DIY foundation pillars step by step instructions. Technology for creating a columnar foundation on your own. Prices for laying the foundation

Depending on the type of soil located on the construction site, you have to choose the right type of foundation structure. If the soil is soft, mobile, with flooding or with a high level of groundwater, then a columnar foundation cannot be avoided. Despite the apparent simplicity of carrying out installation work, the process of constructing a columnar structure requires accurate calculations regarding the load-bearing capacity of each support post. But among all types of foundations for a house, this is the cheapest in terms of material consumption, especially since it is possible to use various building materials for it. Let's look at step-by-step instructions for building a columnar foundation with your own hands.

Advantages and disadvantages of a columnar foundation

One of the advantages has already been mentioned; it is low-cost construction. You can also add to the advantages:

quick construction of the foundation;
there is no need to use construction equipment;
simplicity of the work carried out, so making a columnar foundation with your own hands is not a problem;
lack of additional measures related to thermal insulation of the foundation;
a columnar foundation can be easily repaired;
this type can be erected on frozen soils;
The service life of the pillars, if the technology is strictly followed, is up to 100 years.

As for the disadvantages, there are not many of them:

the load-bearing capacity is not very high, so it is recommended to build lightweight buildings on poles: wooden, frame, panel;
the stability of supports is reduced if they are erected on moving soils;
there is no possibility to organize a basement or subfloor.

Before you start making a columnar foundation with your own hands, you need to familiarize yourself with its classification, materials and carry out calculations.

General diagram of a columnar foundation

General scheme construction work can be divided into several main stages. They are, in principle, no different from the construction of any type of foundation.

The load-bearing capacity is calculated taking into account the number of support pillars and the weight of the building.
A general drawing of a columnar foundation is made with an exact indication of the distance between the racks, the cross-section of the supports and the height of the protrusion above the ground level.
Preparatory work is being carried out: marking exactly according to plan, excavation with digging holes - wells, manufacturing reinforcing frames, adding cushions to the pits, waterproofing and installing frames. If there is a need, then the formwork of the base part is assembled.
Making a concrete solution and pouring it into prepared wells, followed by removing air by baying the mixture. If bricks or blocks are used as the material for the columnar foundation, then they are laid.

The entire assembly of a columnar foundation is a combination of pillars with a horizontal strip, which is called a grillage. It can be concrete, metal, wood, or be the lower crown of a log house.

As you can see, there are not many positions according to the diagram, which is why it is believed that it is not difficult to build a columnar foundation with your own hands.

Classification of columnar foundations by material

Like any foundation for a house, a columnar foundation must be strong and reliable. Therefore, for its construction, building materials are used that can provide the necessary strength and reliability. These include concrete, concrete blocks, bricks, stone, metal and some types of wood, which are used in the form of logs or timber installed vertically.

The choice of material is actually a crucial moment on which the quality of the final result depends. And if the task is to build a columnar foundation with your own hands, then you need to choose the right material for its construction. For example, it is believed that it is better to build monolithic structures on water-unsaturated soils, and prefabricated block structures on damp ones.

Monolithic reinforced concrete pillars

This is the most durable and reliable design. Such a foundation for pillars has high tensile and compressive strength. Of course, if you take into account the correct reinforcement. Moreover, if you correctly distribute the racks along the entire perimeter of the house, taking into account the required cross-section of the supports, then multi-story buildings can be built on such a foundation.

Let us add that a columnar reinforced concrete foundation is constructed in cases where it is necessary to pour it to a sufficient depth, and more often than not, below the freezing level of the soil. It perfectly withstands soil heaving, but is afraid of contact with groundwater. Therefore, care must be taken to waterproof the supports.

Asbestos cement pillars

Asbestos cement pipes are not often used for the construction of foundation pillars. Although they feel great in any soil. Their load-bearing capacity is not high, but it is not required, because the pipes in the foundation structure act as formwork.

Pole made of plastic pipes

The situation here is the same as with asbestos-cement. That is, plastic pipes act as formwork. They do not corrode and are not destroyed by water, so they do not require waterproofing. The only thing is that the supports need to be properly poured under the foundation. Namely: install a reinforcing frame in them and pour concrete mortar.

Made from bricks or blocks

Brick foundation pillars should be treated as the oldest known structures. From the history of European and Russian architecture, they are “long-livers”. Until now, brick pillars stand under huge buildings, and, apparently, they will stand for many more centuries. Because the choice of bricks was taken seriously in those ancient times. Burnt brick was required highest quality. Therefore, when building a house on a columnar foundation, this requirement must be taken into account.

As for block pillars, they are not inferior in strength to brick ones, of course, depending on the material from which the blocks are made. It is better to give preference to concrete blocks; cinder blocks in this regard cannot bear heavy loads, although they are used for light buildings such as a veranda, a bathhouse, and so on.

Block structures include pillars built from stone. Not a bad option, quite strong, but such supports cannot withstand the movements of the soil. Therefore, when building a house on a slope, it is better to abandon stone racks. As a replacement for them - foundations made of rubble concrete. This is when stones are poured into the prepared formwork, and then they are filled with concrete mortar.

Wooden pillars

Such a columnar foundation, like a brick one, has been used in Russia for a long time. Today it is not so in demand, but, for example, for bathhouses installed near a river or lake, they are often found. We must pay tribute the right choice wood The stronger it is, the longer the service life of the pillars. In this case, it is necessary to carry out protective measures very carefully.

Treatment of the entire column with antiseptic compounds.
Treating the part buried in the ground with bitumen mastics and gluing a layer or two of roofing material.

Doing all this yourself is not a problem, the main thing is not only to make protection, but also to install wooden supports under the pillars in the form of a board with a thickness of at least 50 mm and a width over the entire area twice as large as the cross-section of the pillar. The support boards also need to be protected from moisture and the negative effects of the soil.

Wooden racks are mainly used for light structures. although a hundred years ago boyar mansions of several floors were built on them.

Types of columnar foundation by depth

Frost heaving is the force that is taken into account first when designing a columnar foundation. This is a very dangerous pressure, which, if not installed correctly, can tear the foundation of the house. Therefore, a large number of options for building construction are considered from the point of view of the impact of frost heaving on the foundation structure.

The basic design rule states that the foundation should be laid below the soil freezing depth by 30 - 50 cm. And if this indicator is, for example, 1.2 m, then, accordingly, the laying depth will be equal to 1.5 - 1.8 m.

But often a light building cannot exert such pressure on the support posts to contain the forces of frost heaving. That is, even when laid to a great depth, the foundation will be subject to deformation. Therefore, when building a columnar foundation with your own hands, you must take into account that there are two more positions: shallow and surface.

Columnar non-buried foundation

A non-buried columnar foundation or a surface foundation are still the same racks, only their laying depth does not exceed 30 - 40 cm. Often they are simply built on the surface of the soil, having previously made a cushion and waterproofing. Designers classify this type as those foundations whose depth does not exceed a third of the soil freezing level. From our example: 120: 3 = 40 cm.

The construction of a columnar foundation of this type belongs to the category of the cheapest and most rapidly erected structures. As practice shows, they usually use a block modification using blocks, stones or bricks. But since the height of the pillars is not very large, which means their load-bearing capacity is also low, it is therefore recommended to increase the cross-sectional area of the supports. Minimum size – 40 x 40 cm.

Shallow columnar foundation

The name of a shallow foundation suggests that it is buried in the ground, but not to a great depth. In any case, not below the level of its freezing. Designers calculate the depth of their installation at the rate of 0.5-0.7 from the depth of freezing of the ground. Again from our example: 120 x 0.5 = 60 cm.

The main requirement for this design is not to touch groundwater.

Foundation with grillage

The columnar foundation unit - the grillage - has one single task - to distribute the load from the house evenly across all the pillars. As mentioned above, the grillage can be constructed of concrete, metal (channel or I-beam), wood (beam with a cross-section of 150 x 200 or 200 x 200 mm) or be a log from the first crown of a log house.

Attention! If the beam is a monolith with pillars, then during the construction of the latter, the ends of the reinforcing frame reinforcement are exposed, which are connected with a knitting wire to the reinforced belt of the grillage.

Step-by-step DIY construction instructions

Let's move on to the main question of how to properly make a columnar foundation with your own hands. The scheme of work has already been described above, where the first stage was carrying out calculations and drawing up a project. If a house is being built on a columnar foundation, then it is better to delegate this stage of construction to specialists. After all, in order to accurately make all the calculations, it is necessary to take into account a large number of different indicators and nuances. Eg:

type of soil on the site;
groundwater level;
soil freezing level;
the type of building, its number of storeys, what materials it is constructed from;
materials from which the foundation itself is supposed to be built;
additional loads.

Of course, you can use online calculators, but not for established homes. You can use it for baths, verandas, barns. And no one can guarantee that the calculations are 100% correct.

Marking and excavation work

So, if a building design is in hand, then the designers must link the foundation to the area. This makes it easier to find its location on the plane. Usually the reference is made to the boundaries of the site, indicating the distance from the foundation structure to these same boundaries. Therefore, before marking the pillars, it is necessary to set aside these same dimensions from the boundaries and determine the perimeter of the building.

To do this, two rows of strings are stretched along the boundaries of the building, which immediately determine the width of the foundation pillars. The rest is simple:

the turf is removed to a depth of 20 cm;
the installation locations of the pillars are marked: at the corners of the building and between them with the required distance, which is determined by the project;
Using a garden or electric drill, holes are made in the ground, the depth and cross-section of which are also determined by the project.

We must pay tribute that the drawing of the columnar foundation greatly helps in marking. Because it clearly indicates all the parameters of the future design.

Pillow device

The cushion is a layer of sand 20-30 cm thick, which is poured into the wells and compacted using improvised means. It can be a beam, a wooden slat, or a small section of log. Often a pipe is used, to the end of which a metal plate is welded.

The purpose of the sand cushion is to divert some of the water from the supports that gets into the ground. Next, concrete mortar is poured onto the sand, which will subsequently become a support for columnar structures. The thickness of the concrete layer is 10 - 30 cm.

The formwork must be dealt with carefully, because much will depend on what kind of soil is located on the construction site.

If the soil is clayey, that is, strong, then there is no need to make formwork as such, because the clay itself, like a monolith, does not collapse or collapse.
If the soil is weak and sandy, then formwork will have to be installed in the well. In this case, it is necessary to take into account what shape the designers have determined: rectangular or round. If the latter, then pipes are used as formwork: plastic, asbestos-cement or metal. If the first option, then the well will have to be expanded, made of a rectangular section, and formwork made of boards or other flat materials installed in them. This is a large volume of excavation work, so this form is used extremely rarely for buried structures.

As for the first position, usually a rolled-up roofing material is placed inside the shaft. It forms the walls of the foundation and will further serve as waterproofing. Formwork made of roofing felt is a mandatory attribute.

Attention! Regardless of whether the formwork will be installed in the well or not, it is necessary to form a pillar in the base part. This means that the formwork must be assembled here.

Reinforcement

Reinforcement of pillars is mandatory, because it is the reinforcement laid in concrete that makes it possible to restrain loads from the forces of frost heaving. In the project, the number of reinforcing bars, their shape of connection into the frame and diameter must be indicated. Therefore, the reinforcement is simply cut into pieces of the required length and tied into a frame. Its cross-sectional shape can be triangular, square or round. The main task of the assembly manufacturer is to correctly fold the reinforcing bars relative to each other at the required distance and clearly tie them together with wire.

After which the frame is lowered into the prepared well exactly in the middle. After which you can start pouring concrete.

Attention! The length of the reinforcement bars is trimmed taking into account that their ends will be attached to the reinforcement frame of the grillage. Therefore, the rods are cut 10-30 cm longer so that they stick out above the base part pillars

Pouring concrete

The pouring of a columnar foundation must be approached from the standpoint of standard technology. The concrete solution is made using classical technology:

one part of cement grade M 400;
two parts of washed sand, without a large amount of clay impurities;
three parts of crushed stone with granules 5 - 40 mm.

The most interesting thing is that for a columnar foundation there is no need to prepare a large batch. And there is no need to fill all the pillars at once in one day, as is usually done when constructing a strip or slab structure. It is enough to calculate the volume for one column, make a batch and pour it.

For example, a pipe with a diameter of 150 mm is used as formwork, and it is installed to a depth of 1.2 m. It turns out that the volume of the empty pipe is equal to:

V = SxH, where S is the area of the pipe, and H is its length or installation depth. The area can be found using the formula: S = πD²/4=(3.14×0.15²)/4 = 0.018 m³. If converted to liters, it will be 18 liters. Essentially, these are two buckets of solution.

The pipes are filled with concrete, tapped on the formwork, and pinned to remove air. In this condition, the pillars should stand for 28 days. During this time, the concrete will gain its original strength.

Grillage arrangement

We will assume that the grillage will be monolithic according to the project. This means that under it you will have to construct formwork from any flat materials. It is done by weight, so supports made of bricks, blocks, boards, logs and other materials are installed under the lower panels. The formwork is assembled with a rectangular cross-section with complete and strong fastening of the panels to each other.

A reinforcing frame is placed inside it, usually these are two vertical gratings connected by 6 mm wire rod or 6 - 8 mm reinforcement. The reinforcement frame of the grillage must be fastened to the pieces of reinforcement protruding from the pillars. This unit of the columnar foundation is subject to serious loads, so the fastening of two reinforcement structures must be approached carefully. The concrete solution is poured with compaction and bayoneting. After 7 days the formwork is dismantled, after 28 days the foundation can be loaded.

Summarizing

As you can see, you need to approach the construction of a columnar foundation with your own hands with a thorough analysis of all stages of the construction processes being carried out. Miscalculations must not be allowed in the first place. Markings with large allowances cannot be applied. Wells must be accurately drilled to the required depth. Even a few centimeters can play a supporting role in extreme situations.

There is no need to talk about preparing concrete and pouring it. That is, the arrangement of the foundation is an integrated approach to its construction, where there is no room for mistakes and miscalculations.

Columnar foundation with your own hands step-by-step instruction

The technology for installing a columnar foundation with your own hands is not complicated, the main thing is to follow the step-by-step instructions, then you will have a reliable foundation

Depending on what kind of soil is on the construction site, you have to choose the right foundation structure. If the soil is soft, mobile, with flooding or with a high level of groundwater, then a columnar foundation cannot be avoided. Despite the apparent simplicity of installation work, the process of constructing a columnar structure requires an accurate calculation of the load-bearing capacity of each support post.

But among all types of foundations for a house, this is the cheapest in terms of material consumption, especially since it is possible to use various building materials for it. Let's look at step-by-step instructions for building a columnar foundation with your own hands.

Advantages and disadvantages

One of the advantages has already been mentioned; it is low-cost construction. You can also add to the advantages:

quick construction of the foundation;
there is no need to use construction equipment;
simplicity of the work carried out, so making a columnar foundation with your own hands is not a problem;
lack of additional measures related to thermal insulation of the foundation;
a columnar foundation can be easily repaired;
this type can be erected on frozen soils;
The service life of the pillars, if the technology is strictly followed, is up to 100 years.

As for the disadvantages, there are not many of them:

the load-bearing capacity is not very high, so it is recommended to build lightweight buildings on poles: wooden, frame, panel;
the stability of supports is reduced if they are erected on moving soils;
there is no possibility to organize a basement or subfloor.

Before you start making a columnar foundation with your own hands, you need to familiarize yourself with its classification, materials and carry out calculations.

General diagram of the device

The general scheme of construction work can be outlined in several main stages. They are, in principle, no different from the construction of any type of foundation.

The load-bearing capacity is calculated taking into account the number of support pillars and the weight of the building.
A general drawing of a columnar foundation is made with an exact indication of the distance between the racks, the cross-section of the supports and the height of the protrusion above the ground level.
Preparatory work is underway. This is marking exactly according to plan, excavation with digging holes - wells, making reinforcing frames, adding cushions to the holes, waterproofing and installing frames. If there is a need, then the formwork of the base part is assembled.
Making a concrete solution and pouring it into prepared wells, followed by removing air by baying the mixture. If bricks or blocks are used as the material for the columnar foundation, then they are laid.

The entire assembly of a columnar foundation is a combination of pillars with a horizontal strip, which is called a grillage. It can be concrete, metal, wood, or be the lower crown of a log house.

As you can see, there are not many positions according to the diagram, which is why it is believed that it is not difficult to build a columnar foundation with your own hands.

Classification by material

Like any foundation for a house, a columnar foundation must be strong and reliable. Therefore, for its construction, building materials are used that can provide the necessary strength and reliability. These include concrete, concrete blocks, bricks, stone, metal and some types of wood, which are used in the form of logs or timber installed vertically.

The choice of material is actually a crucial moment, on which the quality of the final result depends. And if the task is to build a columnar foundation with your own hands, then you need to choose the right material for its construction. For example, it is believed that it is better to build monolithic structures on water-unsaturated soils, and prefabricated ones on damp ones.

Monolithic reinforced concrete pillars

This is the most durable and reliable design. Such a foundation for pillars has high tensile and compressive strength. Of course, if you take into account the correct reinforcement.

Moreover, if you correctly distribute the racks along the entire perimeter of the house, taking into account the required cross-section of the supports, then multi-story buildings can be built on such a foundation.

Asbestos cement pipes are not often used for the construction of foundation pillars. Although they feel great in any soil.

Their load-bearing capacity is not high, but it is not required, because the pipes in the foundation structure act as formwork.

Pole made of plastic pipes

Made from bricks or blocks

Brick foundation pillars should be treated as the oldest known structures. From the history of European and Russian architecture, they are “long-livers”.

Until now, brick pillars stand under huge buildings, and, apparently, they will stand for many more centuries.

Because the attitude towards the choice of bricks in those ancient times was serious. The highest quality burnt bricks were always used. Therefore, when building a house on a columnar foundation, this requirement must be taken into account.

Block structures include pillars built from stone. Not a bad option, quite strong, but such supports cannot withstand the movements of the soil. Therefore, when building a house on a slope, it is better to abandon stone racks. As a replacement for them - foundations made of rubble concrete. This is when stones are poured into the prepared formwork, and then they are filled with concrete mortar.

Such a columnar foundation, like a brick one, has been used in Russia for a long time.

Today it is not so in demand, but, for example, for bathhouses installed near a river or lake, they are often found.

We must pay tribute to the correct choice of wood. The stronger it is, the longer the service life of the pillars. In this case, it is necessary to carry out protective measures very carefully.

Treatment of the entire column with antiseptic compounds.
Treating the part buried in the ground with bitumen mastics and gluing a layer or two of roofing material.

Doing all this yourself is not a problem. The main thing is not only to make protection, but also to install wooden supports under the pillars. They are made from boards with a thickness of at least 50 mm and a width over the entire area twice as large as the cross-section of the pillar. The support boards also need to be protected from moisture and the negative effects of the soil.

Wooden racks are mainly used for light structures, although a hundred years ago boyar mansions of several floors were built on them.

Frost heaving is the force that is taken into account first when designing a columnar foundation.

This is a very dangerous pressure, which, if not installed correctly, can tear the foundation of the house.

Therefore, a large number of options for building construction are considered from the point of view of the impact of frost heaving on the foundation structure.

The basic design rule states that the foundation should be laid below the freezing depth of the soil by 30 - 50 cm. And if this indicator is, for example, 1.2 m, then, accordingly, the laying depth will be equal to 1.5 - 1.8 m.

Non-buried

Shallow

The name of a shallow foundation suggests that it is buried in the ground, but not to a great depth. In any case, not below the level of its freezing. Designers calculate the depth of their installation at the rate of 0.5 - 0.7 from the depth of freezing of the ground. Again from our example: 120 x 0.5 = 60 cm.The main requirement for this design is not to touch groundwater.

Step-by-step DIY construction instructions

type of soil on the site;
groundwater level;
soil freezing level;
the type of building, its number of storeys, what materials it is constructed from;
materials from which the foundation itself is supposed to be built;
additional loads.

Of course, you can use online calculators, but not for established homes. You can use it for baths, verandas, barns. And no one can guarantee that the calculations are 100% correct.

Video

Video on how to make a columnar foundation yourself.

Marking and excavation work

To do this, two rows of strings are stretched along the boundaries of the building, which immediately determine the width of the foundation pillars. The rest is simple:

the turf is removed to a depth of 20 cm;
the installation locations of the pillars are marked: at the corners of the building and between them with the required distance, which is determined by the project;
Using a garden or electric drill, holes are made in the ground, the depth and cross-section of which are also determined by the project.

We must pay tribute that the drawing of the columnar foundation greatly helps in marking. Because it clearly indicates all the parameters of the future design.

The cushion is a layer of sand 20-30 cm thick. It is poured into the wells and compacted with improvised means. It can be a beam, a wooden slat, or a small section of log. Often a pipe is used, to the end of which a metal plate is welded.

The purpose of the sand cushion is to divert some of the water from the supports that gets into the ground. Next, concrete mortar is poured onto the sand, which will subsequently become a support for columnar structures. The thickness of the concrete layer is 10 - 30 cm.

The formwork must be dealt with carefully. After all, much will depend on what kind of soil is located on the construction site.

If the soil is clayey, that is, strong, then there is no need to make formwork as such. The clay itself is like a monolith - it does not collapse or collapse.
If the soil is weak and sandy, then formwork will have to be installed in the well. In this case, it is necessary to take into account what shape the designers have determined: rectangular or round. If the latter, then pipes are used as formwork: plastic, asbestos-cement or metal. If the first option, then the well will have to be expanded, made of a rectangular section, and formwork made of boards or other flat materials installed in them. This is a large volume of excavation work, so this form is used extremely rarely for buried structures.

As for the first position, usually a rolled-up roofing material is placed inside the shaft. It forms the walls of the foundation and will further serve as waterproofing. Formwork made of roofing felt is a mandatory attribute.

Regardless of whether the formwork will be installed in the well or not, it is necessary to form a pillar in the base part. This means that the formwork must be assembled here.

Reinforcement of pillars is mandatory, after all, it is the reinforcement laid in concrete that makes it possible to contain the loads from the forces of frost heaving.

In the project, the number of reinforcing bars, their shape of connection into the frame and diameter must be indicated. Therefore, the reinforcement is simply cut into pieces of the required length and into a frame.

Its cross-sectional shape can be triangular, square or round. The main task is to correctly fold the reinforcing bars relative to each other at the required distance. Then clearly tie them together with wire.

After which the frame is lowered into the prepared well exactly in the middle. After which you can start pouring concrete.

The length of the reinforcement bars is trimmed taking into account that their ends will be attached to the reinforcement frame of the grillage. Therefore, the rods are cut 10 - 30 cm longer. So that they stick out above the base of the pillars by this size.

The pouring of a columnar foundation must be approached from the standpoint of standard technology. The concrete solution is made using classical technology:

one part of cement grade M 400;
two parts of washed sand, without a large amount of clay impurities;
three parts of crushed stone with granules 5 - 40 mm.

For example, a pipe with a diameter of 150 mm is used as formwork, and it is installed to a depth of 1.2 m. It turns out that the volume of the empty pipe is equal to:

Grillage arrangement

We will assume that the grillage will be monolithic according to the project. This means that under it you will have to construct formwork from any flat materials.

It is done by weight, so supports made of bricks, blocks, boards, logs and other materials are installed under the lower panels. The formwork is assembled with a rectangular cross-section with complete and strong fastening of the panels to each other.

A reinforcing frame is placed inside it. Usually these are two vertical gratings connected by 6 mm wire rod or 6 - 8 mm reinforcement. The reinforcement frame of the grillage must be fastened to the pieces of reinforcement protruding from the pillars.

This columnar foundation unit is subject to serious loads. Therefore, the fastening of two reinforcement structures must be approached carefully. The concrete solution is poured with compaction and bayoneting. After 7 days the formwork is dismantled, after 28 days the foundation can be loaded.

Summarizing

Markings with large allowances cannot be applied. Wells must be accurately drilled to the required depth. Even a few centimeters can play a supporting role in extreme situations. The construction of a foundation is an integrated approach to its construction, where there is no room for errors and miscalculations.

In contact with

One of the popular foundations small houses and outbuildings - columnar. It is attractive due to its low cost, ease of execution and the fact that even a person who is not particularly experienced in construction can build it with his own hands. Another good thing about a columnar foundation is that it can be designed to fit most buildings and conditions.

Device and types

A columnar foundation consists of a number of support pillars that transfer the load from the building to the ground. The pillars can have a rectangular or round cross-section and can be made from:

monolithic reinforced concrete;
bricks (solid ceramic, well-fired);
concrete (made of heavy concrete grade no lower than B15) and reinforced concrete blocks;
rubble and rubble concrete.

The most reliable ones are made of monolithic reinforced concrete. They can be used on soils prone to heaving with high groundwater levels. All the rest consist of elements held together with concrete mortar and are inferior in strength to a monolith. They are recommended for use on normal soils.

The pillars must be placed in the corners of the building, at the junction of walls and piers. If the distance between the supports exceeds 3 m, additional ones are installed. The installation step is on average 1.5-2.5 m. The heavier the building stands, the smaller the step, but there is no point in installing more often than 1 m: the foundation will be too expensive.

Types of grillage

To ensure that the load from the building is transferred evenly to the pillars, they are connected by a transverse beam - a grillage or shallow tape. This eliminates one of the main disadvantages columnar bases— possible uneven shrinkage of supports.

During construction wooden houses or frame frames, a large-section wooden beam is often used as a grillage; sometimes metal is used - a large-section profiled pipe or T-/I-beams. To connect beams and frames during the construction of pillars, studs, special fastening elements are placed in them, or reinforcement is released. The shape of the mortgages is selected based on the planned grillage type.

For heavy houses, a concrete beam is made. It can be composite - from ready-made reinforced concrete beams, or it can be monolithic. Although composite ones are easier to implement (buy, install, connect), a monolithic one is cheaper and even more reliable. Therefore, a monolithic grillage is used more often. It is more suitable for houses made of brick and other heavy materials.

When making a columnar foundation with a monolithic grillage, the reinforcement of the pillars is done with an outlet of at least 70 cm. These outlets are then connected to the reinforcement of the grillage frame.

Extensions and their foundations

If there are lighter extensions to the house—a porch, a veranda, a driveway—the foundations are made separate and incoherent. This means that they make their own outline for the house, and their own for the porch. And they should have no points of contact with each other. Since the grillages (beams running along the top of the supports) are located nearby, a damping layer is laid between them. For example, roofing felt in two layers, cardboard from mineral wool and other similar materials.

This is necessary since the weight of these elements is very different, and the magnitude of the load on the foundation is correspondingly different. If you make it coherent, a large difference will cause distortion, and possibly the destruction of the building.

How to close the gaps between the pillars

When installing a columnar foundation, the building turns out to be raised above the ground and there is a draft under the subfloor. This is good for maintaining normal wood moisture, but bad for heating: the floor becomes too cold. One more thing: all kinds of living creatures like to live under the house. Both homely and not so... For these reasons, they try to close the space between the pillars. You can do this in two ways:

collection device - stone or brickwork between pillars;
by attaching pieces of sheet material or finishing materials.

It's easier, of course, to attach sheet material. It is then cut off in such a way that it does not rest on the ground. The remaining gap will be useful for ventilation and heaving compensation.

They do the removal if they plan to make an insulated blind area around the house. At the same time, it is installed so that it does not support the grillage or the lower frame - it is made at the same level with the outer edge of the pillars (they must be at least 10 cm wider than the wall).

It is advisable to prepare the base for the pick-up: dig a trench at least 20-30 cm deep, pour and compact a layer of sand, and crushed stone on top of it, which is also compacted. Then a decorative wall is placed on this compacted base.

On normal soils, small light buildings with an area of no more than 30 square meters- such as a barn, gazebo and other similar buildings - can be done on a lightweight foundation. It is called support-columnar. Typically this is one or more concrete blocks laid on a sand and gravel bed.

The planning of the pillars is the same: at angles, at the junction of walls and intermediate ones, if necessary. With this type, it is important to compact the cushion well, thereby increasing the load-bearing capacity of the soil. And one more point: do not use this type of base on loose or clayey water-saturated soils. Even under or. He will be completely unreliable.

What is the difference between a pile and columnar foundation?

If you look at a columnar foundation with round pillars and a pile foundation, at first glance there is no difference. But it is there. These are the soils on which they are placed and the depth to which they are buried. Pile foundations are placed on soils with weak bearing capacity and their task is to pass through unstable soils and transfer the load from the house to denser layers. Columnar ones are placed on soils with normal bearing capacity and their depth is determined by the type of soil, climatic zone and groundwater level. Structurally, they are similar, but their tasks are different, as well as their scope of application.

What is soil heaving and how does it affect the choice of foundation?

The most difficult soils for construction are clayey soils. They do not drain water well and it accumulates in small cavities. When frozen, it significantly increases the volume of the soil. As the soil increases in volume, it puts pressure on everything in it, including the foundation. This phenomenon is called heaving (the soil swells), and soils in which they are clearly expressed are heaving.

Heaving forces are applied both from below, trying to push the pillar out, and from the sides, trying to move the support to the side. It is for this reason that in clayey - heaving - soils it is better to make the pillars monolithic with reinforcement.

Also, to prevent the pillars from being pushed upward, the lower part is made wider. This area is called the heel and is usually twice the size of the pillar itself, and its height is equal to 1/3 of the cross-section of the pillar. For example, under a 40 cm pillar they make a heel 80*80 cm, 13 cm high or so.

The seams between blocks/bricks/stones in prefabricated columns are not always able to withstand lateral loads, therefore, to reduce the influence of heaving forces on prefabricated columnar foundations, they are made with beveled walls. This increases their reliability in heaving soils. On normal soils, the pillars are stacked with even walls.

Application area

As already mentioned, a columnar foundation is also called a pillar foundation or on pillars) behaves normally on soils with normal bearing capacity. They are not used on loose sand, peat bogs and other unstable foundations. Its main features are that it is impossible to organize a basement and a ventilated gap between the ground level and the subfloor. They also need to be kept in mind when choosing.

They are suitable for the following cases:

At the same time, there are a number of situations (except for weak soils) when it is not recommended to use foundations on pillars:

with a large difference in height on the building site - more than 2 m;
in complex geology with possible displacement of layers.

In other cases they can be used.

Laying depth

The main criterion for choosing foundation parameters is ensuring its integrity. Therefore, when planning, they always include a safety margin of about 20-40%. It compensates (to some extent) for unforeseen changes in conditions (groundwater levels, unexpectedly low winter temperatures) or loads. This is especially evident when planning foundations: the laying depth is taken with a margin and the bearing capacity is usually underestimated. This is understandable: adding something to an already finished foundation is either a very expensive or unrealistic idea.

The greatest safety margin is laid on heaving soils: it is impossible to calculate their manifestation, so they try to make it as reliable as possible. To do this, for private houses, foundations are buried below the freezing depth of the soil. You will find out the average data for your region, and add about 15-25 cm to this figure. This is how you get the depth of the foundation. For example, in the region the soil freezes to 1.5 m, which means the foundation depth is 1.65-1.75 m.

As you understand, if you make prefabricated pillars - from brick, rubble, blocks - you will have to dig a decent size hole under each one. The bottom must be 20 cm below the laying depth to make backfill. Also, the pit should be considerably wider - you will have to work in it, folding the supports. This is another reason why monolithic pillars are made: holes are drilled under them, gravel or sand is poured onto the bottom and formwork is inserted (most often pipes required diameter). Inside of which a reinforcing element is installed - a frame made of reinforcement or a metal pipe.

This rule works for heavy buildings. But columnar foundations are rarely made for them. They are placed mainly under light buildings: wooden or outbuildings. If a basement is not planned for such a building, it is more advisable to make a shallow foundation (laying depth from 0.5 to 0.7 freezing level) or shallow (from 0.3 to 0.5 freezing depth).

An example of a non-buried columnar foundation with a freezing depth of 1.2 m (1/3 of 120 cm is 40 cm)

With this choice, heaving forces will act on the pillars, but since their area is smaller than that of the tape, the impact will not be as strong. These impacts are successfully compensated by the design of the frame or wooden house. Moreover, additional measures are being taken to reduce the impact of heaving forces:

at the bottom of the hole under the post they make a gravel cushion, which takes on part of the load;
make the side surfaces smooth and additionally lubricate them with grease, bitumen mastic, epoxy resin, etc.
make insulated

As a result, in most cases, the owners do not even notice that the foundation is heaving. Some supports rose slightly, the grillage and trim compensated for them. After the ground thawed, everything returned to its place.

In soils that drain water well, the columnar foundation is made shallow or not buried. It is only important to select the correct area of the columns in order to evenly transfer the load.

Pole sizes

There are minimum dimensions for the supports of a columnar foundation. They depend on the materials:

Monolithic reinforced concrete 30 cm.
Burnt brick pillars - 38 cm;
Rubble, concrete blocks and rubble concrete - 40 cm;
Stonework - 60 cm.

But at the same time, the size of the pillar should be 10 cm larger than the width of the wall. For normal operation of the foundation, it is necessary that the wall lies in the middle of the support and protrudes at least 5 cm on the sides.

Construction stages

As usual, everything starts with cleaning the site and marking it. The turf is removed from the entire site and the fertile layer is removed. He is not considered to be load-bearing and is taken out. At the same time, leveling is done - the mounds are cut off, holes and depressions are filled and compacted. The horizontal position is controlled using a two- to three-meter board with a building level installed on it.

Marking

Along the perimeter of the building, cast-offs are installed - pillars or pillars with nailed slats - benches. They are placed at a distance of about a meter from the perimeter of the future house. Using cords stretched between them, the perimeter and width of future pillars are indicated.

How to mark a foundation

When setting, make sure that the angles are strictly 90°, and measure the diagonals of the rectangles. They must be equal. At the intersection of the stretched cords, a perpendicular is lowered down (using a plumb line), marking the dimensions of the pillars on the ground.

This way you can make them all the same, and also monitor the height when setting up the formwork for monolithic pillars or when laying prefabricated ones.

Digging holes for poles

Under prefabricated foundations, holes are dug manually or using an excavator. If the depth required is up to 1 m and the soil is not loose, you can dig them with straight walls. If the depth is greater or there are signs of crumbling, the slopes are made inclined.

When they have reached the design depth of the foundation, they dig another 20-30 cm lower. The bottom is leveled, its dimensions should be 10-20 cm larger than the planned dimensions of the heel or pillar.

Easier with round posts. Wells are drilled under them using a manual or automated drill. If you plan to expand at the bottom - the heel, you can either make the hole wider - according to the size of the heel, or use a drill with a folding blade. It is called a TISE drill. The additional blade opens after the set depth has been reached.

Installation of sand and gravel cushion

A layer of crushed stone of about 10-15 cm is poured onto the bottom and compacted well. Coarse sand is poured onto compacted crushed stone. It is spilled and compacted. The total layer of sand and gravel cushion must be such as to reach the specified depth of the foundation.

In the case of round posts, the cushion is made in the same way, compaction is done whenever possible. Take a long pole, which is used to compact the bedding.

Heel device

If the pillars are made prefabricated - from blocks, bricks, rubble, it is easier to make the heel from a ready-made concrete block. Place a block-pillow on the sand, leveled. It has a trapezoidal cross-section, which is convenient.

Two types of heel - monolithic from concrete block

For monolithic ones, it makes sense to make a half-shelf from a monolith. The formwork is placed according to the specified dimensions (twice the cross-section of the column and at least 1/3 of the cross-section in height). The reinforcement is laid in two tiers. Use a rod with a diameter of 12-14 mm. Also, reinforcement is installed in the heel, which will then go to the post. The result is a single reinforced concrete structure.

Construction of pillars

If we are talking about a monolithic pillar, then formwork is installed and reinforcement is installed inside. The formwork for square pillars is made from boards; for round ones, you can use plastic pipes of a suitable diameter. There is an economical formwork option - rolled roofing material of the required length. It is twisted into a pipe of the required diameter, screwed onto the standard. After making two or three layers, secure with tape. The result is a reliable formwork that, even in the part protruding above the ground, normally holds the mortar.

For reinforcement, three to four reinforcement rods of class A III with a diameter of 12-14 mm are usually used (for square ones, 4 are required, for round ones, 3 are possible). They are connected to each other into a single structure by transverse dressings installed every 20-25 cm. They can be made from smooth class A I reinforcement, with a diameter of 6-8 mm. It is better to knit the frame rather than weld it - higher strength.

Please note that there must be a distance of at least 50 mm from the edge of the formwork to the reinforcement bar. It is necessary to prevent the metal from rusting. The photo below is an example of incorrect reinforcement: the reinforcement is close to the formwork. It will quickly rust and the pole may break.

If pillars are made of brick, then it must be graded at least 100, solid, well-burnt. If there is a high groundwater level in the area, brick pillars will not work: they will quickly collapse. The mortar for laying brick pillars is made with Portland cement no lower than M 300, and preferably 400 or 500. There are several mortar options:

1 part cement, 3 sand;
1 cement, 2 lime paste, 10 sand;
1 part cement, 1 part clay adze, 10 parts sand.

The masonry is carried out with bandaging, carefully checking the verticality. Even small deviations can then lead to the destruction of the foundation, and maybe even the building.

When laying a rubble columnar foundation, the stones chosen are flat with smooth edges. When laying, the vertical load should be transferred to the entire plane of the stone, and not to its individual sections. The stones are also placed with a bandage, placing the largest fragments in the corners, filling the gaps with smaller ones.

The thickness of the stones should not be more than 30 cm. They are laid on the mortar, fitting tightly to each other. The gaps are filled with crushed stone, compacting it well. To increase strength, such pillars can be reinforced both vertically and horizontally. Horizontal reinforcement is done every 25-40 cm, rods of at least 6 mm in diameter are inserted vertically, you can use reinforcing mesh made of wire of the same diameter.

Important: the pillars must all be driven to the same level. To do this, during construction or pouring, constantly beat off the vertical plane: cutting off the tops is long and difficult.

Grillage arrangement

As mentioned earlier, when pouring monolithic pillars, embedded parts are installed at the tops:

pins for tying wooden or metal strapping to beams;
reinforcement outlets of at least 70 cm in length for connection with the reinforcement frame of the monolithic grillage.

The strapping device is discussed in the description. You can read about the design of a monolithic grillage in the article Everything is the same, right down to the calculation of the load-bearing capacity.

Waterproofing

To prevent moisture from suction from the soil between the foundation/grillage and the framing or the first row of masonry, a layer of waterproofing is required. You can use coating (the most common is bitumen mastic) or roll or a combination of both.

There is no point in insulating the pillars. For concrete pillars, the presence of moisture is not a minus, just as for rubble ones. And it is better to install brick ones on dry soils. It may be worth impregnating their surface with some kind of deep penetration impregnation, which significantly reduces hygroscopicity. The only problem is that they are expensive.

Not so difficult to construct, inexpensive, and most importantly, a strong and durable columnar foundation can be erected with your own hands for any type of building. Usually, of course, such a solution is provided for small buildings made of wood, frame houses or foam block houses. But nevertheless, it sometimes occurs during the construction of rather massive brick structures. This especially occurs when it is necessary to lay the foundation quite deeply, which in the case of C will cost at least 1.5-2 times more.

In some cases, for a rather modest light construction becomes a kind of synonym for the phrase “unnecessary luxury.” And in reality this is so, since it is quite expensive, and in most cases it is possible to build a columnar foundation that will be no less strong and durable.

First you need to understand what a columnar foundation is. In itself, it is supports that are significantly deepened into the surface of the soil and protrude somewhat above the ground. It should also be noted that the upper level must be ideally the same for all supports. In addition, a mandatory requirement is to equip a grillage, which helps to distribute the load evenly.

It should be noted that there is a fairly wide variation in the materials used when making pillars, these can be:

Tree
Concrete
Asbestos cement
Rubble stone
Brick
Metal

Let's take a closer look at each type.

Wooden pillars for the foundation

Today, a material such as wood can rarely be found used for the manufacture of columnar foundations, which is due to its low durability.

In particular, it is used in the arrangement of small wooden buildings or in the construction of terraces. In this case, the diameter of each pillar should be 15-20 centimeters. Additionally, before being immersed in the ground, each support is treated with protective compounds that enhance resistance to moisture, corrosion and combustion. Additional waterproofing of the material is also provided; bitumen-based mastics are often used for this.

Brick columnar foundation

The next type is the arrangement of support pillars made of bricks. In particular, iron ore brick is widely used.

This material is used to construct shallow and shallow foundations, which are used during the construction of light buildings on hard rock soils. A prerequisite is that the pillars must be at least 38 centimeters wide (the pillar itself is square).

Concrete reinforced pillars

This option becomes the most common when arranging a columnar foundation, which is determined by its reliability. When considering the type of such pillars, it should be noted that they can be either monolithic structures or made from already prepared concrete blocks. The width of such a pillar should be at least 40 centimeters.

Pipe poles

And the last option is poles made of metal or asbestos-cement pipes. For the most part, the pipes themselves in this situation play the role of permanent formwork. Because the inside is reinforced and then filled with concrete.

Depth of columnar foundation

The calculation of the laying depth itself depends directly on the type of soil, in addition to the level of its freezing. Thus, it can be divided into two types:

Shallow, the depth of which is 40 centimeters.
Recessed, which is immersed in the soil 20-25 centimeters below the freezing level.

It should be noted that a buried foundation is quite often used in areas where the level of soil freezing reaches two meters, since the provision of other types of foundations in this situation is not possible. In this case, a columnar foundation is built in the standard way, laid 15-25 centimeters below the freezing level.

In this case, the optimal distance between the supports should also be taken into account, which also depends on the characteristics of the soil and ranges from one to two and a half meters.

Grillage

Considering the arrangement of the grillage, which is carried out after the full installation of the supports, in the case of using concrete, then strictly a month after the completion of the pouring work. It should be noted that either wooden or metal beams are used for it, which will subsequently act as a mortgage screw.

Quite often lately we have seen a monolithic concrete grillage, which is poured over the pillars into wooden formwork.

The grillage itself of a columnar foundation can be of two types:

Low, i.e. be located directly on the ground.
Tall, which protrudes at least 35 centimeters above ground level.

Arrangement of basements

It also becomes a rather important factor; in turn, the lack of possibility of arranging basements becomes a disadvantage. In some individual cases, fences are provided between the pillars to organize the fencing of the space. They are made of brick, and a rather important condition is the absence of connection with supporting structures, in order to avoid damage to their integrity.

It is also necessary to equip high-quality insulation and ventilation to ventilate the basement. But such implementation is possible only in individual cases, since quite often the construction of buildings on this type of foundation is carried out with the building being raised to a height of 1-2 meters.

Calculation of a columnar foundation, diagrams and drawings

Initially, it is necessary to carry out a full calculation and draw up project documentation. The best solution would be not to do this yourself, but to entrust this issue to specialists.

An approximate diagram of a columnar foundation looks like this:

Initially, a full calculation of the foundation is carried out, which will ultimately make it possible to calculate the number of required pillars, their dimensions, depth, and installation locations.

To obtain the most accurate data, you will need to fully examine the soil, finding out its type, level of freezing and other characteristics. If you carry out such a calculation yourself, it is recommended to use online calculators.

All data obtained during the study and calculations are entered into the design documentation.

So, it’s time to directly consider the technologies for constructing a columnar foundation

Do-it-yourself support-column foundation: step-by-step instructions

This type of foundation is a purely columnar structure with a grillage. The arrangement of such a load-bearing element is most appropriate for the construction of light structures on sandy soils.

All work is divided into several stages, including:

Carrying out earthworks.
Construction of foundation pillars.
Arrangement of the grillage.

Let's move on directly to the start of work.

Excavation

The first stage is carrying out excavation work. Initially, you should prepare the area. To do this, excess soil is removed and the surface is leveled.

Special attention is given to clayey soils, in this situation it will be necessary to remove a fairly large layer of soil, and then arrange a layer of sand.

The next step is to mark the area. Pegs and construction thread are used. With its help, markings are carried out in accordance with the working drawings. The thread is pulled into two strips parallel to each other, and the distance between them should be the size of the supports and, accordingly, the grillage. Particular attention must be paid to the corners; they must be absolutely even (i.e. 90 degrees). In addition, markings of walls, their intersections and junctions are carried out.

Based on the working drawings, in the places where the pillars should be installed, wells are constructed using a drill. Its diameter can range from 15 to 40 centimeters. At the same time, if the depth of the pillars is more than a meter, then it is necessary to carry out additional fixation of the soil to avoid crumbling. In our case, in addition to arranging the pits manually with a drill, it will be necessary to bring them to a square shape for laying pillars.

After which the bottom of the well is covered with sand, its layer should be approximately 10 centimeters. Next, a control verification of the location of the wells relative to the axes and their evenness is carried out.

The last step of such preparation will be pouring a layer of concrete of 10-15 centimeters, which will serve as a solid foundation for arranging this type of foundation. You can start working immediately after the concrete has completely dried, which takes 28-30 days.

Construction of a columnar foundation

Now let's move on to construction. In this case, brick will be used to construct the pillars.

So, we lay out the basis on which we will be equal. It is made in the form of a square with parameters of 38*38 centimeters. Then we lay out the pillar itself on it, up to 50 centimeters above the ground.

We form the pillar itself with a contour, so that there is free space inside. Next, reinforcement is carried out, with at least 1-2 rods tied together and inserted inside (ideally, this is 3-4 rods). After installing the frame, the space is filled with concrete.

After the concrete center has completely dried, it is necessary to waterproof the supporting structure. It is also necessary to check that all pillars are at the same level. After which the trenches are filled with soil.

In addition, thanks to its unique technology, the installation of a columnar foundation can be carried out using asbestos-cement pipes. Installation is carried out as follows:

The pipe is lowered into the prepared well and then filled with concrete.
The next step is to raise the pipe a little to allow the concrete to spread. This gives a good foundation and hold.
The next step, not reaching 10-15 centimeters from the edge, is to fill the pipe with an additional portion of concrete.

Grillage arrangement

Now we move on to arranging the grillage. It can be done using wooden beams. In this case, each of them should rest on the pole with its edge, and also be linked to another beam.

In addition, reinforced concrete grillage is often used. In this case, a wooden formwork is installed on top of the pillars, and reinforcement is provided inside it, the same type as for a strip foundation. Then it is filled with concrete.

Do-it-yourself columnar foundation: video instructions

Conclusion

First of all, it should be noted that there are significant savings when constructing a foundation of this type. Since you can complete it yourself in a few days, it will require less materials than when constructing other types of foundations. In addition, there is no need to hire construction crews.

A little advice: it is better to complete the construction before the onset of frost, or use concrete slabs, since it is unacceptable to leave the foundation unloaded for the winter. This may entail pushing the pillars out of the ground, as a result of which the foundation will need to be completely redone.

As for buildings, this type of foundation is suitable for building garages, terraces, small and light houses. That's all, you can also familiarize yourself with the technology of constructing other foundations and understand their types in our other articles.

In the article we will look at the columnar foundation of a house and describe the columnar strip foundation (column foundation with a grillage). We will tell you in what cases the construction of a columnar foundation is most applicable. The structure of a columnar foundation, recommendations and errors when installing a columnar foundation are described in separate parts.

General information about columnar foundations.

The preparation stages and manufacturing technology for a columnar foundation and a strip foundation are in many ways similar. Therefore, it is not advisable to repeat general provisions typical for the manufacture of foundations (assessment of soils, freezing depth, presence of groundwater and communications, preparatory work, installation of formwork, pouring concrete, possible errors during design and construction) in this article. To get acquainted with them, just refer to the article.

Along with an overview of all options for columnar foundations, we will focus on foundations made of prefabricated concrete and reinforced concrete blocks.

A columnar foundation is a system of pillars located in the corners and at the intersections of walls, as well as under heavy and load-bearing partitions, beams and other places of concentrated load of the building. To create conditions for the pillars to work together as a single structure and to increase the stability of columnar foundations, to avoid their horizontal displacement and overturning, as well as to arrange the supporting part of the base between the pillars, a grillage (tied beams, rand beams) is made.

The main type of columnar foundations used in mass construction are monolithic reinforced concrete foundations.

As a rule, the distance between the pillars is 1.5-2.5 m, but it can be more.

With a distance between pillars of 1.5-2.5 m. The grillage is an ordinary reinforced lintel. However, it cannot be combined into a single constructive solution attached terrace, veranda, porch. These rooms must have their own foundation, that is, they must be separated by an expansion joint, since the load from the porch is not comparable to the load from the walls of the house, and accordingly their settlement will be different.

You can read more about the design of such a seam in the topic .

When the distance between the foundation pillars is more than 2.5-3 m, the grillage is made from a more powerful, so-called rand beam. The rand beam is made in the form of a monolithic or prefabricated reinforced concrete beam. It can also be metal (I-beam, channel, profile).

for houses without basements with light walls (wooden, panel, frame);
under brick walls, when a deep foundation is required (1.6-2.0 meters, i.e. 20-30 cm below the depth of seasonal soil freezing) and a strip foundation is uneconomical;
when the soils during the operation of the building ensure that the settlement of the columnar foundation (at equal pressures of the pillars on the ground) is significantly less than that of a strip foundation;
when it is necessary to eliminate as much as possible the negative impact of frost heaving on the foundation, because columnar foundations are less susceptible to this phenomenon.

a - prefabricated-monolithic when the groundwater is located at the time of work below the base of the foundations;

b - prefabricated for any location of groundwater;

1. prefabricated reinforced concrete support column with a rod reinforcement cage;

2. the same, with a core made of steel pipe;

3. the same, with a rod reinforcement cage and a shell made of asbestos cement pipe;

4. the same, with a core made of steel pipe and a shell made of asbestos-cement pipe;

5. Prefabricated steel pipe support pole;

6. backfilling with excavated soil;

7. base plate made of monolithic reinforced concrete;

8. precast base plate reinforced concrete foundation;

9. sand cushion.

Let's consider several points in favor of using a columnar foundation:

If the cost of other types of foundations is 15-30% of the cost of the entire house, then the cost of a columnar foundation will be no more than 15-18%.
Columnar foundations are 1.5-2 times more economical than strip foundations in terms of material consumption and labor costs.
Columnar foundations have another positive quality, which is that the foundation soils under free-standing supports work better than under solid strip foundations, as a result of which the settlement under them at equal pressures on the ground is much less than that of strip foundations. Reducing the amount of settlement makes it possible to correspondingly increase the pressure on the ground by 20-25% and, consequently, reduce the total area of the foundation.
The most dangerous forces acting on the foundation of low-rise individual houses are the forces of frost heaving. Therefore, almost all of the given options for constructing foundations are considered from the point of view of their construction on heaving soils. It is generally accepted that when building on heaving soils, the depth of foundations should be lower than the calculated depth of seasonal freezing. However, for lightly loaded foundations of small houses, heaving forces usually exceed the total load from the house acting on the foundation, as a result of which various types of deformations occur.

Therefore, when building houses without basements on heaving soils, it is better to build shallow or non-buried foundations. Let us explain their differences.

Shallow foundations with a laying depth of 0.5-0.7 standard freezing depth are considered. For example, with a standard freezing depth of 140 cm, the depth of a shallow foundation will be 140x0.5 = 70 cm.
Non-buried foundations- foundations are considered to be those whose laying depth is 40-50 cm, and is on average half or a third of the freezing depth.

For large freezing depths in heaving soils, anchor columnar reinforced concrete monolithic or prefabricated foundations are effective. Such foundations are insignificantly affected by frost heaving forces acting on the side surface, since the pillars are made with a minimum cross-section. If the foundation is built from stone, brick, small blocks, or monolithic concrete without reinforcement, its walls must be made tapering upward, this will save material and evenly distribute the load from the walls.

Additional measures to reduce the influence of frost heaving forces can be: covering the side surfaces of the foundation with materials that reduce soil friction, such materials are bitumen mastic, plastic lubricants (synthetic grease “S”, CIATIM-201, BAM-3, BAM-4), organosilicon compounds , epoxy resins, furan-epoxy composition, polymer films, as well as insulation of the surface layer of soil around the foundation. The feasibility and options for such insulation are outlined in the question.

Conditions under which columnar foundations are not recommended:

in horizontally moving soils and weak soils, since their design is characterized by insufficient resistance to overturning. To compensate for lateral shear, a rigid reinforced concrete grillage(his device will negate the cost savings of the difference between columnar and tape).
Their use is limited on weak-bearing soils (peat, subsidence rocks, water-saturated clay, etc.) and in the construction of houses with heavy walls (massive brick thickness more than 510 mm, standard reinforced concrete slabs and blocks);
If you have limited financial capabilities or limited time period for installing a plinth. If with a strip foundation the base is formed as if by itself, then with a columnar foundation, filling the space between the pillars with a wall (taking in) is a complex and time-consuming task;
It is not recommended to install columnar foundations in areas with a sharp difference in heights (the height difference in the area under the foundation is 2.0 m or more).

Let's consider what materials a slab foundation can be made of, depending on the design of the house (primarily its mass and number of storeys):

The stone foundation is made from rubble stone or medium-sized flagstone. It is advisable to select a stone of the same size, and the flatter it is, the better.
It is advisable to make brick foundations from well-burnt red brick (black), preferably iron ore. Poorly fired bricks quickly collapse.
Concrete foundations are made of heavy concrete grades B15-B25;
Rubble concrete;
Monolithic reinforced concrete (a monolithic foundation has increased strength and has the longest service life - up to 150 years);
Ready-made prefabricated concrete and reinforced concrete blocks. In the prefabricated version, the poles are manufactured separately and mounted during installation.
asbestos-cement or metal pipes filled with concrete mixture.

concrete and rubble concrete - 400 mm;
masonry - 600 mm;
brickwork above ground level - 380 mm, and when tied with a pick-up - 250 mm;
from rubble - 400 mm;

Photo of a columnar foundation for a small private (country) house.

Information about the depth of laying columnar foundation supports

It is necessary to pay attention to three main points when determining the depth of laying a columnar foundation:

the depth of soil freezing in your area where the house is being built; (The best option is to lay the pillars below the freezing depth of the soil, thus eliminating deformation of the foundation)..
determination of the type and composition of the soil (fixed soil or mobile, clayey or sandy. The best soil sand can serve, since water drains through it instantly and it has a high load-bearing capacity; it is impossible to build on muddy and peat soils; it is necessary to arrange a partial or complete replacement of the soil with sand);
groundwater level (is there a pond or river nearby? If so, this indicates the presence high level groundwater, it is necessary to do waterproofing or drainage)

These factors must be taken into account in the house project you order.

Also, when calculating the foundation depth, the designer should take into account not only natural influences on the foundation, but also the following indicators:

the weight of the future house;
weight of foundation supports;
the weight of the furniture in the house and the number of people who will live in this house;
seasonal, temporary loads (snow).

It is advisable to contact a designer who has all the necessary data to carry out such calculations (groundwater level in your area, freezing depth, soil structure, etc.). The value of the designer's participation in the design process is that he will calculate the depth of the foundation with absolute accuracy (without excess depth margin). This will allow you to save money building materials, financial resources without compromising the quality and safety of the home.

Construction of a columnar foundation

In this section we will look at the technology for constructing a monolithic reinforced concrete columnar foundation as the most common type in private construction.

1. Preparatory work

Work must begin with cleaning the construction site. To do this, it is necessary to cut off the vegetation layer, preferably at least 2.0-5.0 meters in each direction from the planned location of the foundation. Its thickness is 10-30 cm, and it is not suitable for the base of the foundation. This soil needs to be cut and transferred to the vegetable garden or garden.

If the soil under the cut layer consists of sand mixed with small stones (gravel sand, coarse or medium-grained sand), then it is used as the base of the foundation, regardless of humidity, groundwater level or freezing depth.

If there are clayey soils (clays, loams, sandy loams), then a sand-gravel cushion must be installed. The thickness of the cushion depends on the geological characteristics of the soil.

If you find peaty or silty soils under the cut layer, then it is necessary to complete replacement foundation, in this case, you need to consult a geologist on the composition and design of the artificial foundation.

Garbage and all foreign objects are removed from the construction site.

After the construction site has been cleared, it is leveled. The mounds are removed and soil is poured into the existing holes. Control of the horizontality of the area is carried out with a level, which is installed on a 2-2.5 meter flat board or rail. Preparation ends with the delivery and storage of building materials to the site.

2. Foundation breakdown

The breakdown of the house plan on the site consists of transferring from the drawings to the land plot and fixing the axes and main dimensions of the foundation.

Before laying out the foundation of the house, pillars (cast-offs) are installed along its perimeter, at a distance of 1-2 m from the building. They are nailed level to the pillars on the side of the future walls of the house and parallel to them. wooden boards or slats on which the dimensions of individual parts of the pit (trenches and holes) and the foundation itself and future walls are marked. The accuracy of the center lines is controlled by accurately measuring distances with a tape measure. It is imperative to check the corners of a rectangular or square foundation; they must be strictly straight at 90 degrees. Be sure to check the mark of the bottom of the trench with a theodolite, at least at the corners of the house and at the points where the tapes intersect. It must correspond to the design (that is, if you decide to deepen the foundations by 1.4 m, then the bottom of the trench should be 1.4 m below the zero level of the house).

Check the correctness of the axes, their intersections, the angles must be strictly the same as on the house plan.

As mentioned above, pillars should be under each crosshair of the walls.

The pillow is poured generously with water and compacted using a hand tamper. To prevent water from escaping from the poured concrete, polyethylene or roofing felt is placed on the cushion.

4. Installation of formwork

For the manufacture of formwork, boards of any type of wood, 25...40 mm thick and 120...150 mm wide, are used, planed on one side (the planed part is installed facing the concrete). Lumber for formwork should have a moisture content of up to 25%. Wide boards for formwork, as a rule, are not suitable, since cracks appear during their installation. You can also use particle boards, metal constructions, waterproof plywood.

Wooden formwork is preferable to metal formwork, as it is lighter and has less adhesion to concrete. The disadvantages of wooden formwork include the possibility of its deformation and hygroscopicity. The formwork is installed close to the walls of the pit, strictly perpendicular to the base of the foundation, checking this with a plumb line.

In some cases, if the walls of the pit are dry and do not collapse, concrete can be poured without formwork. At the same time, polyethylene is laid around the perimeter so that water does not escape from the concrete.

You can also use asbestos, ceramic, and iron pipes in the form of formwork. Depending on the design of the building, pipes with an internal diameter of 100 mm or more can be used. Concrete is poured directly into the pipes, and they remain in the ground along with the foundation.

When installing wooden formwork, you must remember that the boards must be damp, for which they are well moistened. Otherwise (dry boards) will absorb water, which negatively affects the strength properties of concrete.

If it is possible to use ready-made panel formwork, then this is a plus. Such formworks have a large number of options for their installation, which is very convenient when constructing foundations with a large number of angles. Inventory formwork panels can be rigid or flexible, their length can be from 0.5 to 3 m.

5. Installation of fittings

The pillars are reinforced with longitudinal reinforcement with a diameter of 10-12 mm with a mandatory device, through 20-25 cm of clamps with a diameter of 6 mm. They are installed vertically and secured with clamps or annealed wire to prevent them from diverging to the side. It is advisable to ensure that the reinforcement extends above the top of the foundation (as shown in the figure) by 10-20 cm, so that the reinforcement of the monolithic grillage can then be welded to them.

Photo of columnar foundation reinforcement.

6. Concrete supply

Everything here is the same as in strip foundations, concrete is laid in layers of 20-30 cm with vibration using hand-held vibrators.

Photo of concrete being fed into the pillar formwork.

7. Grillage arrangement

The grillage can be made in the form of a monolithic or prefabricated reinforced concrete rand beam.

After completing the installation of columnar foundations, check the marks of the top of the columns and, if necessary, level them with a cement mortar of a 1:2 composition. After this, they begin to construct a prefabricated, precast-monolithic or monolithic reinforced concrete belt (grillage).

The installation of a monolithic belt will ensure proper longitudinal rigidity and stability of the foundation. Before installing the belt, the prefabricated jumpers must be securely connected to each other. To do this, the mounting loops are tied crosswise with twisted wire or connected by welding cuttings of reinforcement with a diameter of 8-10 mm. Then formwork is placed on top of the lintels, a reinforcement cage is installed, and M200 concrete mixture is laid.

Photo of the grillage arrangement for a columnar foundation.

The concrete surface is leveled and covered with any waterproofing material for protection from atmospheric influences. After gaining strength and waterproofing, you can begin installing the floor slabs.

8. Pickup device

When installing columnar foundations to insulate the underground space and protect it from debris, snow, moisture, dust, cold air, etc. a fence is installed, a fencing wall between the pillars. The pick-up can be made from various materials, most often made of stone or brick.

To install a fence between the supports of a columnar foundation, it is necessary to make a concrete screed that will serve as its foundation. The concrete screed does not have a depth; it is placed on a sand cushion, which has a depth of 15 to 20 cm. To install a concrete screed, you will need formwork and a frame made of reinforcement, to prevent possible rupture of the screed due to soil movements.

Place the screed on the concrete screed. As in the plinth, technological windows are made in the inlet for supplying various communications. The pick-up is not connected to the supports, since uneven settlement can lead to the formation of cracks.

The height of the fence must be at least 40 cm. The degree of exposure to moisture on the walls of the house depends on the height of the fence; the higher the fence, the less exposure to moisture on the walls of the house. Also, a house with a low base looks squat; visually it may seem that such a house has no foundation and is built directly on the ground, but houses with a high base look much more attractive and reliable. In this case, the height of the supports must correspond to the height of the base. More details about the design of the plinth can be found in the article

9. Foundation waterproofing

Foundation waterproofing can be done in one of the following ways:

Apply a layer of bitumen to the top of the supports and the fence. Lay a strip of roofing felt on this layer and again apply a layer of bitumen, after which you lay another strip of roofing felt;
On the top of the supports and backfill, apply a layer of cement mortar, in which the ratio of cement to sand is 1:2. After you have leveled the mortar, sprinkle dry cement on top - the layer thickness is from 2 mm to 3 mm. After letting the cement “set”, lay the strip roll material(roofing felt or roofing felt).

How to perform such waterproofing, and with what materials, you can read in the article .

Important points when building a columnar foundation

When constructing foundations on heaving soils, it is necessary to have a clear understanding that the construction of a house and its commissioning must be carried out in one construction season. Foundations built on heaving soils and left to winter time without load (without walls, ceilings and roofs), they can become deformed. This is true for all types of foundations, but is especially important for columnar foundations, since each column behaves like a separate foundation (due to the absence of a single rigid frame, unlike a strip or slab foundation). Each pillar gives its own settlement, which in the future (after frost - in the spring) can complicate the construction of the grillage and walls.
Unforeseen deformations can also occur when the built house is not used or heated in winter, and the depth of the foundation was designed for the thermal conditions of the heated house. A favorable time period for laying a foundation is considered to be the period of time when the soil has “moved away” from frost and groundwater descended to the lower layers. This could be the summer months and early autumn.
If you have made the supports of a columnar foundation from monolithic concrete, then you should know that the “readiness” of the concrete is achieved after 30 days. During the entire “maturation” period, no loads should be placed on the concrete supports, and care should also be taken to ensure that the top layer of concrete does not dry out. To do this, you can cover it with film or roofing felt. To ensure that the concrete sets evenly, the supports should be moistened with water from time to time (two or three times a week, depending on weather conditions).
To prepare concrete, it is best for you to use M400 cement. Fine gravel and coarse sand can be used for concrete filler.
An example of calculating components for preparing a concrete mixture:
- cement 20 kg;
- sand 50-55 kg;
- gravel* (crushed stone) 80-85 kg.
Water is added so that the concrete mixture can be easily laid - but not poured!
If the composition of the concrete mixture is too liquid or, on the contrary, too thick, then the strength of the concrete structure is reduced by 25% of the strength of the same structure, during the manufacture of which all the requirements for the proportionality of the components were met.

What mistakes can occur when laying a foundation and how to avoid them

Many developers who decide to build a house on their own often make a number of mistakes when laying the foundation, which lead to varying degrees of damage to the foundation and walls of the house. These errors can be systematized as follows:

An insidious defect of the foundation is the unevenness of its subsidence. This can occur for a number of reasons, which include:
- the foundation depth was not calculated correctly;
- the supports have different depths.
- The load on the foundation supports is uneven.
To eliminate this phenomenon, it is necessary to perform an accurate calculation of the systematic distribution of the load on the foundation. Do not forget to take into account the load on the foundation when adding a second level to the house (for example, building an attic);
The material used was of low quality - the wrong brand of cement, sand that contained an admixture of clay, etc. Or a material, for example cement, has a long shelf life (it should be recalled that when stored for six months, its grade decreases by 25%, and when stored for a year or more by 35-50%);
The load-bearing properties of the soil were not assessed correctly.
A correctly completed project by specialists and constant monitoring of construction by you or an independent expert will help you avoid these mistakes.

Estimated cost of a columnar foundation

Note from the editor: Prices in this article are as of May 2009. Be careful.

The cost of a columnar foundation is determined by the technology of laying the foundation and its depth and consists of the following components:

Prices for laying the foundation:

installation of a sand base 100 mm thick - 80-100 UAH/m2 (or 10-13 US dollars);
construction of a crushed stone base (depending on the fraction) - 80-100 UAH/m2 (or 10-13 US dollars);
concrete preparation device (with a thickness of 10 cm); - 100-120 UAH/m3 (or 13-16 US dollars);
laying reinforced concrete pads or blocks - 160-180 UAH/piece (or 21-24 US dollars);
installation of monolithic reinforced concrete foundation walls - 1300-1500 UAH/m3 (or 179-198 US dollars).

Prices for masonry work:

rubble foundation masonry - 300 UAH/m3 (or 40 US dollars);
laying brick pillars - 250 UAH/m3 (or 33 US dollars);
walls - 600 UAH/m3 (or 80 USD).

Prices for floor installation:

monolithic device reinforced concrete floor(formwork, reinforcement, concreting) - 1300-1500 UAH/m3 (or 170-198 US dollars).

Relationship between contractor and customer.

It would not be amiss to remind you that if the construction of a house is carried out by a construction organization (contractor), then the relationship between you should be built only on a contractual basis.

A construction contract is the main document of the relationship, which stipulates the terms of cooperation, the cost of work, the start and end dates of construction, etc.

The estimate is an integral part of the Construction Contract. It describes all types and costs of work and materials.

The work schedule must include deadlines for completing the work and payment terms for the stages of work.

The contract must also provide for project documents: architectural project object, structural sections of the project and other documents necessary for construction.

For an overview of the types of foundations for a house, read the article.