame is dismantled, and the house is smoothly lowered onto the new foundation.

Important: a columnar foundation is installed according to the same principle, with the only difference being that instead of piles, pillars of the selected type (brick, monolithic, etc.) are installed in prepared pits.

Carrying out work to replace an old foundation with your own hands requires caution, professionalism and mandatory adherence to all technologies. Therefore, if you have even the slightest doubt in your abilities, it is better to invite specialists to carry out the work.

Any reliable and durable wooden house will eventually need major repairs. If technology violations were committed during the foundation of a new house, then the likelihood of large-scale restoration work increases significantly. An incorrectly created foundation affects the balance of window and door openings and contributes to cracking of walls.

When such “bells” arise, urgent action is required. Replacing the foundation is the most rational method, but it is important to pay attention to the following aspects:

If you do the work yourself, you will need specialized tools, so you should take care of this in advance to find a complete set;
after the old foundation is dismantled, you need to install a more reliable foundation of a different type (this is a difficult job, so the help of professionals may be required);
it is worth making sure that the house itself will still serve for a long time.

What does strength depend on?

The condition of the foundation is significantly influenced by changes in the soil, in particular its load-bearing characteristics. They occur mainly due to exceeding the permissible load on the foundation and subsequent loosening of the earth underneath it. The overall load is increased by outbuildings located nearby. This leads to distortion and subsidence of the main structure, since the soil is pressed under significant weight.

Replacement of the foundation may be necessary due to erosion of the soil due to rising groundwater or improper drainage of water.

Reduced strength of the base material is another negative factor. This is possible due to incorrect determination of the freezing depth and inappropriate use of low-quality materials.

Selecting a base

It is important to understand that replacing the foundation of a wooden house should be done after all preparatory work has been completed. First you need to choose the design of a new base. The belt type is optimal for large, heavy buildings. The screw base will perfectly withstand construction like a country house. Among the advantages, it is worth noting the possibility of application in any area. Also, screw piles are distinguished by the possibility of repeated use and relatively low cost.

The columnar base is used for medium-sized houses. Despite its apparent simplicity, it has become widespread due to its reliability. The design consists of several pillars installed at the junctions of the walls - these are the areas with maximum load. Pillars are made of stone, concrete or brick. It is worth noting the need for a mandatory step of 1-2 meters. A bored pile base also refers to a columnar foundation. It acquired its name because it is used as a load-bearing element and filled with a specialized mixture. Soil with a high water level is the optimal place for such a base.

The above-mentioned house foundation, the replacement of which involves the use of piles, is also in demand. It requires less investment, and in the end its strength is comparable to a concrete base. The piles are screwed into the ground using levers. Their level must exceed the freezing depth. Alignment to a certain height and the use of a belt made from a channel beam are required. This type of base is suitable for subsidence and weakened soil types.

Subsidence of the base

Subsidence may be progressive or temporary. Special beacons made from different materials will be useful in determining. It is worth considering that if water gets on paper versions, they become unusable. Plaster plasters are also used as beacons. If they are absent, you can apply an even strip of putty to the wall and make a mark, this way the places where the cracks are widening will be identified in time and the speed of destruction will be determined.

Equipment

Although the work is large-scale, you don’t have to resort to renting expensive equipment: several powerful jacks (at least 4) with a lifting capacity of about 10 tons will be enough. You also need to have auxiliary wedges, a crowbar and a sledgehammer at your disposal. To create a support, various logs, boards and a lot of bricks are required. Before installing the jack, a strong platform is knocked down, with sides of at least half a meter each. It will require a steel plate with a thickness of 6 mm.

Replacing the foundation under a wooden house means freeing it from heavy objects and furniture. Next, the covering is removed and the floor itself is dismantled.

How to lift

After completing the preparatory work, you can install the jacks. They are placed along the perimeter of longer walls, with a mandatory offset from the corners. Pre-designed sites must be stable (a small depression in the soil is possible).

It is worth paying attention to the fact that lifting the house and replacing the foundation with piles alone is impossible. There should be one person per jack. Careful lifting of the building can only be achieved with this approach. The lifting height at a time should be no more than 2 cm. If gaps occur, prepared supports are used to close them. All actions must be performed simultaneously.

Significant sagging of the lower rims during the lifting process indicates a lack of jacks. But further actions must be as careful and precise as possible to avoid displacement of the structure.

Foundation replacement: dismantling

Once the house is raised and firmly secured, the old foundation is removed. Some items may be useful for recycling, so they should be folded separately. After dismantling, a deeper trench is dug in the shape of the letter P. Thanks to the use of this shape, it is possible to connect sections of the foundation laid at different times. If an extension is needed in the future, it is better to immediately lay the foundation for it, so that in the future there will be no need to replace the foundation under the house due to the increased load.

Completion of work

It will take about two weeks for the poured base to completely harden, then it is covered with boards and temporary supports made of brick or wood are placed on top. After replacing the foundation under the wooden house, it is repeated on the other side. Long sections of walls require digging straight short trenches and then joining them together using reinforcement.

After completion of all work, the lower rings are checked for quality and, if necessary, they must be replaced. Next, the structure gradually lowers evenly on all sides, after which the replacement of the foundation can be considered complete.