The distance between pillars in a columnar foundation. Do-it-yourself columnar foundation for a house, step-by-step instructions. Installation of formwork and reinforcing frame

Almost all happy owners of private houses, cottages or country houses would like to have a separate bathhouse on their property. To build it, you can use the services of professional builders or build a bathhouse yourself.

The basis for the strength and durability of every building is undoubtedly the foundation. Often, wooden material is used to build a bathhouse - logs or timber, which makes the construction quite light. That is why it is advisable to build a bathhouse on a columnar foundation, which consists of support pillars buried in the soil made of various materials. Such supports can be mounted from wood, brick, stone, pipes, foundation blocks, reinforced concrete.

Columnar foundation - diagram

Before starting work, it is necessary to clean and level the site for future construction. To do this, we remove the top layer of soil (about 30 centimeters) under the planned building along with all the vegetation.

Then it is necessary to level out all the holes and irregularities as much as possible, and if the soil is clayey, add sand and gravel.

Next, we transfer the plan of the bathhouse directly to the land plot, using a tape measure, a building level, ordinary wooden or metal pegs and construction thread to mark the axes. If the site is located in an area that has a significant difference in height between the sides, then to determine the height of the foundation pillars, it is advisable to use the help of a professional and level the surface. This is a guarantee that the future bath will not have distortions.

Excavation

Regardless of the choice of material for installing columnar supports, all foundations of this type are mounted according to a similar principle (except for the option with a grillage). This also applies to excavation work, before starting which you need to determine the type of soil, proximity to the surface of groundwater and the depth of its freezing.

These factors directly affect the installation depth of the support pillars. To determine the type of soil and groundwater level, you need to dig a hole at least 1-1.2 meters deep (optimally). If there is no groundwater at this depth, and the soil is not heaving - freezing, then this depth is quite sufficient for a columnar foundation of a bathhouse.

Otherwise, you need to dig to a dense, incompressible layer of soil, focusing on the following indicator: freezing depth + 40 centimeters. It must be remembered that heaving soils include those that contain clay. And the more it is contained, the more prone the earth is to freezing. If these conditions are not met, then under the influence of water or sub-zero temperatures the foundation may not only crack or deform, but also completely collapse.

Columnar foundation supports must be located at the corners of the building, at the intersection of walls, along the entire perimeter and under the partitions every 1.5-2.0 meters, depending on the total weight of the structure. Holes for supports can be dug with a shovel, or you can use a special hand-held cone-shaped drill of the required diameter, thanks to which it is possible to obtain the most even holes.

Based on what material will be used for the construction of the columnar foundation, the required diameter of the holes is determined, which should be 7-10 centimeters larger than the following parameters:

• for pillars made of brick and stone, the optimal size is 50x50 centimeters;
• for pillars made of rubble stone - 60x60 centimeters;
• for asbestos-cement pipes Ø200 mm;
• for reinforced concrete supports 30-35 centimeters is enough;
• for intermediate ones it is 25-30 centimeters.

We pour about 20 centimeters of sand into the bottom of each prepared hole, add a little water and tamp it thoroughly, thus obtaining the desired sand cushion. At this point, the preparatory and excavation work is completed. You can begin directly constructing a columnar foundation from the selected material.

Columnar foundation made of pipes

The best option for a columnar foundation of a bathhouse is metal or asbestos-cement pipes Ø200 millimeters, which can be easily cut with a grinder into pieces of the required length. It should be taken into account that a pole made of a pipe should protrude above the surface by approximately 0.4 meters.

Pipes must be protected from moisture and other negative factors. To do this, you need to make waterproofing - wrap the surface of the pipe with roofing material with bitumen, lining waterproofing materials, or treat it with special mastics.

The prepared pipes are carefully and evenly lowered into each hole.

The gap between the pipe wall and the soil is filled with previously dug earth or sand and gravel (layer thickness 40-50 centimeters), which it is advisable to compact thoroughly.

Reinforcing rods Ø12-14 millimeters should be inserted into the middle of the installed pipes at a distance of 7 centimeters from each other, which act as a reinforcing frame. Since the reinforcement must protrude above the finished pillars, its length should be 20% greater than the size of the pipe.

Having carried out these preparatory work, you can begin pouring the foundation pillars. The best option is concrete grade M400. It can be ordered from specialized enterprises or made yourself using a concrete mixer. When making it yourself, it is enough to use M400 cement, coarse sand, fine and medium gravel, which must be mixed in a ratio of 1: 1.5: 3. The required amount of water is 0.4 part of the amount of cement taken.

The process of pouring the concrete mixture itself occurs in several stages (see table).

We cover the piles made in this way with film and let them stand for 7-10 days. During this time, the concrete gains the necessary strength and the construction of the bathhouse can continue.

This method of constructing columnar foundations is one of the most popular due to its high reliability, relative cheapness, and speed of installation with minimal skills.

Prices for asbestos-cement non-pressure pipes

asbestos-cement non-pressure pipes

Preparatory and excavation work before arranging a columnar brick foundation is similar to working with pipes. But for the convenience of the master, holes for future pillars will not have to be drilled, but dug manually or using machinery, which is much faster, but also more expensive. At the same time, do not forget to slightly increase the volume for ease of operation.

We fill the bottom of the prepared pit with a fifteen- to twenty-centimeter layer of sand, which we compact, forming a sand cushion. On top of it it is necessary to pour a concrete base, reinforced with a mesh of reinforcement. To make the mesh, we take reinforcing bars with a cross-section of 12-14 millimeters, cut to the parameters of the pit. We lay them perpendicularly, forming square cells, the intersections of which are fastened with thin knitting wire with a diameter of 2-3 millimeters. For ease of knitting, you can use a special hook, which is worth purchasing at a hardware store. The thickness of the concrete base (M400) together with the reinforcing mesh should not be more than 20 centimeters.

Columnar brick foundation - diagram

After giving the concrete a few days to gain strength, you can proceed directly to the brickwork. It is necessary to take into account that hollow bricks are completely unsuitable for this. It would be optimal to use solid ceramic bricks (for example, M-100), which have the necessary strength and resistance to low temperatures.

When making brickwork, it is advisable to check each row with a level. This will allow you to get an even column. For greater strength of the pillars, you can lay a mesh of reinforcement after 3-4 rows of bricks. We bury the brick support of the foundation 15-20 centimeters above ground level and protect it with waterproofing material - mastic or roofing felt with hot bitumen. After 5-7 days, we fill the finished brick pillar with earth, which we compact thoroughly.

Despite the popularity of this columnar foundation, it has its drawbacks. The seams between the bricks make such a support quite fragile and under the influence of unfavorable factors it can be destroyed.

Brick prices

For its production, industrial concrete foundation blocks are used. Most often we use a solid block or with minor voids measuring 20x20x40 centimeters.

This is a durable building material that can withstand significant loads. A columnar foundation made of blocks is mounted similarly to brick supports, taking into account some differences:

• due to the greater weight of the blocks, the thickness of the monolithic reinforced concrete base on top of the sand cushion varies from 50 to 70 centimeters;
• It is permissible to make it from coarse and medium fraction crushed stone instead of sand bedding. This helps remove any moisture present;
• before installing the first row of blocks, it is necessary to make a cushion of mortar, on which the building material should be installed;
• the row being installed must consist of at least two blocks. Each subsequent one is installed perpendicular to the previous one and fastened to it with ordinary cement mortar for masonry.

The last row of blocks is mounted 20-30 centimeters above the ground and covered with waterproofing material to protect the seams and the blocks themselves from moisture and low temperature conditions, which together can lead to the destruction of a columnar foundation of this type. When laying blocks on the surface, you need to carefully control their location relative to the marked axes of the future bathhouse building. We fill the gap around the mounted block supports back with previously dug soil, which we also tamp.

Block foundation - photo

Laying blocks on a sloping area requires special attention. Under no circumstances should block supports be laid at the same depth. This can lead to subsequent distortion of the bathhouse and destruction of the columnar foundation.

Concrete columnar foundation

A reinforced monolithic columnar concrete foundation is considered the strongest and most reliable.

To manufacture it, we carry out preparatory and excavation work in accordance with general technology. From reinforcement Ø12-14 millimeters we make round and square frames (we use 3 or 4 rods, respectively) of the required length, taking into account the protrusion above the post by 15-20 centimeters. To do this, we connect the rods with thin wire to round or square rings bent from smooth reinforcement Ø6-8 millimeters.

It is possible to fill a foundation pillar of the required size only with the help of formwork, which should be made from edged boards, wood chips and other suitable materials. However, this method is quite time-consuming, labor-intensive and financially expensive.

At the bottom of the prepared pit, pour a layer of 10-20 centimeters and compact it with a sand cushion, on top of which we lay roofing material or polyethylene, which is necessary to retain moisture in the poured concrete.

We immerse the assembled formwork into the hole and install a reinforced frame there.

Columnar foundation - formwork and reinforcement diagram

We pour concrete grade 400 into the formwork, which is prepared from cement grade M 400, coarse sand, fine and medium gravel, mixed in a ratio of 1:1.5:3 with water in the amount of 0.4 parts of the cement used.

Every 30-35 centimeters of pouring we tamp the concrete, removing air.

We cover the finished support with film and let it sit for several days, after which we remove the formwork from the hardened concrete.

We cover the finished supports with waterproofing materials and fill the sinuses with previously dug earth.

To reduce costs and time when arranging a columnar foundation for a concrete bathhouse, instead of rigid formwork, you can use permanent soft formwork, which is a roofing material with a fiberglass mesh. In this case, holes for the support must be made using a drill of the appropriate size. Having cut the roofing material to the required length, twist it and install it in the prepared hole. At the same time, a sand cushion and a bottom insulating layer are also necessary. Next, we install the reinforced frame and pour concrete as with removable formwork. Using this material, we obtain a finished pile, immediately covered with waterproofing material. And immediately after the concrete gains strength, the next stage of work can be carried out.

Photo – pouring process

Prices for roofing material

roofing felt

Video - Pouring a columnar foundation

When constructing a heavier bathhouse building (for example, made of brick) or if you want to equip a basement, you can mount a columnar foundation with a grillage. This is a monolithic reinforced concrete strip structure that connects the top points of all foundation elements buried in the ground.

To fill the grillage, you will need formwork material: edged board with a thickness of 20 to 40 millimeters, plywood, OSB or other similar building material. As well as reinforcement with a cross-section of 10-12 millimeters and concrete of at least grade 150. Most often, grade 200 concrete is used to fill the grillage, and if you make it yourself, you need to mix M400 cement, coarse sand and medium or fine crushed stone in a ratio of 1:2, 5:4,5.

Let's calculate the amount of lumber for formwork. It must be taken into account that the height of the grillage should be at least 0.3 meters, and its width should be 10 centimeters greater than the width of the manufactured columnar supports.

1. We determine the immediate height of the grillage and add another 0.2 meters to it since the height of the formwork must be greater than the level of concrete poured into it.
2. We fix the thickness of the formwork material in meters.
3. We measure the total length of the future grillage.
4. We multiply all the obtained parameters together and get the required amount of material for formwork in cubic meters.

From the prepared lumber we knock down the formwork box. In its lower part, holes should be cut for the previously made pillars, which should rise slightly above the lower part of the formwork.

Video - Installation of formwork

From reinforcement rods it is necessary to make frames with transverse square clamps, which can be bent from thinner smooth reinforcement or from wire Ø6-8 mm. They will give the necessary strength and reliability to the structure. Every 30-35 centimeters we connect clamps and reinforcement rods with knitting wire in an amount equal to the entire perimeter of the grillage. We calculate the size of the frame in such a way that there is 5-7 centimeters from it to the walls of the formwork.

If the finished foundation pillars are located at a considerable distance from each other, then for reliability you can strengthen the formwork with wooden supports, which must be installed strictly horizontally.

Before pouring concrete into the formwork box, we will install a reinforcing frame, fixing its lower part to the reinforcement protruding from the columns.

Video - Columnar foundation. Formwork, reinforcement, pouring

If pouring is done from a concrete mixer truck, then pour the entire concrete mixture at once, removing air with a construction vibrator, a reinforcement rod, or simply using a shovel.

If you have to mix the concrete yourself and the pouring takes several days, then:

• at one time we fill in part of the grillage, divided vertically, not forgetting to remove the air;
• Before pouring the next part, the edge of the finished block with already hardened concrete is generously moistened with water.

Fill the formwork completely with concrete mixture, cover it with film and let it stand for several days. Then we carefully remove the wooden box and our hanging grillage is ready.

It is worth noting that regardless of the material used to construct the columnar foundation, this version of the foundation for a future bathhouse is more reliable than the traditional strip one, and at the same time is much cheaper (almost half).

Video - Pile-grillage foundation

Video - Nuances of constructing a pile-grillage foundation

The durability of each building directly depends on the strength of the foundation underneath it. But is it always justified to install a massive continuous foundation strip if you plan to build a light wooden or frame building? Increasingly, in this case, a columnar foundation that is less expensive and can fully withstand the expected load is installed. Support pillars are made from various materials, using different methods and technologies. Next we will talk about the foundation of the building, made of concrete pillars.

Features of a columnar base

Such a foundation resembles a pile foundation, with the difference that the finished piles are driven (screwed) into the ground, and the pillars are poured or laid out in place in prepared recesses. A base made in this way makes the work much cheaper and less labor-intensive.

However, a columnar foundation is not always suitable. If the mass of the above-ground part of the building is significant (the walls are made of brick, concrete, cinder block or other heavy building material), a large area of ​​​​support on the ground is assumed. In this case, it is better to prefer the construction of a buried or shallow (depending on the soil structure) strip base with a sufficient base area.

If the house is supposed to be built from light building materials (wood, foam concrete, materials for frame construction), a columnar foundation, or rather the area of ​​its support on the ground, is sufficient.

Important! The area of ​​the base of the columnar foundation is also calculated. This indicator is regulated by the number of vertical supports and their own transverse area.

A symbiosis between the strip version of the house foundation and the columnar one is the columnar-grillage foundation, when the vertical supports are additionally reinforced and connected to each other by a shallow reinforced concrete strip. This is done not only to strengthen the pillars, but also in situations where the usual shallow strip foundation of a building may be unreliable due to loose or heaving-prone soils on the site. In this case, the pillars, resting their soles on deeper and more reliable soil layers, act as piles that strengthen the main belt.

Advantages and disadvantages of a pillar foundation

The installation of concrete piles has a number of obvious advantages, such as:

• relatively low consumption of materials;
• much less labor intensive (compared to a strip base);
• greater efficiency and strength in waterlogged, loose soils and those prone to heaving;
• the ability to combine with other foundation structures.

However, there are also disadvantages that limit the construction of a columnar foundation in some cases:

• cannot be constructed in case of a large expected load on the foundation (heavy buildings);
• impossibility of constructing a basement;
• instability to horizontal movements of soil layers;
• void under the base floor (to cover it, a fence is constructed around the perimeter of the base).

That is, the construction of a foundation structure from pillars, including concrete ones, is not always permissible, but only under certain conditions. However, taking into account the trend towards accelerated construction of buildings from lightweight materials, the construction of inexpensive foundations from pillars is becoming more relevant every year.

Principles for calculating a columnar foundation

The construction of such a foundation for construction also requires calculations. It is necessary to calculate the number of support pillars, their location and the total area of ​​support on the ground.

The supports are arranged according to this principle. The pillars must be at the corners of the building and in places where the piers adjoin the external walls. The location of the remaining pillars depends on the calculations of the load on the base. However, regardless of the calculated area of ​​the sole, the distance between adjacent supports should not exceed 2-2.5 m (depending on the chosen grillage design). The minimum appropriate distance between pillars is 1 m.

If the calculation of the required total area of ​​the foundation base shows the need to further reduce the distance between the supporting structures, it means that a columnar foundation may be ineffective for the mass of a given building. In this case, it is better to choose a strip foundation for the building or its combination with pillars or piles (if the type of soil does not allow pouring a simple shallow concrete strip).

Methods for pouring concrete pillars

Before proceeding with the installation of concrete foundation supports, the site for construction is marked according to the project. With the help of stretched threads, external contours and right angles are formed. If it is planned to install a column-grillage foundation, the inner perimeter corresponding to the edge of the trench is also hammered out with threads, after which the latter is dug to the calculated depth.

The most common way to construct pillars is to pour concrete into pre-prepared forms. The process looks like this.

1. Along the perimeter of the future foundation of the building, the installation locations of the supports are marked according to the calculations performed.
2. The holes are prepared using a hand drill. Their depth depends on the degree of soil freezing in the region and the level of occurrence of stable soil layers. Even if the stable soil is shallow, the base of the pillar is 15-25 cm below the freezing level. The diameter of the supports must correspond to the calculated area of ​​each pillar.
3. A cylinder (2 layers) is formed from rolled waterproofing material (roofing felt, waterproofing), 3-4 cm deep into the already prepared recess. The longitudinal joint is secured with tape, and several fixing stitches are made around the prepared cylinder.
4. The form for pouring concrete is placed in a recess, and a sand and gravel cushion is poured onto the bottom. A reinforcing structure formed from several metal rods is welded or twisted with knitting wire. One reinforcement, usually the central one, is made 30-40 cm longer than the others so that it protrudes beyond the head of the cylinder. It will be connected into one structure with the reinforcing frame of the concrete strip.
5. The pipe formed from waterproofing material is gradually filled with liquid concrete. It is advisable to shake the cement mortar layer by layer using a vibrating device. The upper edges of the poured pillars must be located in the same horizontal direction, for which purpose the pipes are aligned using a water (laser) level before pouring. The poured pillars are allowed to stand until the concrete has completely set, after which they move on to constructing a grillage.

The most common method of arranging supports is described above. As an option, they often use ready-made pipes (PVC sewer pipes) or lay out pillars from ready-made concrete blocks. The second method is more labor-intensive, since you have to dig a hole under each post. With a large depth of placement of the base of the pillar, this is very inconvenient.

Options for grillage installation

One option is to pour a shallow concrete foundation tied and supported by columnar supports. To fill it, a trench is dug (as described above) and vertical wooden formwork is installed around the perimeter of the future building and under the internal walls.

Before pouring the tape, a reinforcing structure must be formed, which is connected to the protruding reinforcement of the pillars. This results in a monolithic structure, where a surface-constructed concrete strip rests on formed pillars. This achieves the following goals:

• cheaper design (compared to the installation of a buried belt);
• sufficient strength of the base;
• a solid base for the construction of walls (there is no need to make a fence between the supports).

After reinforcement, the formwork cavity is filled with concrete, and when it hardens, the wooden enclosing structure is dismantled. Before starting the construction of wall structures, the concrete is allowed to gain strength (mature), after which the foundation surface is waterproofed.

The second option for a grillage is to install wooden logs (beams) on top of the pillars. This design is prepared for lightweight frame, frame-panel type buildings or wooden houses. In this case, an empty space is formed between the bottom of the house and the ground surface. In order to protect the lower structures from weather influences and to improve the overall appearance of the building, a fence is made between the supports - a fence that covers the space between the ground surface and the bottom of the walls.

Collection device options

Nowadays, fencing the space between foundation pillars is done in several ways using various materials. Wood is often used to cover the base between the pillars under a wooden house. Also used as building materials:

• brick (masonry);
• concrete (pouring with reinforcement);
• sheet materials (corrugated sheets, flat slate, dense insulation (extruded polystyrene foam).

The peculiarity of the construction of the fence is that the structure should not be rigidly connected to the foundation supports and have ventilation holes. The first condition is met so that the enclosing structure does not collapse due to possible settlement of the foundation and ground movement. Ventilation holes prevent excess moisture from accumulating in the space under the building, which has a detrimental effect on building structures. One of the most popular options is to make a wooden fence like this.

1. Between the pillars along the perimeter, a trench is dug about 30 cm deep at the lowest point of the ground. The bottom of the ditch is covered with crushed stone and sand and a beam (log) is placed on the formed cushion after it has been compacted and leveled. The second beam is attached to the bottom of the building’s perimeter wall.
2. Boards are vertically attached to the beams and protected with waterproofing material from below to ground level. Afterwards, the trench is filled with crushed stone or expanded clay and concreted on top.
3. The above-ground part of the boardwalk is processed and painted or sheathed with some external finishing material. If cladding is intended, the boards are not attached continuously, but with a certain step, forming a sheathing for fixing the finishing material.

A columnar foundation made of concrete supports costs owners about half as much as a strip foundation, even taking into account the need for a back-up device. In terms of strength, the foundation of the building, made of pillars, is not inferior to a solid reinforced concrete strip.

One of the popular foundations for small houses and outbuildings is 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 of columnar foundations - possible uneven shrinkage of the supports.

When constructing 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, mineral wool cardboard 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:

• installation of a fence - 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 built 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 of the 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 construction of a 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 pole. 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.

This material is devoted to pouring a columnar foundation with your own hands with step-by-step instructions. Let us immediately clarify that such a structure consists of pillars that are installed at the junctions of the internal partitions of the building and at its corners. Such foundations are often found in the construction of frame, wooden or foam block houses, as well as other utility rooms (baths, summer kitchens, sheds) that are light in weight.

The technology for their creation is quite simple, so even a beginner can install a columnar foundation with his own hands, without the help of professionals. We will tell novice builders how to complete all the steps, and step-by-step instructions will help us with this.

Varieties

To begin with, we note that a columnar foundation can be qualified according to several parameters. So, according to the manufacturing method, it can be:

• monolithic - that is, created from seamless concrete pillars reinforced with reinforcement;
• prefabricated - consisting of bricks, stone or reinforced concrete blocks;
• wooden - consisting of wooden posts dug into the ground.

A monolithic foundation is more durable, while a prefabricated foundation is installed much faster, but otherwise their scope and functions are the same. The duration of the operational period of the base is directly affected by the depth parameters calculated taking into account the characteristics of the soil. Regarding the laying depth, the foundation can be:

1. Recessed. Mounted 0.5 m below the soil freezing zone, recommended for clay soil with high humidity.
2. Shallow. In this case, the pillars are installed in the ground to a depth of 40 to 70 cm. This difference depends on the composition of the soil and the final mass of the building being erected.
3. Unrecessed columnar foundation. It consists of short supports, the distance between which is 1-2m.

Step by step instructions

1. Before making a columnar foundation with a grillage, it is necessary to prepare the site at the site where it will be constructed, for which purpose all vegetation is removed from the intended area and the turf is removed (25-30 cm and 45-50 cm for clay soil). Then all the depressions and irregularities are covered with sand and gravel.
2. After laying the sand and gravel cushion, mark out the dimensions according to which the support columnar foundation will be poured with your own hands. At this stage you will need pegs and cord. With their help, it is necessary to mark the distance between future pillars strictly according to the diagram (no more than 2 m). The main rule of this step is accuracy, and it must be strictly observed.
3. In order for the columnar block foundation to be securely anchored in the ground, you need to dig holes for the piles. Depending on the type of soil and base material, the depth can vary from 30 cm or more relative to the limits of the base (gap for a cushion of sand and gravel). It is recommended to strengthen deep wells (from 1 m) with special wooden supports.

Further, step-by-step instructions for installing a shallow support columnar foundation will differ depending on what design features need to be implemented, as well as on the material of the support pillars.

A grillage is a structure that is placed on the surface of the pillars and connects their upper parts to each other. It also serves as the basis for the load-bearing walls of the building.

Reinforced concrete columnar foundation with a grillage is the most popular among developers, because it is reliable and strong. Here, the pits for supports should exceed in width the similar parameters of the columns (the difference between them will be at least 15 cm). It is necessary to install wooden formwork in these recesses, which must be reinforced with reinforcement and concreted. After the solution hardens, the pillars are connected with a grillage - reinforced concrete, metal or wood. This method has its drawbacks, since the technology for its production is quite labor-intensive.

Shallow columnar block foundation(20x20x40 cm) has its advantages, but it also has disadvantages. The advantages of such structures include accessibility and ease of installation, while the disadvantages are lower strength compared to the previous version, which is why it is categorically not recommended to make them on moving soils. Their installation technology looks like this:

• the width of the recesses is 40 cm;
• gravel and sand are poured into the pits in layers;
• 4 blocks are installed (one on top of the other), fastened together with cement mass.

A grillage columnar foundation made of blocks can be installed on a reinforced concrete slab, which serves as additional support. The advantage of this solution is that it prevents soil subsidence.

Brick support-column foundation, as the name suggests, is assembled from brick and reinforced with metal mesh. Such structures must be equipped with roofing felt or bitumen waterproofing. The base of asbestos pipes implies the installation of permanent formwork. Using the same principle, a shallow foundation is assembled from steel pipes or screw piles.

Columnar bases are assembled according to the following scheme:

1. Wells are drilled in the ground, with a diameter 5 cm larger than the piles themselves. If you plan to build a lightweight house, you can limit yourself to supports with a diameter of 20 cm. Before vertical installation of the pillars, the bottom of the wells must be tightly compacted, and the pillars themselves are compacted with sand and earth.
2. Concrete is poured to a third of the depth of the piles, then they are raised so that the solution evenly covers the bottom and gives the support additional strength.
3. A reinforced frame is placed inside all pipes with the condition that the rods protrude 20 cm from the hole. The remainder of the solution is laid in layers to the zero mark, and it is correct to subject the base to periodic vibratory compaction.

It is not recommended to leave a grillage foundation made of pipes unloaded for a long time, otherwise the soil may push the piles out and their depth will be uneven. No more than 3 days should pass between the installation of supports and further construction from the moment the solution hardens.

Wooden shallow columnar foundation assembled from beams pre-treated with antiseptic agents. The diameter of the supports must be at least 20 cm, otherwise the house will tilt and quickly collapse. The choice of wood is between oak and coniferous species. In this case, the depth of burial will be no less than half a meter.

A shallow columnar foundation is an excellent option for the construction of lightweight buildings that create minimal pressure on the ground.

When installing bathhouses and sheds, you don’t have to reinforce the supports with reinforcement and don’t add a concrete pad before installing them.

The block base is not suitable for the construction of heavy, much less multi-storey buildings, the height and dimensions of which are quite impressive. It does not require laying waterproofing material, so it is ideal for constructing outbuildings. To create the foundation of frame houses, it is better to give preference to asbestos or metal pipes, but we must not forget about their reinforcement and concrete base.

A grillage columnar-strip foundation is quite difficult to implement, as it consists of two different stages that are radically different from each other. Initially, pillars are installed in the drilled wells and reinforced with reinforcement. If this process is carried out correctly, then each pile can withstand a load of 10 tons. Then they begin to pour the strip base, on which the future building will rest. By the way, it will be possible to erect walls no earlier than a month after the solution has dried and the monolithic layer has acquired the necessary strength.

To avoid errors and troubles during the work process, and to ensure that the construction technology is fully complied with, experts advise paying special attention to analysis and calculations, namely:

• determine the depth of the bookmark;
• find out the composition of the soil, the depth of groundwater flow and the freezing point of the soil;
• calculate the weight of the future building and its load on the soil;
• determine the climatic features of the region.

If you become the owner of a plot with heaving soil, it is advisable to put the new building into operation in one season, otherwise it may become deformed in the cold season.

It is better to start construction in the spring, when the soil has completely thawed, and you will carry out the work during the warm season. During this process, make sure that no water gets into the trench.

We really hope that our material helped you understand the construction of foundations for houses, bathhouses, gazebos, you noted all the advantages of such a design and now you can build a columnar foundation with your own hands.

Only a professional builder can design and implement a columnar foundation with his own hands according to the recommendations of SP 50.100, 22.13330, 32.13330, 45.13330, 27.13330. These grounds are too unreliable; the results of geological surveys should be studied in as much detail as possible.

The technology for installing a grillage along pillars depends on the construction technology of the building for which the foundation is being constructed. Columnar bases are made from structural materials:

• reinforced concrete - pouring into formwork on site, installing the finished product in a 1F or 2F glass;
• wood - logs with a widening base;
• brick - clinker, solid ceramics;
• blocks - wall, only with dense fillers, hollow;
• rubble concrete - stone is introduced into the formwork after partial filling with ready-mixed concrete.

In addition to the strip grillage, a slab structure can be used. This is the only option for a columnar foundation suitable for a brick cottage on sandy soils with a groundwater level (GWL) below 1 m. In all other cases, columnar foundations are created for log houses, half-timbered buildings, buildings made of SIP panels, panel and frame buildings.

Types of columnar foundation by depth

Depending on the geological characteristics of the building site and wall materials, columnar foundations are:

• buried - below the freezing mark, groundwater level, but may not reach the bearing layer;
• shallow - 40 - 70 cm below ground level;
• non-buried - instead of the removed fertile layer, non-metallic material is filled in, the underground part is absent.

The height of the pillars above the zero mark depends on the grillage design and the technological solutions used in the project. The head is embedded into a monolithic grillage at 20 cm, the beams of the prefabricated grillage are installed on top of the piles. Therefore, the height above the surface is always individual. The construction of buried pillars is justified if there is a bearing layer at this level. This type of shallow foundation is stabilized by soil against lateral shift. Non-buried has a minimal construction budget.

Columnar foundation design

The fundamental difference between columnar foundations and piles is the occurrence of the base, as a rule, above the freezing mark, the level of groundwater level, and layers with bearing capacity. Therefore, in any case, the support-column foundation is protected from heaving forces and movements in several ways:

• a sand cushion under the base slab; if the base of the foundation is located below the freezing depth, a sand cushion is not required;
• drainage of soil by drainage system;
• insulation of the blind area and basement.

For the last two activities, open excavation of the soil in the building area is required.

Even with a small depth of the pillar itself, you will have to take into account the thickness of the widening (20 - 40 cm slab) and the underlying layer (cushion of 20 cm sand + 20 cm crushed stone). In addition, you will need a ring ditch for laying drains and access for workers to the lower level. Therefore, the size of the well and trench increases several times; it is inconvenient to carry out work from the ground at depth.

Manufacturing columnar foundations by analogy with bored piles is a gross violation of technology. It is difficult to widen the sole; there are heaving forces underneath it. The side walls without backfilling with sand are subject to tangential forces of the same processes.

Thus, the correct design of a columnar foundation looks like:

• preparation - sand (layer thickness 20-40 cm) with layer-by-layer compaction with a vibrating plate, pouring;
• footing - serves exclusively for laying waterproofing, is a 5 cm screed;
• stepped plate (sole) – distributes loads due to the increased surface of the sole;
• pillar - a vertical post made of monolithic or precast concrete;
• grillage - reinforced concrete products, monolithic structure, timber or rolled metal (channel, I-beam).

Unlike piles, pillars do not have spatial rigidity, so the grillage beams must not just rest on their heads, but must be attached to each pillar to be connected into a single structure.

Step-by-step instruction

Due to the variety of operations for constructing a grillage on pillars, step-by-step instructions are necessary for the individual developer as a guide. If you skip any stage, you will have to redo the work later or return to it, spending more effort and money.

For example, the instructions recommend laying drains at the excavation stage. If you forget about them at the beginning and remember them when landscaping the area, the trenches will have to be dug again, construction will be delayed, and the site will again be clogged with soil. The height of the pillars is selected 20 cm above the bottom of the grillage for walling in concrete.

Below we will tell you how to make a columnar foundation with your own hands correctly.

Geological surveys and calculations

The technology for constructing a columnar foundation depends on the results of geotechnical surveys, wall material, and construction technology. For example, it is prohibited to leave unloaded poles in the winter even if they are tied with a grillage.

Prefabricated loads (the weight of the building, residents, furniture, belongings, wind, snow loads) may not be enough to compensate for the extrusion forces, or the building will gradually sink into unstable soil with excess weight.

Unlike the test screwing of screw piles in the technology of the same name to find the depth of the bearing layer, full-scale surveys are required here, costing at least 30 thousand rubles. The designer needs the following data:

• layered arrangement of layers;
• composition and characteristics of the three upper layers;
• GWL level;
• frost mark.

The cross-section of the pillars should be greater than 40 x 40 cm for concrete or brickwork, 20 x 20 cm or 20 cm in diameter for a monolithic reinforced structure.

Marking and excavation work

Unlike bored piles that reach the bearing strata, it is much more difficult to pour columns into wells. The main problem will be the lack of sand filling in the sinuses:

• after a few years, the soil near the body of the pile will self-compact;
• will gain moisture and freeze in winter;
• heaving forces will pull the pillar out like a carrot from a garden bed;
• if there is a lower widening, the column will rise upward due to heaving forces, and soil will crumble under the base;
• the slab will not allow you to pull out the entire column, but it will no longer be able to get back into place.

We dig holes to widen the columnar foundation.

Therefore, the only correct way would be to mark the trenches, taking into account the width of the base, the drainage contour, and the construction of formwork. Instead of a square shaft of 40 x 40 cm, you will have to remove much more soil, 1 x 1 m minimum. In this case, the thickness of all layers of the foundation pie and the height of the groundwater level are taken into account. If the last characteristic is slightly below a meter, you need to go deeper by 0.6 m, no more.

Preparation

By default, the construction of a monolithic foundation of a dwelling should provide protection from corrosion and destruction. In the absence of oxygen, the only aggressive environment underground remains moisture, which should be removed from the base with drains and stopped at the surface of concrete structures along the entire height with a waterproofing carpet.

Construction is carried out in stages:

• layer-by-layer backfilling - 20 cm of sand with moistening, vibration compaction twice (total height 40 cm);
• footing – screed height 5 cm, no reinforcement;
• waterproofing – 2-3-layer carpet of rolled material on a fiberglass base;

Reinforcement

The technology for constructing an armored belt for a column with an expanded base is as follows:

• knitting reinforcing mesh to the size of the slab, taking into account the side protective layers (40 mm from the formwork to the metal) with a cell of 15 x 15 cm or 20 x 20 cm with a thickness of 12 - 16 mm;
• joining to the mesh rods bent at right angles of 12 - 16 mm, protruding 20 - 30 cm above the base of the grillage (usually 4 pieces in the corners, one in the middle of each side);
• vertical rods are reinforced with horizontal square clamps made of 6–8 mm reinforcement;
• the structure is installed on a waterproofing carpet, which extends 10-15 cm beyond the dimensions of the sole, for subsequent bending onto the side edges of the sole.

It is prohibited to lift the reinforcement structure with metal scraps, bricks, or crushed stone to provide a protective layer.

Widening the pillar

The construction of the sole involves pouring the slab into the formwork. The widening area is twice the cross-section of the pillar, the height of all elements is a multiple of 30 cm. The formwork is simple - four boards fastened with screws, corners or bars at the bottom of the pit or trench.

Reinforcement of the widening and pillar.

The sides of the formwork should be slightly higher than the design level in order to properly level the concrete surface. The permissible error in the horizontal plane is 1 cm. Filling is carried out after installing the reinforcement structure.

Formwork

We install and strengthen the formwork for the columnar foundation.

Drainage and waterproofing

From the perimeter of the building it can be made at any stage, from foundation pit to backfill. To install drains, a circular trench with a uniform slope towards the underground tank is required. Dornite or geotextile is spread at the bottom, and 10 cm of crushed stone is backfilled. Perforated pipes in the filter are laid in it, and inspection wells are installed. After which, the communication is filled with another 10 cm of crushed stone and covered with the remains of geotextiles.

Waterproofing device - several technologies using different materials:

• impregnations - contain penetrating additives that change the molecular structure of concrete, making it waterproof throughout its entire depth;
• rolled materials - Bikrost, TechnoNIKOL and other fiberglass-based analogues, laid in two layers;
• coatings – epoxy and bitumen based mastics;
• paints – enamels based on bitumen resins.

Most often, combined methods are used to achieve a 50-70 year service life. Rolled coating materials will have to be renewed every 15 years.

Ready-made columnar foundation with reinforced concrete grillage.

backfilling

After installing drainage and a continuous waterproofing layer over the concrete surface, it is necessary to protect the side surfaces from heaving forces. The sinuses are filled with sand; compaction is necessary, since loose soils are extremely unstable. The chernozem of the fertile layer is saturated with organic matter and settles after it rots. Other soils contain clay, which swells in cold weather. Therefore, exclusively non-metallic materials are used, in which there is less heaving.