How to raise a wooden house to place a foundation under it: step by step

February 8, 2022 Stroyexpert Home page » Foundation » Repair

Raising a wooden house to replace the foundation

The basis of any structure is the foundation. The service life of the structure depends on how this base is made. An unscrupulous approach to work at the stage of foundation construction can lead to the fact that the foundation begins to collapse.

House lifting technology

It is possible to raise a house without the use of special equipment; in this case, you will need to use hydraulic jacks that can handle a load weighing 10 tons. In order to dismantle the foundation, you should use a sledgehammer, a crowbar, and also dismantling wedges.
Timbers, massive chocks and bricks can serve as temporary supports. And the boards will become spacers. The platform for installing the jack will be beams and boards, which should be combined into a shield; if such material is not available, you can use any other that is durable. A steel plate, the minimum thickness of which should be 5 mm, will evenly distribute the forces exerted by the jack rod on the first crowns of the building. If work will be carried out with a foundation on supports with a back-up, the latter must be dismantled

At the preparatory stage, it is important to rid the building of heavy things and furniture. Moreover, the floor must also be disassembled. In order to raise the house onto the foundation, jacks should be installed on both sides at a distance of 0.5 meters from the corners

If the jacks are installed correctly, they will handle the lift. Errors when placing jacks can cause deflection of the beams, which are part of the lower frame, which will lead to uneven lifting, separation of the logs and their breakage. Before raising the house, you need to make sure that the jacks are located in places where the wood has not been exposed to rotten influences

In order to raise the house onto the foundation, jacks should be installed on both sides of it at a distance of 0.5 meters from the corners. If the jacks are installed correctly, they will handle the lift. Errors when placing jacks can cause deflection of the beams, which are part of the lower frame, which will lead to uneven lifting, separation of the logs and their breakage. Before raising the house, you need to make sure that the jacks are located in places where the wood has not been exposed to rot.

It is necessary to install gaskets, which can be steel plates, this will facilitate the correct transfer of forces to the bars from the jack rod. It is permissible to replace the plates with pieces of wood. Jacks should be installed on a prepared site; if necessary, they should be deepened into the soil, which will ensure their more reliable stability.

Concrete is first poured into the formwork and then compacted.

Sections of beams that are used in the process of arranging temporary supports should be used in such quantities as the lifting technology will require. If you intend to lift the entire house at once, the number of supports should be 2 times larger. The support should be assembled using sections of beams; ultimately, the support should take the shape of a well.

The supports must be given a height that is 10 cm greater than the difference in distance from the height of the jack to the ground. This is explained by the fact that during the lifting process the supports will settle, pressing into the soil. The technology involves lifting houses from both sides simultaneously, the lift on each side should be uniform, but at one time it should not exceed 1.5 cm. The result obtained must be immediately recorded using temporary supports.

Lifting can lead to kinks in the first rims, which indicates the need to install additional jacks. At this stage, it is necessary to ensure that the building does not move to the side, because then this will cause a change in the center of gravity.

In order to replace the foundation, the building will have to be raised to a height of at least 6 cm. Afterwards, the building can be lowered onto scraps of logs, which need to be placed on temporary supports.

After the house has been raised to the required height and secured with temporary supports, dismantling of the old foundation should begin. To do this, you will have to disassemble the rubble and brickwork using chisels, but you can use any tools that are convenient. Old supports must be removed from the ground by rocking them to the sides. Some materials that have been well preserved can be used in arranging the future foundation.

The fundamental structure is the support of a residential building, the destruction of which entails negative consequences. Old houses made of wood or panel material are lifted with a special device and a new foundation is formed. The construction of residential buildings without foundations is the choice of European developers. In the domestic space, this technology is just beginning to be developed and implemented. Therefore, most repairs involve raising a wooden house with your own hands.

Causes of foundation destruction

The cause of destruction of the foundation of the house may be adverse environmental influences:

High humidity.
Problematic soil.
Sudden changes in temperature.

It is impossible to predict the actions of nature, but some factors can be taken into account at the design stage.

But the cause of foundation deformation can also be the human factor:

Incorrectly designed project.
Incorrect type of foundation.
Neglect of reinforcement and waterproofing when pouring the foundation.
Use of low-quality materials.
Failure to comply with technological construction requirements.

As a result of the influence of one or several factors, the foundation ceases to perform its functions. Therefore, it is time for repairs. Depending on the degree of destruction of the foundation of the house, repair work is carried out in two types: complete replacement of the foundation or strengthening it. In both cases, you will first have to raise the structure. To do this, you can use a crane installation and slings. But most often construction jacks are used to lift wooden houses.

Instructions for raising a wooden house

If there is only one jack, the corners of the house are lifted one by one, placing the bars

You can lift a building with one or more tools. In the first case, the power of the jack should reach at least ¼ of the weight of the building. The lifting capacity of multiple lifts will be less.

Different technologies are used for this:

If there is only one jack, the house is lifted one by one. The tool is installed at the corner of the building, raised no more than 5 cm and a beam is placed. Then they pull it out, set it at a different angle (not the opposite, but on the same side) and repeat the operations.
2 jacks are placed on both sides of the corner. It is impossible to hang both sides at once; each corner is raised in turn. Otherwise, the house moves and its walls become deformed.
If 4 jacks are used, the corners of the building are still lifted one at a time. But since the tool does not need to be pulled out and installed in a new place, the process takes a minimum of time.

Otherwise, the technology is the same and includes the following steps.

Determine the lifting height. If you need to repair a columnar foundation, you will have to dismantle the old one and replace it with screw piles. If it is only necessary to increase the foundation, the building is raised only slightly above the new foundation level.
It is safest to use 2 jacks to lift 1 corner. The instruments are placed on both sides at the same distance. Places are chosen carefully: the tree in this area must withstand heavy loads, so it must be durable, without rot or mold.
Raise the angle by 2–5 cm. Then lay a beam or brick, creating temporary support. It is recommended to install supports not only at the angle itself, but also along the wall being raised every 1.5–2 m.
The building can only be moved vertically. After each lift, the position is checked with a plumb line.
The jacks are pulled out, installed near the next corner and the actions are repeated.
When the house is raised to the desired height, repairs or replacement of the foundation begin.

The nature of the repair depends on the causes of the destruction. If a frame house on a columnar foundation warps, it is better to replace it with a strip foundation - dig trenches, install formwork and fill it with concrete. If the damage is not so great, it is recommended to reinforce the existing structure.

Often the cause of damage to an old foundation is poor-quality concrete. In this case, the base needs to be replaced: smash the old structure with a sledgehammer, remove all the remains, deepen the trench if necessary and use concrete of the appropriate class for pouring.

Determining the number and placement of jacks

When planning work, first of all, they determine how many jacks are needed, the lifting capacity of the equipment and in what places it is installed. The criteria for selection and calculation may include the following process features:

Construction of the house and length of the walls. For a building of elements up to 6 m long, one lift for each corner is sufficient; for larger sizes, additional ones must be added under the joints of the crowns.
The total weight of the building, which can be determined by the cubic capacity and approximate density of the wood (mostly 800 kg/cubic m). Don’t forget to take into account the weight of the cladding, floor and roof in your calculations. It is recommended to leave a carrying capacity reserve of at least 30%.
Type of work performed. Sometimes, to repair a certain area of the foundation, it is enough to lift only one side or corner. If, after raising the building, it is planned to pour the foundation, the mechanisms are placed closer to the edges of the wall and at the points where the timber is built up, fixing their upper parts on the lower crowns. When performing local repairs to the base, lifts should also be located in the area of the corners. When dismantling and installing a new crown, the heads of the jacks are attached to the lower parts of the opposite and adjacent walls.

To lift an average-sized building, 6 mechanisms of 5–10 tons each are sufficient. Two-story structures require the same amount of equipment to replace the base, but with a load capacity of up to 20 tons. When lifting one short wall, you can limit yourself to 2 lifts, for long ones you will need 3. One A jack will be enough only in one case - for minor and relatively quick repairs of a corner that has sagged relative to the rest.

Preparatory work, necessary materials and tools

At the preparatory stage, it is necessary to inspect the building, assess the degree of complexity and duration of the planned repairs, determine the method of lifting, and carry out work to protect the structure from destruction during movement.

If there are problems with the foundation, there are two options - build a new house or try to restore and replace it

The need for repairs by lifting a wooden building is indicated by visual signs:

significant skew or tilt of the house;
the appearance of a network of cracks on the interior and exterior finishes;
local or complete subsidence;
deepening part of the foundation into the ground;
significant violation of the integrity of the foundation.

The vertical movement of the structure is carried out to carry out the following types of activities:

Performing partial or major repairs of the foundation.
Preventing subsidence of the structure.
Replacement of rotted support beams around the perimeter of the building.
Alignment of box distortions.
Carrying out protective treatment of wood.
Eliminating mistakes made by builders.

Most often it is necessary to raise a wooden house when problems arise with the foundation

In order to determine the method by which the house will be raised using special devices, the following factors are analyzed at the preliminary stage:

mass of the building. Each jack must provide a 40% lifting capacity. To do this, the total weight of the structure is calculated by multiplying the cubic capacity of the box by the specific gravity of wood equal to 0.8 t/m3. The weight of the floor, roofing and finishing is added to the resulting number;
dimensions of the building box. With a building length of more than six meters, there is a high probability of beams or logs subsiding in the splice zone. Additional installation of supporting elements at the joining areas will be required;
presence of internal lining. Using plasterboard sheets or plaster to decorate walls indoors complicates the implementation of activities. Installing 50 mm thick boards on the outside of the corners will avoid repeated repairs indoors;
soil features. Depending on the structure of the soil on which the lower plane of the lifting device will rest, it may be necessary to use concrete blocks or special panels of increased area. This will prevent the jack from sinking;
travel height. The length of the working stroke of the rod is limited by the design of the lifting device. The use of special pads made of durable square-section timber with a side size of 100–150 mm will allow you to gradually achieve the required moving height;
duration of repair activities. The duration of the repair is determined by the degree of complexity; if it is carried out for a long time, it is undesirable to rest the structure on the rod. It is advisable to use temporary structures made of metal and wood that have sufficient supporting area.

Sometimes a bad site is chosen to build a building, then they put a new foundation in another place and drag the house

Raising the house to the height required for repairs can be carried out using the following equipment:

By crane.
It is used mainly for the purpose of lifting to move buildings to another site.
Powerful jacks.
A widespread method of moving wooden buildings in a vertical plane.

When planning to raise a house on jacks, you should prepare:

cut off the power supply;
turn off the gas supply;
shut off water mains;
turn off the sewer system;
ensure free movement of a stove installed on an independent foundation through the roof of the chimney;
disconnect the individually mounted boiler from the heating pipes;
dismantle the floor in the area of the stove and heating boiler;
secure the immobility of the box with steel plates screwed to the corners.

Use a jack to lift the frame slightly. Only 2-3 cm at a time

Where would you prefer to live: in a private house or apartment?

To complete the work you will need the following materials and tools:

Hydraulic type jack with a lifting capacity corresponding to the design value.
Support panels made of wood, allowing to reduce the load on the ground when installing lifts.
Set of metal pads measuring 20–30 cm.
Grinder equipped with a disc.
A set of tools for detaching the support beam around the perimeter of the building.

Jack selection

To lift the building, you will need 4 jacks, the load on which will be distributed evenly.
When choosing a jack, you must correctly calculate the weight of the house. The result obtained is divided by 4. When lifting a small house, you need to have a reserve of half the mass. On small structures, only 4 lifting mechanisms are installed in the corners. For larger ones they are installed more often.

After calculating the masses, the type of mechanism that is suitable for the designated purposes is determined. The jack for lifting a wooden house at a short distance from the installation point to the crown must be inflatable or rolling. If the distance from the lifting point to the ground is more than 30 cm, bottle and scissor hydraulic lifts are suitable.

The weight of the building is calculated based on the weight of worn round logs - 700-800 kg/m³. The volume is calculated in m³. It includes all walls, ceilings, partitions. The weight of all property not removed is added.

Preparing to lift the house

In order for the result to be of high quality, it is recommended to use professional services - specialists with equipment. Working independently without understanding the key points is dangerous. Preparation for lifting includes the following steps: 1. Selection of a new foundation based on the results of soil assessment, the level of freezing of soil and groundwater. For heavy, several-story log houses, a poured strip version is used. Screw piles are suitable for light timber buildings. To come to the right decision, you should contact the geodetic department of the area, where everything is known about the nature of the soil.

When is repair needed?

Complete replacement of the foundation under a standing wooden house is a rather radical, time-consuming and expensive procedure. Therefore, you should regularly check the condition of the base to avoid serious problems, because repairing the material is much easier, faster and cheaper. For example, if small cracks are found in the foundation, then it is enough to fill them with cement to avoid further destruction.

Repair and strengthening of the foundation is carried out in cases where:

the degree of subsidence of the building is higher than permissible standards;
there is a need to build a second floor;
the structure is constantly exposed to some kind of vibration.

Strengthening is carried out by installing micropiles, cementing, updating brickwork, expanding the base of the house and other available methods. Such manipulations will help get rid of cracks that have appeared and evenly distribute the load on the foundation when the house is standing.

We are preparing to strengthen the foundation of a private house

At the preparatory stage of work you should:

assess the condition of the base;
carry out preventive work;
choose the right repair method.

Please note the following points:

material used;
compliance with masonry technology;
number of problem areas;
depth of cracks;
condition of concrete.

A dilapidated foundation will become stronger if it is surrounded by a new reinforced concrete tape firmly connected to it

The method for diagnosing the condition of the foundation involves performing the following work:

Gluing paper beacons to cracks. The sticker must be applied perpendicular to the crack, ensuring maximum tension on the paper.
Visual check of the integrity of control elements. Tearing of the paper indicates increasing damage and the need for reinforcement.

Before carrying out work to strengthen the problem base, the following types of preventive measures can be performed

lay drainage. It will reduce soil moisture and avoid problems associated with subsidence;
insulate the foundation. High-quality insulation will protect against destruction caused by deep freezing of the soil.

Perform drainage installation following the given algorithm:

Extract the soil along the contour of the house to the groundwater level.
Dig a drainage well away from a residential building.
Lay pipes from the drainage ditch to the well.
Lay geotextiles on the bottom of the pit.
Pour a layer of crushed stone and lay drainage pipes.
Connect the drainage to the drain line.
Fill the pipes with crushed stone and fill the pit with drainage mixture.

The work of renewing the foundation under a building is labor-intensive, but not as impossible as it may seem

When installing thermal insulation, follow the sequence of operations:

Dig a pit along the contour of the house.
Place a layer of sand on the bottom.
Place sheets of polystyrene foam on the sand bedding.
Assemble the panel formwork in the trench.
Hammer the pins into the masonry and install the reinforcement cage.
Fill with M300 concrete mortar.

After performing preventive maintenance, you should decide on the repair technology.

Tape frame

In this case, a trench is dug for the tape along the perimeter of the building.
In this case, a trench is dug for the tape along the perimeter of the building. 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.

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.

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

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. Vertical piles are controlled 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.

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

Replacing a structure with raising the house

Laying the foundation in this way will require the presence of powerful pneumatic jacks, which are brought under the corners of the log house and lifted. Lifting begins from the most damaged corner and is performed gradually, no more than 2-3 cm in one action.

As the house moves up, wooden planks are placed under the crowns. The house is leveled horizontally, installing additional supports around the perimeter.

Having raised the frame to a height of at least 20 cm, the replacement begins. The work consists of the following stages:

Dismantling the base. Destruction begins from the corners, then all parts of the old structure are removed.
Digging a trench, laying a sand and gravel cushion on the bottom.
Pouring the pillow with concrete. Layer height – 15-20 cm.
Laying a reinforcing belt in a trench. The reinforcement is placed in the trench 3 days after pouring the sand and gravel pad, when the concrete layer “sets.”
Installation of formwork, pouring concrete using standard technology. The filling process is carried out continuously. Often, inexperienced developers use stage-by-stage pouring, which causes the concrete to form many seams and lose strength.
The house can be lowered when the concrete has completely hardened, no earlier than after 20-30 days. Concrete gains its final strength 40 days after pouring. The procedure for lowering the log house is carried out as gradually as raising it was carried out.

Stages of raising a building

To raise an old house and refurbish its foundation, you will need a technological algorithm. It would be useful to look through SNiP 3.02.01.87, where departmental building standards are indicated on how to raise a house and pour the foundation.

How to properly raise a building?

Technologically, it would be correct to adhere to a strict sequence. Digging a pit will greatly facilitate the work. The process of raising a building looks like this:

Raising a house made of wood from wood involves installing 4 jacks, each with a lifting capacity of at least 5 tons, at the corners of the building.
Having raised the building to a height of about 2 cm, a lining is installed from a wooden or metal beam. It is responsible for the stability of the product.
The building must be lifted smoothly. Sudden movements and an increase in height to 2.5 m will lead to distortion of the residential property.
If the width of the gap between the structure and the surface increases, replace the beams with larger ones.
The final distance from the structure to ground level must be at least 6 cm.

Dismantling of a residential property

Rubble and brickwork are dismantled using chisels.
Old supports are removed from the ground by rocking.

Construction of a new foundation

Pouring a fresh foundation for a wooden house begins with digging a U-shaped trench in the place of the removed foundation. A U-shaped pit is required for the installation of a future frame with reinforcement, combined into one rigid structure. You need:

Line the bottom of the resulting pit with a layer of river sand.
Assemble formwork from boards and plywood. The frame is installed using support stakes along the perimeter of the base.
Fill the trench channel with crushed stone with medium fractions.
Lay steel reinforcement from rods with a diameter of 8-14 mm.
Pour concrete dough from cement, sand and plasticizers.
During long-term use, wood loses its quality characteristics and deteriorates, so it is advisable to replace the lower beams from the walls of the house with new ones.

Types and types of foundations for wooden buildings

At the moment, the following types of foundations for a wooden house are distinguished:

tape;
columnar;
pile;
slab.

Strip foundation

The tape design is the most widespread today. It can be divided into the following groups:

Recessed.
Shallow.
Not buried.

The construction of a buried strip foundation is relevant if the depth of soil freezing is significant, groundwater is very close to the surface, or the structure will have a basement, ground floor or garage.

Shallow construction is best suited for wooden houses. This is explained by the fact that the weight of such buildings is much less than brick ones. The height for a wooden house above the ground varies from thirty to fifty centimeters. For this reason, it is used in situations where it is necessary to save on the foundation without losing its quality.

A shallow foundation is suitable for small wooden buildings or those that are needed only temporarily.

The process of constructing a strip foundation can be represented in the following stages:

Digging a pit. The depth of the foundation of a wooden house must necessarily be greater than the depth of soil freezing (about twenty centimeters). As for the width of the pit, this value is equal to the width of the foundation, to which half a meter is added for formwork and ease of work.
Creating a cushion from sand and cement. A mixture of sand and cement is placed at the bottom of the pit. The thickness of the layer should be at least fifteen centimeters, and preferably twenty centimeters. The mixture must be compacted: to do this, it is first watered with plain water and then compacted. The purpose of the sand-cement cushion is to reduce the load on the structure.
Creation of formwork. In order for the surface of the structure to be as smooth as possible, the formwork must be knocked down from the inside, and nails must be driven in from the outside. Following this advice will also make dismantling the formwork easier.
Installation of spacers.
Laying of reinforcement. Under no circumstances should elements be connected to each other by welding: only wire can be used.
Pipe laying. They are necessary for communications.
Pouring concrete.

Columnar foundation

This design is suitable for soil with a serious freezing depth, which at the same time regularly swells. Also, this foundation can be used on uneven terrain.

The construction of a columnar structure involves the use of concrete blocks, bricks and asbestos pipes. Therefore, it is not suitable for buildings with a basement or ground floor.

The technology for constructing a columnar foundation is as follows:

The location where the pillars will be installed is determined. Despite the fact that the distance between them is determined by the size of the house, it should not be less than one and a half meters.
Installation of pillars. They go deep into the ground by approximately 50 - 70 cm. In this case, a sand-cement cushion must be made under each of them.

Pile foundation

Such houses are built in areas with uneven terrain or when the soil is unstable. It is also suitable in situations where the groundwater level is high or changes frequently.

The pile structure is constructed in almost the same way as a column structure. The only difference is that the elements in this case are not simply driven into the ground, but are screwed into place. This is possible due to the fact that there is a drill at the end of each pile.

Slab foundation

A slab foundation is indispensable for moving soil. The construction of this foundation involves the production of a monolithic concrete slab with reinforcement. Its area exactly matches the area of the house. One of the advantages of such a slab is that it is movable, so the house is not damaged when the ground moves.

The slab foundation is erected as follows:

First, a pit is dug out. Since it will be large in size, it will most likely not be possible to do without the use of special equipment.
Creating a pillow from cement and sand.
Laying of reinforcement.
Pouring concrete.

Installing a slab foundation is not an easy task. The main difficulty of this work is to achieve uniform drying of the concrete over the entire surface of the slab. Therefore, if a tiled foundation is the only possible option, then it is best to seek help from a specialist.

Sequencing

First, it is worth assessing the condition of the building and especially the lower crowns. If the outside of the log house is lined with clapboard, it is removed and an awl is stuck into the beam or log. If it goes in easily, then the wood is damaged and will need to be replaced. This means you buy a beam of a suitable cross-section (even if the frame is made of logs), tape for compaction, and antibacterial impregnation for wood in contact with the ground. You process the timber and lay it out to dry.

The lower crowns in the log house rotted; they were removed before lifting and replaced with timber

If there is a brick stove in the house, you need to dismantle the floor around it a little, making room for the passage of the chimney through the ceiling and roof. If the furnace has a water register, you will also need to cut off the supply and return pipes - then they will need to be slightly altered and welded again. You will also need to disconnect all communications if they come from the underground - water supply, sewerage, etc.

If the house has extensions under a common roof or connected to the walls of the house, the matter is more complicated. It is necessary to vacate the house (the best option) or fix the extension to the main house and lift everything together. The second option is more complex; it is implemented if at least one wall has a rigid connection with the main house - for example, it is solid with the wall of the house. But even in this case, you cannot do without prior consultation with a specialist. It is much easier to lift a house if nothing is pulling it and does not interfere with the lifting. Later the extension can be raised separately. This is an option if it is made unconnected or the connections are only staples or other similar ties.

Immediately before work, you will still need to open the windows and open the doors. This will prevent them from being damaged by distortions.

How many jacks to install and where to place them

If the house is built on a strip foundation and the strip is equal in width or larger than the size of the log house, you will have to cut openings in the strip for installing jacks. Otherwise you won't be able to install them.

It will be easier if the building stands on a pile or columnar foundation. These are usually light structures such as a bathhouse, a small country house or garden house. In this case, the soil in the places where the jack is installed is leveled, compacted, and a rigid, level base is placed on it. This is a piece of a wide board or a sheet of thick metal. It is important to provide good, reliable support - when lifting a wooden house in this case, the load is transferred to the ground pointwise, in the places where the jacks are installed. And the load at these points is very large. To prevent the jack from “moving” during operation, a reliable base is required.

Openings for installing jacks

If the house stands on a strip foundation, first of all, use a sledgehammer to break out openings in the foundation for installing jacks. They are made along the perimeter, approximately 2-2.5 meters apart, but at least half a meter away from the corner. A platform at the cutting site is required - a wall. Make the opening so that the jack stands freely and the platform is level. Also, along the perimeter of the house, the studs with which the frame was attached to the foundation are cut. Next, after clearing the openings of construction debris, install the jack. It is advisable to lay a metal sheet under it. It will distribute the load more evenly and will not allow the material to crumble under the emphasis.

A little about the number of jacks and their load capacity. You can have at least one. But then the work will be lengthy - it will have to be rearranged in each of the holes, raised to the selected level, and then moved on. This is exactly what they usually do when lifting a house on their own. But there can also be two or three jacks - they can be installed in adjacent openings and raised all to the same height. The work will go faster, but the risk of distortion increases. Those who professionally lift houses usually have enough jacks to install them on two opposite sides and lift a wooden (log or panel) house at the same time.

The lifting capacity of jacks depends on the size of the house and their number. Usually they take 8 or 10 tons. These are ordinary lifts for trucks, there are a lot of them on the market, and they cost relatively little.

Such brackets must be installed below, fastening several lower crowns, or in the place where the extensions are attached, if they rise along with the house

One more point: it is advisable to additionally secure several lower crowns of the log house by driving in large metal brackets. It is also worth recording the extension, places of cuts and other problem points. This will prevent the house from falling apart during work. The same “clips” are installed in the replaced areas.

The process itself

Use a jack to lift the frame slightly. Only 2-3 cm at a time. No more. Previously cut linings (pieces of boards) are placed into the gap formed between the log house and the entire part of the foundation. When laying supports, they try to give them the shape of a truncated pyramid - boards of greater length are placed downwards, and shorter ones are placed above. This design is more stable than bars of the same length stacked on top of each other.

This design for supporting the log house is more reliable

If the house has walls (cuts), it is also advisable to prop them up. As you rise, pads must also be laid in these places, not only at the point where they intersect with the main walls, but also in a couple of places along the length (under the house). If at first it is impossible to do this due to the low height of the subfloor, they do it later, when the height has already been gained at least a little. They will hold up for some time due to their elasticity, but then it is advisable to give them support.

After installing the shims, the jack is lowered, removed, go to the next opening, raised again, lay the shims, and so on. During the work process, several thin pads made of boards are replaced with more massive ones made of timber - the smaller their number, the less likely it is that they will slip out or fall apart.

The direction of movement - clockwise or counterclockwise - does not matter. It is important to go around all the points sequentially. The amount of lift is the same everywhere. You can orient yourself relative to the entire part of the foundation - measure the distance to the lower crown. After each lift, the house is inspected. It should not crack or have a visible slope.

Having completed one circle, they move on to the second, then the third, and so on until the required height is reached. Usually they lift it by themselves by 30-35 cm, but professionals can do it by 80 cm. Next, the required work is carried out - the foundation and/or frame is repaired or replaced.

What's next

If after the lifting the foundation is dismantled, the house is moved to new supports and hung up. To do this, take a large cross-section of timber (usually a pair), bring it under the frame, and secure it on both sides. Two such stops are installed at each corner - on both sides. Total - at least eight. If the wall is long, install the same support in the middle.

This is what the timber stop looks like from the outside

The support beam can be laid on folded brick or concrete pillars. It is better not to use an earthen support for this - it may “float”. After all the supports are installed, you can dismantle the old foundation and carry out further work.

This way the stops can be fixed inside

This is classic technology. But, as you understand, it is not very reliable - these stops can fall, settle, etc. Repairing or replacing a foundation is a long-term undertaking, and anything can happen. A more reliable way is to weld supporting pedestals from a thick-walled metal corner or small I-beam.

Classic technology and metal cube

What else are good about cubes? They do not interfere with the reinforcement of the foundation. You pass reinforcement through them, then pour everything into concrete. You are studying a monolith with super-reinforcement. A very good option: it is reliable from a safety point of view, does not interfere with work (less interference for sure), and increases the reliability of the foundation.

Required tools and materials

The main reasons for the loss of structural strength include changes in groundwater levels and precipitation. The peculiarities of buildings made of lumber lie in their lightness and the method of arrangement. It is quite possible to build your house on a replaced foundation; the main thing is to set a goal and purchase the necessary materials. To make a foundation for an old wooden house, you may need the following tools and materials:

concrete mixture (cement, sand, crushed stone or gravel of medium fraction);
steel rods for foundation reinforcement;
wooden formwork;
jacks;
shovel;
large sledgehammer;
scrap steel;
wedges

Using these materials, it is easy to independently raise an old house and build a new foundation underneath.

Repair or replace completely

In cases of minor damage, local foundation repairs will be sufficient. But to get a truly strong and reliable foundation, it is better to replace it completely. You can also pour a new foundation around the old one - the so-called concrete cage method. The video shows how the jacking, leveling and replacement of the foundation of the old house, which the owners decided to preserve, were carried out.

Types of foundation deformation

In addition to finding out the reasons that led to the destruction of the foundation, it is necessary to give an adequate assessment of its extent. This will allow us to determine the possibility of strengthening the foundation and the feasibility of this event. Maintainability is determined in accordance with the following criteria:

1. Damage is minor

This includes violating the integrity of the foundation finishing. The presence of phenomena of this kind does not affect the strength of the foundation and does not reduce its bearing capacity. Eliminating them is easy.

2. The damage is moderate

The occurrence of cracks is associated with the process of subsidence or destruction of the base. Before starting work, it is necessary to differentiate the nature of the cracks. Their horizontal arrangement poses less danger compared to vertical or zigzag

In addition, it is important to find out what the nature of the process of foundation subsidence is. That is, this phenomenon is temporary or progressive. Average damage

Average damage

To clarify this circumstance, beacons are used. Plain paper can be used as them, but there is a risk of it getting wet. The use of plaster plasters is recommended. The simplest method involves applying a small amount of putty to the surface. Then, using a spatula, a mark is made in the form of a straight line. Even a slight shift of the tested surface will be noticed. In addition, when using this method, you can find out at what speed the destruction process occurs.

Temporary subsidence will not be detected by beacons. In this case, most likely, some shift of the soil located under the foundation occurred, it was fixed in a certain position and the probability of further movement is low. Therefore, to eliminate defects, it is sufficient to carry out routine repairs.

When lighthouses are destroyed, it can be argued that the destruction process is progressing. Sealing cracks will not give the required effect, since the deformation is close to catastrophic.

3. The damage is catastrophic.

The presence of defects of this kind can cause destruction of the structure. Timely work to strengthen the foundation will prevent extremely negative consequences from occurring. However, in practice there are situations in which this opportunity is missed.

The choice of technology depends on the type of foundation. In this case, each specific case considers its strengthening or replacement.

4. It is not possible to eliminate deformations

The condition of the foundation is so poor that repairs are impractical. In such situations, the most correct solution is to demolish the building. From an economic point of view, dismantling a house is much cheaper and simpler than measures to strengthen the foundation. The construction of a new cottage on the site of the previous one in accordance with building codes and regulations will allow you to have comfortable and safe housing.

Sometimes the only right solution is to demolish the building

Reasons for replacing the foundation

Beds lying in the ground deteriorate over time under the influence of dampness. Freezing in winter, in spring they thaw, swell and begin to crack and rot. After several decades, in such conditions, the logs become completely unusable. There are several reasons for the destruction of the old foundation under the house:

too much load;
errors in calculations for bed depth;
the foundation under the building has rotted from age.
unsuccessful reconstruction, which led to an increase in the weight of the structure;
improper foundation laying;
freezing of the soil, which caused cracking of logs.

Restoration of the foundation under a wooden house must be carried out immediately after defects have been discovered. Rotting of the beds leads to destruction of the base. After this, the structure begins to settle to one side. Failure to distribute the weight of a building causes it to collapse. Living in a dilapidated house is unsafe.

Preparatory work

The preparatory work stage occupies an important place in the process of building a house. First of all, it is necessary to clear the area of construction debris, cut down excess trees and uproot stumps, remove dry grass

Preliminary zoning of the site will allow you to effectively use every corner during operation. It is best to level the surrounding area before starting construction work and laying the foundation. This will not only give the site an attractive appearance, but will greatly facilitate construction work at all stages. The terrain with large differences requires stepwise leveling of the territory.

Next, the exact location of the house is determined and the foundation is marked. To do this, pegs are installed in all corners of the future building. If the house is a standard rectangular shape, the result should be a figure with perfectly equal angles of 90°. If the angle is not maintained, it is necessary to achieve this result by moving the limit cord in one direction or another.

Along the future walls, at the same distance from each other, pegs are also installed and a rope or cord is pulled between them. The diagonals drawn between the corners of the building must be exactly equal to each other.

An example of checking angles in markings - if the diagonals are equal, then all angles are 90°Source homeframe.ru

When marking for a strip foundation, it is necessary to retreat from the walls of the house at a distance equal to the width of the foundation. Most often this figure is no more than 20 cm.

You can dig a trench either by hand or using specialized equipment. It is formed at least 20 cm below the freezing point of the ground, characteristic of the area in winter. It is necessary to dig a trench strictly following the markings and forming a flat bottom.

Dismantling the old base and installing a new one

Replacing Lower Timbers and Repairing the Foundation
After raising an old house, it may be necessary to replace not only the crowns, but also the foundation. The old frame is disassembled using a jackhammer, hammer drill, crowbar, or sledgehammer. To dismantle a powerful foundation, construction equipment will be required. The waste generated by raising the house and replacing the foundation is left behind. They will come in handy when pouring a new foundation.

Features of dismantling different types of foundation:

Dismantling of the belt begins with an assessment of the complexity and volume of work. A small one can be disassembled with a handy tool. For fittings you should use a grinder. Large structures require special mechanisms and equipment.
Dismantling a precast concrete base is not particularly difficult. The joints between the blocks are broken off with a jackhammer. The mounting loops are brought to a vertical position. Using construction equipment, FBS blocks are pulled out, loaded onto a vehicle, and taken away. Reinforced concrete blocks are a durable material. It is possible to reuse them at less critical facilities.
The top of the destroyed pile base is cut off. If the damage is severe, reinstallation will be required.
The monolithic slab is destroyed in the same way as the strip base. If necessary, part of the base is used or expanded to change the area.
Other types of bases - rubble, columnar, can be disassembled with improvised tools using an angle grinder, a jackhammer, a sledgehammer.
The destroyed screw foundation is cut to a whole part and built up with a metal pipe.

It is natural that dismantling work is the most labor-intensive. They require responsible decisions and compliance with safety standards.

You can dismantle the foundation using hand tools or an excavator.
Methods for destroying the foundation:

hand tools;
excavator, heavy equipment;
chemicals;
explosion;
ultrasound;
hydrocline.

In private housing construction, the first 2 methods are most often used. When dismantling, the main thing is to correctly calculate your strength. In some cases, hiring a professional team is more profitable than doing it yourself.

Stages of installing a new foundation:

After removing the foundation, a trench is formed for a new support. When the old foundation is deep, the sand cushion is renewed - it is added, spilled with water, and compacted. In the case of a shallow foundation, the trench is deepened by 20 cm and a shock-absorbing cushion is also added.
Removable or permanent formwork is installed in the trench. Places for installing jacks are bypassed. Subsequently, the technological holes are filled with bricks.
Waterproofing and a reinforcing belt are placed in the formwork. The lattice in it is welded or knitted with wire. The edges of the reinforcement must be spaced at least 50 mm from the outer layer of the foundation to prevent premature corrosion.
In the corners, the reinforcement cage should be bent and not welded. These are the most stressed parts of the foundation.
The prepared formwork is poured with concrete in 1 time or at least 1 shift.
After the concrete has hardened, the logs are replaced. Using the tapping method, rotten areas are identified and cut down. Logs are replaced until they are well preserved.

When installing, be sure to use hydro-thermal insulation. This will extend the life of the walls and foundation. With good care, the log house will last another 30-40 years before repair.

How to choose a method of raising a house?

To raise a log house correctly, you need to consider the following factors:

weight of the building;
the length of the walls and the overall dimensions of the house;
type of building (frame, timber);
the duration of operation of the old house, the condition of its foundation;
soil structure under the foundation;
type of house foundation, materials used (stone, wood, concrete);
the purpose of raising the building.

If the entire foundation is affected, then it is necessary to raise the house completely. If you can get by with replacing only one part, then there are ways to partially raise it.

Builders have the following methods at their disposal to lift the structure:

using a crane (used if the house from the log house needs to be moved to another location);
using ropes that move under the structure (the method is optimal for light-weight and small-sized structures);
using a jack (a universal method recommended for different types and dimensions of the building).

How to determine the lift height?

In order to easily and accurately control the step height when lifting the corners of a building, it is necessary to install a rail with a pre-marked mark. It also needs to be moved to the corner of the building from the log house. When the house begins to rise, the mutual movement of the two marks will indicate the step height.

The jack rod is not suitable for measuring the lifting height. It gives inaccurate readings due to possible subsidence under the pressure of the structure. When lifting, it is necessary to control the position of the mechanism. If even the slightest deviation is noticed, work must be stopped and corrected.

What houses can be raised and why do it?

In a wooden house, the lower logs usually need to be replaced due to rotting.
A feature of the operation of wooden log structures and country houses made of timber is the periodic repair of the lower part of the building. Over the course of many years of operation, the lower crowns fail and rot. Periodic replacement of the first rows is beneficial for hardwood buildings. Oak and larch can stand for centuries and only a rotten foundation will threaten to collapse.

Also, jacking is a necessary condition for replacing a worn-out foundation, moving a wooden building, and installing it on piles.

Only one-story buildings made of logs, timber or frame structures are allowed to be lifted with a jack for repairs.

It is recommended to replace the lower crowns in increments of 15-20 years. Modern buildings are more susceptible to rotting due to poor ecology and insufficient preparation of the forest during construction.

Carrying out calculations

Before replacing the foundation of a wooden house, you will need to make accurate calculations. Before renovating a country house, it is necessary to measure the outer perimeter of the building. This will be required in order to calculate the amount of concrete solution that will need to be prepared if the decision is made to replace the foundation using a strip type foundation. The volume is calculated by multiplying the length of the foundation by its width and height. If you know exactly how much sand, crushed stone and cement is needed to fill 1 m3, then knowing the total volume, it will not be difficult to calculate how much building materials should be prepared.

Without a blind area, the new foundation will not last long, so calculations regarding the construction of this element should also be made. The concrete protection layer around the entire perimeter of the building must be at least 10 cm, but it will also be necessary to lay a metal reinforcing mesh and a sand and gravel cushion, which should also be taken into account when making calculations.

If the old foundation is being replaced with screw piles, then in this case it is also necessary to calculate in advance the amount of material used. When making such a foundation, you will need to choose the correct length of supports. Piles can be purchased from specialized trade organizations. The most popular products are with lengths from 1650 to 7000 mm.

You should also correctly determine the load on the base. As a rule, such repairs are carried out by raising the house and replacing the foundation, so you need to be 100 percent sure that the new foundation will fully cope with the load. For such purposes, the following models of screw piles can be used:

SVS-57 – permitted load up to 800 kg per element.
SBC-76 - used for the construction of powerful foundations, with a load of up to 3,000 kg per support.
SVS-89 – up to 5,000 kg.
SVS-108 - up to 9,000 kg.
SVS-133 – up to 14,000 kg.

Knowing the approximate load, piles of a certain model are selected, but in any case, the number of such elements cannot be less than 4 pieces. In order for the base to cope well with loads, including wind, after replacement, it is necessary to use products with a safety margin.

How to replace completely?

If the old foundation has subsided greatly and can no longer cope with its functions, it must be completely replaced with a new one.

Methods

Below are several ways to reconstruct foundations.

Cosmetic. This method does not require large financial expenditures, therefore it is the most affordable. It involves replacing a damaged or rotten part of the foundation with a wooden element. However, this method is not suitable for replacing a full-fledged base.

With the dismantling of the walls. This is a very labor-intensive process, since you will have to completely dismantle the walls. However, after this it will be easy to completely replace the slab foundation.
With dismantling the base. This option involves dismantling the lower crown of the building in order to fully and efficiently repair or completely change the foundation of a wooden house.

Selecting a base

To replace the foundation, the same material from which the old foundation is made is used. For example, for a concrete foundation you will need concrete and reinforcement.