The base of a wooden house exhausts its service life faster than the frame itself. This is due to the fact that the platform constantly interacts with soil moisture, does not have underground ventilation, or was not sufficiently protected during the construction process. In addition, it is worth taking into account the weight of the house and the constant shrinkage, which subsides over time, but does not disappear altogether. How to replace the foundation under a wooden house yourself? This is discussed below.
Preparing the base and solving each type of defect
First, a thorough visual inspection is required. An inspection is carried out on all surfaces, external and internal. Armed with a powerful flashlight, you should identify defects in the basement - replacing the foundation, complete or partial, does not bypass the cellar.
This applies to monolithic tape. The slab and piles require repair or replacement of elements, respectively, which is much easier than making a new fill. So, what can be revealed as a result of the inspection:
- Cracks: small, fracture, longitudinal. The former are eliminated by expanding the space and pouring a liquid solution inside. The second requires replacement of the area, the third indicates delamination of concrete, which is also fraught with destruction.
- Oversaturation with moisture. This will be indicated by moss growth and a large number of concrete crumbs. The undestroyed monolith is cleaned, then formwork is arranged and poured according to technology.
- Exposure of reinforcement. Reinforcement is required by gating and inserting a new rod.
- Fragments of pieces of concrete. Talks about the aging of the platform.
There are many reasons for the appearance of any type of defect. Aging, uneven shrinkage, poor-quality materials during construction, attached objects without following technology, etc. In rare cases, a simple repair using cement mortar will be sufficient; usually the foundation of a wooden house is replaced in whole or in part.
To eliminate the fundamental causes or completely replace it, the wooden house must be lifted using jacks. They must be placed symmetrically around the entire perimeter. Lifting is carried out by at least two to three workers, observing the strictest safety precautions.
- First, trenches are dug around the perimeter of the entire house, regardless of the location of the destruction. The width of the ditches should not only be suitable for filling, but also for convenient work for the craftsmen. The depth is determined independently; perhaps it will become greater due to voids formed due to uneven subsidence of the foundation.
- Next, strengthen the jacks. Depending on the model, they are screwed in or securely installed on the ground. The object is lifted as follows:
- the height is determined and each mechanism is adjusted symmetrically over the course of several days.
- wooden blocks are installed in open spaces. The walls are supported with logs for safety.
- after complete raising, the foundation is left to dry, promptly covering it from natural precipitation.
- Cleaning the old platform. To avoid unnecessary expenses, it is necessary to completely replace the foundation under a wooden house only in case of obvious damage that threatens the safety of the building.
This happens extremely rarely, so the old base is not pulled out, but serves as a rubble - reinforcing the “filling” of the foundation. It is tapped and the exfoliated pieces are removed. Subsequently, they can also be used to fill trenches before pouring, after crushing them.
- Reinforcement. It should occur somewhat wider, covering the residual foundation and passing through it. Transverse reinforcement can be achieved by using a hammer drill. They drill through holes through the monolith and insert a reinforced rod so that its ends are sufficient to connect with the longitudinal elements.
- The formwork is built, a sand-gravel mixture and crushed debris are poured into the trenches. Filling occurs. It is not always possible to use automatic assistance - this requires free access to the house. Therefore, concrete is laid by hand.
A large amount of work in resolving the issue of how to replace the foundation of a wooden house cannot be done right away. Therefore, the work proceeds with long breaks, allotted for the solidification of the previous section. Owners should take care of their place of temporary residence - replacement or elimination of defects may take months.
When the tape is completely ready, it is tarred, insulated and the house is put in place. Slowly and evenly, the jacks are lowered. If you do this quickly, curved walls, cracks in the cladding and violation of the level will be a pattern.
To warn means to prevent
If we are talking about repairing the foundation after using the house for the prescribed period - up to 50 years, then the question of how to change the foundation of a wooden house is by no means a whim. There is a concept of fatigue for all structural units. However, often owners are faced with the need to change the platform after a short service life. What does this mean:
- An incorrectly chosen foundation taking into account the terrain can lead to detrimental savings.
- Unscrupulous suppliers and low-quality concrete raw materials.
- Handmade.
- Neglect of filling technology.
In order not to wonder about the solution to the question of how to change the foundation under a wooden house for a long time, below is more about preventing destruction due to the described reasons:
- When designing a future facility, using the services of a surveyor is extremely useful. The specialist knows the specifics of the customer’s area. If there are any doubts, he will arrive at the site to assess the condition of the soil and give a detailed answer as to why this or that type of foundation cannot be used.
- It's no secret that the construction market is a vast field of activity for all kinds of scammers. Anyone can pass off their own product as super concrete, but not everyone can distinguish the quality. How to buy what you need?
It’s simple - buy a small batch and “blind” it, for example, into a blind area for a well. If it does not produce visible changes in six months, then replacing the foundation under a wooden house made from this raw material will not take a long time.
- Do not use automatic mixers - from the series of saving money to the detriment. Firstly, you can overstrain yourself, and secondly, you cannot cast the entire volume manually at once, even if you invite Schwarzenegger to do the work.
Thirdly, gradual filling threatens delamination. In addition, the production output complies with the recipe in accordance with GOST and there will be no surprises. The main thing is to choose a reputable supplier.
- It is extremely important to follow concrete pouring technology. It lies not only in the correct design of the formwork, but also in the actions after laying the concrete. It is necessary to carefully expel the air from the thickness, piercing it in all places.
Any foundation may not justify the trust of the home owner, especially for columnar and pile supports, which over time or due to non-compliance with construction technology, begin to bulge or fall on their side. All this naturally leads to changes in the position of a wooden house, the appearance of cracks in the material, and jamming of doors and windows. In some cases, the only solution to the problem is to replace the old foundation with a new foundation of a different type.
As a preface
Replacing the foundation can rightfully be considered a radical measure caused by the need to restore the reliability and safety of the house, as well as to increase its service life. It is advisable to carry out such a solution for wooden buildings, the structure of which, if the base is replaced, can last for many more decades. Of course, you can implement your plans on your own, but if you are not confident in your own abilities, it will be in your best interests to pay money to qualified specialists. In this case, the information presented below will allow you to navigate the issue and control the situation. If you decide to do everything yourself, then this article will serve as good instructions for carrying out repair work.
Preparatory work
You can raise a house without the use of special construction equipment - in our case we will use hydraulic or any other design of jacks capable of developing sufficient force to lift a load weighing 10 tons. If they are not available, you should not think about buying equipment - you can rent it in one of the railway depots.
We will also need a steel scrap, wedges, and a sledgehammer - tools that are mostly needed to dismantle the old foundation. As temporary supports, you can use chocks, massive beams, bricks, as well as boards of different thicknesses, which will act as spacers. The jack must be installed on a strong square base with sides of at least 50 cm. As such a platform, you can use boards and beams knocked into a shield, or any other durable material. In order to evenly transfer the force from the jack rod to the lower crowns of the house, you will need to cut or find a steel plate at least 5 mm thick.
If you have to deal with a columnar foundation with a backfill, then the latter will have to be dismantled before starting work on replacing the base. It is recommended to remove all furniture and other heavy items from the house and dismantle the floors.
The building is lifted using jacks, which are installed on both sides of the building at a distance of 0.5 m from its corners. The jacks are fixed on a specially prepared support platform, which, if necessary, is buried in the ground to give it maximum stability. The house is lifted, if possible, simultaneously from both sides, evenly, no more than 1.5-2 cm at a time. Immediately fix the result obtained with temporary supports.
If strong bends in the lower crowns are noticeable as a result of raising the house, additional jacks are installed. At this stage, it is important to control the process so that the building does not move to the side, because as it rises, its center of gravity changes.
Dismantling the old foundation
When the house is raised to a sufficient height and securely secured to it with temporary supports, they begin to dismantle the old foundation. Rubble and brickwork are broken using a crowbar, chisels and any other convenient tools. Some of the materials that have retained their quality indicators can be used to form a new base.
Construction of a new foundation
In our case, we will consider replacing the columnar base with MZF - an option that is best suited as a foundation for one-story houses. The construction of a new foundation begins with excavation work: a trench is dug, the depth of which must necessarily exceed the depth at which the base of the old foundation was located. The trench is dug in a U-shape - this is necessary to form a frame with reinforcement outlets to combine all sections of the foundation into a single rigid structure. If it is planned to build new structures adjacent to the house, then the trench is dug based on the design data. For example, at this stage it is best to think about the foundation for an extension to the house.
A sand cushion is placed at the bottom of the trench, then a reinforcement frame is knitted, formwork with waterproofing is installed, and a concrete mixture is poured - you can read more about the MZF in this article.
After the time has passed during which the concrete has acquired sufficient strength (about two weeks), boards are laid on the first element of the strip base, on which temporary supports are installed. In turn, temporary supports are dismantled on the opposite side of the house, and the site is developed similarly to the method described above. The same is done with the remaining elements, only straight sections of the trench are dug out for them, and reinforcement is carried out by connecting the existing reinforcement outlets to the frame of the new section of the tape.
At the final stage, the house is lowered onto a new waterproofed foundation, ensuring the uniformity of the process. If necessary, before lowering the house, you can replace the lower crowns.
Sometimes owners of country houses are faced with the problem of foundation subsidence. This occurs as a result of changes in the underlying soil, construction work on the land or in the house itself. For example, adding a second or attic floor increases the load on the foundation, and if it was not designed for such a mass, it will begin to settle. In addition, improper installation of the base and lack of high-quality thermal and waterproofing lead to similar problems.
To avoid the problems listed above, it is important to choose the right materials, install and finish the base. Read which foundation is suitable for a wooden house. For minor damage, cosmetic repairs can be made or the base can be strengthened. But if the structure has already begun to settle, cracks have appeared at the base or the walls are warped, a complete replacement of the foundation under the house is needed. Otherwise the building will soon collapse.
In the article we will find out when it is really necessary to replace the foundation under a wooden house, and when you can get by with some light repairs. Let's look at how to change the foundation of a house with your own hands, if necessary.
Types of foundation damage
- Minor damage includes peeling trim. These defects can be easily noticed and eliminated without problems. They do not affect the load-bearing characteristics of the structure, they simply violate the aesthetics of the appearance;
- Moderate damage includes cracks that appear due to structural failure and ground subsidence. Vertical cracks and cracks in the form of zigzags are considered the most dangerous;
- Severe damage includes a large number of cracks, fractures in the foundation and distortion of the walls of the structure. Then the foundation is strengthened or completely replaced;
- Irremovable deformation mainly occurs in old buildings and foundations. There is nothing left to repair here. It is necessary to completely dismantle the structure and build a new, high-quality wooden house in compliance with modern building codes and regulations.
How to repair cracks in the foundation
Cracks at the very beginning of formation can be easily eliminated. Do not miss the moment and do not delay repairs, as the cracks will grow and increase. Then the damage will develop from moderate to severe. To determine the degree of danger of cracks, the rate of subsidence and the nature of destruction of the foundation, beacons are made.
Apply a little putty to a clean, dry foundation wall, use a spatula to draw a straight line and make a mark up to 5 mm thick. Such a beacon will break with any movement of the surface. Instead of putty, plaster plasters or plain paper are also used. But if the paper gets wet, it will no longer provide reliable results.
If the subsidence is temporary and does not pose a threat, the mark remains motionless. This means that the foundation has moved along with the soil and taken its place. In this case, cosmetic repairs of the cracks can be carried out. To eliminate the defect, the crack is widened, cleaned and sealed with a primer. The resulting seam is secured with cement.
Strengthening and strengthening the foundation
Strengthening the structure is used if there is deformation, but the soil is stable. In addition, the foundation needs to be strengthened if it is planned to add another floor. Strengthening will help the foundation cope and redistribute the increased load. Then the structure will not collapse and settle. Strengthening includes the following actions:
- A trench is made along the perimeter of the base. The surface is cleaned of soil, dirt, debris and dust;
- Drill holes whose diameter should be 1 mm larger than the reinforcement. Reinforcement is hammered into the holes;
- They make a reinforced belt. The reinforcement is welded to the installed pieces in several places, and secured with wire in the rest;
- The formwork is installed and the concrete mixture is poured. After it hardens, the formwork is removed. The structure is then left to dry for another two to three weeks. While drying, cover the surface with film and periodically water it with water.
After installation, waterproofing and a drainage system are made. To do this, along the perimeter of the foundation in the interval of 70-100 centimeters, you need to dig a trench 20-30 centimeters wide. The depth of the trench should not be lower than the concrete pouring level. Geotextiles are placed at the bottom with an overlap on the walls. Gravel is poured on top and a drainage pipe is installed. The angle of inclination of the pipe is 5 mm per 1 m.
The pipe is covered with gravel on top, the protruding edges of the geotextile are wrapped and compacted with earth. The drainage pipe will subsequently collect water and drain it away from the house into a hole or a special well. To enhance waterproofing, you can cover the outer walls of the foundation with protective solutions, plaster, bitumen mastic or primer and liquid rubber.
Waterproofing can be done before installing the foundation. To do this, roofing material is laid at the bottom of the pit and formwork, and the joints between the materials are coated with bitumen mastic. High-quality waterproofing will prevent the appearance of cracks and distortion of the walls. In addition, without proper protection, the basement and first floor will be cold and damp.
At the end of the work, blind areas are made around the house and foundation to drain water from the building. They will prevent flooding of the basement and building. The blind area is a horizontal strip 60-120 centimeters wide, which runs along the perimeter of the house at a slight slope. The path is made of concrete, crushed stone, paving slabs or stone paving stones.
Partial and complete foundation replacement
Replacement of the foundation is resorted to in case of serious defects and destruction of the structure. In case of partial replacement and cosmetic repairs, part of the structure is dismantled, the deformed element is removed and a new one is inserted. This dismantling can be done independently, but it is not suitable for every type of base. For example, a reinforced concrete strip foundation or a monolithic slab cannot be partially disassembled.
Partial dismantling also requires lifting the house and using special equipment. Therefore, the cost of work will not decrease significantly compared to complete dismantling of the foundation. At the same time, partial replacement reduces the strength and reduces the service life of the base. In addition, it violates the integrity of the structure. Therefore, experts recommend resorting to the method of completely replacing the foundation.
Complete replacement of the base is a complex job that is difficult to do on your own. It includes raising and lowering the house, dismantling the old one and installing a new foundation. Let's look at how to properly raise a structure and how to replace your foundation under a wooden house.
Technology for raising a wooden house
To lift a house made of timber or logs, you will need at least four jacks with a lifting capacity of 10 tons each. Before starting work, check and evaluate the corners of the building. It is important that the log house does not fall apart when moving. Window and door frames are removed from the house, furniture and other items are pulled out. It is important to leave the room empty. To prevent damage to the roof, the chimney is separated from the ceilings.
A trench is made around the house to simplify access to the foundation. Jacks are installed along the long walls of the house at a distance of 0.5 meters from the corners of the building. A solid platform with parameters of 50x50 centimeters is made for each jack. The bases can be recessed to prevent equipment from slipping.
Temporary supports are installed in the corners of the house and where walls intersect. The materials used are timber, logs or brick. The log house is lifted simultaneously with support on the lower crown of logs. To prevent the lower crown from bending, it is tightened with a steel hoop. Or, when lifting at the bending point, use another jack.
The first rise should not exceed two centimeters. The structure is installed on temporary supports, then the house is raised another 1.5-2 centimeters. Thus, the frame is gradually raised to 10-15 centimeters and securely fixed on temporary supports.
How to dismantle the old and install a new foundation
To dismantle a foundation made of cement mortar or rubble materials, wooden wedges are driven into the foundation seams. To work, you will need a hammer drill, sledgehammer, crowbar, hammers and other tools. The structure must be dismantled down to the ground.
After dismantling the old foundation, they begin to install a new one. The space is cleared, a bed of gravel and sand is made, formwork and reinforced lattice are installed. The formwork is poured with concrete and waterproofing material is laid on top in several layers. Roofing felt is good for this. During work, make sure there are niches for jacks to lower the house safely.
The log house is lowered smoothly and gradually also by 1.5-2 centimeters. After this, the foundation is finished, which includes the installation of waterproofing and insulation, cladding, drainage and blind areas. Niches for jacks are sealed with bricks.
Replacing the old foundation, raising and lowering the house, and installing a new foundation is a labor-intensive and dangerous process. It is important to carry out high-quality work and follow safety precautions. To get a reliable and solid foundation and avoid problems during construction work, contact professionals!
The craftsmen of the MariSrub company will quickly and efficiently replace the foundation, install a new foundation for a wooden house, select materials and carry out finishing. We carry out waterproofing and insulation, organize a drainage and blind area system. As a result, the foundation will last a long time!
You can determine whether a foundation needs repairs by taking just one look at it. The fact that the days of the foundation of the house are already numbered is indicated by the skew of the building, cracks on the walls and subsidence of the house. It is impossible to insure a building against such deformations, because over time the foundation materials deteriorate. Therefore, one day the time comes when the owners of a wooden house have to decide what type of repair to do - partial or complete.
Conditions for partial and major repairs
In order to find out the extent of damage to the foundation and determine the necessary measures to restore it, you need to carefully study the current state of the foundation and identify characteristic defects that may affect the strength and integrity of the building or its individual elements.
If cracks appear on the foundation, then you need to think about the need to repair it.
The foundation is restored in fragments if it has sunk lower but has not begun to collapse. Complete repairs are resorted to when cracks and other damage are detected.
The decision on what basis to replace a completely damaged structure is made taking into account the type of soil, the terrain and the type of foundation originally created.
If the foundation of the house has sunk into the ground, it’s time to repair it
With a strip base, they often proceed as follows: the destroyed areas are dismantled and the structure is reinforced along the entire perimeter. In case of serious destruction of the foundation strip, it is decided to completely replace it.
If there are serious defects in the strip foundation of a house, it makes sense to think about its complete replacement.
Repair of a columnar foundation is almost always carried out completely: all the old supports of the building are replaced with new ones. To do this, the house is raised to the height of the pillars using jacks. New reliable supports are fixed on reinforced concrete “pillows”.
The columnar foundation is most often completely replaced with a new one
A foundation made of wood, which has already been slightly damaged by fungus, is usually replaced with a strip or columnar structure. To do this, the building is raised to a certain level and concrete blocks or bricks are placed under it.
Strengthening the foundation of a wooden house
When repairing the foundation, it makes sense to immediately strengthen it. This can be done if you are confident in the stability of the soil, which is below the foundation level of your house. Strengthening the structure under the building may also be required in the case where it is planned to add another floor to the house, but there is a suspicion that the previously installed foundation will not withstand the increased load.
You can strengthen the foundation in two ways, depending on the load it has to withstand.
Instructions for strengthening the strip structure
To make the foundation more durable, perform the following work:
- A trench is dug along the perimeter of the base. The hole must be wide, otherwise it will be inconvenient to work. In addition, we must take into account that the new foundation will become stronger.
- The soil is removed from the excavated foundation. To do this, use a metal brush.
The trench must be wide enough to make it comfortable to work in.
- Holes are made in the old base with a drill. It is important that their diameter exceeds the thickness of the purchased reinforcing bars by no more than 1 mm. In this case, the metal elements will be installed securely and without gaps.
- Reinforcement rods are inserted into the drilled holes using a hammer. They will help connect the new foundation to the old one.
Reinforcing bars are driven into the drilled holes, to which the vertical grid is attached.
- Further metal elements are welded to the hammered rods, forming a reinforced belt. It is better to solder the reinforcement with already installed rods only in a few places. For the most part, it is wiser to tie metal elements with wire to avoid deformation of the reinforcing belt during pouring and hardening of concrete.
The reinforcement cage will firmly connect the old foundation with the reinforcing concrete structure
- The formwork is installed and filled with concrete. After waiting for the solution to harden, the structure of the boards is dismantled. The new foundation is not touched for several days so that it becomes even stronger.
Formwork is installed around the reinforcement cage and concrete is poured into it. After the reinforcing layer has hardened, the formwork is removed
- The created base is covered with waterproofing material. An asphalt strip is created around the foundation at an angle.
Thanks to the reinforcement, the weight of a wooden building is distributed over a larger area. This method allows you to stop subsidence and destruction of the house.
Video: how to strengthen a strip foundation
Replacing the foundation under a timber building
The method for replacing the base depends on its type.
Replacement of strip foundation
Overhaul of the base in the form of a tape is carried out in stages:
- In order to reduce pressure on the foundation, furniture is removed from the house, floors are dismantled, and the stove is dismantled. Only heating equipment located on a separate concrete platform is not subject to dismantling.
- The building is raised slightly. If the house is small, then its level in relation to the ground is changed using a kind of lever for lifting weights - a beam measuring 8x8 cm, placed at the corner of the building. A log will serve as a support for it. For heavy construction, it is better to choose thicker lumber. The wooden structure is raised by applying pressure to the timber.
The house is raised on jacks and temporary supports are placed under it.
- A trench is dug around the house or only in areas where the wooden building needs to be raised.
- A jack is placed under the old foundation. There may be several mechanisms for raising a building. The number of jacks is determined by their load capacity and the weight of the house. The mechanisms can only be installed in areas where there is no damage.
- Using a jack, the house is slowly raised to the desired level. It is important that it rises evenly above the ground. Since there is a risk of unsuccessful installation of the jack, it is advisable to play it safe - place wooden wedges between the structure and the base pad.
The house is raised evenly on several jacks. For insurance, wooden blocks are placed under the load-bearing beams.
- The lower crown of the raised wooden structure is tightened with a steel hoop or hammered with strong boards. This technique will protect the overloaded lower beams of the house from damage.
- The house is freed from its former foundation right up to the surface of the earth. If you are not ready to spend a lot on repairing the base, then you can partially disassemble the structure - remove only the damaged areas.
A hammer drill is used to destroy the old foundation.
- A cushion of sand-cement mixture is made under the reconstructed base of the house. Supports made of concrete or bricks are placed at the corners of the building. Instead, you can use piles. By installing supports, the size of which must correspond to the height of the foundation being constructed, in the future the foundation will be able to withstand increased pressure.
- Construct a reinforcing belt necessary to strengthen the base. Elements of a metal structure are connected not by welding, but by wire.
- Formwork is made from boards. The finished structure is filled with concrete mortar.
Formwork with a reinforcing frame inside is reinforced with side supports and filled with concrete
- After 3 days, the concrete hardens, so the formwork is removed, but no further work is carried out yet, waiting for the foundation to strengthen.
- A few days after dismantling the formwork, the new base is covered with a waterproofing sheet, for example, roofing felt.
A few days after the formwork is removed, the foundation is covered with waterproofing material
- The house is lowered, acting as slowly as during the raising of the building. The front side of the base is covered with waterproofing and facing materials. A blind area is made around the house, which will not allow rainwater to seep into the foundation.
Video: how to repair a strip concrete base
Repair of support pillars
To replace a columnar foundation, proceed as follows:
If it is necessary to replace just a few pillars, they act differently: they make tunnels in the area where they are located, and pipes are immersed in them and filled with concrete. Old supports are dismantled after the solution has hardened.
Video: replacing a columnar foundation with your own hands
Converting a rubble or brick foundation into a monolith
Since the brick foundation is characterized by increased fragility, it is more advisable to replace it with a concrete foundation.
To build a concrete foundation in place of a brick or rubble foundation, perform the following steps:
Video: brick foundation repair
Repairing the foundation of a wooden house with your own hands
The wooden foundation is mainly made of pine or larch. A wooden structure always requires complete replacement, since over time it becomes completely covered with fungus and rots. Replacing old elements of such a base with new ones is carried out as follows:
The damaged foundation of a dilapidated wooden house can be put in order. To do this, you need to obtain the necessary knowledge and choose a repair or replacement technology. You can do the reconstruction of the foundation of a house yourself, if you have the desire and at least a little experience in construction work.
Over time, the building may shrink. This occurs due to violations of construction technology, natural aging, geological and climatic conditions. Raising a house and replacing the foundation is a fairly common option for major renovations. There are other ways to restore the integrity of the building's foundation. Before starting work, the main thing is to correctly determine the degree and cause of shrinkage of the building. Sometimes it is necessary to change the entire structure of the foundation under the house.
Foundation replacement and repair methods
The most popular method of replacing a foundation is raising the house on jacks. You may need from 2-4 to 10-12 pieces. Raise the building by installing jacks on both sides of one wall. Lifting diagonally is unacceptable.
In one go they reach a height of 1.5-2 cm, no more. Temporary supports are immediately inserted into the resulting space. Additional jacks are installed in places where the lower edges of the frame deflect.
Another method involves removing a layer of soil under the house, 200-250 mm thick. After this, the wooden crowns are replaced and the foundation of the house is repaired.
Methods that are labor-intensive and require special skills include complete dismantling of the walls for a convenient approach to the foundation. After this, the base structure is repaired or completely replaced. Then the walls are reassembled, replacing rotten and deformed elements.
If the wear is minor, cosmetic repairs may be sufficient. This is the cheapest restoration method.
What type of base to choose
It happens that the old foundation has failed and needs to be completely replaced. Before replacing the foundation under an old wooden house, you need to decide which type of foundation is best suited for the given geological conditions and type of construction.
Types of foundations and their characteristics are presented in the table:
| № | Base type | Properties |
|---|---|---|
| 1 | Tape | It is a monolithic or prefabricated concrete strip that can withstand significant loads. For small wooden buildings, a shallow foundation is sufficient. But if the site is dominated by heterogeneous soil or water-logged soil prone to frost heaving, then you need to choose a different type of foundation. |
| 2 | On screw piles | Screw piles are driven into the ground. They can be combined with a grillage or operated without it. This is an inexpensive type of base that can be quickly installed with your own hands. Suitable for light buildings built in areas with differences in relief, deep levels of ground freezing, and small flooded areas. |
| 3 | On bored piles | Allows you to reduce land work. It consists of wells filled with cement mortar, interconnected by concrete beams or a slab. |
| 4 | On brick, stone, concrete pillars | The pillars are mounted in increments of 1-2 m; installation is required at the points of intersection of walls and in other places with a maximum load-bearing load. Is a reliable support for small light buildings. |
The type of foundation for a wooden house is chosen depending on many factors. If it is difficult to make a decision and calculate all the loads yourself, it is better to turn to professionals who will help you make the right choice.
Foundation replacement
Replacing and repairing a foundation will require some knowledge and patience. In order not to completely destroy the building, you need to do the work slowly, strictly adhering to the technology.
Jacks can be rented from the railway depot; they must be designed to lift loads weighing 10 tons.
Bricks, strong beams and boards can be used as backing elements.
Before raising the house, lighten its weight as much as possible. They dismantle the floors, take out furniture and all household items.
Under the jacks, a base is made in the form of a square of wood with sides measuring 50 x 50 cm.
Calculations
In order for the new foundation to serve as a reliable foundation for the building for a long time, its parameters must be correctly calculated.
When calculating, you need to take into account:
- soil freezing level;
- proximity to underground sources;
- seismic activity;
- relief of the site;
- soil type;
- a lot of housing construction.
The foundation is buried at least 500 mm under load-bearing walls, and at least 400 mm under partitions.
Raising a house with jacks
They make a platform for jacks. Install it slightly deeper into the ground, at a distance of 50 cm from the corners of the building. The jacks are secured to a wooden stand.
Simultaneously, both sides are lifted to a height of no more than 2 cm in one go. Jacks are placed in places where the wood has not lost its strength. Lifting devices cannot be installed in rotten areas.
To properly transfer the load to the logs, it is necessary to provide for the installation of metal plates that perform the function of a gasket.
Immediately place strong backing elements into the resulting gap. Raise all the walls one by one until the desired height is reached. They check the stability of the building; it should not be mowed. Firmly fix the desired level by installing support elements.
Dismantling the old foundation
After raising and securing the wooden house, the foundation is repaired or dismantled. These works are quite easy to do with your own hands; you will need several assistants and simple tools: a crowbar and a sledgehammer.
If you dismantle the old foundation carefully, the remaining intact materials can be used for further construction work.
What you need to know
The degree of shrinkage of a house depends on the type of soil and the level of location of underground sources. If they are close to the surface, you need to provide a drainage system around the perimeter of the house.
If the soil is prone to landslides, it is strengthened. To do this, fill the area around the foundation with a mixture of liquid glass and water or drill small wells and pour resin into them.
If groundwater is close, winter soil heaving will be significantly higher. Freezing groundwater increases in volume and pushes everything in it out of the soil. When melting, the volume of water decreases and shrinkage occurs.
Installation of foundation on screw piles
If you decide to build a new foundation on screw piles, you need to calculate their length and diameter. You should not skimp on material, since the reliability and safety of your home will depend on its quality.
To construct the foundation of a small wooden house you will need 8-12 screw supports.
Step-by-step instruction:
- After raising and securing the house building, I-beams are laid under its load-bearing walls and partitions. They are cut 5-7 cm longer than the estimated length. In the future, they will serve as a grillage.
- In pairs, at a distance of 300-400 mm from the walls, screw piles are screwed in, which are the support for the beams. Make sure that the structures are positioned clearly in level.
- To add strength and protect against corrosion, the pile cavity is filled with concrete mortar.
- A head is placed on the upper edge of the support, and the grillage channel is attached to it.
- Dismantle the old base.
- They carefully lower the house.
The columnar base is mounted using the same technology as the installation of a screw foundation. The only difference is that you need to dig wells for the pillars, which are subsequently filled with concrete or laid out with bricks.
Installation of strip foundation
They prepare the site, remove construction debris, plant root systems, and sweep away dust.
Instructions on how to change the foundation of an old wooden house with your own hands:
- They dig a pit below the freezing level of the soil and below the location of the old foundation. The shape of the trench should be U-shaped so that it is convenient to remove the reinforcing frame and make its bundle.
- Pour sand onto the bottom in a layer of 150 mm. Moisten and compact. Pour a layer of crushed stone and compact it well.
- Metal rods with a cross-section of 12-16 mm are tied into two longitudinal rows connected by vertical jumpers.
- Formwork is made from boards; it will serve as a form for pouring cement mortar.
- Concrete solution is poured. At the same time, openings are provided for installing jacks to lower the building.
- After it has completely hardened, the formwork is dismantled.
- Temporary supports are attached to the poured foundation. Work is beginning to replace the foundation on the other side.
- Openings for jacks are filled with bricks.
- Check the integrity of the lower crowns and floor boards. If there is any damage, the damaged elements need to be repaired. Rotten and damaged areas are cut out and replaced with new ones.
- Work is being carried out to waterproof the foundation and basement of the building.
- Smoothly and carefully lower the house onto the new foundation.
There is another technology, according to which support columns are first poured at the corners of the house, and then, after drying, the house is supported on them and a concrete strip is installed around the entire perimeter. All other stages correspond to the sequence described above.
You can watch the video to see how to restore and raise a house:
Replacing the foundation is a job of increased complexity. You need to realistically assess your strengths and skills in performing construction work. If a mistake is made, workers may be injured or buildings may be destroyed. If you lack strength and knowledge, it is better to hire professionals with experience in this field.
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