Do-it-yourself columnar foundation: step-by-step instructions, video. Do-it-yourself columnar foundation step-by-step instructions for making a columnar foundation correctly

In the family of point-support foundations, the columnar structure looks like the black sheep. Unlike pile-screw schemes or options on bored piles, a columnar foundation cannot ensure the stability of a building on a slope or on decrepit peat soil. Even the most desperate amateur house-builders do not try to install columnar structures on a swamp or heaving foundation.

How to install a columnar foundation

But in fact, the columnar version has two remarkable features. Building a columnar foundation with your own hands is accessible even to beginners in construction, and the cost is approximately half the estimate for a shallow-depth tape. If you need to build a hut on a sandy area, near a pine forest or on hard calcareous soils, the easiest way to solve the problem of arranging the foundation is in one of the following ways:

From the above list, the first two options will require the use of construction equipment and handling equipment; for a brick scheme, the skill of a mason is required. The last method from the list above requires only time and a little patience in working with your own hands and following the recommendations of the practical guide.

Important! A cast columnar foundation can be safely called universal; if there is drainage and drainage on the site, it can be placed even on small slopes without the need to work with a grader to level the horizon on the site plan.

In fact, a columnar foundation is the best option for building a small summer kitchen, gazebo or bathhouse on a country plot with your own hands. For large and heavy buildings, a columnar foundation is weak and dangerous.

How to make a columnar foundation with your own hands quickly and easily

Casting concrete columnar structures will require lengthy and rather dirty work with mixing cement mortar, installing and strengthening columnar formwork, leveling and cleaning working surfaces. You can take a simpler route and buy ready-made blocks with a length of 40 cm and a cross-section of 20x20 cm. A foam concrete block of the structural grade D1200 or heavy expanded clay concrete grades are best suited.

For heavier versions of the house, granite blocks can be made. To do this, blocks are cast on a manual machine for pressing cinder blocks filled with heavy rock. Such a block will be able to withstand a load of 300-400 kg, which corresponds to the weight of the walls of a timber house. If you have experience working with your own hands with laying stone on cement mortar, then you can build 6-8 columnar supports in half a work shift.

In addition to standard rectangular blocks, massive hollow blocks in the form of a truncated pyramid with a reinforcing frame are cast on the machine. A pin or threaded rod is placed in the upper base of the pyramidal columnar support, which allows you to tie the installed pillars with a wooden beam or steel profile. It is enough to compact and fill the horizontal platform in order to install a finished foundation field of columnar supports along stretched cords.

Do-it-yourself columnar foundation step-by-step instructions

Casting foundation supports from cement is no more difficult than working with a shallow-depth tape, but the volume of concrete and earthworks is three times less. Most of the time is spent on the first columnar support, made with your own hands. From practice, it turns out that the next two columnar supports take the same amount of time as the previous one. The entire technology for arranging a columnar foundation comes down to five simple operations:

• Preparation of the cushion and pit at the site of marking the columnar support;
• Assembling the formwork to be poured with concrete;
• Installing reinforcement into the formwork and pouring concrete into the form;
• Assembling and tying the foundation.

Advice! To make a foundation field, it will take at least three days and three to four sets of split formwork. If we assume that one columnar support will require three days to cure the concrete, then in a week you can make a columnar foundation of 8 supports with your own hands.

The optimal option for arranging the base of a columnar block

The most serious problem with columnar foundations is not the weak load-bearing capacity of the supports, but their tendency to tip over when the lateral component of the load increases. Strong winds and uneven subsidence of the foundation, when some supports sink into the ground, while others are torn off by beams from the cushion, leads to tilting and overturning of the foundation pillars, as in the photo.

Therefore, when preparing a cushion for a columnar foundation, it is necessary to pay attention to the presence of reinforcement in the form of a backfill of gravel and soil. For columnar supports installed on the surface or in a slight recess, it is recommended to strengthen the base by expanding the support spot or use fungal types of pillars. In the latter case, the foundation structure can be made in the form of two independent elements: in the form of a round concrete platform, buried 10-15 cm into the ground, and a vertical support of a round or rectangular cross-section, connected to the platform by one reinforcement cage.

In any case, to install the supports of a columnar foundation, you will need to dig a pit to a depth of immersion plus 20 cm of sand and gravel cushion and 20-25 cm of a layer of large rubble or crushed stone material. The filling mass is placed on the bottom of the pit in layers of no more than 10 cm, with compaction of each layer using a hand or electric tool.

It is clear that for the manufacture of supports, formwork boxes of exactly the same size are most often used. This makes it possible to obtain columnar foundation supports of the same height, but only under one condition - if the crushed stone cushion in all pits has the same height. Therefore, it would be correct to do the following:

1. Dig the required number of mini-pits for the foundation supports, trim and level the walls so that the soil and fertile layer do not fall on the gravel bed;
2. Drive a reinforcement rod into the center of the bottom of the foundation pit for the future column, align it with the stretched foundation marking cords;
3. Pour the gravel-sand mixture onto the pillow using a compactor. The compaction of the cushion must be done with the utmost care, the main thing is to prevent the centering rod from moving or deflecting. We constantly check the height of the pillow by the distance from the cord to the backfill plane using a clogged piece of reinforcement.

Installation of formwork and reinforcing frame

To obtain a homogeneous, defect-free concrete casting, you will need to make collapsible, reusable formwork of a box-shaped or tubular structure. The inner surface of such a box is covered with plastic film, or materials with a laminated surface are used. Thus, a support with smooth and even walls is obtained. In addition, the internal coating of the formwork significantly reduces the swelling of the wooden structure and helps maintain the original shape of the foundation pillars.

Before installing the formwork, it is recommended to tighten the dimensional cords, which can be used to align and fix the wooden frame of the form with a minimum error. In addition to the horizontal supports of the walls, it will be necessary to install additional fixing wedges to prevent the formwork from floating under the influence of concrete pressure on the lower part of the wooden form.

At the next stage, a reinforcing frame is installed inside the wooden form, welded from 4 or 6 rods with a diameter of 8-10 mm, photo. Like formwork, the reinforcement is aligned inside the form and fixed in a vertical position, after which you can proceed to pouring the concrete mixture inside the support.

Leveling and pouring concrete

Filling the formwork with concrete must be done as carefully as possible to prevent displacement of the installed support elements. Long foundation columns are poured in several portions, with each layer being “punched” inside the support using a vibrator or manual tamper for 10-15 minutes. In total, it will take 35-40 minutes to fill out one support form. 2-4 studs are embedded in the concrete surface of the upper part of the post, allowing the strapping beam to be subsequently secured to the concrete surface of the support. The poured formwork is covered with a plastic bag to reduce moisture loss and prevent the foundation concrete from being washed away by rainwater.

Important! If you have made the formwork boxes high, but not rigid and strong enough, especially in the central or bottom part, then a situation may arise where the concrete mass crushes and expands the lower part of the foundation form.

The result is not a rectangular shape of the support, but a barrel-shaped one. Everything would be fine, but the volume of the form increases, and the level of concrete drops, which means the height of the foundation column will decrease. Therefore, the formwork has to be poured several millimeters higher than the calculated one. After about a couple of hours, the surface can be sprinkled with damp sand to reduce cracking and shrinkage of the foundation columns.

After the concrete mass has set, the formwork is disassembled and removed, after which that part of the support surface that will be under the soil layer must be treated with waterproofing bitumen coating. After 7-8 hours, the space around the columnar base can be covered with layers of a mixture of gravel, expanded clay and sand.

Conclusion

No matter how hard you try, a columnar base does not have a perfectly flat and horizontal top surface. After about a couple of days, until the concrete reaches the design strength, the plane of each support must be trimmed horizontally and vertically with a grinder or grinder. Before tying the columnar foundation supports, treat them with mastic and lay roll waterproofing. Next, you can lay a wooden beam and tie it to the supports of the columnar foundation, but the construction of walls and further construction is permitted no earlier than a month later.

Pillar foundations have been used for many years to be placed under lightweight structures made of wood, foam blocks or frame buildings. According to estimates by experts, the cost of such a foundation is 1.5-2 times lower than when pouring a strip foundation. In addition, making a columnar foundation with your own hands using step-by-step instructions is simple and takes a minimum of time.

Price columnar foundation more acceptable, and strength and durability are no different from expensive structures

How to make a columnar foundation with your own hands?

To build a country frame house, you cannot do without pouring a solid foundation - a columnar foundation. It will be quite enough for the building to last for decades. The cost of this option is more acceptable, and the strength and durability of the foundation is no different from other expensive structures.

A columnar foundation is an excellent basis for placing on it such buildings as:

• frame house;
• wooden bath, sauna;
• outbuildings;
• summer kitchen made of brick;
• patios, pergolas, verandas;
• terraces attached to the house;
• gazebos with fireplace.

In recent years, craftsmen have been using asbestos or plastic pipes to make a columnar foundation under a building.

A columnar foundation can be used in the construction of any lightweight building. The use of this option is especially justified if a deep foundation is required. When pouring the tape version, a huge amount of material, time and effort will be spent.

Among the main disadvantages of a columnar foundation under a building is the lack of possibility of arranging a basement. Columnar foundations are not used in the construction of multi-story, heavy structures. The maximum weight of the building should not exceed 1 ton per m 3.

When planning construction activities, it is worth choosing the type of foundation. The most common types are:

• monolithic;
• brick;
• stone.

In recent years, craftsmen have used asbestos or plastic pipes to make a columnar foundation under a building, which, after reinforcement, are filled with concrete mortar. In this case, the pipe is used as formwork and protects the concrete from external influences.

The support system is placed at points of concentration of maximum load, and these are the corners of the building, the intersection of walls or beams

Do-it-yourself columnar foundation: step-by-step instructions

The support system is placed at points of concentration of maximum load, and these are the corners of the building, the intersection of walls or beams. Each foundation column is connected to each other using a grillage - a reinforced concrete or log frame on which walls, partitions and other structural elements rest. The distance between supports is from 1.5 to 2.5 m.

Depending on the type of soil, columnar foundations are distinguished:

1. Recessed. Its depth usually exceeds 1 m.
2. Shallow. The laying depth is about 50-60 cm.
3. Not buried. It is used in the construction of very light and temporary structures and its depth is no more than 20-25 cm.

To make a columnar foundation with your own hands, we recommend following these step-by-step instructions, which include carrying out such construction work as:

Do-it-yourself columnar foundation made of pipes And

The construction of a columnar foundation using pipes takes a minimum of time, and even a novice builder can cope with the work. Step-by-step instructions include the following construction work:

• drilling a well of the appropriate diameter;
• careful compaction of the base of each well;
• installation of plastic or asbestos pipes;
• fixing each column with soil;
• making concrete mortar using a concrete mixer;
• filling the lower part of the pipe with approximately 30 cm of solution;
• at the next stage, the pipe is lifted, and the solution from it will fill the entire space of the well, thus the master will receive a concrete pad at the base of each pillar;
• filling the inside of the pipe with concrete solution halfway;
• installation of a reinforcement rod 12-14 cm in diameter;
• Fill the remaining void again with the solution, but do not forget about the need to thoroughly compact the mixture.

Now it remains to give enough time for the solution to harden and gain strength. This usually takes 2-3 weeks. During construction, some craftsmen make formwork that is wide at the bottom and narrow at the top. This form has a number of advantages compared to the traditional one. With a wide base of a columnar foundation, its load-bearing capacity increases significantly, since the load is evenly distributed over the entire base. This form of foundation has high resistance to winter soil heaving.

Video about making a columnar foundation with your own hands, step-by-step instructions:

Do-it-yourself columnar foundation, step-by-step instructions - this is what interests those who want to build a frame house or other building on the site. You will find important recommendations, tips, and features of pouring a foundation in this article.

The choice of the type of foundation for a cottage or country house will primarily depend on what material the building itself is planned to be constructed from. For example, relatively light buildings can be erected on a columnar foundation. In addition, this type of foundation is suitable for unstable swampy, peat, sandy or waterlogged soils, as well as for regions with deep freezing.

A columnar foundation can be built with your own hands in a relatively short period of time. Moreover, most often this does not require the help of any special or heavy equipment.

Types and purpose of columnar foundations

A columnar foundation is most often used for various wooden buildings - this could be a frame cottage, a gazebo, a bathhouse, as well as outbuildings, such as, for example, a barn or a chicken coop.

It is not particularly recommended to raise brick or stone buildings on a columnar foundation, since if they are too heavy, the supports may sag, which will lead to deformation of the walls, and subsequently to their destruction. However, there are special technologies that are used in industrial and residential construction, most often in regions with permafrost. But it is precisely in these cases that special approaches and specialized equipment are required - such methods will not be considered within the scope of this article.

There are several types of columnar foundations. It is the design of the device that unites them, and what makes them different is the material used for the construction.

• A monolithic reinforced concrete structure can be called the most durable and reliable for the construction of residential buildings of all existing columnar foundations.

This option has the highest compressive and tensile strength (of course, with proper reinforcement), which is very important when constructing a structure on unstable, moving soils.

It is permissible to build not only one-story, but also two-story wooden houses on a monolithic foundation.

• A brick columnar foundation can be called the most widespread from this type of base. It should be noted that such a structure, built from high-quality materials, can last even a hundred years or more - this is evidenced by numerous ancient monuments in Russian and European cities. True, in order to achieve such “longevity” for this building you need to choose exclusively baked bricks and only of excellent quality.

This type of foundation is also suitable for building a house of one or two floors when building on dense soils. Brick foundation supports are usually given a cross-sectional size of at least 400 × 400 mm.

• A foundation made of blocks, which can be made of different materials, has the same qualities as a brick structure. However, its reliability and durability will depend on the quality and type of material used.

Concrete blocks are considered the most durable, capable of withstanding heavy loads.

• It is not recommended to install a columnar foundation made of rubble stone on the slopes of a hilly area, as it will have low stability on moving soils.
• A columnar rubble concrete foundation is quite reliable and can be made in different ways - it is concrete mixed with rubble, laid in rows, or poured into a well made of rubble.

Concrete, falling between the stones, reliably holds them together, making the structure strong and capable of withstanding high loads.

• Small wooden buildings can be installed on a foundation, the supports of which are also made of wood that has undergone special treatment. Houses that have stood for tens and hundreds of years prove that properly treated wood can last quite a long time.

At present, however, due to the fact that more reliable materials for the foundation have appeared, wood is used less and less for this purpose. Although for extensions to the house, such as a veranda or terrace, wooden posts with a diameter of 150 ÷ ​​200 mm are ideal. However, we must not forget that in order for them to last for a long time, before digging in they are treated with antiseptic impregnations and covered with waterproofing materials - bitumen mastics, onto which roofing felt is fixed.

• A columnar foundation can be made of asbestos pipes of small diameter (about 150 mm) if a light wooden structure will be erected on it, and 250 ÷ 400 mm if the structure is planned to be quite massive. Asbestos pipes of large diameters can become a kind of ready-made formwork for pouring support piles with concrete and strengthening them with reinforcing bars.

• Another option for a columnar foundation can be a structure made of metal piles that are screwed into the ground. This method of arranging the foundation for a building is good because the pile goes through all the unstable layers, and then is screwed into dense layers of soil - this is what allows it to securely anchor there. On such a foundation, a wooden structure can be erected, installed on both flat and fairly rough areas of the territory.

By the way, with the help of piles you can not only lift/move a house, but also completely replace the foundation or partially reconstruct it.

Types of columnar foundations by degree depth

In addition to varieties based on the base material of manufacture, columnar foundations are divided according to the degree of “immersion” in the ground relative to ground level. Yes, there is shallow and buried types of foundations. The choice based on this criterion directly depends on the characteristics of the soil on the site.

Shallow option applies if available fine-fragmented, sandy and rocky soils with deep groundwater. Foundation columns of this type are installed to a depth of only 650 ÷ 700 mm. This should be quite enough, since the soils in which they are immersed are little susceptible to displacement.

The piles of the columnar recessed foundation go 1500 into the soil thickness — 2000 mm and even more. They are usually used in areas with deep soil freezing, which exceeds 400 ÷ 500 mm. In addition, such foundations are more suitable for unstable moving soils.

The distance between foundation pillars is usually from 1000 to 2000 mm.

Basic columnar foundation design

The columnar foundation has a fairly simple overall structure.

• At the base of the columns, a 100 ÷ 200 mm sand layer is laid and compacted. Sand is a kind of drainage that helps remove moisture from the foundation columns that can accumulate in the soil.
• Next, a concrete solution is laid on top of the pillow, which forms a monolithic slab with an average thickness of 400 ÷ 500 mm.
• Next comes, in fact, the columnar support itself, which needs to be strengthened with reinforcing rods - this will need to be done even if the columns are built from stone or brick. The second important action with the support is to ensure its reliable waterproofing.
• The columns should be raised one level above the ground, and a grillage or other belt connecting the supports should be placed on top of them, which evenly distributes the load on the entire structure of the columnar foundation.

The grillage is often made of wooden beams with a cross-sectional size of 150 × 200 or 200 × 200 mm. For wooden houses or outbuildings, the grillage can simultaneously become a foundation crown for future walls.

In addition, on a columnar foundation made from any ofmentioned above materials, in addition to wood, a reinforced concrete grillage can be installed. It is made by constructing a structure in which a reinforced structure is laid and then filled with concrete.

The grillage can raise the lower edge of the building to a height of up to 800 ÷ 900 mm above the ground, or it can be located only 300 ÷ 350 mm from the ground or even “lie” on the surface of the ground. In the latter case, from the outside it will look exactly the same as the strip foundation.

• The disadvantage of a columnar structure, which raises the house above the ground to a considerable height (about 1000 ÷ 1500 mm), is that it is impossible to build a full-fledged basement under the building. However, sometimes home owners find a way out of the situation by installing a fence between the foundation pillars, which should not be connected to the foundation by the reinforcement structure. A fence is an inter-pile wall made of slabs or bricks, and sometimes simply knocked together from wood.

When installing it, it is necessary to ensure normal ventilation in the underground space, which will not allow the walls and floors in the house to become damp. Therefore, ventilation holes must be made in the built-in enclosure, which are “dressed” in grilles or deflectors in order to protect the semi-basement from the penetration of small animals, birds, insects, etc.

• Columnar foundations are often used in areas where a high risk of flooding due to river floods is common. In this case, the pillars can go into the ground to a depth of 2000-2500 mm, and rise above it to the same height. Taking into account all the features of the area, it will not be possible to build a basement under such a house, and it makes no sense, so there is no need to build a fence.

Calculation of a columnar foundation

The first step is always, even before the start worksbypreparing the site for installation foundation, planning is underway, that is, drawing up an appropriate project. This issue definitely requires a professional approach. In drawing up the project, it is necessary to involve a special organization engaged in architectural calculations, taking into account a whole range of initial data - from local climate and soil characteristics to the specific wishes of the customer.

Of course, the basic data for starting design will be the total area of ​​the building and its total estimated mass, the location of the proposed construction. Geodetic survey and geolocation of the object on the ground are required. In addition, designers will take in:

• Specific features of the soil at the site of construction of the building.
• Location of groundwater aquifers and their depth.
• The freezing limit of the soil, the degree of its swelling during freezing.
• The number of floors in the building being built and its total height.
• The main materials from which the building is supposed to be constructed, including types of floors and type of roof.
• All possible additional loads that will fall on each key point of the foundation.

As a result, the number and exact placement of support pillars, the material of their manufacture, installation technology, laying depth, protrusion height above ground level, type of grillage and, possibly, other necessary data must be determined.

Of course, you can try to carry out the calculations yourself, using the specialized ones available on the network. online calculators, which are intended to determine the parameters of foundations of various types.

However, you should not rely too much on such capabilities, since such software still cannot take into account all the specifics of a particular construction site. But specialists working in this region probably know the features of this area and will certainly make the calculations more accurate. Moreover, with professionally prepared design documentation it will be much easier to carry out all procedures for registration and approval of other registration and permitting documents for construction.

Video: calculation and construction of a pile foundation for a frame house

Preparatory excavation work

• The first of the activities preceding the installation of the foundation structure is the preparation of the site and marking for its installation.

To do this, based on the drawn up project, using reference points, the area intended for the construction of the building is first precisely limited. This place is immediately marked with twine and pegs. Moreover, as a rule, two parallel threads are stretched, which immediately determine the width of the future foundation. The angles at the intersection of the threads must be straight - this is best controlled using a surveying tool. If this is not the case, you need to very carefully check the perpendicularity and parallelism of the lines. Be sure to compare the length of the diagonals of the rectangles - if it is the same, then the marking was done with high quality.

• Next, a fertile layer of soil 150 ÷ ​​200 mm thick is removed from the intended area.
• Then the installation locations for the foundation pillars are determined, also in strict accordance with the dimensions specified in the design documentation.
• After this, using a manual or mechanical drill, holes are drilled at the designated points. The diameter of the selected wells is also indicated in the project - it can be from 150 to 400 mm.

• Provided that these holes are drilled to a depth of 800 ÷ 1000 mm, fixing their walls will most likely not be required.

• In the event that the foundation is deeper, it will be necessary to make supports for the walls to prevent the soil from collapsing.
• If the pillars are square in cross-section, then the drilled holes are expanded using a bayonet shovel to the desired size.
• Next, sand is poured into the bottom of the dug wells in a layer of 100 ÷ 200 mm, moistened and compacted well.
• 150 ÷ ​​170 mm of coarse concrete mortar is poured onto the sand cushion, which will become a reliable base for the pillars and will not allow moisture from the mortar to be absorbed into the sand and soil.

Prices for hand garden augers

Hand garden augers

How to install columnar supports

When the holes for the pillars are prepared, you can begin to manufacture the supports themselves.

In the context of individual construction, not all of the structures mentioned at the beginning of the article are used equally often. It is worth considering the most affordable ones for self-installation and therefore the most popular of them.

Support pillars made of bricks or blocks

• Formwork made of roofing felt is installed in the prepared pit; it can be arranged in either a round or square pit. The same roofing material will subsequently also play the role of a waterproofing agent.
• Next, a reinforcement structure is lowered into the pit, which should be level with the ground surface.
• Then, a concrete solution made from cement and gravel or medium-fraction crushed stone is poured into the pit.
• The pit is filled completely, the solution is leveled on top and left to harden and harden. This will take at least 8 ÷ 10 days.
• Then, two or three layers of roofing material are laid on the resulting concrete column - it will become a reliable waterproofing for brick or block masonry.

• Brickwork is laid on top to the required height of the support. The column can be lined with a well - in this case, its internal hollow part will subsequently be filled with concrete. Another option is when the pillar is made entirely of brick.

In exactly the same way, pillars are erected from small concrete blocks.

Monolithic foundation reinforced concrete pillars

This option for making concrete pillars is produced slightly differently.

• Roofing material, rolled in two layers into a pipe, is installed in a round prepared hole. The height of the pipe must correspond to the level to which the foundation must be raised.

• To ensure the stability of this unique roofing felt formwork, it can be installed in a light metal mesh, also rolled into a pipe. Stability is needed so that the structure, after pouring concrete into it, can be shaken and released air bubbles that entered the solution during the mixing process.
• A reinforcement structure is installed into the resulting formwork, and then concrete made from gravel and cement is poured on top of it.

• If a concrete belt is placed on top of the concrete pillars - a grillage, then the reinforcing bars should be higher than the foundation pillars. This is necessary for connecting the reinforcement parts of the pillars and the grillage reinforcement system.

• Before installing the formwork for the concrete belt, the supports on top must be treated with bitumen mastic, which will create additional waterproofing for the columns.

Video: pouring concrete pillars of a pile foundation

Asbestos cement pillars

A columnar foundation can also be constructed from asbestos-cement pipes, which are installed on a concrete pad, just as in the previous case, where roofing felt was used. However, the process of filling columns here has its own characteristics.

• For stability, two holes are made in the lower part of the pipe, which will be located in the pit. A piece of metal rod is passed through them, and then an asbestos pipe is installed in the pit and covered with crushed stone around it so that it covers the fittings sticking out on both sides. The pipe is given a perfectly vertical position.
• Then one-third of the concrete solution is poured into the pipe formwork.
• After this, you need to install fittings in the middle of the pipe, in the poured uncured solution - this can be one or several rods.
• Next, the solution is poured to the top of the pipe and leveled from above.

• Around the pipe you need to immediately fill the entire space with loam or the soil that was selected from the pit. All this backfill is carefully compacted.

Metal piles

Metal piles can be screwed into a pre-arranged hole made with a hand drill, but the piles go much deeper into the ground. For such a foundation, you do not have to prepare a hole by filling it with sand and pouring a concrete pad.

Sometimes piles are screwed directly into the soil surface, without first digging wells. But in any case, you can’t cope with screwing in piles alone; you will need at least one assistant.

• When screwing in piles, their verticality is constantly monitored. The piles are screwed in until the design depth is reached.

• Once all the piles have been screwed in, they should be filled

• To make this operation easier, a special funnel is installed in the pipe, and the solution is poured into the cavity through it until the pipe is filled to the top.
• Once filled, the concrete should set and harden.
• Metal platforms can be welded on top of the finished piles, onto which a wooden grillage is fixed.

• Another option for a grillage can be metal lintels - they become a belt that connects the piles into a single structure. They can be welded not only on top of the installed pillars, but also at ground level, which gives additional rigidity and reliability to the entire foundation.

Screw-in piles are convenient for use on heavily crossed areas where it is necessary to bring the foundation pillars to the same height, since they can be adjusted - raised a little or lowered lower.

Video: foundation on screw metal piles

Prices for screw piles

Screw piles

Pile foundation grillage

The grillage or lintel, which is laid on top of the foundation pillars, is both a connecting element for the entire structure and a reliable support for the construction of walls.

On any type of columnar foundation, you can lay wooden lintels made of powerful timber, a reinforced concrete structure or a grillage made of rolled metal.

The jumpers are secured in different ways, depending on the material used to make the posts and the grillage itself.

• Wooden lintels are most often secured using anchors.
• A metal belt (channel, I-beam or angle) is attached either by welding seams or powerful bolts.
• Reinforced concrete belt With secured with the help of common reinforcement, previously installed in the column and passing through the grillage, where it is twisted with wire with the reinforcing grid of the lintel itself.

So, the conclusion. WITH A column foundation is much more economical to construct than a monolithic or strip foundation. In addition, it is quite possible to build it on your own. If you decide to make a light extension to your house in the form of, for example, a veranda or terrace, then you simply cannot find better and simpler foundations for them than a columnar foundation.

A columnar foundation is a variant of a non-solid structure, which is used for the construction of light buildings, frame and panel houses. Its main advantage is the speed and ease of construction, minimal costs for building materials. The step-by-step instructions for constructing a columnar foundation with your own hands consists of several main stages: calculating the number of columns, breaking down the site, excavation work and building the foundation.

The calculation is based on two indicators:

• soil resistance,
• bearing capacity of supports.

The first value is tabular, therefore it is selected taking into account the type of soil at the construction site (see table No. 1). It depends on it what cross-section the pillars will have. The second is calculated, where the weight of the building is mainly taken into account. But since the support-column foundation is constructed for light one-story buildings, it is possible to simplify the calculations by taking the location of the supports as a basis. They must be erected at the corners of the building, as well as at the junction of partitions and external walls. Intermediate pillars are placed within a range of 1-2 m from each other, depending on their cross-section.

For example, if for the construction of supports a solid concrete block with dimensions of 390x180x190 mm is used, laid in pairs, then the distance between the posts can be left 2 m. If masonry of one and a half bricks is used, then the spacing should be reduced to 1.5 m.

Materials for columnar foundation

A foundation structure of pillars is constructed on dense soils; on heaving soils, a pile type, strip or slab, should be used. Therefore, a columnar foundation is either a shallow structure or one laid 20-30 cm below the freezing point of the soil.

It is erected from block materials (brick, concrete or gas silicate blocks, logs or timber) or in the form of a monolithic element by pouring concrete mortar into the formwork. The formwork can be collapsible or non-dismountable from pipes (plastic, steel, asbestos-cement).

Marking the locations of pillars, for example, a rectangular foundation, is an accurate marking of the perimeter of the structure on the plane of the construction site. The main thing here is to set the corners of the building at 90°. It's easy to do. We must take as a basis the rule of the “golden triangle”, also known as the Pythagorean theorem. That is, one side of the angle should be 3 m, the other 4 m, and the distance between the ends of the sides, which is also the hypotenuse of a right triangle, should be 5 m.

The perimeter of the building is marked with strong string or twine, which is stretched between wedges driven into the ground at the corners of the building. You can finally check the correctness of the applied markings by measuring the diagonals. They should be equal in length.

Excavation

Here it all depends on what material it is decided to build the columnar foundation from:

1. If these are block materials, then a rectangular hole is dug under them with a shovel. The depth is determined at the calculation stage. Typically, the block variety is a shallow or surface structure.
2. If it is a concrete solution, then round holes are drilled under the pillars, for which you can use a garden drill. For example, a monolithic support with a cross-section of 200 mm² and a depth of 1 m can withstand 3-7.5 tons of load, depending on the type of soil.
3. A monolithic structure can also be of rectangular cross-section, for which it is necessary to construct formwork of the appropriate shape under each pillar. In this case, the volume of excavation work increases greatly, because space is needed to install the formwork. Therefore, the size of the pits is increased by 40-50 cm on each side.

Construction of a columnar foundation

Let's consider all varieties separately, taking into account the building materials used.

Pits with a square cross-section have been dug, and in them you need to make a compacted cushion of sand 30 cm thick. This size is not chosen in vain. Sand of this thickness additionally performs waterproofing functions. Through such a layer, water from below will not reach the foundation pillars.

Now about assembling the blocks:

1. One concrete block at a time is placed in the pits located in the corners of the building. They are laid closer to the outer wall.
2. Using a string stretched between the blocks and a level, the blocks are aligned in the same horizontal plane. Usually, sand is poured under those that are lower, raising them to the required level (up to the laces).
3. Next to the already laid blocks, one more is laid so that both elements form a single upper plane located exactly along the horizon.
4. Intermediate posts are laid and positioned along the stretched laces.
5. After which the second row of blocks is laid on the masonry mortar on top of the first row, only across, to form a band. Here the sequence is exactly the same: the corner elements are assembled, the lace is pulled between them with horizontal alignment, and the intermediate pillars are built up.

If a columnar foundation is constructed of brick, then the assembly technology is no different from the previous one.

Laying stones must be carried out with a sling not only vertically, but also horizontally.

There are two methods of pouring, which differ from each other in the presence or absence of formwork. If the soil on the site is dense clayey, then there is no need to install pipes in prepared wells. A piece of pipe will only be needed to form the base part (above the ground). It is important to align the pipes horizontally with each other.

This must be done in exactly the same way as when setting up pillars made of block materials:

1. To do this, sand is poured into the well and compacted.
2. A piece of roofing felt is twisted into a tube with a diameter equal to the diameter of the well, into which it is inserted.
3. A pipe with a height equal to the height of the outer part of the support column is installed on top of the well.
4. A reinforcing frame made of reinforcement can be installed inside. If the structure is light, for example, a gazebo or a summer terrace, then the reinforced frame may not be used.
5. The concrete solution is poured using a tamper.
6. After 28 days, the foundation can be loaded.

If the soil on the site is soft (loose), for example, with a lot of sand, then it is better to install pipes in the wells. Their installation, alignment in a horizontal plane, and pouring of concrete mortar are carried out in the same way as in the previous case.

This is a more complex process because it involves the assembly of formwork, which must be disassembled and removed 7 days after pouring concrete.

1. A sand cushion is poured into the prepared holes.
2. Square formwork is assembled from boards or flat durable materials: plywood, OSB, metal sheet, corrugated board, etc. The main requirement for the structure is strength, because the concrete solution poured inside will put pressure on the walls of the formwork with its weight.
3. A reinforcing frame is installed from steel reinforcement, which is shaped like a cage with a pitch between the rods within 10-20 cm.
4. Concrete is poured and compacted.
5. After a week, the formwork can be dismantled, and the support pillars can be loaded after 28 days. During this time, the concrete will gain its original strength.
6. After demoulding, the pillars are covered with soil using a tamper.

Stone pillars

Natural stone is often used as a material for the construction of columnar foundations. The structures made from it are strong and reliable. Purely technologically, stone pillars are erected using two technologies:

Masonry technology is considered complex because it is necessary to select pieces of material according to size. Large stones are laid down. As the pillar rises, their dimensions can be reduced, but it is better that all the blocks are the same. At the same time, the chipped surface of the stones makes it difficult to fit one element to another. The work contractor must have experience in laying stones in pillars.

In this regard, the rubble concrete method is simpler, but in terms of concrete solution consumption it is unprofitable, because the mixture must fill all the voids between the stones. And this is a large volume. Rubble concrete pillars are constructed using the following technology:

• formwork is assembled;
• a sand cushion is poured into it;
• stones are laid in one row;
• concrete is poured to fill the voids;
• the second row of stones is laid;
• concrete is poured;
• And thus to the required height of the support column, or rather, to the upper edges of the formwork.

Any formwork method for constructing support pillars requires precise alignment of the formwork, both in the height of each element and horizontally between all of them. To adjust the height of the pillars, the last layer of stones can be laid out from small pieces or by pouring a thick layer of concrete.

Video: Installing pillar formwork, reinforced frame and pouring the heel of a columnar foundation

Video 2: Backfilling and pouring the pillar

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

General information about columnar foundations.

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

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

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

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

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

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

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

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

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

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

b - prefabricated for any location of groundwater;

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

2. the same, with a steel pipe core;

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

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

5. Prefabricated steel pipe support pole;

6. backfilling with excavated soil;

7. base plate made of monolithic reinforced concrete;

8. base plate of prefabricated reinforced concrete foundation;

9. sand cushion.

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

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

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

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

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

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

Conditions under which columnar foundations are not recommended:

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

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

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

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

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

Information about the depth of laying columnar foundation supports

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

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

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

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

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

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

Construction of a columnar foundation

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

1. Preparatory work

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

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

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

If you find peat or silty soils under the cut layer, then it is necessary to completely replace the base; in this case, you need to consult a geologist on the composition and design of the artificial base.

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

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

2. Foundation breakdown

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

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

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

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

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

4. Installation of formwork

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

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

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

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

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

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

5. Installation of fittings

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

Photo of columnar foundation reinforcement.

6. Concrete supply

Here everything is the same as in strip foundations, concrete is laid in layers of 20-30 cm with vibration using manual vibrators.

Photo of concrete being fed into the pillar formwork.

7. Grillage arrangement

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

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

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

Photo of the grillage arrangement for a columnar foundation.

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

8. Pickup device

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

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

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

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

9. Foundation waterproofing

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

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

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

Important points when building a columnar foundation

• When constructing foundations on heaving soils, it is necessary to have a clear understanding that the construction of a house and its commissioning must be carried out in one construction season. Foundations built on heaving soils and left unloaded during the winter (without walls, ceilings or roofs) may become deformed. This is true for all types of foundations, but is especially important for columnar foundations, since each column behaves like a separate foundation (due to the absence of a single rigid frame, unlike a strip or slab foundation). Each pillar gives its own settlement, which in the future (after frost - in the spring) can complicate the construction of the grillage and walls.
• Unforeseen deformations can also occur when the built house is not used or heated in winter, and the depth of the foundation was designed for the thermal conditions of the heated house. A favorable time period for laying a foundation is considered to be the period of time when the soil “moved away” from the frost and groundwater descended to the lower layers. This could be the summer months and early autumn.
• If you have made the supports of a columnar foundation from monolithic concrete, then you should know that the “readiness” of the concrete is achieved after 30 days. During the entire “maturation” period, no loads should be placed on the concrete supports, and care should also be taken to ensure that the top layer of concrete does not dry out. To do this, you can cover it with film or roofing felt. To ensure that the concrete sets evenly, the supports should be moistened with water from time to time (two or three times a week, depending on weather conditions).
• To prepare concrete, it is best for you to use M400 cement. Fine gravel and coarse sand can be used for concrete filler.

  An example of calculating components for preparing a concrete mixture:

  • cement 20 kg;
  • sand 50-55 kg;
  • gravel* (crushed stone) 80-85 kg.
  Water is added so that the concrete mixture can be easily laid - but not poured!
• If the composition of the concrete mixture is too liquid or, on the contrary, too thick, then the strength of the concrete structure is reduced by 25% of the strength of the same structure, during the manufacture of which all the requirements for the proportionality of the components were met.

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

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

1. An insidious defect of the foundation is the unevenness of its subsidence. This can occur for a number of reasons, which include:
   • the foundation depth was not calculated correctly;
   • the supports have different depths.
   • The load on the foundation supports is uneven.

   To eliminate this phenomenon, it is necessary to perform an accurate calculation of the systematic distribution of the load on the foundation. Do not forget to take into account the load on the foundation when adding a second level to the house (for example, building an attic);

2. The material used was of low quality - the wrong brand of cement, sand that contained an admixture of clay, etc. Or a material, for example cement, has a long shelf life (it should be recalled that when stored for six months, its grade decreases by 25%, and when stored for a year or more by 35-50%);
3. The load-bearing properties of the soil were not assessed correctly.

   A correctly completed project by specialists and constant monitoring of construction by you or an independent expert will help you avoid these mistakes.

Estimated cost of a columnar foundation

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

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

Prices for laying the foundation:

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

Prices for masonry work:

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

Prices for floor installation:

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

Relationship between contractor and customer.

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

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

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

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

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

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