Column foundation for the house. Do-it-yourself column-strip foundation. An example of determining the number of base pillars

A durable and inexpensive columnar foundation is usually built under buildings whose walls can be called lightweight - and these are wooden and panel baths, framed and made of foam blocks. But it happens that a zero level of this type is also laid under a heavy brick bath - when a deep foundation is needed and the strip foundation in this case can ruin. After all, columnar ones cost at least one and a half times cheaper than the last option, which, in fact, are good.

For a usually light and small bath, massive strip foundations are often akin to unnecessary luxury - but columnar foundations are much more suitable for such construction: both in price and in strength. Yes, the traditional arrangement of a columnar foundation does not imply the presence of a basement - but the Russian steam room just does not need it.

Budget columnar foundation with grillage

If you build a columnar foundation with your own hands, then the first step is to make its exact calculation. Why is it necessary to calculate the mass of the bath, and here it is important to take into account its snow load - in the Moscow region it is about 100 kg per square meter of area. As well as the weight of the internal filling of the bath: furniture, stove and people - that is another 100 kg per meter.

By the way, if it is difficult to calculate the bearing capacity of the soil in a certain area, then it is better to proceed from this calculation: 0.5-0.6 kg per cm2. In fact, these are the parameters of a peat bog or an old drained swamp. In all other cases, things are much better.

Stage I. Making pits

The easiest way is to take a drill with a diameter of 25 cm and drill small holes in the ground with it - 15-20 cm. This will be the basis for making the lower part of the pillars. It is necessarily reinforced with a fine mesh and covered with sand concrete of the 200th grade.

In the central part of the pit, you need to insert several bars of reinforcement so that they peek out of the pit no more than 10 cm. These can be old and unnecessary pieces of pipes, pieces of iron and debris.

And so that the cement milk is not absorbed into the soil, pieces of roofing material or even ordinary plastic bags will help.

Stage II. Pole installation

A piece of asbestos-cement pipe is taken, with a diameter of 10 cm, two reinforcing bars with a diameter of 1.2 cm are placed in it, and all this is placed on the “shoe”. You need to fill it with the same sand concrete, simultaneously tamping everything with another rod. From above - either a bolt, or another piece of reinforcement.

Stage III. Second drilling

It takes about 4-5 days for the concrete to harden after the last steps. Next, you can start the second drilling. To do this, you need a drill - they make a hole with a diameter of 30 cm and always below the estimated freezing depth. In this opening, you need to quickly insert the resulting pillar - so that it does not crumble. Its strength can reach up to 11 tons of load.

Stage IV. Construction of a grillage

A grillage for such a columnar foundation can be made of metal, concrete and even wood - here is what anyone likes more. The main thing is only that the grillage itself hangs above the ground by more than 10 cm.

The main advantage of this type of foundation is that it is suitable for almost any baths that do not have a strong weight - log, timber and frame. And he serves for a long time - at least a hundred years, and even when he stands in a swamp.

Solid support-columnar foundation

Of course, the foundation pillars can be of very different materials - concrete, brick or stone. But the most popular today for individual construction is affordable and practical reinforced concrete.

So, this is how a standard columnar foundation for a bath is built:

Stage I. Site preparation

It all starts with cleaning the site - for this, the entire top layer of soil is cut off, right along with the plants. Its thickness is usually a little over 30 cm, and it cannot be left under the foundation.

If there is clay on the site, then you need to make additional gravel-sand bedding. Its thickness depends on the geological features of the soil.

Now all irregularities are removed on the landscape, soil is poured into the pits, and with the help of pegs and ropes, you can start marking for the future foundation.

Stage II. foundation plan

Next, from the drawings to the land plot, you need to transfer the plan of the future bath - where and what will be. This can be done with standard materials, fixing the axes and noting the main dimensions of the future foundation. How accurately everything will be marked up - it will be so much easier to work later.

Stage III. Pit preparation

Pits for reinforced concrete columnar foundations are dug either manually or with the help of an excavator - which, of course, is both easier and more expensive. They will be located along the axes.

If the depth of the pit does not exceed a meter, its walls can not be strengthened. If more, you will have to dig with slopes and install fasteners from boards with special spacers.

The pits should turn out 30 cm more than the calculated depth of the foundation - so that gravel-sand bedding can be done. The width is taken a little more than it will be - so that the formwork and spacers become free.

Stage IV. Formwork installation

To make a good formwork for the columnar foundation of the bath, you will need planed boards up to 40 mm thick and 150 mm wide. Alternatively, chipboard, metal sheets and moisture-resistant plywood can be used instead of wood. You need to put the boards to the concrete.

Stage V. Foundation reinforcement

It is necessary to reinforce the foundation pillars in the longitudinal direction with A3 rods and a diameter of 12-14 mm. Horizontal jumpers should be placed in increments of 20 cm - a wire of 6 mm in diameter is quite suitable for this.

In order to then connect the pillars with the grillage through the reinforcing cage, it is necessary that the rods go out above the edge of the foundation by at least 10-15 cm. By the way, something more solid can also serve as a grillage - this is how the column-strip foundation is built, which has its advantages, but, however, not always justified for a bath.

Stage VI. Pouring foundation pillars

Concrete must be poured already into the installed pipes, which will then remain in the ground with the foundation.

It is necessary to lay it in layers - 20-30 cm each, using manual vibrators for the convenience of the process. This will ensure the homogeneity of the mixture and all the air will leave the solution.

Stage V. Waterproofing of the columnar foundation

You can protect the future foundation from moisture with the same materials as the tape one. These are mastics of cold and hot preparation, gluing membranes, roofing material on bitumen - and all new and well-proven materials.

Stage VI. Construction of a grillage

A monolithic belt makes both a solid and a columnar foundation made of blocks more rigid and stable. And you can make it from prefabricated reinforced concrete rand beams or immediately monolithic.

So, if a prefabricated belt is being made, then the jumpers must be well connected to each other with trimmings of reinforcement - welding them by welding with mounting loops. Further, the formwork, the reinforcing cage are already installed and everything is poured with concrete of the M200 brand.

As soon as the concrete hardens and becomes strong, and waterproofing is carried out, the sinuses of the pits can be covered with soil and the installation of floor slabs can begin.

By the way, in order to protect the underground space under such a bath from snow and cold air, a fence is usually made between the pillars - a special wall, most often made of brick. It is not necessary to tie it to the poles - after all, the bath will still settle, and so cracks may appear. And already in the pick-up itself, technological holes are made for communications. Outwardly, all this is beautifully decorated with false panels and siding - that's all.

Under a certain structure (for example, a house), it is planned to equip a specific foundation. Column bases are among the cheapest and easiest to build. More often, low-rise industrial and public buildings, one-story suburban buildings are built on such a foundation. A number of features of supporting foundations suggest some limitations in their use, which cannot be ignored.

What is a column foundation?

This type of base for the house is constructed from a supporting frame, where the decks carry the main load. Supports are mounted along the perimeter under the bearing walls. The first harness of the house is laid on them. Consequently, decks are installed in loaded places: in corners, at the junction of walls, under ceilings and spans more than 2.5 meters in length.

The dimensions and distance between the pillars are determined by calculation, taking into account the category of building material, the type of construction of the supporting elements, the nature and total mass of the building. The average distance between the supports varies within 1.5-2.5 m, the inner cut of rectangular products is 25-40 x 25-40 cm, round - 20-25 cm. The height of the ground structural element above the foundation should not exceed 50 cm. This the parameter for the part located underground is selected depending on the depth of penetration.

Peculiarities

The supports of the column base should be positioned so that the pillars rest against a stable and durable earth layer. It is not allowed to place support decks on soft humus soils. The upper part of the decks is made in one horizontal plane. Will rely on them.

When erecting light buildings, a grillage is not needed. Instead, metal or wooden beams are used. The elevation of the heads should be located at least half a meter above the ground. This will prevent moisture from entering the house.

If it is intended to connect the column to the pole, a “glass” recess is made in its upper part or fixing anchors are installed to ensure rigid fastening of the support and the supported structure.

Kinds

Features of the arrangement of supported foundations and the choice of the type of decks are determined by the type of building, the nature of the soil and other operational requirements. Decks come in different sizes and sections. There are rectangular, square, round supports.

The columns can be made of concrete (reinforced concrete), block material, rubble stone, brick. According to the manufacturing technology used, the foundations on the decks are classified into such types as:

• monolithic, when pits are dug, formwork is mounted and a concrete solution of a grade of at least M400 is poured in layers;
• prefabricated, when ready-made elements from blocks, bricks or stones of a certain brand are used.

The laying depth determines the individual types of support bases:

1. Non-buried foundations on pillars, when the sole is located on the ground or a sand cushion. Such foundations differ in the cost-effectiveness of construction, but are used exclusively for the construction of one-story buildings from lightweight materials on weak and non-porous soils.
2. Buried foundations, during the construction of which the columns are laid to a depth of up to or below the freezing point of the soil. This design is used for heaving soils with loams or clays. They are the least economical.
3. Shallow, the depth of which is 0.5 - 0.7 parts of the depth from the freezing point of the soil. Half of the foundation is a monolith of a certain shape, and the second is. Suitable for arrangement on small and non-clay lands.

According to the design features, foundations are available with or without a fixing beam. The grillage is attached to the pole and distributes the load from the total mass of the house evenly over the base. The grillage beams prevent decks from tipping over due to the horizontal movement of the soil. However, this element significantly increases the cost of construction, increases the time for arranging the foundation.

Most non-massive buildings are erected on supporting foundations without a grillage. In this case, the first strapping is mounted directly on the decks, on top of the waterproofing layer. However, this design is less resistant to horizontal soil shifts and overturning loads.

Feasibility of construction

The expediency of erecting foundations on supports takes place in cases where:

• on the ground layer during the operation of the building, the pressure from the decks is less than from the tape structure;
• buildings without basements are erected on panel, wooden and lightweight frames;
• brick walls are built with the required support depth of up to two meters or a quarter of a meter below the freezing point of the soil;
• it is necessary to avoid the destruction of the foundation due to the increase in soil volumes at low temperatures.

However, there are cases when the use of the underlying foundations is not justified:

1. Due to the instability of the support decks, it is not recommended to install them on weak and horizontally moving soils.
2. The bases on the decks are unsuitable for the construction of massive walls made of heavy materials: brick, reinforced concrete with a block thickness of more than 51 cm.
3. It is not necessary to arrange a foundation on pillars in places with a strong elevation difference (from two meters).

Construction

The pouring of the pillars to the foundation is carried out in an open way in several stages. At the first stage, the position of the supports under the foundation blocks or monolith is marked. For this, the type, shape, size and depth of the support decks are initially selected. The construction of a building according to the drawing involves entering into the document a predetermined clear distance between the supports.

When self-marking at the construction site, one should take into account the fact that the pillars should be from 1.5 to 2.5 meters apart. A greater distance can lead to an increase in construction costs due to the need to construct a more powerful grillage. Supports should be located in areas of maximum loads - in the corners, at the junction of walls, under ceilings.

At the second stage, work on the ground is carried out. Pits are dug under rectangular rubble, concrete, rubble concrete, block or brick pillars. If the pillar must have a sole at the bottom, then when digging a hole, its dimensions are taken into account. Wells need to be prepared for tubular supports. They are drilled with drilling machines, manual or garden drills. The well should be made with a cross section of 5-10 cm larger than the diameter of the support pipe.

At the third stage, concreting of the pillars is carried out. More often, reinforced concrete monoliths of the required section are used as supports. You can build monolithic pillars yourself. To do this, a pillow of sand and gravel 15-20 cm high is laid in the prepared pit. To erect the above-ground part of the support above the pits, formwork is constructed from wooden boards in accordance with the required dimensions of the pillars. The formwork boards and the inner walls of the pit are covered with roofing felt or polyethylene to provide waterproofing.

Then a reinforcing frame made of rods with a cross section of 1-1.2 cm is placed in the pit. The rods are interconnected by segments from the same reinforcement. You can use special wire clamps for this purpose. The distance between the reinforcing mesh and the walls of the support should not be less than 3 cm. This will allow the frame to be completely filled with concrete.

The height of the reinforcing skeleton depends on the use or rejection of the reinforcing beam (grillage). If the installation of the element is required, then the length of the reinforcement should rise above the upper base of the support. Otherwise, the reinforcing skeleton is located 3 cm below the formwork. To fix the first trim, embedded studs are mounted on top of the post.

After reinforcement, concreting of the supports is carried out. For this, ready-made concrete is used not lower than grade 200-300. For self-preparation of concrete mixtures, the M400 cement grade is more suitable, mixed with sand 1-1.2 mm, gravel and water in a ratio of 1: 3: 5: 0.4, respectively. The mixture is laid in layers, each of which is carefully rammed.

When constructing a foundation on supports with a shoe (expansion at the bottom), a hole is dug in the form of this expansion, a pillow of sand and gravel is poured, and concrete is poured. After strengthening the pour, the formwork of the column is formed. Then the above work is repeated. After the mixture has hardened, the formwork can be removed, the walls of the column can be treated with waterproofing and backfilled and compacted with the soil removed from the pit.

If a grillage is used, at the last stage, its installation on supports is performed. To do this, along the perimeter of the future foundation base, a formwork is horizontally mounted in a form for tying all decks. Inside the formwork, a frame of reinforcement is inserted and fixed on the outlets of the reinforcing skeleton of the pillars. The pouring of the cement mortar is carried out so that the surface of the grillage is located in one horizontal plane.

Within a week, the concrete needs to harden and harden, after which the formwork is removed.

Do-it-yourself owners of land plots, private households, and dacha cooperatives think about the construction of a columnar foundation when they themselves need to build a small and preferably light structure - a bathhouse, a room for keeping birds and animals, a veranda, an extension for inventory, a barn. Unlike a strip foundation, making a columnar foundation with your own hands is much easier, and one and a half to two times cheaper. This is especially true for heavy swampy, peaty and waterlogged soils, where sometimes only heavy equipment can cope with this difficult task. But the columnar foundation can be equipped by one person with an assistant, quickly and efficiently without special mechanisms, if he knows how to do it. So the request is " how to make a do-it-yourself columnar step by step instructions» users choose quite often. Let's stop and we on this question.

Types and purpose of the columnar foundation

Most often, the device of a columnar foundation is performed under buildings made of wood. Experts do not recommend erecting heavy brick or stone structures on it, the foundation supports under the weight can be deformed and crack over time, which will lead to the destruction of the entire building. Of course, there are special technologies used in permafrost regions, where the construction of a columnar foundation is the only way to build any structure, but this will require special equipment and knowledge.

Types of columnar foundations.

There are several main types of support-column foundations, united by the same type of their construction, but different in the materials used in the construction process.

1. A monolithic reinforced concrete structure is the strongest of the existing columnar foundations. It can be used for one - two-story residential wooden buildings.
2. Brick columnar foundation - is most common, an example of this is a structure 100 and even 200 years old. The main condition for its construction is high-quality burnt brick. On this basis, it is also possible to build 1-2-storey wooden houses on dense soils, and the cross section of the columns should not be less than 400x400mm.
3. The foundation of the blocks - has the same properties as the brick. They are distinguished only by the use of materials of different strength. The most reliable are concrete blocks. A limitation for rubble stone blocks is the high mobility of soils in your area. If rubble material is available, it is better to pour a columnar foundation, combined - Rubble-concrete. Concrete, getting between the buta stones, will fix them and make the structure monolithic and durable.
4. Wooden-pillar - used everywhere for light buildings. The main task of builders is to give the entire structure durability, for which long-term and reliable impregnation of wood immersed in the ground is carried out. Wooden supports are treated with antiseptic impregnations, bituminous mastics, after which a layer of roofing material is fixed on their surface. Most often, wooden posts with a diameter of 150-200 mm are used for the extension of verandas and terraces.
5. Asbestos columns - are used for the construction of both light - diameter up to 150mm, and heavier buildings - diameter 250-400mm. It is possible to use such hollow structures for formwork, followed by pouring a concrete composition inside the pipe, reinforcing it with reinforcing bars.
6. Metal piles - great way construction of buildings on rough and uneven terrain. Finished structures are screwed into the thickness of the earth until they reach dense and stable soil layers. On an uneven site, it is possible to correct the relief due to the different lengths of the selected piles.

Construction of a columnar foundation with varying degrees of deepening

To correctly build a columnar foundation with your own hands, you need to calculate the depth of its occurrence in the ground. It depends on many factors, so the recommendations of specialists in your area should not be neglected. Ideally, you need to create a project that will take into account:

• Depth of soil freezing;
• geological features of the site relief;
• groundwater level;
• soil composition;
• climatic features of the area;
• building weight.

There is a shallowly recessed option, when a depth of 650-700mm is sufficient for mounting the posts. Such a foundation is recommended for deep groundwater in sandy, rocky and finely broken soils that are subject to minimal displacement.

The buried foundation is located at a depth of 1500-2000 mm, and often even lower. It is recommended to adhere to such a depth in areas with deep freezing of soils from 450-500mm or with high soil mobility in the construction region. The approximate distance between adjacent posts is 1000-2000mm.

The main structures of columnar foundations

The construction of a columnar foundation usually does not cause any particular difficulties due to its fairly simple design. The photo shows several options for the basic structures for installing a columnar foundation.

• The bottom layer in each of the structures is a sand cushion 100-200 mm thick, designed to remove moisture from the foundation area, which is also drainage.
• The next poured layer is concrete, 400-500 mm thick, forming a concrete pad.
• Next, you should place the columnar support itself, reliably waterproofed and reinforced with reinforcing bars, to give strength and durability to the entire structure.
• As a rule, the posts are raised above the ground to a certain level for the installation of a grillage or other linking all the supports of the belt. It will not only tie the structure together, but also evenly distribute the load between all the erected supports.

A grillage for light buildings is usually made of a wooden beam with a section of 150x200 or 200x200mm. In the absence of a beam, it is possible to arrange - reinforced concrete, metal, brick, rubble-concrete grillage. It can lie directly on the ground, in the form of a strip foundation, or hover above it at various heights of 300-900mm, and sometimes even higher. The disadvantage of a high grillage will be the impossibility of building a basement under the building, and residents of flooded areas will appreciate the dignity.

Do-it-yourself column foundation step by step instructions

1. Preparatory stage

Before building a columnar foundation, you need to select and clear a place, removing all household debris, weeds, uprooting stumps and overgrowth. After that, we proceed to remove the top layer of soil of at least 20 cm and an area that goes beyond the dimensions of the proposed structure by 2-3 meters.

The next work at the preparatory stage is to compare the relief of the site with filling in the resulting holes and cutting off the hillocks. To do this, use excess soil or a special sand and gravel composition.

Please note that it is impossible to pour a columnar foundation for the future. It is necessary immediately, after hardening, to continue construction, giving a load to the foundation. Otherwise, flooded columns may crawl out of the ground after wintering in the ground.

2. Marking for supports

The most important stage of work on the transfer of all calculated values ​​from paper to the terrain. First, the corner posts are cut off, the main axes of the future house are fixed, they will serve as a guide for drawing all the main lines for laying the foundation and observing the exact dimensions. After that, the location and dimensions of all other foundation supports are determined.

Here you can watch a video with a properly located foundation of the house.

3. Construction of a column foundation

This stage begins with the preparation of pits for the installation of supports. Pits can be dug by hand, drilled with a hand drill, an excavator can be invited for these purposes, and in any other available way. The depth of the pit should exceed the size of the installed support by the depth of the drainage sand cushion (15-20 cm).

If formwork is required in the technological process, then the width of the pits must be increased for its construction.

After preparing the pit, sand is poured into it and water is poured to compact it. For a reinforced concrete monolithic structure, the sand is fixed with cement milk, which helps to maintain its optimal moisture content.

For the prefabricated foundation, everything is ready to go. For a monolithic one, it is required to make an armoframe. For pipes - carry out anti-corrosion treatment and impregnation before installing pipes in prepared pits. Asbestos pipes - immediately ready for use.

Photo how to make a columnar foundation with your own hands.

After the preparatory work, concrete is poured directly, with its periodic vibration, to get rid of voids and obtain a strong monolith. This will ensure high strength of the base and increase its service life.

For a more even distribution of the load between all the supports of the house, a grillage or a binding layer is created. It can be metal - ranbalka, reinforced concrete, in the form of a strapping beam. It depends on the type and material of the future building erected on this foundation. Before proceeding with its construction, all parts of the supports protruding above the surface are adjusted in height. The video can be viewed here.

4. Waterproofing works

Ground and flood waters bring great harm to the foundations being built and houses based on them. Therefore, it is not enough to make a columnar foundation correctly - you need to securely waterproof it, capturing the grillage. To protect the supports, special bituminous compounds are often used, and to isolate the walls of the building, a layer of roofing material fixed on bituminous mastic, pasting membranes are laid between the grillage and them. Such work is carried out carefully, the humidity regime in the built room depends on them. After that, all the voids formed around the supports are covered with soil, or better, with a sand and gravel composition. Such work is carried out in several stages, with diligent compaction of the laid layer.

5. Pickup

Buildings erected on columnar foundations often do not have a basement. Therefore, the distance from the ground surface to the lower part of the building requires additional sheathing. This is a kind of basement of the building and a lot depends on its arrangement:

• floor temperature;
• No drafts from under the floors;
• Protection against ingress of moisture and dust into the subfloor.

Before full sheathing, ventilation ducts should be provided, the laying of engineering communications - water supply, sewerage.

The fence, after its arrangement, is decorated with brick, stone, facing tiles, decorative plaster - there are no restrictions in this process.

Before starting the construction of the fence, it is required to make a screed with a thickness of 180-220mm, it will serve as a support for the walls of the building. The height of the pick-up base depends on the height of the grillage and the length of the supporting pillars protruding above the ground. It is better to leave at least 300-400 mm for such, which, firstly, is aesthetically pleasing, but also practical. In areas with floods and high groundwater levels, the height of the intake can reach an impressive size and this is economically justified. In addition, the house, hovering above the ground at a great height, looks quite impressive, despite its design, color and materials used in its construction.

Conclusion

We examined the main stages of work and learned in more detail how to properly make a columnar foundation with our own hands. But entrusting the design of such a foundation and the entire structure is still better for specialists, especially if it is planned to build not just a barn or a toilet in a summer cottage, but a 1-2-storey house for the whole family to live. Such costs will pay off over time, when the house will stand idle for more than a dozen years and will be inherited by children and grandchildren. For these works, specialists use a special software, and today their cost has become more democratic and affordable.

Only a professional builder can design and implement a support-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 of the grillage on the pillars depends on the construction technology of the building for which the foundation is being built. Columnar bases are made of structural materials:

• reinforced concrete - pouring into the formwork in place, installation of the finished product in a glass 1F or 2F;
• tree - logs with a widening sole;
• brick - clinker, full-bodied ceramics;
• blocks - wall, only with dense fillers, hollow;
• rubble concrete - a stone is introduced into the formwork after partial filling with ready-mixed concrete.

In addition to the tape grillage, a slab construction 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 cabins, half-timbered houses, buildings from SIP panels, panel, frame buildings.

Types of columnar foundations according to the depth of laying

Depending on the geological characteristics in the building spot, wall materials, columnar foundations are:

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

The height of the pillars above the zero mark depends on the design of the grillage and the technological solutions used in the project. The head is embedded in a monolithic grillage by 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 mark. A shallow foundation of this type is stabilized by soil against lateral shear. Unburied has a minimum construction budget.

Column foundation design

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

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

For the last two activities, open excavation is required in the building spot.

Even with a slight deepening of the pillar itself, it will be necessary to take into account the thickness of the broadening (20 - 40 cm plate), the underlying layer (pillow of 20 cm sand + 20 cm crushed stone). In addition, you will need an annular ditch for laying drains, access for workers to the lower level. Therefore, the size of the well and trench increases several times, it is inconvenient to work from the ground at a depth.

The manufacture of columnar foundations, by analogy with bored piles, is a gross violation of technology. The sole is difficult to widen, there are heaving forces under it. The tangential forces of the same processes act on the side walls without backfilling with sand.

Thus, the correct design of the columnar foundation is:

• 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 the load due to the increased surface of the sole;
• column - a vertical stand made of monolithic or prefabricated concrete;
• grillage - reinforced concrete products, monolithic structure, timber or rolled metal (channel, I-beam).

Unlike piles, pillars do not have spatial rigidity, therefore grillage beams must not only rest on their heads, but be attached to each pillar for tying into a single structure.

Step-by-step instruction

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

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

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

Geological surveys and calculation

The technology for constructing a columnar foundation depends on the results of geotechnical surveys, wall material, and construction technology. For example, it is forbidden to leave unloaded poles in the winter even when 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 ground with excess weight.

In contrast to the test driving of screw piles in the same technology 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 information:

• layered arrangement of layers;
• composition and characteristics of the top three layers;
• GWL level;
• freezing mark.

The cross section of the pillars should be more 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 earthworks

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

• after a few years, the soil near the pile body will self-compact;
• pick up moisture, freeze in winter;
• heaving forces will pull out the pillar, like a carrot from a garden;
• in the presence of a lower broadening, the column will rise up by heaving forces, the soil will crumble under the sole;
• the plate will not allow you to pull out the entire column, but it will no longer be able to stand in place.

We dig holes for the widening of the columnar foundation.

Therefore, the only the right way there will be a marking of trenches, taking into account the width of the sole, the drainage contour, the work on the construction of the formwork. Instead of a square shaft of 40 x 40 cm, you will have to take out much more soil of 1 x 1 m at least. This takes into account the thickness of all layers of the foundation cake, the height of the groundwater level. If the last characteristic is slightly lower than a meter, you need to go deep by 0.6 m, no more.

Training

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

Construction is carried out in stages:

• layered backfill - 20 cm of sand with moisture, vibrocompaction twice (total height 40 cm);
• footing - screed height 5 cm, no reinforcement;
• waterproofing - 2-3-layer carpet of rolled material on a fiberglass basis;

Reinforcement

The technology of the armo-belt device of a column with an expanded sole has the form:

• knitting a 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;
• docking to the grid of rods bent at a right angle 12 - 16 mm, protruding above the sole of the grillage by 20 - 30 cm (usually 4 pieces in the corners, one in the middle of each side);
• vertical bars are reinforced with horizontal square clamps from reinforcement 6 - 8 mm;
• the design is installed on a waterproofing carpet, which is produced beyond the dimensions of the sole by 10-15 cm, for subsequent bending onto the side edges of the sole.

It is forbidden to lift the reinforcing structure with metal scraps, bricks, crushed stone to provide a protective layer.

Post widening

The construction of the sole is the pouring of the slab into the formwork. The broadening area is twice the section of the column, 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, trench.

Reinforcement of broadening and column.

The sides of the formwork should be slightly above the design level in order to qualitatively level the surface of the concrete. The permissible error in the horizontal plane is 1 cm. The pouring is carried out after the installation of the reinforcing structure.

formwork

We install and strengthen the formwork for the columnar foundation.

Drainage and waterproofing

From the perimeter of the building can be made at any stage, from the pit to the backfill. For the installation of drains, an annular trench is required with a single slope to the underground tank. Dornite or geotextiles are spread at the bottom, 10 cm of crushed stone are backfilled. Perforated pipes in the filter are laid in it, manholes are installed. After that, the communication is covered with another 10 cm of rubble, covered with the remains of geotextiles.

Waterproofing device - several technologies with different materials:

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

Most often, combined methods are used to achieve a 50-70 year resource. Roll, coating materials will have to be updated every 15 years.

Ready columnar foundation with reinforced concrete grillage.

backfilling

After the drainage device, a continuous waterproofing layer on the concrete surface, it is necessary to protect the side surfaces from heaving forces. The sinuses are covered with sand, compaction is necessary, since loose soils are extremely unstable. The chernozem of the fertile layer is saturated with organic matter, sits down after it rots. In the rest of the soils there is clay that swells in frost. Therefore, only non-metallic materials are used, in which heaving is less.

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Among all the varieties of concrete foundations used today, the columnar-strip foundation deserves special attention. Most often, this design is used in the arrangement of heavy and massive construction projects.

Subject to competent construction, the column-and-strip structure will have the highest performance. At the same time, relatively little time and money are spent on arranging such a foundation, and all the required work can be done on its own.

Read the general information about the column-strip bases, study the guide for arranging such structures and get to work.

The use of such a construction will be justified when performing construction works in areas with a large depth of soil freezing.

In such situations, the construction of an ordinary deep strip foundation will require irrational financial investments, and a shallow structure simply cannot cope with the tasks assigned to it.

In such conditions, a column-strip foundation is an excellent option. Even a beginner can cope with the arrangement of such a design.

An additional advantage of the base under consideration is the possibility of its arrangement on inclined sections. But if the underground aquifer is located too close to the soil surface, it is recommended to refrain from such a decision.

In the considered design, the largest part of the load falls on the base of the pillars. In this case, the pillars must be placed in the ground at least 200 mm below the freezing point of the soil. Thanks to this, maximum indicators of durability and reliability of the structure will be ensured.

So that in the future the tape does not rise under the influence of natural changes in the structure of the soil, its lower part must be made somewhat expanded.

In the construction of the column-and-strip type, the tape performs the functions of only the upper grillage, which is necessary for connecting the pillars into a single structure and additionally increasing the strength of the base. In this case, the tape does not exert any load on the ground.

With the help of the tape, the most even distribution of the load on the main foundation pillars is ensured.

The foundation must be designed so that after the construction is completed, at least 150-200 mm of free space remains between the lower edge of the grillage and the top layer of soil. Due to the presence of such a gap, the foundation will not receive any significant damage even with strong swelling of the earth.

What are the poles made of?

Before proceeding with the independent arrangement of the column-strip base, you must choose the optimal material for the manufacture of supports. Available solutions include: wood, concrete blocks, bricks, as well as pipes made of asbestos cement and metal. Check out the features of each option and choose the solution that best suits your situation.

They are rarely used due to their relatively low durability. Pillars made of wood are only suitable for arranging a foundation intended for installing a terrace or other similar structure.

The optimal diameter of wooden poles is 150-200 cm.

Before deepening the pillars of the material in question into the ground, they must be treated with antiseptic and flame retardant impregnation. Thanks to this treatment, the resistance of the material to decay, pest damage and fire will be significantly increased.

For waterproofing wood, bitumen-based mastics are best suited.

Brick-iron ore is well suited for arranging a columnar-ribbon structure. With its use, shallow-depth columnar foundations are also erected.

Supports in the form of concrete pillars, additionally reinforced with reinforcement, are considered the most reliable. In view of this, it is these supports that are most popular.

Concrete pillars can have either a solid (monolithic) structure or consist of several blocks.

It is important that the width of the pillars is at least 40 cm.

Pipes made of asbestos cement or metal are very easy to install. Installation is reduced to the placement of hollow pipes in previously prepared recesses, the installation of reinforcement bars inside the pipes and the final filling of the cavity with concrete mortar.

The work is done extremely quickly and simply. The optimal pipe diameter is selected individually, taking into account the expected load on the base being built.

Stages of arranging the foundation

The construction of the foundation of this type is carried out in two stages. First you will need to create the base of the structure from the pillars, and then equip the shallow concrete strip.

pillars

Before starting work, determine the optimal depth of the column-strip base. At this stage, consider the following options:

• type and features of the soil structure;
• ground freezing level;
• depth of groundwater passage.

There are shallow and deep foundation structures. When arranging a shallow base, the pillars are usually immersed in the ground by 40 cm, while in the case of building a deep base, the supports are deepened 10-50 cm below the freezing point of the soil.

Keep the installation step of the supports within 100-250 cm in accordance with the future load. The higher the loads on the base, the smaller the space between the installed supports. Professional builders strongly do not recommend placing supports with a step of more than 250 cm, because. this will lead to a significant decrease in the strength of the finished structure.

Proceed with the installation of support pillars. This is a fairly simple job done in a few steps.

First step. Prepare the site for upcoming events. To do this, remove the fertile ball of soil and level the site. If the top layer of soil in your area is clayey, remove a larger volume of it and cover the resulting base with a small layer of sand.

Second step. Perform site marking. For this, any suitable pegs and a noticeable rope will do. Pull the thread at a distance corresponding to the width of the future concrete tape.

Watch the angle of intersection of the cords. It is important that the threads intersect strictly perpendicular.

Mark the intersections and junctions of the internal partitions and the external walls of the building, the corners of the future structure and the areas that will be subjected to the most serious loads.

Third step. Dig a trench in the place where the strip part of the foundation is arranged. A hole with a depth of about 400 mm will suffice. The width of the trench should be 70-100 mm greater than the width of the tape. Such a gap is necessary for the installation of formwork boards.

Fourth step. Make recesses in the places of future installation of support pillars. A drill or other suitable device will help you with this. Select the diameter of the recesses individually in accordance with the expected loads on the foundation. The higher the load, the larger the diameter of the support pillars should be.

If, according to the project, the pillars will lie more than 100 cm, be sure to install supports made of durable boards. They will prevent soil erosion. If the pits have a depth of up to 100 cm, the installation of props can be abandoned.

Fifth step. Backfill the bottom of each recess with a 100mm layer of sifted sand.

Sixth step. Start arranging the pillars. In this example, the supports are made of asbestos-cement pipes.

Preliminary perform waterproofing of the supports. To do this, paste over them with a double layer of roofing material or other similar material. Insert the waterproofing pipe into the recess until it stops.

Tie a reinforcing frame of steel bars and tie wire. Use rods with a diameter of 12-14 mm. The fittings should have such a length that its upper ends protrude from the pipes by 150-250 mm.

Start filling. First you need to pour concrete in the free space in the pits around the supports to about 20 cm of the height of the recesses, and then pour the pipes directly.

Leave the finished posts to dry and gain strength.

Ribbon

Proceed to the arrangement of the tape part of the structure.

First step. Tie a frame of reinforcing bars and steel tie wire. Weld the structure and screw it to the rebars protruding from the concreted support posts.

Second step. Perform the installation of the formwork for pouring the tape. Collect the formwork from boards 40 mm thick and about 150 mm wide. Boards can be replaced with chipboard, plywood or sheet metal.

Third step. Cover the inner surface of the formwork with moisture-proof material. Polyethylene is suitable for waterproofing, and more modern membrane materials can also be used.

Fourth step. Fill the formwork with concrete mortar. To save time and effort, you can order ready-made concrete. If desired, the solution can be prepared by hand. Fill in one pass. Pour the solution horizontally. Vertical joints are strictly prohibited - they will crack even before the concrete has completely hardened.

Treat the poured concrete with a special vibrator. This treatment will eliminate voids and excess air. If you don't have a vibrator, at least pierce the concrete with rebar in several places, and then carefully seal the holes with concrete.

The fill will dry for a month. It is recommended to dismantle the formwork only after the casting has completely hardened. For some time (usually 1-1.5 weeks), the poured concrete must be additionally moistened, otherwise it will crack.

Determine the frequency and duration of dampening individually in accordance with the "behavior" of concrete and weather conditions.

Waterproof the hardened and cured concrete, backfill the remaining trenches with earth, and proceed with the planned construction activities.

Successful work!

Video - Do-it-yourself column-strip foundation