How to add a foundation to an old wooden house

December 26, 2016 Stroyexpert Home page » Foundation » Repair

Pouring a foundation for an old house

The process of deterioration of an old house and all its elements is inevitable. Sooner or later, property owners are faced with the need to partially or completely replace individual frame crowns, floor joists, and foundations. The technology for this work is quite complex and requires large financial and physical costs. Today we’ll talk about how to lay a foundation for an old wooden house.

Methods of restoration and replacement

After assessing the destruction of the foundation, it is restored or completely replaced. Each technology requires adherence to a certain sequence recommended by experts.

Strengthening. Minor damage to the strip foundation can be eliminated by pouring a new concrete layer around the perimeter. Restoration is carried out according to the following scheme:

A trench is dug along the perimeter of the house, deep to the bottom of the foundation.
The soil is removed from the brickwork with a metal brush.
Holes are drilled in the old base and reinforcement is inserted into them.
A mesh harness is welded to the clogged reinforcement, which will serve as the basis for the concrete pour. To ensure reliable adhesion, the mesh is screwed to the reinforcement with wire.
Formwork is installed along the perimeter of the foundation and filled with concrete. Filling is carried out in layers, in small sections no more than 2 meters in length. After each poured layer, the concrete is allowed to soak into the soil and base.

After strengthening, the concrete will firmly bond with the old foundation and soil, the house will receive additional support area, will stop deforming, and the foundation will stop collapsing.

Important Steps

Regardless of the option for reconstructing the foundation under a wooden house, you should:

add and compact a sand-crushed stone cushion before starting concreting;
add, if necessary, cement laitance to the bottom of the trench;
make high-quality waterproofing and insulation of the underground structure;
lay casings for input/output of utilities in a concrete monolith;
perform backfilling with layer-by-layer compaction.

In case of partial destruction of an underground structure, there is no need for its complete restoration. In this case, only weak areas are repaired by filling the foundation. To connect individual fragments, metal rods are driven into existing monolithic pieces of concrete tape, leaving protruding sections.

Dismantling the old base and installing a new one

So, the house is raised, now it is necessary to remove the old frame.
So, the house is raised. Now you need to remove the old frame. To do this, use a chisel, a hammer drill and other complex powerful equipment. We are not in a hurry to throw away waste from the old foundation. They will still come in handy.

As soon as the old frame is removed, you can begin to form a pit for a new one. To do this, you can deepen the existing one a little or simply install a durable sand cushion 20 cm thick if the trench is deep enough. The sand is slightly moistened and compacted well.

Formwork is installed in the trench, taking into account the bypass of those places where jacks and support posts are located. These holes can later be simply filled with bricks.
A reinforcing belt is placed in the formwork, and care is taken that in the corners of the house it is bent and not welded. Since it is the corners of the building that will be responsible for the strength of the entire frame.
The solution is poured into the prepared formwork and waited for it to dry completely.
As soon as the concrete has dried, the crown logs are replaced if necessary. They can be tapped for rotting. If, when you knock on a log, it emits a ringing hum, then the wood is good. If the log has a dull echo, it means that it is rotting inside and requires replacement.
Logs are replaced down to those that are well preserved.

Upon completion of all work, the house is also simultaneously and gradually lowered onto a new foundation. Windows, doors, floors and roof are returned to their place. The new foundation is sprinkled with the remains of the broken old foundation and compacted with soil.

A wooden log house is ready for use for another 30-40 years, provided that the wood is well cared for.

How to raise a wooden house with a wooden foundation

Wooden foundations (chairs) sometimes have to be replaced due to their rotting, especially if the groundwater lies high ( 30-40 cm from the surface), which creates a zone of variable humidity.

that have expired can be identified by tapping the logs with the edge of an ax or shovel. Rotten wood is immediately visible.

The support must be urgently changed if the logs have rotted by half or more than 50 % of the original diameter. In place of the damaged butts, new ones are placed, or brick (stone, concrete) pillars are built, and then the distance between them is filled with cement-based mortar.

The depth of the new foundation should be the same as the old one, but not less.

In places where chairs are replaced, it is necessary to disassemble part of the base and free the logs from all nearby and adjacent building elements (usually logs and floor boards):

The temporary support is mounted at a distance of 0.6-1.2 meters from the rotted chair under the lower crown of the house, and it is better to do this on both sides. As supports, you can use beams or the same butts, but a little shorter.

It is necessary to lift the walls one by one using a jack or a long lever so that the frame crown is freed from the tenons of the foundation chair. Then you need to place temporary supports under the logs and wedge them.

The damaged chair must be removed and a new one installed in its place. The depth of shrinkage of the old one should be added to the length of the future support. After this, you need to lower the wall so that the tenon of the new chair fits into the groove of the crown.

When installing a new wooden chair, it is impossible to avoid cracking of the plaster and distortion of window and door openings . Therefore, it is better to replace wood with stone or concrete pillars in order to reduce the need for reconstruction.

Sometimes it is necessary to replace the rotten lower logs of a house; this process can be observed on an amateur video:

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 destruction process is continuing.

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.
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.
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.
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

The procedure for choosing a restoration method

Before proceeding with the restoration of a damaged foundation, it is necessary to study the condition and make an informed technical decision. Foundation analysis can be done in the following way:

Dig a ditch about half a meter wide along the entire outer perimeter and completely clean the surface of adhering dirt.
Determine the foundation material, its condition, and eliminate visual problems with the structure.
Calculate an estimate for restoration work, taking into account the cost of labor, materials and the necessary lifting equipment.
Choose the best method to restore the foundation.

After collecting the data, the builder decides whether to replace the base or restore it. Basic ways to solve the problem:

Complete replacement of the base.
It is possible to raise the house to a certain height by extending the existing structure with a grillage.
You can strengthen the existing building by creating an additional belt or installing pile elements.

Any of the above methods is quite expensive, but takes place under certain conditions.

We prepare and pour the foundation for an old house

Everyone has seen at least once in their lives houses with deep cracks and warped walls.

And it doesn’t matter at all whether the old house is made of brick or wood, it’s still possible to make a new foundation

To solve this problem, you can do several things:

Completely replace the foundation.
Strengthen the existing foundation.
If there is no foundation at all, raise the house onto the foundation.

It is clear that these methods are radically different in terms of complexity. To understand how much, you can watch a video of pouring the foundation for a house with your own hands on the Internet.

Let's take a closer look at each of the methods of pouring the foundation for a house.

Complete replacement of the foundation under an old house

In this case, there is no other choice but to take up the arrangement of a reinforced strip foundation. To do this, the old timber house is raised using large jacks, the old destroyed foundation is dismantled and a new one is poured. Let's talk in more detail about all these works.

Raising the house

If it is not clear how to raise the house to pour the foundation, you just need to support the corners of the old wooden house. Then you need to raise those corners of the building that sag the most. For work, it will be enough to take or rent 2 jacks capable of lifting weights up to 5 tons. When one corner is raised, a wooden block or thick piece of metal is immediately placed.

It is important that when raising the sides of an old house, cracks do not appear. Therefore, you should not lift more than 20 mm

By the way, you don’t need to trust the jack 100%. To be sure, it is better to place wooden blocks under the walls every 5 mm.

Gradually it will be possible to raise the entire structure to the desired height. Install a few extra supports under the longest sides of the house, thereby protecting the builders from a possible fall.

Replacement

This stage of replacing the foundation for a house is carried out using the following technology:

The old foundation is dismantled in its corners, we fill the base with medium grade crushed stone and only then the footing is poured.
Then the reinforced frame is prepared. A concrete structure with it will have high strength. Do not forget to tie the reinforcement cage together, plus release the reinforcement slightly from under the base.
Then you can make the formwork.
While pouring concrete, use a vibrator to force out any air pockets.
When the poured concrete dries, the remaining sections of the old foundation are dismantled and filled with new concrete, and so on until the entire foundation is replaced. In other words, it is possible to completely replace the old foundation with a new one only in separate parts. That is why it is more rational to divide the entire perimeter of the house by 2 meters. It is imperative to carry out concrete work through one segment. This will significantly increase occupational safety.

Until the foundation has hardened sufficiently, the house cannot be lowered.

Making a new foundation if there is no foundation under the old house at all

It is highly not recommended to pour the foundation for a house without reinforcement, since the foundation will not be strong and will collapse over time.

It may turn out that an old private house does not have any foundation. Then you need to “wrack” your brain on how to lift it onto the foundation without damaging it. Usually, old wooden huts were built without a foundation.

Technology for raising a house to its foundation

You need to dig a trench along the entire perimeter using a spade bayonet (25 cm).
Then logs or reinforced concrete piles should be installed under the bottom of the wooden house.
The dug trench is filled with crushed stone to a height of 15 cm.
Then the formwork is made from the inside under the house.
Then you can move on to arranging it using metal frame reinforcement.
Then you can make formwork on the outside (it is made a little higher). This will make it possible to add concrete when the formwork has already been removed.
Adding fine crushed stone and further pouring concrete.

Strengthen the existing foundation of an old house

If the building already has an old foundation, it can be strengthened. In other words, you need to pour a new portion of concrete under the foundation of the old house. You need to follow these steps:

A trench is being dug around the perimeter of the house. Reinforcement is driven into the old foundation. But at the same time, it is necessary not to damage the existing foundation. After the problems are eliminated, the trench is filled with concrete

It is important that the concrete mixture penetrates into all holes in the old foundation.

Gain Options

Reconstruction of the foundation is carried out in several ways. Can:

make a new encircling reinforced concrete frame;
pour a foundation under the old structure;
put a wooden house on a replaced foundation.

The collapsing strip foundation is reinforced with reinforced concrete on both sides - external and internal. To do this, the dug trench is deepened to the level of the base of the problematic structure. The standing monolith is drilled at a certain pitch, after which metal rods are installed in the holes. They are connected into a spatial frame using vertical reinforcing meshes located on both sides of the foundation wall.

Next, formwork is made into which the ready-made concrete solution is poured. This technology makes it possible to strengthen a weak strip foundation with metal meshes, fastened together by rods passed through the concrete body. In addition, the new tape is wider, which means its load-bearing capacity increases.

The second reinforcement option is intended for a fairly strong concrete base, when problems with subsidence arise due to:

incorrect geological studies;
illiterate calculations;
unstable position of soil layers.

In this case, you will need to make the bottom cushion wider, and the underground support itself will need to be deepened to a denser layer of soil, if any. The technology involves the gradual excavation of earth from under the corners and individual supports of the building so that reinforcement cages can be placed under them, the formwork can be knocked down, and concrete mortar can be poured and compacted.

In order to make a reinforced concrete pad for a strip foundation, work is carried out in several stages. The plots are divided so that the wall does not collapse into a hole dug below the level of the foundation base. They move on to the next fragment only after the concrete has cured in the previous section.

Reliable retention of the old foundation on the new one occurs due to unevenness on their surface.

The individual parts of the reinforced concrete pad are connected to each other by means of metal rods protruding from the structure. Additional frames are mounted at the corners. And the new foundation is made wider than the existing foundation.

Replacing the underground part of the house

A wooden house can be placed on a new foundation if the old one cannot be restored. A similar technology is used for small buildings. It is not suitable for multi-story or massive brick buildings.

A special feature of moving the house onto a strong, reliable foundation is to lift the box off the ground using hydraulic jacks. At least two temporary support beams made of metal profiles or beams are placed under the bottom trim or crown. Their cross-section is chosen depending on the approximate weight of the structure, and their length - taking into account the fact that the beams on both sides of the house will have to protrude by at least 0.5 meters. To make it easier to install temporary supports, the old foundation is partially destroyed.

Before lifting the building, the maximum amount of furniture and household appliances is removed from the house. Often, to facilitate the construction, windows and doors are dismantled, and boards are removed from the floor.

A wide, reliable base is installed under each 5-10-ton jack so that when lifting a house, the tool does not sink into the ground. This can be a thick sheet of iron, a concrete block or another product that can withstand increased point loads. In the process of raising the house, safety supports are placed under its frame, which are increased as the distance above the ground increases.

The structure should be raised gradually and evenly, avoiding distortions. After a centimeter change in height with one jack, move on to the next, etc. This is done until the box rises above the foundation to the required distance (usually up to 8-10cm). After this, they begin to dismantle the old foundation and install a new underground structure.

The building is lowered only after the final curing of the concrete monolith. Temporary support beams are disposed of, and the remaining holes are sealed.

Complete replacement of the house foundation

Using the house hanging method, the old foundation is removed and a new one is installed.

It is necessary to reduce the load on the foundation as much as possible. To do this, you need to completely empty the house of all heavy things and furniture. In other words, leave only the supporting frame.
The load of the house is calculated. To do this, you need to obtain data on the density of wood, its quantity used and the final mass. As a rule, the floors in such wooden houses are also made of wood and are lightweight. But even this must be taken into account.
Special construction jacks are purchased or rented, which can temporarily replace the main foundation and take on the entire load.
Trenches are dug under them. Even if water appears in the trench, it is not fatal, because the boundary level of groundwater rise will immediately be revealed.
Then the jacks are brought in, installed under the base of the house and carefully and evenly raise it.
The condition of the lower parts of the house is being analyzed. If the deformation does not affect them, then you can begin to dismantle or repair the base itself.
To do this, a sand and gravel cushion is made, on which concrete or brick supports are installed at the corners of the building and at the intersection of load-bearing walls. It is also possible to install new piles, but this is only possible if there is sufficient space on the construction site.
After installing the new foundation, the entire structure is reinforced. here it is advisable to create a flexible connection with the old foundation, if its complete dismantling is not envisaged.
Formwork is installed into which concrete is poured. After the concrete has dried, the new base is waterproofed.
Only after a few days is the air released from the jacks evenly and simultaneously, and the building is lowered onto a new foundation. If desired, finishing work can be carried out.

Base replacement technology

The first step is to dismantle the corners of the base, then level and prepare the soil for the future supporting structure of the house. The following stages of replacement work:

At the bottom of the trench, arrange a sand and gravel cushion or fill the primary layer with concrete.
Mount the formwork, install a reinforcement cage inside and provide outlets for future connection to the existing house.
Fill the trench with formwork with concrete using standard technology.
Leave the concrete to dry.
Replace the remaining sections of the foundation.

Pouring one section of an old wooden building with concrete

Sometimes, after obtaining data on the condition of the foundation, it is enough to pour concrete into individual areas and strengthen them. In such cases, only individual sections of the foundation are excavated, damaged elements are removed, and a local reinforcement layer is installed. Then this area needs to be filled with high-grade concrete and the reinforcement connected to other parts of the house. Upon completion of the work, you need to carefully lower the house onto the new structure.

It is recommended to do a complete replacement in separate segments, with the perimeter of the base being divided into separate sections. The created new reinforcement frame is connected to the corner posts, and the release of rods for further tying is ensured. The formwork is installed in the same way and concrete is poured. It is also necessary to provide space between the new foundation and the base of the structure for a waterproofing layer.

Construction of a new foundation:

a trench 30-40 cm wide is dug along the outer perimeter of the future foundation, but not less than the calculated thickness of the load-bearing walls of the house;
supports are installed under the raised house;
a sand and gravel cushion and formwork are installed at the bottom of the trench;
the reinforcement frame is installed.

Then you need to fill the trench with concrete mortar and after a few weeks lower the wooden house onto a new strip foundation.

General principles for strengthening the foundation

Strengthening the foundation along the perimeter: 1. sand cushion; 2. old foundation; 3. metal mesh; 4. anchor; 5. place of destruction; 6. formwork; 7. concrete.

Before you begin strengthening the foundation, it is necessary to conduct a thorough inspection of it. It may well turn out that initially the foundation of the building was laid with a large margin of safety, with the expectation of erecting the next floor. In this case, you are very lucky. But it also happens that the existing foundation raises many questions about the adequacy of the builders and their professionalism. Many amateur builders who are building a house for themselves or relatives without the involvement of specialists may well ignore full calculations, thinking that it will do just fine. Therefore, the stage of inspection, identification of damage and carrying out calculations is exactly where it is necessary to begin even before directly strengthening the foundation of the house.

Having completed the first stage, it is necessary to strengthen the walls. This work is carried out using both external and internal supports. It is also necessary to take into account the fact that if the house has a ground floor or basement, and you plan to deepen the building, then such work requires a scrupulous attitude. This is due to the fact that as soon as you start digging a trench along the entire length of the building before strengthening it, the load on the walls will be significantly increased and this can lead to its complete destruction. Therefore, when you start strengthening the foundation, under no circumstances immediately dig such a trench, do not expose it.

What should you do if such a continuous trench cannot be dug? This can be done gradually. To do this, you first need to excavate certain areas along the foundation of the old house. The distance between these areas should be 1 m.

Basic methods of foundation repair and strengthening.

It is necessary to dig from the corners of the old house. You need to continue digging in those places where the outer and inner walls connect. After this, an excavation is made along the entire length of the old building. At the same time, it is necessary to clean out the excavation areas as well. If it is planned to concrete a new foundation, it is necessary to provide small gaps of up to 30 cm between the new and old foundations of the building.

After the excavations have been made, it is necessary to build pits under the buildings. Reinforcement is placed in them and concrete is poured. The concrete solution must be thick and when pouring it, it is necessary to ensure that it evenly and sufficiently fills the space under the base of the building. To do this, you need to use professional equipment, in this case it is a good vibrator. After the work on strengthening the foundation is completed, it is necessary to build a blind area around the building up to 60 mm high from the ground, which should reliably protect the foundation from precipitation and floods.

In addition, it is necessary to provide for the strengthening of its walls, which is carried out in a certain sequence. Perimeter walls cannot be reinforced. First, any wall of the house is strengthened along its length, if the house has a rectangular shape. After strengthening this wall, the wall opposite is strengthened. After completing the strengthening of the walls of the house along its length, they proceed to strengthening the walls along its width.

Causes of destruction

It is unlikely that any building structures can be called eternal. Even the most reliable of them can collapse over time, not counting those that were built in violation of the technological process. There are many known reasons leading to foundation failures:

negative environmental impacts, including the impact of groundwater or surface water;
incorrectly performed geological studies;
design or calculation errors;
temporary factors;
horizontal or vertical displacement of soil layers;
improperly performed or absent drainage;
use of low-quality materials in construction;
ignoring technological processes;
illiterate determination of the depth of the foundation;
poor quality waterproofing or antiseptic treatment.

The specific reason for the appearance of destruction or subsidence of the underground part of the house is identified after a thorough audit or examination of the structure. Only after this is it determined how to properly lay the foundation and what needs to be done to ensure that it becomes a reliable support for the structure.

How to replace the base

If the house is already warped, a more serious reconstruction is needed; you will need to add a foundation to the old foundation along the entire perimeter of the building. More serious work will be required: the house will be raised, and then it will be put back on a new foundation structure. What to prepare for work? What tools will you need:

shovel;
Master OK;
hammer;
jacks, for lifting a weight of at least 5 tons, about 5 pcs.;
reference apparatus.

Materials:

gravel;
sand;
cement mortar;
roofing felt;
bars.

Progress:

Everything possible is removed from the premises: furniture, equipment. This process is necessary to make the structure lighter; sometimes the floor, doors and windows are dismantled.
At least 2 beams are placed under the bottom layer of timber; these are temporary supports. Ordinary beams or metal blanks are suitable; their thickness must correspond to the weight of the house, and the length is selected so that they protrude half a meter. To put them in you will have to destroy part of the foundation.
Next, jacks are installed, and a solid foundation is placed under each of them so that it does not sink into the ground during operation. You can use an iron sheet or a piece of concrete; anything that can withstand the load will do, but in no case will the foundation support itself be suitable.
Gradually, as the space increases as the building is raised, supports are placed under the base.
If the walls are long, it is necessary to install additional channels so that the logs do not sag under their own weight.
The structure is lifted evenly, trying not to create distortions; lift it a centimeter with one tool and move on to the next.
Work continues until the house rises to the desired height. Usually 8 or 10 cm is enough.
Then the defective base is dismantled.

After removing the old material, you need to properly add the foundation; there are some nuances here:

dismantling and filling should begin from the corners;
The base is replaced in parts of 2 meters through one element.

Filling is carried out according to the usual scheme:

formwork is being built;
a cushion of sand and crushed stone is poured;
the solution is poured.

A small space should be left for laying waterproofing roofing felt. The house can be placed on the foundation after the concrete has completely dried.

general information

It should be noted right away that it can be much easier to update the foundation under a wooden house than under a brick building. And if in the first case you can try to do the work yourself, then in the second you should turn to professionals. The fact is that if the integrity of the masonry is accidentally broken, it behaves completely unpredictably, becoming covered with cracks and breaking into separate pieces almost instantly. The result of experiments can be spontaneous destruction, leading to serious consequences, the most harmless of which will be a pile of stones appearing instead of a residential building.

Another reason why you should not independently restore the foundation under a brick wall is the greater weight of the house compared to a wooden structure.

Specialists have the necessary tools and equipment to lift a brick box without destroying it. They have experience and, importantly, they are responsible for the work performed.

Problems with underground structures almost always appear on the facade of a brick house or on the base of a wooden one. These could be skewed openings, poorly closing doors and windows, cracks, cracks, etc. Don't think that the situation will improve on its own. You need to place beacons in questionable places and watch them for a while. If there is noticeable movement, restoration work should be started immediately.

Strengthening the foundation of a house on columns

Strengthening the foundation using the drilling method.

The general case discussed above is why, how and in what sequence work is carried out to strengthen the foundation of a building. In particular cases, questions arise about how to carry out such work, i.e. pour the foundation under the old house, which is located on columns. This not only gives the building a more aesthetic appearance, but also strengthens the foundation of the house. In addition, this can make the space under the house warmer, and therefore insulate the entire house.

To strengthen the foundation in such a house, it is necessary to dig a trench between the columns from the outside of the building. The depth of the trench should not exceed the bayonet of a shovel, and its width should be equal to the width of the column. After this, sand is poured into the dug trench to a level of at least 10 cm.

On the inside, which is located under the building, it is necessary to make formwork. To do this, you can mount boards or use chipboard, plywood, edged boards with a thickness of 20-30 mm. The formwork must be secured using racks and stops. This is done so that it does not fail when pouring concrete.

Repair of the foundation of a stone house.

Then, before pouring the concrete, reinforcement must be laid. If possible, secure the reinforcement to column supports. What is suitable as fittings? This can be corrugated reinforcement, mesh, both masonry and cut, steel wire and any scraps that are lying around in the yard.

It is necessary to take into account that the outer side should not be left without formwork. Install it in such a way that the gaps left allow concrete to be poured, and after its removal it would be possible to seal the remaining niche. In cases where the formwork has significant gaps or cracks in its walls, it is necessary to use polyethylene film, securing it with a stapler. This will prevent concrete from spilling through such gaps.

The requirements for poured concrete are such that it should resemble sour cream in terms of viscosity or fluidity. As for crushed stone, use as fine as possible. If the crushed stone is large, voids may form and it will be difficult to compact the concrete.

You can avoid pouring concrete if you make brickwork instead, for which you can use old bricks from already dismantled masonry. This option eliminates the need to make formwork, and the unsightly effect of using old brick is removed by plaster from the outside. If the building has a basement and it is assumed that it will be covered, for example, with siding, then in this case there will be no need for plaster.

But even with brickwork, it is highly recommended to use both steel wire reinforcement and a sand bed. If you neglect this requirement, you can soon get a sad result in which the brick run between the supports may fail. This option is most likely for heaving soils. Don't skimp on this and don't create difficulties for yourself in the near future.

Construction of a deep foundation on non-heaving soil according to SNiP standards

The picture shows a diagram of the construction of a deep foundation on non-heaving soil according to SNiP :

Foundation . Cement-concrete mixture.

Backfilling . Made of sand and crushed stone.

Support cushion . Consists of crushed stone. Depth: 50-70 cm.

Cushion width . At least 20 cm wider than the thickness of the foundation.

Depth . It is 120-150 cm.

When removing old masonry, materials should be visually sorted according to suitability for use in the new one. If the building is built on a shallow support, then after leveling and building up it is necessary to install drainage, a blind area and a protective covering to prevent water from penetrating under the base of the foundation.

If the house was deformed or began to collapse due to the uneven rise and fall of the pile foundation, which can be caused by soil heaving during severe frosts, then after a new foundation is laid, the soil should be protected from freezing so that the process of heaving and pushing out stops.

The protection consists of covering the ground around the foundation with a layer of thermal insulation.

Straw , sawdust , expanded clay , expanded polystyrene , slag wool are suitable for this . You can also arrange soil heating by laying a pipe manifold near the pile foundation, through which hot water or steam will pass.

If soil freezing cannot be prevented , then the destructive zone near the base should be reduced. To do this, in winter or late autumn, holes are dug around the pile foundation at 60-70 % of the freezing depth. Thanks to this, the earth “woodens” gradually and does not block the access of groundwater to the foundation.

The piles are coated several times with bitumen or antifreeze lubricant , then they are wrapped in several layers of waterproofing. A protective composition of petroleum products is also placed between these layers. The last operation is to fill the hole with non-heaving soil.

Foundation grouting technology

Adding a foundation to an old house requires the use of special tools that will raise the structure while the procedures are completed. The first step is to dig a trench around the perimeter of the house; the process has the following procedure:

The corners of the building are dug out.
Ground procedures are carried out at the intersections of walls where it will be necessary to open holes, with dimensions suitable for inspecting structures.
Then continuous trenches are dug around the base along the perimeter of the house.

To avoid soil shedding, the walls of the pit should have an inclination angle of 30 to 40 degrees. The width of the trench should not exceed 1 m. The depth of the pit should be below the base of the old base.

Preparatory processes for pouring concrete mortar.

The base structure is cleared of adhering soil, its walls are leveled and cleaned. If the wooden building has a columnar base, you will need to dig a hole near each pillar to assess the strength of each support. To increase safety, it is recommended to install special jacks at each corner of the building.

Inspection of the condition of the foundation part

Analysis of the situation is complicated by the fact that the problematic structure is located underground, while the above-ground part may look quite decent. To allow a visual inspection, it is necessary to dig a trench about 70 cm wide around the entire perimeter of the house so that the standing strip foundation is exposed as much as possible. You should start from the problem corners. If the wooden house is located on pillars, then only them should be dug in. In this case, a trench will not be required.

It is not allowed to carry out excavation work in several places at the same time. Only sequentially - section by section.

You should dig carefully so that the weak support does not collapse. At the slightest suggestion of a dangerous situation, and even more so when movement has begun, the process of opening the foundation must be stopped immediately, and then immediately leave the emergency site. When doing work with your own hands, it is very important to follow safety rules. It is strictly forbidden to support structures manually! This is dangerous!

Analysis of the condition of the foundation of the house

Before you begin directly repairing the foundation of an old wooden house, you need to carefully study its condition and make the right decision regarding the method of performing this task.

Therefore, the first thing you should do is conduct a detailed analysis of the quality of the existing foundation. How to perform this procedure correctly? Simple enough:

It is necessary to dig a ditch along the entire perimeter of the building, the width of which will be 0.7 m with a permissible deviation of 20 cm. This trench should be located very close to the existing foundation of the house.
Only after you see with your own eyes all the problems with the foundation and determine the material from which it is made, can you decide whether to make a complete or partial repair. In addition, you can decide which method to choose.

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Replacement of existing structure

First, you need to raise the house so that you can dismantle the old one and build a new foundation. At this stage, it is necessary to use at least two jacks, the lifting capacity of which is from 5 tons. It is more convenient to carry out this work with professional equipment. In the video you will see how the foundation of an old house is replaced.

A wooden house should be raised from the most sagging corner of the building. You must immediately place a wooden block (or a metal stand) into the resulting gap. If the walls of the building are of considerable length, then it is necessary to gradually lift and install supports around the perimeter (corners first).

Replacing the foundation of an old house

To avoid excessive load, it is forbidden to lift the old house by more than 2 cm. It is recommended that every 5 mm of lift be secured by installing supports, which should be placed on a reliable, rigid surface. It is prohibited to place them on fragile structures of the old foundation.

The old foundation is replaced with separate segments, dividing the perimeter into sections 1.5-2 meters long. Each adjacent segment is dismantled one by one. After lifting and securely securing the frame, you can replace the foundation, adhering to the following sequence:

dismantle corners;
arrange a cushion (sand, crushed stone), and sometimes (depending on the characteristics of the soil) pour it under the concrete;
build a reinforcing frame that guarantees the required load-bearing capacity of the base; reinforcement should be produced for connection with other areas;
install the formwork, fasten it securely to avoid concrete leakage or disruption of the shape of the base;
pour concrete with compaction of the mixture;
after achieving the required strength, you can replace the remaining sections of the base;
dismantle the segments located near the corners; the remaining sections guarantee safety;
mount a reinforcement cage with outlets to connect the adjacent segment;
build formwork;
pour concrete.

There should be room for waterproofing between the fresh foundation and the house. It is allowed to lower a wooden house only onto a ready-made, frozen foundation. It is first necessary to lay waterproofing, more often roofing felt (several sheets) is used. This way you can lay the foundation for an old standing house, having previously removed the destroyed areas.

If not only reconstruction of the foundation is required, but also replacement of the lower destroyed crowns of the building, then this part of the work should be carried out by professionals. To avoid destruction of the log structure, it is imperative to apply special safety measures.

This is how the old foundation is repaired. At the same time, the supporting area of the building increases, the reliability of the building itself increases and the service life of the structure is extended.

Residents of private houses are very often faced with the problem of carrying out constant preventative and repair work, which allows the existing building or several buildings on the site to serve for a long time and conscientiously. Almost no season can go by without patching up the roof, painting the fence, or strengthening the foundation. Of course, an initially well-built foundation will last for several decades before requiring repairs.

Laying scheme

However, not everyone makes a home from scratch. And not everyone’s construction of private property begins with laying the foundation. The fact is that a significant part of summer residents and residents of suburban settlements often buy a plot with an old house on it, which is restored over time. And this matter is extremely complex. The very first question is how to make a foundation for an old house. After all, without a foundation, even a veranda cannot function, not to mention a living space.

A new foundation is poured not only in cases of its absence, but also to strengthen the existing or dismantled foundation, to improve the appearance of the building, to insulate the space directly under the house (basement, subfloor, ground floor) and in many other cases.