How to replace the foundation under an old wooden house. How to replace the foundation under a wooden house. Causes of damage to the foundations of wooden houses

Wooden houses built several decades ago are now getting a rebirth thanks to the development of building technologies and the emergence of new finishing materials. If such a house is made of high-quality wood material, properly processed and well-built, it has a chance for a long and happy life. Repair and replacement of the foundation will help extend the service life of a wooden house.

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

Things to consider when replacing a foundation

If the house shows signs that the foundation needs to be repaired, urgent action is needed. Repair can be done in several ways:

• Cosmetic the method is the least expensive, but not reliable enough. If an insignificant part of the wood 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 laborious.
• The work can be done by removing about 20 cm of soil, then renew the crowns and repair the foundation.
• Most popular method using jacks... At the same time, the house is raised, construction work is carried out quickly and in the required volume.

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

Types of foundations for a wooden house

• Tape with base is the most reliable option. Suitable for heavy houses, very resistant to the destructive effects of the external environment. Subdivided into monolithic and prefabricated. Monolithic is being erected using concrete poured into the formwork. Prefabricated is a structure made of concrete and reinforced concrete blocks.
• A foundation on screw piles will make it easier to work on uneven areas. The building material is quite affordable and can also be reused. But it cannot be used on unstable soils.
• Columnar it is used in the construction of lightweight structures made of wood, panels and frame houses. Bearing pillars made of brick, stone or concrete are installed in corners, intersections of walls. 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 a high level of groundwater.

Pile and columnar structures need in strict observance installation technology, otherwise there is a high probability that the bearing pillars will begin to collapse.

The main stages of work on replacing the foundation under a wooden house

Complete replacement of the foundation is carried out in four stages: raising the house, destroying the old foundation, assembling the new one and lowering the house to the new foundation.

Raising the house

To raise a wooden house, you need at least four jacks 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 foundation and a side size of about 50 cm is equipped under the jack. To avoid the jacks sliding off, the platform 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 pushing through the tree on the lower rim, a metal plate about 5 mm thick is used for laying.

Before lifting, you must make the house as easy as possible, take out all the furniture, things from it, if possible, disassemble the floors.

Prepare material for temporary supports. They will be bricks, beams, logs, wooden chocks.

The jacks are placed in prepared places. Design raise simultaneouslyresting on the logs of the lower crown. A one-time lift should not exceed 2 cm. It should be borne in mind that if the lift is not synchronized, a difference of one centimeter at the bottom gives a skew at the ridge height by several centimeters. They substitute temporary supports, then raise the house by another 1.5-2 cm. So, in steps, they reach a lifting height of 10-15 cm and securely fix the house on a temporary support. Support elements are installed at all four corners and at the intersection of the walls.

If the bottom log finds significant bend, an additional jack must be used at the bend point.

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

Strip foundation device

The installation of the base is carried out in turn 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 bundling reinforcement that strengthens the concrete base of the new foundation.

At this stage, if it is necessary to increase the area of \u200b\u200bthe house, they provide for the installation of the foundation for new extensions.

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 the device of 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 foundation is installed on the other side of the house.

You can organize the work flow in a different way. In this case, first corner posts are poured, and after their hardening, the entire foundation tape is mounted. At the same time, the house rests on temporary supports at the corners.

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

Carry out revision of the logs of the lower crown and floor lags, if necessary, replace. Further, the foundation and wooden structures are waterproofed. The formed voids are covered with earth.

At the end of all work and the final hardening of the concrete, the structure is lowered onto the new foundation, acting smoothly and accurately.

Foundation construction on modern screw piles

After raising the house and strengthening it on temporary supports under the foundation i-beams are startedcut to the dimensions of the base with a tolerance of 5-7 cm for fastening piles. Beams are used for grillage and are installed under the external and load-bearing walls of the building.

For the device of the entire foundation, 8-10 screw piles are needed. They are twisted in pairs at a distance of 30-40 cm from the wall of the house in such a way that they are support for beams... When performing work, they use the building level for control. After installation, the inner space of the pile is filled with concrete to give strength. Then a head is welded onto the top of the pile, on which the grillage channel is attached. After the end of the installation, the old structure is destroyed. The wooden base of the house is evenly lowered onto the new pile foundation.

Replacement technology columnar foundation about the same. Instead of installing piles, holes are drilled under the pillars and supports are mounted made of concrete, brick or reinforced concrete.

When replacing the old foundation, it must be borne in mind that such work belongs to the category of increased complexity and can be dangerous for performers. You need to soberly assess your strengths, avoid haste and inaccuracies, observe safety precautions for construction work.

Over time, the building may shrink. This is due to the violation of construction technology, natural aging, geological and climatic conditions. Lifting a house with replacing the foundation is a fairly common option for major renovations. There are other ways to restore the integrity of the base of the building. Before starting work, the main thing is to correctly determine the degree and cause of the building's shrinkage. Sometimes it is necessary to change the entire structure of the base under the house.

Foundation replacement and repair methods

The most popular method for replacing a foundation is jacking up the house. They may need from 2-4 to 10-12 pieces. Raise the structure by placing jacks on both sides of one wall. It is not permissible to lift diagonally.

In one run, they reach a height of 1.5-2 cm, no more. Temporary supports are immediately inserted into the resulting space. Additional jacks are installed in the places of deflections of the lower edges of the log house.

Another method involves removing a 200-250 mm thick layer of soil under the house. After that, the wooden crowns are replaced and the base of the house is repaired.

Time-consuming and requiring special skills methods include complete disassembly of walls for a convenient approach to the foundation. After that, the base structure is repaired or completely replaced. Then the walls are assembled in a new way, replacing the rotten and deformed elements.

If wear is negligible, cosmetic repairs may be sufficient. This is the cheapest recovery method.

What type of base to choose

It happens that the old foundation is out of order and a complete replacement is necessary. Before replacing the foundation under an old wooden house, you need to decide what type of foundation is optimal for the given geological conditions and type of construction.

The types of foundations and their characteristics are presented in the table:

The type of foundation for a wooden house is chosen depending on many factors. If it is difficult to make a decision and calculate all the loads yourself, it is better to turn to professionals who will help you make the right choice.

Replacing the foundation

Replacing and repairing the foundation will require some knowledge and patience. In order not to completely destroy the building, you need to do the work slowly, strictly adhering to the technology.

Jacks can be rented at the railway depot and must be designed for lifting loads of 10 tons.

Bricks, strong beams and boards can be used as underlays.

Before raising the house building, its weight is lightened as much as possible. They dismantle the floors, take out furniture and all household items.

Under the jacks, a base is made in the form of a square of wood with sides measuring 50 x 50 cm.

Calculations

In order for the new foundation to serve as a reliable foundation for the building for a long time, its parameters must be correctly calculated.

When calculating, you need to consider:

• the level of soil freezing;
• proximity to the location of underground sources;
• seismic activity;
• site relief;
• soil type;
• a lot of housing construction.

Under the load-bearing walls, the foundation is buried at least 500 mm, under the partitions at least 400 mm.

Lifting the house with jacks

A platform is made for jacks. Install it, slightly deepening into the ground, at a distance of 50 cm from the corners of the building. The jacks are fixed on a wood support.

Simultaneously, on both sides, they are raised to a height of no more than 2 cm in one run. Jacks are placed in places where the wood has not lost its strength. Do not install lifting devices in rotten places.

For the correct transfer of the load to the logs, it is necessary to provide for the installation of metal plates that serve as a spacer.

Immediately place strong underlays in the gap formed. All walls are raised one by one until they reach the desired height. Check the stability of the building, it should not be mowed. They firmly fix the desired level by installing underlays.

Dismantling the old foundation

After raising and fixing a wooden house, the foundation is repaired or dismantled. These works are quite easy to do with your own hands, you will need several assistants and simple tools: a crowbar and a sledgehammer.

If you disassemble the old foundation carefully, then the materials that remain intact can be used for further construction work.

What you need to know

The degree of shrinkage of the house depends on the type of soil and the level of the location of underground sources. If they are close to the surface, you need to provide a drainage system around the perimeter of the house.

If the soil is prone to landslides, it is strengthened. For this, the area around the foundation is poured with a mixture of liquid glass and water, or small wells are drilled and resin is poured into them.

If the groundwater is close, the winter heaving of the soil will be much higher. Freezing groundwater increases in volume and pushes out everything in it from the soil. When melting, the volume of water decreases and shrinkage occurs.

Installation of the foundation on screw piles

If you decide to build a new foundation on screw piles, you need to calculate their length and diameter. It is not worth saving on material, since the reliability and safety of the house will depend on its quality.

For the foundation of a small house made of wood, you will need 8-12 screw supports.

Step-by-step instruction:

1. After raising and fixing the house building, I-beams are laid under its load-bearing walls and partitions. They are cut by 5-7 cm more than the estimated length. In the future, they will serve as a grillage.
2. In pairs, at a distance of 300-400 mm from the walls, screw piles are twisted, which are the support for the beams. Make sure that the structures are clearly level.
3. To give strength and protect against corrosion, the pile cavity is poured with concrete mortar.
4. A head is put on the upper edge of the support, and the grillage channel is already attached to it.
5. Dismantle the old base.
6. The house is carefully lowered.

The columnar base is mounted using the same technology as the installation of the screw foundation. The only difference is that you need to dig holes for the pillars, which are subsequently poured with concrete or laid out with bricks.

Installation of strip foundation

Prepare the site, remove construction waste, plant root system, sweep away dust.

Instructions on how to change the foundation of an old wooden house with your own hands:

1. They dig a pit below the level of freezing of the soil and below the location of the old base. The shape of the trench should be U-shaped so that it is convenient to remove the reinforcing frame and make it a bunch.
2. Sand is poured onto the bottom, with a layer of 150 mm. Moistened, compacted. A layer of rubble is poured, it is well tamped.
3. Metal rods are tied, with a section of 12-16 mm in two longitudinal rows, connected by vertical bridges.
4. Formwork is made of boards, it will serve as a form for pouring cement mortar.
5. Pour concrete solution. At the same time, openings are provided for installing jacks for lowering the building.
6. After its complete hardening, the formwork is disassembled.
7. Temporary supports are attached to the poured foundation. Work begins to replace the foundation on the other side.
8. Openings for jacks are laid with bricks.
9. Check the integrity of the lower rims and floor boards. With the existing damage, it is necessary to repair the damaged elements. Rotten and spoiled areas are cut out, replaced with new ones.
10. Carrying out work on waterproofing the foundation and basement of the building.
11. They gently and gently lower the house onto the new foundation.

There is another technology, according to which the support posts are first poured at the corners of housing construction, and then, after drying, the house is supported on them and a concrete tape is mounted around the entire perimeter. All other steps follow the above sequence.

How to restore and raise a house, you can watch the video:

Replacement of the foundation refers to work of increased complexity. You need to really assess your strengths and skills in performing construction work. If a mistake is made, workers may suffer or house building may collapse. If you lack the strength and knowledge, it is better to hire professionals with experience in this field.

As you know, one of the main elements in the construction of any house is the foundation. The reliability and durability of any structure depends on its quality. Over time, the foundation can collapse. This occurs most often when the soil subsides. The soil can reduce the bearing capacity of the foundation of a wooden house, as a result of which it will have to be replaced over time. Replacement of the foundation can also be carried out if it was erected incorrectly, when poor-quality concrete was used or the hydrogeological features of the area were not taken into account.

Subsidence of the foundation under a wooden house gradually leads to complete destruction and then the replacement of the old foundation is simply necessary.

Among them, the level of standing of groundwater and the depth of soil freezing are of particular importance. If initially the foundation of a wooden house was laid not to the proper depth, then groundwater can destroy the foundation of the house. Replacing the foundation under a wooden house can be done on your own or with the help of a team of specialists. In both cases, it will take a long time. You need to stock up on strength and patience. Replacement of the foundation of a wooden house can be partial or complete. In the first case, only the destroyed structural elements are removed, the surviving part can be used to build a new foundation. Let's take a closer look at how the foundation under a wooden house is replaced with our own hands, the main stages of work.

What is the way to replace the old foundation?

The use of wood in the construction of houses greatly facilitates the repair work. This also applies to the dismantling of the settled foundation. Replacing the foundation under a wooden house can be done in several ways.

One of the most famous and simplest is the method using jacks.

These units allow you to raise the house evenly, after which dismantling is carried out. The second technique involves cosmetic repairs. It is relevant only when the foundation under the house has minor defects. The area that has rotted must be removed, and a new wooden structure is installed in its place.

When the foundation under a wooden house is changed, the integrity of the entire structure is largely violated. Some people prefer to use wall demolition. It is the most time consuming. In this case, you will have to completely disassemble all load-bearing walls and replace the lowest crown of the wooden frame. This method is very effective. Often, the usual dismantling of the foundation is also used, in which only the upper part of the base of the house 20 cm thick is removed and the wooden crowns are replaced.

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The use of jacks

The easiest way to change the foundation of a house with your own hands is using lifting devices. For a wooden house, a minimum of 4 jacks are required, which are installed in each corner of the structure. It is recommended to place jacks at a distance of half a meter from the corner into the interior of the house. Of great importance is the fact that for a wooden house jacks are required to be placed only in the most durable areas where there is no rot. If the rise of the house is uneven, then the lower logs may bend or break, this will significantly complicate the work. The second important aspect is that a metal spacer is required between the jacks and the logs.

To lift a wooden house, jacks are installed in the strongest places to prevent further destruction.

Its thickness is 5 mm. They are needed for rational load transfer. Jacks must be fixed on a special platform. It is better to immerse it a little in the soil to give stability. Before dismantling the foundation under a wooden house, it is necessary to prepare supports. These can be bars or hemp. The technology for lifting load-bearing walls is simple. The minimum height to which they must be raised is 6 cm. Next, the destroyed structural elements must be removed.

It is important that the lifting of the walls with the help of jacks must be carried out evenly, at once from all sides. At the same time, in one approach, you cannot raise the house on one side by more than 2 cm. After raising, a support is immediately placed, and so on in each corner of the house. At the same time, you need to monitor the condition of the lower logs. If they begin to bend, then you need to increase the number of jacks. It is required to put tow between the timber and the logs of the house. To avoid the development of mold and decay, it must be treated with an antiseptic solution. When the base of the wooden house is raised to the required height, the old foundation is dismantled. The destroyed brick is removed. If the base is concrete, it is replaced with a new one. A sledgehammer, crowbar, chisel and other tools can help here. When the base is cleaned, proceed to the next stage of work.

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Construction of a new foundation

The jacks are replaced with steel supports, then the frame reinforcement is tied and the formwork is installed.

You need to start building a new base for a wooden house with earthworks. You will need to dig a trench. It should be deeper than the previous one. The width of the trench is on average 40 cm. At the bottom it is necessary to lay a layer of sand 15-20 cm thick, and on it there is rubble. The thickness of the crushed stone is the same. Then again you can pour a layer of sand, and so on to the full depth. Each layer is carefully rammed. On top of it, you can pour cement mortar or concrete 5-10 cm thick. This is the most reliable technology.

To build a new foundation, you will need to make a formwork. It represents the form into which the mixture will be poured. For formwork, you can use thick plywood, boards 2-2.5 cm thick, or any other materials, such as slate. The height of the formwork is made just above the level of the strip foundation. The boards are fastened together. In order for the foundation to be even throughout, a horizontal line must be drawn from the inside of the boards, which will become a guideline when pouring concrete. The next stage is reinforcement with metal rods and wire. The thickness of the rods is 8-12 mm. Welding is not recommended. Do not forget about waterproofing.

The next step is mixing the concrete solution and pouring it. To increase the service life of a new foundation under a wooden house, it is necessary to use concrete of a grade of at least 200. The concrete mixture is poured manually or using a gutter system. It is necessary to check the flatness of the strip foundation. Approximately 2-3 hours after preparation, the concrete begins to set. Finally, it will harden no earlier than after 2 weeks. When the raising of the house with your own hands and the installation of a new foundation under the wooden house are completed, the structure is lowered. The lowering process is carried out slowly.

Subsidence of the foundation of wooden structures is a frequent occurrence. This process occurs from all sorts of hydrological and physical and mechanical changes in the lower soil, which reduce its bearing capacity. Often, changes in soil properties are caused by construction work carried out on the backyard territory. Under these conditions, replacing the foundation under a wooden house becomes the only way to prevent further subsidence, leading to destruction.

1. Cosmetic - the simplest way that does not involve significant financial investments. In this situation, the rotten area is simply cut out, and a suitable wooden element is inserted instead. But it should be borne in mind that with such a partial replacement, the integrity of the house is inevitably violated.
2. Dismantling the walls - type of construction work, involving the complete dismantling of the walls, after which the lowest crown of the log house is replaced. The method is reliable, but it requires a fair amount of patience and time from the craftsmen to disassemble and assemble the structure.
3. Dismantling the foundation... To do this, it is necessary to remove a layer of 20 cm, replace the wooden crowns and restore the foundation.
4. Replacing the crowns by lifting the structure with a jack - the most popular method for replacing the foundation quickly and efficiently.

Replacing the foundation of a wooden house - a second life for a building

Jacks not only greatly simplify the process, but also allow you to raise the house evenly

Important! The above methods of replacing the foundation require the use of different tools that must be prepared in advance so as not to be distracted by the search for suitable equipment during the work. So, the cosmetic method can be carried out with only a chisel, a sledgehammer and a hacksaw in the arsenal.

Dismantling the foundation will require a device with which it will be possible to implement the task. The choice will depend solely on your preferences and technical capabilities.

You should also worry about temporary supports on which the house will be held during repairs.
If you intend to use jacks, then their number, depending on the length of the walls, can vary from two to ten.

Depending on the length of the walls, the number of jacks varies from 2 to 10

How to choose a new foundation for a wooden house?

It is important to understand that replacing the foundation of a house is a process that requires careful preparation. First of all, you should decide on the design of the future foundation, which will replace the old one. There are the following types of foundations for wooden houses:

• - a structure adapted to support relatively light houses with panel, frame or wooden walls that do not create a significant load. Despite the apparent simplicity, a columnar foundation is a sure way to provide reliable support for a garden or country house, a light bathhouse or a low-rise country cottage. It is represented by a system of poles that are installed in places of maximum load, i.e. at the points of intersection of the walls. The poles are made of brick, concrete, stone and are mounted at a distance of 1-2 meters from each other.

Column foundation is a sure way to provide reliable support

• A bored pile foundation is a type of columnar foundation, only asbestos-cement pipes filled with a special mixture are used as load-bearing components. The structure of such a foundation consists of piles and a grillage connecting them. The load-bearing elements are located under the most significant points of a wooden house, for example, at the corners of a building or at the intersection of main walls. The bored pile foundation is optimal for buildings on soils with high water.

Bored pile foundation is an excellent but expensive option

• The pile screw foundation is the most interesting type of foundation, originally intended for military purposes. The foundation is valuable because it can be used on any area, even uneven ones. The low price and the possibility of repeated use of screw piles are additional pluses in the piggy bank of advantages.

To erect a pile-screw foundation, you will need special construction equipment

• The strip foundation allows you to build heavy houses and at the same time provides a good level of reliability and security. Shallow strip foundation is subdivided into monolithic and prefabricated. The first consists of formwork based concrete, the second is made of concrete and reinforced concrete blocks.

Shallow tape foundation - the best option for small buildings

The main stages of replacing the foundation

In order for the replacement of the foundation to be performed efficiently, it is necessary to follow the sequence of stages.

We will consider the most common type of replacement - with the help of jacks.

Stage 1. Installation of jacks

Jacks allow you to raise the house evenly, otherwise (with an uneven rise) the logs of the lower harness will bend, which leads to their separation and breakage. The jack should be installed in places where the wood is not damaged by rot. Do not forget to install spacers - steel plates (5 mm) - this is necessary for the correct transfer of force from the jack rod to the logs.

Stage 2. Raising the house

It is necessary to raise the wall to a height of at least 6 cm, remove the rotted extensions and lower the structure to trim the beams placed on the end - temporary supports. Between the beams and logs, an antiseptic-treated tow is laid in a width equal to double the thickness of a wooden bar. Brick battle and a 10 cm layer of gravel are poured under the proposed foundation strip.

Start of work - lifting the house on jacks

Stage 3. Making the foundation and removing the jacks

After the log house is safely lowered onto the brickwork, they are taken for the manufacture of the foundation tape. It is necessary to clear the space under the walls and line the formwork. Other walls at this time rest on temporary supports. It is important to take care of the niches for the jacks so that later there will be no problems with lowering the structure. After installing the house, the niches are covered with bricks - the work is completed.

Temporary supports will ensure the stability of the building during the renovation

As you can see, this process is painstaking and requires an organized approach, nevertheless, replacing the foundation with your own hands is quite real if you approach the work wisely. A little patience combined with the knowledge gained guarantees an excellent result - a new reliable foundation for your wooden country house.