What is a columnar foundation. Do-it-yourself technology for creating a columnar foundation

The feasibility of choosing columnar foundations

Pillar foundations are erected mainly under houses without basements with light walls(wood, panel, frame). They are also laid under brick walls when deep laying is required and the strip foundation is uneconomical. Pillar foundations are 1.5-2 times more economical than strip foundations in terms of material consumption and labor costs.

Depending on the design of the building (primarily its mass and number of storeys), the pillars for the foundation can be stone, brick, concrete, rubble concrete, reinforced concrete and other materials. Most often, when constructing columnar foundations, ready-made prefabricated concrete and reinforced concrete blocks are used. Columnar foundations must be installed at the corners of the house, at the intersection of walls, under frame racks, heavy and load-bearing walls, beams and other places of concentrated load. To reduce pressure on weak soils, columnar foundations made of piece materials are widened in the lower part, making ledges at least two rows of masonry high.

If the depth of the columnar foundation is more than 1 m and the construction of the foundation from small-piece material is difficult, apply reinforced concrete pillars, asbestos-cement or metal pipes. If there is no water in them when digging holes, such foundations can be made with a base plate of cast-in-situ concrete laid on the bottom during the installation of the pillars. The distance between the poles is assumed to be 1.2-2.5 m. Strapping beams must be laid on top of the poles to create conditions for their joint work. With a distance between the foundation pillars of more than 2.5-3 m, more powerful rand beams (reinforced concrete, metal) are laid on top of them.

The minimum section of foundation pillars, mm, is taken depending on what material they are made of: concrete - 400; rubble concrete - 400; natural stone masonry - 600; from buta flagstone - 400; from brick above ground level - 380, and when dressing with a pick-up - 250.

It is preferable to build columnar foundations on heaving soils, since they can be installed below the freezing depth at minimal cost. At the same time, the effect of tangential forces caused by frost heaving of the soil on the surface of the pillars is minimal. It is not always possible to avoid the negative impact of frost heaving forces only by increasing the depth of the foundation below the freezing level. The tangential forces of frost heaving are neutralized as follows: the base of the foundation is made broadened in the form of an anchor platform, which does not allow the foundation to be pulled out of the ground during frost heaving. Inside such a foundation, it is desirable to lay a reinforcing cage that will protect the foundation from rupture. If the foundation is erected from stone, brick, small blocks, monolithic concrete without reinforcement, its walls must be made tapering upwards.

With a large freezing depth in heaving soils, anchor columnar reinforced concrete, monolithic or prefabricated foundations are effective. On such foundations, the effect of frost heaving forces acting on the side surface is insignificant, since the pillars are made with a minimum cross section (see Fig. 1).

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, as well as warming the surface layer of soil around the foundation. The depth of foundations is directly dependent on the depth of soil freezing and the level groundwater.

To increase the stability of columnar foundations, in order to avoid their horizontal displacement and overturning, as well as to arrange the supporting part of the basement, a grillage is made between the pillars. When arranging columnar foundations for wooden buildings, the function of a grillage can be performed by a wooden strapping made of logs or timber. In this case, the space between the planning mark of the earth (blind area) and the strapping is filled with a pick-up.

The supporting part of the base with stone and brick walls a reinforced concrete grillage laid on top of the pillars can serve. The grillage is also made in the form of an ordinary jumper, reinforced with 4 - 6 reinforcing bars with a diameter of 10 - 12 mm, laid on a concrete layer 70 mm thick. The height of an ordinary jumper should be 1/4 of the span, but not less than 4 rows of masonry. The grillage can be made in the form of a monolithic or prefabricated reinforced concrete rand beam.

When constructing monolithic reinforced concrete columnar foundations, additional costs will be required associated with the manufacture and installation of reinforcing cages, the preparation and laying of the concrete mixture, the assembly and disassembly of the grillage formwork and other works. When constructing foundations on heaving soils, it is necessary to have a clear idea that the construction of a house and its commissioning should be carried out in one construction season. Foundations erected on heaving soils and left on winter time without load (without walls, ceilings and roofs), can be deformed.

Unforeseen deformations can also occur when the built house is not operated and not heated in winter, and the depth of the foundation was designed for the thermal regime of the heated house.

Prefabricated column foundations have the following advantages over strip foundations:

column foundations, depending on the pitch of the supports at the same depth of laying, are approximately 1.5 - 2 times more economical than strip foundations in terms of material consumption and cost;

the use of prefabricated columnar foundations significantly reduces the labor intensity of work and the duration of the zero cycle work by about half;

the cost of columnar foundations can be reduced by approximately 1.5 times if the columns are made monolithic in inventory formwork, reducing their cross section by half compared to prefabricated ones.

Column foundations have another positive quality, which lies in the fact 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 soil 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 total area foundation.

As already mentioned, 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 the construction of foundations are considered from the point of view of their construction on heaving soils. It is generally accepted that during construction on heaving soils, the depth of foundations should be lower than the estimated 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 kinds of deformations occur. Therefore, when building houses without basements on heaving soils, it is better to build shallow, shallow or shallow foundations. Let's explain their differences.

Foundations with a laying depth of 0.5 - 0.7 of the standard freezing depth are considered shallow. For example, with a standard freezing depth of 140 cm, the depth of a shallow foundation will be 140x0.5 = 70 cm.

Shallow foundations are those foundations where the ratio of the height to the width of the base of the foundation does not exceed 4. Non-buried foundations are those whose laying depth is 40 - 50 cm.

Properly executed shallow foundations will provide:

reduction of seasonal fluctuations in heaving of soils and foundations;
reduction in the scope of work and the timing of the construction of foundations;
reducing the cost of building foundations by reducing the consumption of materials and labor costs;
the possibility of building foundations in almost any hydrogeological conditions of the site.

Column foundation structures

Pillar foundations made of ready-made standard concrete blocks are a structure consisting of a set of individual blocks laid on a cement mortar. The number of blocks depends on the depth of the foundation (Fig. 2). For the installation of foundation pillars, pits of the required depth are dug with slopes. The dimensions in the plan depend on the width and length of the prefabricated elements used, plus at least 20 cm on each side for the installation of a sand cushion.

Depending on the bearing capacity of the base soil, the total load acting on 1 m2 of the base of the foundation, the bearing area of the foundation is determined. The area of the prefabricated columnar foundation can be increased by replacing concrete blocks F 4.5.3 (Sf = 1900 cm2), F 4.4.3 (Sf = 1520 cm2) with FBS 9-5-6 (Sf = 4440 cm2). If such an area of the foundation block is insufficient, then pillow blocks of the FL brand are laid under these blocks, for example, FL 6-12-3 (Sf = 7080 cm2) or FL 8-12-3 (Sf = 9440 cm2). Technical data of foundation blocks are given in Table. 15 and 16.

Construction industry enterprises manufacture prefabricated foundation elements of various sizes and assign their own marking to them. For small garden houses for columnar foundations, for example, FSD-1 blocks (Sf = 1500 cm2) can be used - dimensions 500x300x300 mm, weight 108 kg, concrete volume 0.045 m3.

Pillar foundations with grillages

For the stability of the pillars and the support device for erecting the walls of the house, after aligning the marks of the upper edge of the foundation pillars (mounting horizon), a grillage is made of precast concrete elements or monolithic reinforced concrete. A variant of a columnar foundation with a grillage of standard elements is shown in fig. 3.

Rice. 3. Column foundation with grillage from prefabricated standard elements: 1 - blocks strip foundation FL 8-12-3 (1180*800*300 mm); 2 - concrete blocks FBS 9-5-6 (880*500*580 mm); 3 - grillage made of reinforced concrete lintels 5 PB-25-37 P (2460 * 250 * 200 mm); 4 - wire twist; 5 - reinforced monolithic belt

Rice. 5. Recessed columnar foundations, arranged on heaving soils: a - prefabricated foundation; b - prefabricated monolithic foundation; 1 - sand preparation with a thickness of 10 -15 cm; 2 - foundation block FL 6-12-3 (1180*600*300 mm); 3 - asbestos-cement pipe with a diameter of 200 - 300 mm; 4 - concrete class B15 (M200); 5 - release of reinforcing bars of at least 10 - 15 cm (rebar class A-III, diameter 18-22 mm); 6 - base plate made of monolithic reinforced concrete; 7 - core made of a metal pipe with a diameter of 80 -100 mm

Instead of reinforced concrete lintels 5PB-25-37P, lintels 5PB-30-37P or BU-28-1 with a length of 2980 mm can be used. If the loads on the lintels exceed their design bearing capacity, then a strapping monolithic reinforced concrete belt is arranged along the top of the lintels (Fig. 4). This is especially true in cases of construction of columnar foundations on subsidence and bulk soils.

Columnar shallow foundations can be made of brick and monolithic concrete (Fig. 1). To do this, wet sand is poured into an open pit with layer-by-layer compaction with a layer 50–60 cm thick, roofing felt or roofing felt is spread so that cement milk from concrete (mortar) does not seep into the sand, and brickwork is started on M50 cement mortar, and with a monolithic version - laying concrete M200. The walls of the pillars are made tapering upwards, as shown in Fig. one.

After the completion of the installation of column foundations, the marks of the tops of the pillars are checked and, if necessary, leveled with a 1: 2 cement mortar. After that, they proceed to the device of a prefabricated, prefabricated-monolithic or monolithic reinforced concrete belt (grillage), and during the construction of a wooden house - strapping from logs or beams. The device of a monolithic belt will ensure proper longitudinal rigidity and stability of the foundation. Prior to the installation of a monolithic belt, prefabricated jumpers must be securely connected to each other. To do this, the mounting loops are tied crosswise with a wire twist or connected by welding trimming reinforcement with a diameter of 8-10 mm. Then formwork is arranged on top of the jumpers and a layer is spread cement mortar M100 with a thickness of 4 - 5 cm, install the reinforcing cage and lay the concrete mix M200. The surface of the concrete is leveled and covered with any rolled material to protect it from atmospheric influences. After gaining strength and waterproofing, you can proceed with the installation of floor slabs.

Foundations in deep-freezing heaving soils

When building houses in deep-freezing heaving soils, in order to reduce the influence of frost heaving forces, it is advisable to arrange columnar foundations below the level of soil freezing. To do this, you can use not only traditional foundation elements, but also asbestos-cement, concrete and metal pipes. Variants of the arrangement of such foundations are shown in Fig. 5.

The device of the prefabricated foundation (Fig. 5, a) is performed in the following technological sequence. A block of the FL type is laid on the prepared sand cushion, an asbestos-cement pipe of the required length is installed vertically and its position is fixed at ground level. At the base at an angle of 45 °, a concrete block is made, fixing the position of the pipe on the foundation block. The surface of the concrete forget-me-not is covered with roofing felt (roofing material) and sprinkled with soil (sand). Instead of a solid pipe, the foundation pillar can be assembled from individual components. After the device of the concrete forget-me-nots, they proceed to the device of the next columnar foundation, giving time for the curing of the concrete of the forget-me-nots. Having completed the installation of all foundation blocks, they return to the first columnar foundation and backfill with soil with careful layer-by-layer compaction. When constructing a columnar foundation from separate pipe sections, backfilling with tamping is performed in parallel with their installation. Having thus fixed the foundation pillar, they proceed to install reinforcing bars or a core from a metal pipe. To prevent the reinforcement from shifting during concreting, concrete is first poured into the asbestos-cement column to a height of 10 - 15 cm and the core of the metal pipe or individual reinforcing bars are immersed in it in the center at a distance of 25 - 35 mm from the wall of the column, better - a spatial reinforcement cage made from the same individual reinforcing bars connected with a reinforcing wire clamp with a diameter of 3 - 5 mm. The reinforced foundation pillar is filled in layers (30 - 40 cm) with plastic concrete mix M200 with a cone draft (OK) of 6 - 8 cm. Concrete is compacted deep vibrator or by baying with smooth bar fittings with a diameter of 20 - 25 mm of class A-1.

When erecting a precast-monolithic columnar foundation (see Fig. 5, b), the installation of an asbestos-cement pipe and a metal core is carried out on a freshly laid concrete mixture of the base slab, sinking the core into the body of the slab by 10 -15 cm. Otherwise, the sequence of work is similar to the prefabricated version foundation.

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 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 groundwater level, layers with a 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 operations for the construction of the grillage on the pillars step-by-step instruction necessary for an individual developer as a benefit. 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.

Unlike trial screwing screw piles in the technology of the same name, to find the depth of the bearing layer, full-scale surveys are needed 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 with concrete or brickwork, 20 x 20 cm or 20 cm in diameter for a monolithic reinforced structure.

Layout 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 sand filling 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 correct way would be to mark the trenches, taking into account the width of the sole, the drainage contour, and 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, at least 1 x 1 m. 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.

The durability of each building directly depends on the strength of the foundation under it. But is the installation of a massive continuous foundation tape always justified if it is planned to erect light wooden or frame building? Increasingly, in this case, a less expensive and well-supported columnar foundation is being installed. Support poles are made from various materials, applying different ways and technology. Next, we will talk about the foundation of the building, made of concrete pillars.

Features of the columnar base

Such a foundation resembles a pile foundation, with the difference that the finished piles are driven (screwed) into the ground, and the pillars are poured out or laid out in place in the prepared recesses. The base, made in this way, greatly reduces the cost of work and makes it less laborious.

However, the device of the columnar foundation is not always suitable. If the mass of the above-ground part of the building is significant (the walls are made of brick, concrete, cinder block or other heavy building material), a large area of \u200b\u200bsupport on the ground is assumed. In this case, it is better to prefer the construction of a deep or shallow (depending on the soil structure) strip base with a sufficient sole area.

If the house is supposed to be built from light building materials (wood, foam concrete, materials for frame construction), a columnar foundation, or rather the area of \u200b\u200bits support on the ground, is enough.

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

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

Advantages and disadvantages of the foundation of the pillars

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

relatively low consumption of materials;
much lower labor intensity (in comparison with the tape base);
greater efficiency and strength in swampy, loose soils and those prone to heaving;
the ability to combine with other foundation structures.

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

it cannot be built in case of a large expected load on the base (heavy buildings);
the impossibility of building a basement;
instability to horizontal movements of soil layers;
void under the base floor (to close it, a pick-up is built along the perimeter of the base).

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

Principles for calculating a columnar foundation

The arrangement of such a foundation for construction also requires calculations. It is necessary to calculate the number of support pillars, their location and the total area of \u200b\u200bsupport on the ground.

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

If the calculation of the required total area of the base of the foundation shows the need to further reduce the distance between the supporting structures, then the columnar base may not be effective for the mass of this building. In this case, it is better to stop at the construction of a strip base for a building or its combination with poles or piles (if the type of soil does not allow pouring a simple, shallow concrete strip).

Methods for pouring concrete pillars

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

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

Along the perimeter of the future foundation of the building, the installation sites of the supports are marked according to the calculations.
Recesses are prepared with a hand drill. Their depth depends on the degree of soil freezing in the region and the level of occurrence of stable soil layers. Even if the stable ground is not deep, the sole of the pillars is made 15-25 cm below the freezing level. The diameter of the supports should correspond to the calculated area of each pillar.
A cylinder (2 layers) is formed from a rolled waterproofing material (roofing material, waterproofing), 3-4 cm of the already prepared recess. The longitudinal joint is fixed with tape, it also makes several fixing stitches around the prepared cylinder.
The form for pouring concrete is placed in a recess, a sand and gravel cushion is poured onto the bottom. A reinforcing structure formed from several metal rods is welded or twisted with a knitting wire. One armature, usually central, is made 30-40 cm longer than the others in order to protrude beyond the cylinder head. It will be connected in one structure with the reinforcing frame of the concrete tape.
The pipe formed from waterproofing material is gradually filled with liquid concrete. It is desirable to shake the cement mortar in layers with a vibration device. The upper edges of the filled pillars should be located in the same horizontal line, for which, before pouring, the pipes are set using a water (laser) level. The poured pillars are allowed to stand until the concrete has completely set, after which they proceed to the grillage device.

The most common method of arranging supports is described above. As an option, they often use ready-made pipes (PVC sewer pipes) or lay out pillars from ready-made concrete blocks. The second method is more laborious, since it is necessary to prepare a deepening by digging for each pillar. With a large depth of placement of the sole of the column, this is very inconvenient.

Grill device options

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

Before pouring the tape, a reinforcing structure is necessarily formed, which is associated with the protruding reinforcement of the pillars. This is how a monolithic structure is obtained, where a superficially arranged concrete tape rests on the formed pillars. This achieves the following goals:

cheaper design (compared to a buried tape device);
sufficient strength of the base;
a solid base for the construction of walls (there is no need to make a pick-up between the supports).

After reinforcement, the formwork cavity is poured with concrete, upon hardening of which the wooden enclosing structure is disassembled. Before starting the construction of wall structures, the concrete is allowed to gain strength (mature), after which the foundation surface is waterproofed.

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

Pick-up device options

Now the fencing of the space between the pillars of the foundation is done in several ways using various materials. For sewing a plinth between posts under wooden house wood is more commonly used. Also used as a building material:

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

The peculiarity of the construction of the intake is that the structure should not be rigidly connected to the foundation supports and have ventilation holes. The first condition is observed so that the enclosing structure does not collapse with a possible settlement of the foundation and soil movements. Ventilation holes they do not allow excess moisture to accumulate in the space under the building, which adversely affects building structures. One of the most popular options is a wooden fence.

A trench about 30 cm deep is dug between the pillars along the perimeter at the lowest point of the soil. The bottom of the ditch is sprinkled with gravel and sand, and a beam (log) is laid on the formed pillow after tamping and leveling. The second beam is attached to the bottom of the perimeter wall of the building.
Boards are vertically attached to the bars and protected with waterproofing material from below to the ground level. After the trench, it is covered with gravel or expanded clay and concreted from above.
The above-ground part of the plank fence is processed and painted or sheathed with some kind of external finishing material. If sheathing is supposed, the boards are not fastened in a continuous way, but with a certain step, forming a crate for fixing the finishing material.

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

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

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

Varieties

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

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

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

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

Step by step instructions

Before making a columnar foundation with a grillage, it is necessary to prepare a site at the site of its installation, for which all vegetation is removed from the intended area and the sod is removed (25-30 cm and 45-50 cm for clay soil). Then all the recesses and irregularities are covered with sand and gravel.
After laying the sand and gravel cushion, mark out the dimensions according to which the supporting columnar foundation will be poured with their own hands. At this stage, you will need pegs and a cord. With their help, it is necessary to mark the distance between future pillars strictly according to the scheme (no more than 2 m). The main rule of this step is accuracy, and it must be strictly observed.
In order for the columnar foundation of the blocks to be securely fixed in the ground, you need to dig holes for the piles. Depending on the type of soil and base material, the depth may vary from 30 cm or more relative to the limits of the base (clearance for sand and gravel pad). Deep wells (from 1 m) are recommended to be reinforced with special wooden supports.

Further, the step-by-step instructions for installing a shallow-depth support-column foundation will differ depending on which design features need to be introduced, as well as from the material of the supporting pillars.

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

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

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

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

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

Brick pillar foundation, as the name implies, is assembled from brick and reinforced metal mesh. Such structures are necessarily supplied with roofing material or bituminous waterproofing. The basis of asbestos pipes implies the installation of fixed formwork. By the same principle, a shallow foundation is assembled from steel pipes or screw piles.

Columnar bases are assembled according to the following scheme:

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

It is not recommended to leave the grillage foundation of pipes unloaded for a long time, otherwise the soil may push the piles out and their deepening will be uneven. Between the installation of supports and further construction, no more than 3 days should elapse from the moment the mortar has hardened.

Wooden shallow-depth columnar foundation assembled from bars pre-treated with antiseptic agents. The diameter of the supports must be at least 20 cm, otherwise the house will tilt and quickly collapse. Choosing wood is between oak and coniferous species. In this case, the depth of penetration will be at least half a meter.

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

When installing baths and sheds, you can not reinforce the supports with fittings and do not add a concrete pad before installing them.

The block base is not suitable for the construction of heavy, and even more so multi-storey buildings, the height and dimensions of which are quite impressive. It does not need to lay waterproofing material, so it is ideal for the construction of utility blocks. To create the basis of frame houses, it is better to give preference to asbestos or metal pipes, but we must not forget about their reinforcement and concrete cushion.

The grillage column-strip foundation is quite difficult to implement, as it consists of two different stages that are radically different from each other. Initially, poles are installed in the drilled wells and reinforced with reinforcement. If this process is performed correctly, then each pile is able to withstand a load of 10 tons. Then they proceed to pour the tape base, on which the future construction will rely. By the way, it will be possible to erect walls no earlier than a month later, after the mortar has dried and the monolithic layer has acquired the necessary strength.

Column and tape type

To avoid mistakes and troubles in the process of work, and the construction technology was fully observed, experts advise paying special attention to analysis and calculations, namely:

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

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

It is better to start construction in the spring, when the ground is completely thawed, and you will carry out work in the warm season. During their implementation, make sure that water does not get into the trench.

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

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 around the perimeter under 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, type of construction supporting elements, character 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. 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 the column is supposed to be connected to the pole, a “glass” recess is made in its upper part or fixing anchors are installed to ensure hard mount support and 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. There are decks 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.

Scheme of the device of the columnar foundation.

Depth determines certain types support bases:

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.
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 on heaving soils with loams or clays. They are the least economical.
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.

By structural features foundations come 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:

Due to the instability of the support decks, it is not recommended to install them on weak and horizontally moving soils.
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.
It is not necessary to arrange a foundation on pillars in places with a strong elevation difference (from two meters).

Building

The pouring of the pillars to the foundation is carried out 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. wooden planks in accordance with the required dimensions of the pillars. formwork boards and internal walls the pits 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.

Pillars are poured with ordinary concrete of a grade not lower than M-200.

After reinforcement, concreting of the supports is carried out. For this, ready-made concrete is used not lower than grade 200-300. For self-cooking concrete mixes more suitable brand of cement M400, 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.