Laying a foundation for a wooden house - a step-by-step guide. Technology for constructing a strip foundation Which blocks are better for the foundation of a wooden house

One of the advantages of wooden houses is their light weight relative to brick or concrete buildings. This means that they require a lighter and cheaper foundation. In addition, the need to fill the foundation arises not only during the initial construction, but also during the reconstruction of old wooden houses. In this article we will consider in detail the most popular types of foundations and methods for their repair.

Before proceeding to the description and methods of constructing foundations suitable for wooden houses, it is worth talking about the principles of their selection, based on geodetic data of the site allocated for construction.

  • It is not recommended to rely on numerous tables that are posted on the Internet with average data on soil freezing in different regions and cities. This indicator depends on several factors, such as the thickness of the snow cover, hydrogeological features and soil type. In addition, it may be affected by the presence of an insulated foundation in a house under construction or nearby hot water communications.
  • The most common foundation option for a wooden house is a strip foundation with drilled piles located below the level of seasonal soil freezing. For central Russia and the northwestern part, this parameter ranges from 1.5-2 m. This means that the foundation turns out to be quite massive and expensive. But due to the large safety margin, which is almost 10 times greater than the minimum allowable, it turns out to be very expensive. Therefore, future owners of lightweight wooden buildings (up to 3 floors) are looking for an alternative that is cheaper, but not inferior in strength.

Columnar foundation for a wooden house

Most often, a columnar foundation for a wooden house is made of reinforced concrete. But for small wooden buildings it can be mounted from brick or even wood. The pillars are usually connected by a grillage (reinforced concrete lintel). Sometimes it is replaced with a channel or even a wooden beam.

Advantages of a columnar foundation:

  • high cost. Based on the general estimate for building a house, its share does not exceed 15-20%, while strip houses are almost twice as expensive;
  • simpler and faster to implement;
  • with a properly organized blind area and drainage system around the house, it is resistant to seasonal soil heaving.

Wooden column foundation

  • Very often in villages, old wooden houses have a wooden foundation. And if the log house itself can stand for more than a year in excellent condition, requiring only cosmetic repairs, then its base often needs to be changed. Often, new owners want to preserve the authenticity of such buildings, or the time simply comes to update it with minimal financial costs. Larch is best suited for these purposes, whose strength characteristics are maintained for several decades. But it is also allowed to use oak.
  • Such a foundation consists of wooden pillars with a diameter of 20 cm or more, buried in pits. Sand is poured onto the bottom, and a cross made of the same material is stuffed onto the supports themselves to increase the load-bearing area. When reconstructing, it makes sense to make a concrete pad and lower the pillars into the solution that has not yet hardened so that they adhere to it most firmly.
  • The number of wooden supports depends on the bearing capacity of the soil, the area and weight of the building. But they are always placed in corners and at intersections with load-bearing walls. Along the entire remaining length they are located in increments of no more than 2.5 m.

Advice: to increase service life, the use of modern impregnations is not as effective as the proven method of impregnation with tar. As an alternative, it is possible to use modern oil-based impregnation with the addition of antiseptic components.

DIY reinforced concrete columnar foundation for a wooden house

  • Work begins with preparing the site for construction (this is not only the perimeter of the foundation, but also three meters of indentation on each side for a blind area and the ability for construction equipment to drive up). They consist of removing large debris and relatively leveling the site.
  • Next, markings are made for future pillars. To do this, their location is transferred from the construction plan to the site. First, pegs are hammered into the corners of the building, checking that they are correctly positioned diagonally (it must coincide). A rope is pulled tightly between them, which will become a guide for marking the wall supports around the perimeter. Then, using a tape measure, measure the distance of the load-bearing walls and also mark them with twine. Depending on the design load of the house, the pillars are placed in increments of 1.5 to 2.5 m from each other.
  • The holes for the foundation are dug with reserve, since formwork from boards 5 cm wide will be installed on the sides, and a drainage cushion made of sand or crushed stone will be installed at the bottom. The depth and width of all holes must be the same.

  • In the case where the columnar foundation for a wooden house is made of asbestos pipes, wells for it are dug with a drill with blades of the appropriate diameter.
  • Often they save on the sole by simply filling the bottom with 15-20 cm of sand. This is enough for a light wooden building, such as a barn or a bathhouse. But for the construction of a residential building, it is recommended to follow all the technology. The first layer is dense geotextile, which prevents sand from getting into the ground. Then crushed stone or sand is poured in a layer of 15 cm and compacted or spilled with water. Sometimes experts recommend pouring a concrete pad up to 20 cm thick on top without reinforcement.
  • The formwork is assembled from boards or wooden panels and fastened with self-tapping screws. OSB, moisture-resistant plywood with a thickness of 1 cm or more, is also suitable for these purposes. It will be dismantled upon completion of the work.
  • But there are cases in which the soil characteristics are so dense (for example, clay soils) that they make it possible to do without formwork along the entire height of the support, but only hammer it for the above-ground part. In this option, the walls of the pit are dug out as evenly as possible and the vertical level is checked, then they are covered with roofing felt with overlaps, which will later act as waterproofing.
  • A connected reinforcement frame of 4 vertical rods with a diameter of 10 mm or more is placed in the finished formwork. Both metal and fiberglass are suitable. It should be located at a distance of several cm from the walls. In order for it to stand firmly, concrete is poured to the bottom and reinforcement is immersed in the liquid mixture.
  • The level of filling of all pillars should be the same, regardless of the slope of the area. It takes a week for the concrete solution to fully set.

  • When the formwork is removed, the pillars are coated with a liquid waterproofing compound in two layers. You can wrap them in roofing felt or apply a layer of liquid glass.
  • Next, bury the free space around the pillars. Most often, the soil previously selected from the same place is used for this, but it is better to use crushed stone or OPGS.
  • The time has come to connect all the free-standing pillars into a single foundation structure. For this, a grillage is made. It can be done in several ways, and again, each of them depends on the design load of the future home. Reinforced concrete is considered the most durable. For it, formwork is constructed from three sides, reinforcement is laid and concrete is poured. This is an expensive and time-consuming method, but for a wooden two-story house it is the most acceptable.
  • For a light frame house or a one-story log house, it is quite enough to make a frame from thick timber.

Advice: for the necessary ventilation of the subfloor, which will allow you to preserve the wooden floor joists of the first floor, the distance between the ground and the grillage should not be less than 0.5 m.

Wooden foundation of a house video

Arrangement of a strip foundation for a wooden house

  • The depth of the strip foundation for a wooden house depends on the characteristics of the soil. This parameter is calculated individually for each developer each time.
  • Then the location of the house is determined on the site and its first corner is marked. A peg is driven in at this point. Then the required distance is measured and the second corner is also marked with a peg, and a string is pulled between them. When all 4 corners have been measured, their correct location is checked diagonally and adjusted if necessary. The procedure is repeated under all load-bearing walls of the house.
  • The bottom of the trench being dug must be at the same level, regardless of the slope of the area being built. This is checked using a building level.

  • If you want to save money or because it is impossible to access construction equipment, earthworks are carried out manually.
  • Waterproofing is laid in the dug trench with such a reserve that it is sufficient along the entire height of the blind area. It can be classic roofing felt or any modern rolled material.
  • The basis of the strip foundation for a wooden house will be a sand cushion. The recommended thickness of its layer is 20-25 cm. After backfilling, the sand is leveled and compacted with a vibrating plate or spilled with water from a hose.
  • Then the formwork is put together. Due to the light weight of wooden houses, it is not as wide as for brick ones. The blind area is made of boards, thick plywood or any other durable sheet material. It is most convenient to assemble the shields in advance and place them in ready-made sections in the trench. Pegs are driven in from the outside and fastened to them. To enhance strength, spacers are installed in increments of 1.5-2 m.
  • As a rule, the formwork is 30 cm higher than ground level at the highest point. Next, the foundation is laid with red brick.
  • It is convenient to use fiberglass rods with a diameter of 0.8-1 cm as reinforcement. They are connected to each other with wire. The reinforcement cage should not reach the walls of the formwork by 2-3 cm.

  • Filling should be done in one stage. You can often find that private developers, in order to save money, mix and pour concrete themselves. The result is a non-monolithic structure with a large number of seams. When the solution is completely poured, it is recommended to tap the formwork to remove air bubbles.

Considering that a light wooden house is being built, work on its construction can begin in 7-10 days.

Repair of the foundation of a wooden house

  • Often the foundation of wooden houses begins to settle, more often this happens with old buildings, but sometimes, due to violations during construction, new houses are also subject to this problem. There may be several reasons - these are natural changes in the physical and mechanical parameters of the soil, and groundwater, which negatively affects the bearing capacity of the soil. It is possible that a pit dug too close to a neighboring house or other extensive excavation work could have led to such disastrous consequences. In any case, the foundation requires immediate repair or replacement to avoid the destruction of the house.
  • Repair of the base of a wooden house can be divided into several types:
    • cosmetic. This is the simplest and cheapest method, which consists in replacing individual rotten areas, which are replaced with elements of the required size. As a rule, this is used for old buildings, whose base was immediately laid out from logs without brickwork. But, despite the tempting ease, such work will inevitably compromise the integrity of the house. Therefore, it is not recommended to use it for renovation of residential buildings, but only for small country houses;
    • dismantling all wooden walls. This method will allow for high-quality repairs, but will require a lot of physical effort and financial costs from the performers. It will be necessary to disassemble all the logs step by step, right down to the lower damaged crown. After its complete replacement, the walls are erected again;
    • replacing logs using a jack. This is the most popular method, which allows you to perform work quickly and efficiently. With their help, it is easy to repair the foundation and level the house itself without dismantling the walls.

  • Depending on the chosen method of replacing the foundation of a wooden house, various tools will be required. So, if only cosmetic repairs are to be made, then it is quite possible to get by with a hacksaw, a sledgehammer and a chisel. But when dismantling the walls, you will have to dismantle the roof, which means you need to stock up on a whole list of hand and power tools.
  • You also need to take care in advance about temporary supports when repairing the foundation. When lifting a house with jacks, their number will depend on the length of the walls. So, for a small country house, 2 jacks per wall are quite enough.
  • The foundation is the basis of the house, its reliability and durability. Therefore, if the need arises to replace it, everything must be carefully thought through and prepared so that in the future it will serve as long as possible without additional repairs. First, the type of foundation is determined, whether it will be columnar, bored, strip or pile-screw.
  • The most popular for wooden houses in dachas and gardens is a columnar foundation. Despite the apparent fragility of the structure and simplicity of execution, it will become a reliable support for many decades for a frame, log or timber house.

DIY foundation for an old wooden house

  • It is most convenient to pour a foundation for an old wooden house when the distance between the ground and the first row of a wooden frame allows a person to easily fit in a lying position. A shallow trench is dug outside along the perimeter of the house (about the size of a spade bayonet); its width should correspond to the size of the temporary supports. Strong wooden posts or concrete blocks are suitable for them.

  • After installing the blocks, a trench for the foundation is dug under the house and on the inside. A sand cushion is poured onto the bottom in a layer of 15-20 cm and, if possible, compacted. Next they make the formwork, just like when building a new house. That is, shields are made from boards and nailed to wedges driven at a distance of 1.5-2 m from each other. If the height of the subfloor allows, then it is advisable to make several spacers from wooden blocks driven into the ground at an angle to the formwork.

Advice: if a strip foundation is poured under an old wooden house that does not have a basement or subfloor, then a small hole should be left on one of the outer sides so that later it will be possible to climb inside to dismantle the blind area and waterproof the base. In the future, it can be decorated by making the door insulated with penoplex and covering it with base cladding material.

  • For reinforcement, it is best to buy special reinforcing bars, whose diameter will correspond to the calculated load data of the house. But any scraps of thick wire, steel gratings, or suitable-sized scraps of old fittings will do.

  • Concrete is poured from the outside. It is convenient if the concrete truck is equipped with a special hose. Otherwise, the solution is poured in buckets or using a construction wheelbarrow. Level it immediately, stirring with a shovel.
  • After the composition has hardened, the temporary supports are dismantled. In their place, in some cases, formwork is installed and similarly filled with concrete mortar. Sometimes these places are left, covered and then insulated with facing material along with the entire base.

Replacing the foundation of an old wooden house with screw piles

  • The method of reconstructing the foundation under an old wooden house using screw piles is very popular. This is facilitated by quick turnaround times and the ability to immediately continue operating the building, without having to wait until the concrete solution gains strength. In addition, it does not require large-scale excavation work, construction of blind areas and waterproofing, which is especially important when working in such cramped conditions.
  • Screw piles are hollow tubes made of durable steel with helical blades and a sharp tip. They are screwed directly under the load-bearing walls of the house to the required depth.
  • To make their twisting possible, you will need to alternately lift the sides and corners of the house with jacks. For greater strength, concrete is poured inside the screw pile, filling the entire cavity to the top.

  • If the house is small, for example a wooden country house, then it is enough to tighten the piles only along the outer perimeter in increments of 2.5 m and in the corners.

Advice: There are cheaper screw piles on sale, made in an artisanal way with a welded tip. When reconstructing a house, it is better to avoid them, since the integrity of the structure is insufficient and the likelihood of rust formation is high. The best option is cast copies.

Foundation for a wooden house video

Replacing the foundation of a wooden house using jacks

  • The main value of jacks lies in the uniform lifting of the house. This is especially important for working with a log wooden house, since when it is skewed, there is a high probability of the bottom frame bending and further breaking or separation of the logs. Therefore, the golden rule when installing jacks is to look for places where the wood is strongest and has not been rotted.
  • Before lifting, gaskets in the form of steel plates 0.5 cm thick are installed at the points where the jack is connected to the wood. This will allow the force to be evenly transferred during lifting.

  • Then the house is simultaneously raised by all jacks to the required height. Having fixed it, remove all rotten wood and foundation elements that interfere with the repair. Timber or bricks are laid as temporary supports.
  • Now they begin to equip the base, depending on the chosen type. For the belt, they dig a shallow ditch (remove the fertile layer), add a layer of crushed stone or sand and install the formwork.
  • The reinforcement is placed in it and everything is filled with concrete. When it sets, the temporary supports are removed and the house is carefully lowered onto the new foundation. Thus, it turns out to qualitatively repair a section of the foundation that has become unusable.
  • When a wooden house is being built or the foundation of an old one needs to be repaired, the choice of foundation is based on two important factors. The first is geodetic features and the weight of the structure. The second is the price of a foundation for a wooden house. And only after assessing all the nuances will you be able to make the right choice.














The foundation is the foundation of the house. The heavier the house, the more solid the foundation should be. Since a wooden house is relatively light, there may be several options for its foundation. But this does not mean that the choice should be approached carelessly - here it is doubly important to choose the right option, taking into account the complexities of the natural material, because organic matter can begin to deteriorate at the point of exposure to moisture, air and soil three times faster. Plus, the financial issue often comes first. As a result, which foundation is best for a wooden house has to be chosen based on the landscape of the site and the available budget.

The foundation for a wooden house can be made of different materials

Types of foundations that can be used for a house

There are only four main types of foundations and almost all of them can be used to build a wooden house. Since the weight of a wooden house is usually relatively small, the main choice is made based on the characteristics of the soil and the financial issue.

Concrete strip

The strip foundation for a wooden house is one of the most beloved by our compatriots and, perhaps, the most reliable. Its width is the same around the entire perimeter, and leaves 50 cm “plus” to the width of the walls.

It is divided into three subspecies: deep, shallow and non-buried. Deeply buried is designed for “difficult” conditions: in the presence of basement premises (garage, basement), multi-story buildings, heaving soil on the site, large freezing depth. It is designed to hold the building stably even when weather conditions change and the ground moves. It is believed that such a base should be buried at least 200 mm lower than the freezing depth (the values ​​for a certain latitude are known and can be easily recognized from the reference book).

Classic strip foundation for a wooden house

If the soil allows, then for the construction of low-rise wooden houses, a shallow foundation is most often used - it is buried to a depth of about 500-700 mm, which, although less than the freezing depth, is quite enough to support a light-weight house. And, of course, it will cost much less than a deep-seated belt one.

In the case of very light buildings (sheds or utility rooms), you can get by with a shallow foundation. This type of foundation can be made of concrete or brick, stone or blocks.

A relative novelty on the construction market is a foundation made of permanent formwork, which consists of ready-made elements that are combined into blocks, and then concrete is poured into them.

A non-buried foundation is essentially a base on a sand cushion

The production time for any strip foundation is about a month, since after pouring it is necessary to wait a certain time until the concrete reaches its design strength.

Slab concrete monolithic

A slab foundation is simply a large concrete slab. This is a good choice for heaving and mobile soils, since the slab base has the ability to move along with the soil when it shifts. You should not think that the house will move around the site - moving soil means displacements of a couple of centimeters per year, but even such values ​​can cause cracks to appear on the walls when using a strip base.

Making a monolithic foundation cannot be called an easy task - in terms of installation time, they are approximately equal to those of a strip foundation. It also requires clearing the site, deepening it, pouring concrete - and, given the harsh conditions, some experts ask for a grade no lower than M400, in principle, given the cost, you can get by with M150, but these are very minimal requirements. A big problem is also the uniform drying of the slab surface (a large area dries poorly, and it will take a long time to dry completely and begin the next stage of work). It will also be necessary to arrange a sand cushion for cement, a blind area on the finished foundation and waterproofing (as a means of protecting concrete from water - film or special compounds).

Ready slab foundation

Pile: steel screw or concrete driven

A pile foundation for a wooden house is a good choice for a site where there are problems with groundwater, and, in addition, the site itself has unevenness, the leveling of which will require significant effort. Proper calculation of the pile field makes such a foundation reliable and stable. In addition, the cost of a pile foundation is significantly lower than a concrete one, and installation is carried out in one day.

The main disadvantage is that with a pile foundation it will not be possible to create a basement or ground floor in the house. Auxiliary buildings on the same foundation as the piles are undesirable - due to the elevation above the ground. Entering a garage, for example, will not be very practical.

Video description

What are the pros and cons of a pile screw foundation? Is it possible to make a high-quality foundation for little money? Watch in this video:

The installation technology itself is quite simple - a drill is taken, the piles are screwed into the ground, below the freezing level, then filled with concrete. If the piles are concrete, then they are driven with a piledriver to the required depth. Immediately after installation of the pile field, you can begin the next stages of construction.

On our website you can get acquainted with the most popular projects of wooden houses from construction companies presented at the exhibition of houses “Low-Rise Country”.

Columnar: brick, block or concrete

Columnar foundations do exist as a separate type of foundation, but it must be noted right away that they cannot be used for the construction of a residential building.

In general, this is an inexpensive and easily erected foundation, which is a hole 50-70 cm deep, at the bottom of which sand and crushed stone cushions are laid, on top of which the pillar itself is built.

The methods for making “pillars” are completely different - bricks, pouring concrete into formwork, asbestos pipes, ready-made blocks. As with any technology that uses concrete, care should be taken to ensure that sand cushions, formwork and reinforcement are installed when making the bases on site.

The distance between the pillars, regardless of unevenness, should not be more than 1.5-2 m; in addition, pillars must be present at the corners of the building and at the intersections and junctions of walls. Columnar foundations are installed almost everywhere, with the exception of floating areas (areas completely unsuitable for construction), using special device technologies - for example, TISE, where the pillars “expand” at the bottom, giving additional strength to the structure. But even when using this technology, you should also take care of additional insulation and waterproofing, and this work must be performed together with the construction of the walls (that is, the places where the pillars adjoin the walls are processed together).

Considering that columnar foundations are suitable exclusively for ultra-light buildings - gazebos and the like, it can be argued that they do not have many disadvantages. But in any case, such foundations are not suitable for complex soils - loose, with a large freezing depth.

No specialist would use such a foundation for a residential building. In addition, it is strongly recommended not to experiment with such a foundation when building a house through the efforts of “gray” construction crews, who do not care what they build, because they do not bear warranty obligations.

If the soil is even slightly mobile or susceptible to heaving (and usually it is), then eliminating the consequences will cost a pretty penny.

Incorrect use of a columnar foundation - the work will have to be redone

On our website you can find contacts of construction companies that offer house design services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Video description

What kind of work will have to be done if the columnar base is squeezed out by frost heaving, see in the video:

Pros and cons of a pile-screw foundation

After considering the main types of foundation, it would seem that choosing a pile-screw foundation is the most optimal, however, there are both advantages and disadvantages.

Advantages:

    Installation speed - just determine the freezing depth and order a drill, and literally within a day the piles will be installed;

    Simple process - does not require additional time and money;

    Versatility - good performance of this type of foundation was obtained on all types of soil, including peat;

There are only two disadvantages, but they must be taken into account:

    Calculation complexity - the heavier the building and the more complex its shape, the more careful calculations will be required;

    If a geological examination of the soil was not carried out before installing the pile field, then in the case of loose or peaty soil, a certain percentage of subsidence of the structure is possible - unfortunately, often uneven.

Pile field for a wooden house

Screw foundation with channel or beam strapping

If you choose a screw foundation for a wooden house, then after installation you need to decide on the type of strapping, which is divided into beam and channel strapping.

Bonding is a method of stabilizing a foundation of piles after they have already been installed and concreted.

Timber strapping looks good under wooden buildings - bathhouses and houses. The main requirement is that all piles be cut to the same height, but then the frame can play the role of the lower crown of your log house, taking into account that the floor joists are located quite high (at least 2-3 crowns higher).

A channel (rolled metal in the shape of the letter “P”, if viewed from the side) is used in cases where the alignment of all piles is difficult (for example, there are too many of them), and, in addition, the channel supports heavier structures. It is laid around the entire perimeter and along load-bearing partitions. It will be a little more expensive, because with this technology you will need to order special equipment. The channel can be laid on top of the piles (a more common option) or between them. It is also worth considering that channel tying must be done immediately after the stage of screwing in the piles in order to avoid changes in their position.

Anti-corrosion treatment is carried out after installation of the harness.

Criteria for choosing a base

The main criteria are, of course, the condition of the soil and the climatic features of the region:

    Freezing depth - the greater it is, the deeper the foundation should lie;

    Material consumption is also an important criterion;

    Aesthetics – the foundation of the house must be combined with the environment and the building itself;

    Position of the house - if possible, you should choose places away from cliffs and ravines;

    Plinth and its use - is the device planned to be installed in the basement of a garage or other ancillary premises? Depending on the answer to this question, you will need to use a certain type of foundation;

Video description

What types of foundation are there? How is the foundation built and how much does it cost? See all this and much more in this issue.

    Dimensions of the house - the larger and heavier the house, the stronger the foundation will be needed;

    The terrain of the site - it is worth assessing in advance the possibilities for leveling the soil; if there are none, then you may need a pile or columnar foundation;

    The soil and its characteristics - the bearing capacity greatly depends on this, and directly - the type of recommended foundation;

    Depth of water – groundwater, if properly neglected, can greatly damage the soil and “undermine” the foundation.

If you do not make slopes and do not take into account groundwater, the ground near the foundation will constantly get wet

Installation stages

Regardless of the choice of base type, it all starts like this:

    First, a geodetic study of the soil is carried out and the results are compared with reference information (how much the soil freezes in this strip, what is the composition of the soil, what is nearby - floating rocks, ravines);

    The type of foundation itself is selected using the information received and the budget;

    Drawings with markings and territory surveying are carried out;

Video description

How marking is done is shown in the following video:

    Soil preparation includes uprooting stumps and trees, clearing the area of ​​debris, and removing the top layer of soil;

    In the case of slab and strip foundations, a pit is dug;

    The foundation work itself (installing a sand cushion, driving and concreting piles, pouring slabs or pillars);

    Auxiliary work (piping, waterproofing, cutting piles, etc.).

The time and cost of work depend on the type of foundation, soil characteristics and area. On average, the time can range from a week or two to install a pile foundation bound with timber, to several months to prepare a slab foundation in difficult conditions.

The main problem with working with large volumes of concrete is long drying times.

Strip foundation for a bathhouse

Often, a strip foundation is the best choice for building a wooden bathhouse. In addition to the reliability of the design, this option can also be considered from an aesthetic point of view - to play on the contrast of materials.

For the construction of a bathhouse, a shallow strip foundation is recommended - it is quite enough to support a structure that is not too heavy. If the soil is heaving and the freezing is deep (over 1.5 m), you will have to opt for a deep strip foundation.

Conclusion

Even knowing what types of foundations exist, stopping at any of them without a geodetic examination of the soil will be a big mistake, fraught with the need to redo the work done in the future. Therefore, it is strongly recommended that when building a house, you contact a competent construction company that will do all the work quickly, and, importantly, once.

You can often find old wooden houses that do not stand on a foundation, since previously the house was installed on wooden supports, which were tarred logs. And of course, over time they collapse, and the foundation has to be changed, and the foundation will need to be laid under an old wooden house. How to do it?

An example of pouring a new foundation for an old wooden house

The time has come, because over time the old foundation or foundations have become unusable. Many people are frightened by this situation, because they think that for this they will have to dismantle the entire structure and then reassemble it. This will not only take a lot of time, but will also be very labor-intensive. We want to reassure you - there is no need to disassemble anything.

It is enough to decide what type of foundation you will put under an old wooden house, and there are several of them:


Reasons for the destruction of the old foundation

If a foundation has already been laid under the house, and it collapses, then there may be several reasons for this:

  • erroneous calculations for depth;
  • the old foundation has eroded over time.

    • The most common reason for the destruction of the foundation of an old wooden house is time. If there were wooden floors under the house, then they can simply rot, causing subsidence and distortion of the structure. Also, the foundation may collapse if the house has been reconstructed, and the specific weight of the structure has increased, and the foundation was not designed for such a load.

    The reason may also be insufficient foundation depth. So, when the soil freezes, and then during spring thawing, the foundation experiences a strong load, which can cause cracks to appear on it.


    There can be many reasons for the destruction of the foundation, and if upon examination of the foundation it turns out that it cannot be repaired, measures must be taken, such as pouring a foundation under an old wooden house.

    Important! You should not waste time, thinking that the house can stand on a destroyed foundation for several more years. Measures must be taken immediately, as complete destruction of the entire old wooden house may occur.

    Foundation replacement

    So, an inspection of the old foundation showed that it was impossible to do without. Where to begin?
    First, to determine what kind of foundation you plan to install in your home. This must be done before you begin work on raising the house and dismantling the old foundation, since the stages of the work will be different.

    Preparation

    The most common way to add foundation to an old house involves using car jacks. If you are not sure that you can handle this work yourself, then it is better to invite specialists. But when deciding to do everything yourself, you will need one assistant. So, you need to follow the following instructions:


    Tape base

    If a foundation has already been laid under the old house, it must be completely dismantled. It is necessary to remove not only the old base, but also the sand cushion under it.


    Making a trench for pouring a strip foundation

    The trench is deepened, depending on the soil, but not less than 30 cm. The soil at the bottom of the trenches is thoroughly compacted and a new sand cushion is filled in. After this, it is produced, which can be made from bars and old boards. Supports are installed on the outside of the formwork to prevent it from falling during concreting.

    The next stage will be tying - it is done using reinforcement with a cross-section of 18 mm and tying wire.

    Will help strengthen the base. Once all the preparatory work is completed, you can begin concreting. The foundation must be poured in one step so that there are no seams. As soon as the concrete is poured to the edge of the formwork, it is leveled with a spatula and given time to set. After the foundation has cooled, it must be covered with cellophane film or pieces of roofing felt and left to dry.


    Scheme for pouring a strip foundation for an old house

    After a few days, you can remove the formwork; in total, the foundation will dry within a month. Often, when pouring the foundation for an old wooden house, it is necessary to replace the two lower crowns, as they usually become unusable. You can prepare logs (preferably leafy wood) while the base is drying.

    Columnar foundation

    If the house is small, then you can pour a columnar foundation; this is a less expensive option. Let's look at how to do it right:


    Interesting: for greater stability and strength of the structure, some craftsmen use steel rods with a cross-section of 50 mm instead of reinforcement, installing it instead of reinforcement strapping. Once the concrete has set, the formwork is removed and the pillars are left to dry. Some owners make a concrete lining of the columnar foundation; this prevents the pillars from skewing in cases where the soil is unstable or with close groundwater.


    As soon as the columnar foundation has reached its final strength, you can build on it.

    Pile foundation

    A new foundation for an old wooden house with application can be an inexpensive and easy-to-implement solution. Piles can withstand heavy loads well and are inexpensive.
    To raise a house in this way you need to follow these steps:


    But a complete replacement of the foundation is not always required; sometimes only a part is destroyed or requires repair, for example, if the old foundation is made of brickwork. In this situation, you can carry out work using. The video shows the process of pouring a pile foundation for an old wooden house.

    Sooner or later, owners of wooden houses are faced with the problem of foundation destruction. There are quite a few reasons for this phenomenon: violation of construction technology, weather phenomena or the ruthless influence of time.

    Regardless of the underlying factors, the result is the same - the house begins to bend, door and window openings become warped, and the possibility of destruction arises. It is noteworthy that the structure itself is in good condition; the foundation usually begins to collapse.

    When faced with an unpleasant situation, you should not immediately think about moving. You can simply pour the foundation for a standing wooden house. This is quite a complex and time-consuming job, but completely doable on your own.

    Causes of destruction

    To create a foundation for a dwelling, concrete or the best blocks for the foundation of a wooden house are usually used. Even a person far from construction knows that concrete is considered an almost eternal material and after many years does not lose its technical characteristics.

    However, this prejudice is not entirely true. Even good and high-quality concrete deteriorates over time, especially if operating conditions are not met or there is a negative influence of external factors. All types of foundations for wooden houses (strip and column) are not immune to destruction.

    The main reasons for this unpleasant and even dangerous phenomenon are:

    • violation of construction technology. If during the process of pouring the concrete base you forgot to install the reinforcing bond, the life of the foundation will be noticeably reduced. Reinforcement, even when the base is destroyed, does not allow individual pieces of the foundation to fall out, maintaining the integrity of the base;
    • groundwater. The seasonal factor plays a role here, when high-lying waters gradually undermine the foundation or wash away the soil. As a result, the concrete cracks and can no longer perform its primary function. Careful selection of a site for building a house or installing drainage systems will help you avoid problems;
    • neglect of waterproofing. Many people believe that if the house has an unused basement, you can refuse waterproofing. This is mistake. Even if there is a clay floor and the groundwater is deep, the concrete base must be insulated. This will help protect the material from destruction in the event of a sewer break or melt water entering the basement;
    • increase in load. A fairly common situation is when an ordinary one-story house begins to grow with additional floors and living quarters. When laying out the foundation, the grade of concrete is selected taking into account the expected loads, and if the design conditions are not met, the foundation begins to crumble.

    Regardless of the reasons that led to the destruction, the foundation needs repair, so it is important to know how to lay the foundation for finished wooden houses with your own hands.

    How to determine technical condition

    Before making a strip foundation for a wooden house, you need to analyze the current state of the existing foundation. This is quite easy to do. It is enough to dig a hole 70–90 cm wide around the entire perimeter of the house to the depth of the foundation. This will help to present the picture in full and choose the optimal method of restoration.

    Recovery methods

    After a preliminary assessment, the type of restoration work is determined. Foundation repair can be partial or complete.

    In the first case, the most problematic areas are identified that need to be replaced with brickwork or concrete. This restoration option is suitable for columnar and strip foundations. If the base can no longer be restored, it is completely dismantled, new formwork is installed and concrete is poured. This is not easy to do, given that the house stands on a foundation. It is important to follow detailed step-by-step instructions when performing work.

    Important! When doing partial repairs, you must proceed with extreme caution so as not to cause more damage to the foundation. It's no secret that partial repairs will cost much less than a complete replacement of the base, so there is no need to aggravate the situation.

    Materials and tools

    Ideally, the foundation for an old wooden house is poured using construction equipment: a crane, an excavator, a concrete mixer truck. However, using special equipment to perform the work significantly increases the cost estimate and is not always possible due to objective circumstances. Houses rarely stand on a vacant lot; they are usually surrounded by outbuildings, beds with crops and fruit trees. To maintain the integrity of the infrastructure, work will have to be done manually.

    For this you will need:

    • Jack.

    Considering that lifting equipment will be installed at every corner of the house, four lifting tools are stocked. To simplify the work process, it is better to use hydraulic jacks, not mechanical ones, with a nominal load capacity of at least 10 tons.

    • Construction tool.

    The old foundation will have to be dismantled, so you need to prepare crowbars and sledgehammers. If your budget allows, you can rent a jackhammer.

    • Supports.

    Pouring a new foundation means that the house will have to be raised. This will require spacer wedges, bars, bricks or metal beams. There are no special requirements here, the main thing is that the temporary supports are strong enough to withstand the load.

    • Wooden shields.

    They will be needed to create formwork for pouring concrete mixture. Considering the specifics of the application, it is better to give preference to moisture-resistant plywood of increased strength.

    • Steel plates.

    The elements are used as a substrate for jacks and the lower crowns of the house to more evenly distribute the load during lifting operations.

    • Fittings.

    Required for foundation reinforcement. To ensure sufficient strength, the diameter of the reinforcement must be at least 12 mm.

    • Concrete mixer.

    If subsequent construction is not expected, it is better to rent equipment. A compact concrete mixer will be needed to mix the concrete mixture: doing such a volume of work manually will be problematic.

    It is quite natural that to pour concrete you will need cement, crushed stone and sand. In addition, it would be useful to immediately purchase waterproofing materials.

    Important! To simplify the lifting of the house, you need to unload the interior spaces as much as possible, freeing them from furniture and household appliances. Professionals recommend removing windows and doors to avoid accidental damage.

    Sequence of work

    The construction of a new foundation is a rather complex process, where the correct implementation of each stage guarantees the integrity and durability of the house as a whole.

    Raising the house

    To do this, the most sagging corner of the building is selected, supports are placed under it and a jack is placed on each side. Lifting the house must be done as carefully as possible, and it is better to do it simultaneously from all sides to avoid distortion of the walls.

    The following rules must be observed:

    • jacks are placed as close to the foundation as possible to reduce the load on the lever;
    • every 10–15 mm of rise, supports are placed under the wall, which serve as insurance in case the jack falls off;
    • During the lifting process, you need to constantly monitor the stability and correct position of the jack.

    When the house rises to the desired height, supports are placed under the lower crowns. If the wall is long, several supports are installed under it, located at equal distances, to avoid sagging and deformation.

    Foundation demolition

    The implementation of this stage depends on the selected type of repair and restoration work. If partial restoration is intended, then only heavily damaged areas of the foundation are dismantled. If the entire foundation is in poor condition, it is completely demolished. In this case, the foundation is destroyed in small pieces 1–2 m long.

    Construction of the trench

    The ditch is being dug for the new foundation to be poured. Depth and width are calculated individually, depending on the length and thickness of the walls of the house. When digging a trench, the condition of the soil is always taken into account: freezing depth, groundwater, stability and other important factors.

    When the trench is dug, the bottom is strengthened with a sand and gravel cushion, which is wetted with water and compacted to the most dense state.

    Formwork

    Without this element it is impossible to pour a concrete foundation. The formwork is made from waterproof plywood and installed to the inner walls of the trench. Here it is important to ensure maximum tightness of the structure, otherwise the cement laitance will pour out through the cracks, leaving sand and crushed stone inside. This negatively affects the strength of the foundation.

    To create durable formwork, it is better to use material 2.5–3 cm thick. At the joints, support posts made of metal are placed, which are driven into the ground. Wooden elements are fastened together with screws or nails.

    Reinforcement

    Reinforcing elements are placed inside the formwork. The structure consists of longitudinal and vertical reinforcements, which are fastened together by spot welding or wire. Reinforcement is carried out along the entire perimeter of the formwork.

    Pouring concrete

    For this, a concrete mixture of sand, cement and crushed stone is prepared. Water is added to the composition in portions to achieve the optimal consistency of the mixture. The concrete should not be too liquid, but it is better not to make a thick mixture either: such concrete requires vibration compaction, otherwise it will not fill all the existing voids.

    After pouring, the concrete must dry. Depending on climatic conditions, this may take 2–7 days. Concrete gains strength only after 28 days from the moment of pouring, however, to continue work you need to wait for minimal setting.

    When the mixture has hardened, you can begin to remove the formwork. Some novice builders believe that the formwork can be left in place. This is mistake. Wooden elements are susceptible to rotting, and this process shortens the life of concrete. Without formwork, the foundation will dry out faster. Dismantling usually begins from the corners of the structure; the wooden panels are knocked down very carefully so as not to damage the concrete.

    Base insulation

    In order not to repeat all of the above manipulations after a short time, the foundation must be protected from the harmful effects of moisture. For this purpose, coating or roll waterproofing is used. Rolled materials require exposure to temperature, so they are soldered with a blowtorch. Coating waterproofing is applied like regular paint, penetrates the concrete and fills all pores and voids.

    Let's lower the house

    When the foundation gains strength, the free space of the trench is filled with earth, which is compacted. After this, the jacks are raised slightly, the supports are removed and the walls are lowered.

    The supports must be removed gradually: if the jack accidentally slips, the wall will fall onto a temporary foundation, rather than collapse onto a freshly poured foundation. When the walls are completely lowered, you need to check the perimeter of the house for any remaining gaps and carefully seal any existing cracks.

    It is possible to build a new foundation under a standing house, but this is a rather labor-intensive process that requires patience and accuracy. If you don’t have confidence in your abilities, it’s better to entrust the work to professionals.

    The construction of a private house begins with design. This article is intended for those who are interested in building a residential building made of wood (timber, logs, frame houses).

    As you know, wood, even treated and prepared, deteriorates faster than other building materials.
    At the same time, the process of destruction begins in the place where the tree simultaneously comes into contact with water (moisture), earth and air. That is, at the place where it adjoins the foundation.

    Accordingly, the correct installation of the foundation for a wooden house can be called the key to the long-term functioning of the structure.

    Foundation for a wooden house - SNiP, GOST, regulatory documents

    The construction of the foundation begins with calculations and familiarization with the requirements. Among the documents that regulate certain aspects of foundation construction are:

    • GOST 13580-85 “Reinforced concrete slabs for strip foundations”.
    • SNiP 3.02.01-87 “Earth structures, foundations and foundations.”
    • SNiP 2.02.01-83 “Foundations of buildings and structures.”
    • SNiP 2.02.03-85 “Pile foundations”
    • SP 50-101-2004 “Design and installation of foundations and foundations of buildings and structures.”
    • Guidelines for the design of foundations and foundations on heaving soils.
    • Other regulations (regional or those that relate to work on specific types of soil).

    It is worth noting that the recommendations given in the regulations and standards only determine the requirements for the construction process at key points. But a private house may differ in size, number of floors, and construction materials. Accordingly, the installation of a foundation for a wooden house will have a lot of variations used in each specific case. However, it must be taken into account that the foundation must exceed the ground level by 500 mm.

    Construction of a foundation for a wooden house

    To answer this question, you need to consider the factors that determine the type of foundation:

    • location of the house. It is the starting point for all subsequent geological surveys. It is important not to build a house near cliffs, ponds, or unstable soils. And also take into account in advance the possibility of connecting to communications (gas supply, electrification, water supply);
    • dimensions and number of floors of the house. The greater the weight of the house, the stronger the foundation under it must be. But, at the same time, an increase in floors leads to a greater load on the foundation, but an increase in the total area of ​​the house does not put forward such requirements, because the total load per unit area remains unchanged;
    • designed basement, ground floor;
    • terrain. With large unevenness, the construction of strip-type foundations will entail the need to remove a significant amount of soil;
    • soil type and bearing capacity. There are five types of soil. To determine the type of soil on a site, it is not necessary to contact special organizations; it is enough to observe the soil after rain;
    • Clay soil slowly absorbs moisture and becomes crusty during drought.
    • Loamy soil will absorb moisture quickly, but will dry completely only after a couple of days.
    • Sandy will quickly absorb moisture, and you can start working almost immediately after the rain.
    • Vegetation does not grow well on peat, and it takes a long time to dry out.
    • Calcareous soil is able to quickly absorb moisture and is characterized by the appearance of a light gray tint to the soil during drought.

    The type of soil determines its bearing capacity;

    • groundwater depth. The more moisture there is in the ground, in close proximity to the foundation, the greater the likelihood that the soil will swell when freezing/thawing;
    • soil freezing depth. The base of the foundation must be below the freezing level of the soil;
    • material consumption, timing and cost of work. Determined by the developer independently;
    • aesthetic design. Also depends on personal preference. In any case, further covering the foundation of a wooden house with basement siding, plaster, etc. will achieve the desired effect.

    Calculation and consideration of the above factors will allow you to select the desired type of foundation. Which foundation for a wooden house is better? You can choose the appropriate option after assessing all the factors described above.

    Types and types of foundations for wooden houses

    The low weight of wood suggests the use of the following types of foundation:

    1. tape;
    2. columnar;
    3. pile;
    4. slab

    1. Strip foundation for a wooden house

    Strip foundation is one of the most common types of foundation. It has the same cross-section along the entire perimeter. Its width should be 50 mm. wider than the calculated width of the wall.

    Subtypes of strip foundation:

    Deeply buried strip foundation. It is poured around the perimeter of the building and internal walls. Applies if:

    • the soil on the site is classified as heaving;
    • at a significant depth of soil freezing;
    • when groundwater flows in close proximity to the soil surface;
    • if there is a basement, ground floor, garage;
    • in case of multi-storey construction.

    Construction of a strip foundation for a wooden house

    Construction technology:

    • digging a pit. The depth of the foundation for a wooden house should exceed the soil freezing level by 200 mm. And the width is equal to the estimated width of the foundation, plus 400-500 mm. on formwork and ease of use;
    • installation of a sand-cement cushion. To do this, a layer of mixture 150-200 mm thick is poured onto the bottom of the pit. To compact the mixture, you need to pour it with water and then compact it. Arranging a cushion will reduce the load on the foundation between seasons;
    • installation of formwork. In order for the foundation surface to be level, you need to knock down the formwork from the inside and hammer the nails in from the outside. This technique will simplify the dismantling of the formwork.

    Nuance. So that the dismantled formwork can still be useful, we advise you to choose the material for its construction based on further needs. For example, if you plan to use metal tiles as a roofing material, use cut boards for formwork. If bitumen shingles, then give preference to plywood. In this case, you need to fill the inside of the formwork with film. Thus, lumber can be used to construct a rafter system.

    • To prevent the formwork from creeping under the pressure of concrete, spacers must be installed.
    • installation of reinforcement. Metal rods can be laid in several rows. However, it should be remembered that welding work is not carried out when tying the reinforcement. The reinforcement bars are fastened to each other using wire;
    • Pipes are installed between the fittings. They are needed for laying communications and ventilation.
    • pouring concrete. Moreover, if the work lasts for several days, then each previous layer must dry. And the filling is carried out using the “wet” method.

    Important. After each stage, you need to check the horizontal level with a building level.

    Before starting construction of the building, the foundation must stand for several weeks. During this time, the foundation may sag and there will be time to fix the problems. Otherwise, shrinkage of the foundation will lead to shrinkage and deformation of the walls.

    An alternative to a monolithic foundation is a block foundation. In this case, the blocks are laid out in several rows to the required height, fastened together with cement mortar and tied with reinforcing mesh.

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