Foundation with heel. Types of foundations and their technical characteristics. Reinforcement of grillage and strip foundation

Choosing the right foundation is a task even more important and responsible than building the house itself. After all, the durability of the entire building will depend on the strength, stability and reliability of the foundation. That is why we will dwell in detail on what types of foundations there are, in what cases they are used and on what soils.

To choose the right foundation for your home, you need to consider a number of factors:

Structure and condition of the soil at the site. Which foundation to choose is largely determined by the initial conditions of the site. There are heaving soils that, when freezing or other changes in atmospheric conditions, can move and expand, squeezing out the structure. Heaving soils include clay, sandy loam, loam, and peat bogs. There are also non-heaving soils that can serve as a fairly solid foundation for a foundation. These are sand, gravel and rocks.

Groundwater level. If water is nearby, it can have a very negative impact on many types of foundations.
House weight, material, from which the walls will be built.
Features of the house architecture: the presence of a basement or ground floor.
Landscape features: Flat or sloping terrain.

An important nuance is also the financial component. Typically, at least 25% of the cost of constructing the entire house is spent on building a reliable foundation. And this is quite justified, given how important the strength and durability of the foundation is. It is strongly not recommended to save on materials for the foundation; this can lead to bad consequences in the future.

So, below are the most common types of foundations for a house, cottage, bathhouse, garage, extension and other structures.

Strip foundation

The most common type of foundation at the moment is the strip foundation. It is a tape that runs under all load-bearing walls. In addition to the fact that the foundation strip is located around the entire perimeter of the house, it can also be under internal walls or important heavy elements, such as columns.

Depending on the type of materials used, a strip foundation can be:

Rubble.
Concrete.
Rubble concrete
Reinforced concrete.
Brick.

Also he may be monolithic or prefabricated For example, a foundation made of prefabricated concrete or reinforced concrete blocks is used if the construction of a house is planned to be completed in a short time during the summer months before the onset of rainy autumn or winter. In this case, there is no need to wait for the concrete to gain strength. A foundation made of ready-made blocks can immediately serve as the basis for the construction of walls after installation.

But I would also like to note that a non-monolithic strip foundation has less strength, since the joints of concrete blocks are a weak point. Water can seep into them, the joints do not withstand bending stresses well, even if reinforced with mesh, so it is likely that the foundation will rupture at the junction of the blocks.

Monolithic foundation is arranged using formwork. Rubble and rubble concrete foundations are made in regions where rubble is a local, cheap, common material. The width of a rubble foundation is usually 0.6 m if the masonry is made of torn rubble, and 0.5 m if the masonry is made of rubble slabs. The laying of rubble foundations is carried out on concrete mortar with mandatory ligation of vertical seams using reinforcing mesh.

Monolithic concrete and reinforced concrete foundations are the most common. Their width can be smaller than rubble ones, from 35 to 50 cm, depending on the thickness of the building walls and the bearing capacity of the soil. Typically, the width of the foundation is taken to be 20% greater than the width of the wall.

A strip foundation can serve as the basis for such buildings:

Brick house (made of red or sand-lime brick).
Reinforced concrete house of medium weight.
House made of stone.
Log house.
House made of aerated concrete.
Block buildings.
Garages, bathhouses, extensions, fences, etc.

Advantages of a strip foundation:

Possibility of arranging a basement or ground floor.
Withstands quite heavy loads from heavy 2-3-story buildings.
You can install heavy floors made of concrete slabs.
Relative ease of construction, all work can be done independently.

The disadvantages of a strip foundation include the cost of materials: cement, crushed stone, sand and reinforcement. But the end result is worth it.

There are two options for strip foundations in terms of depth: shallow and recessed.

The depth of a shallow foundation usually does not exceed 50 - 60 cm. It can be built on soils that can serve as a solid foundation. These are non-heaving sand, crushed stone soil and rocks.

It is also important to know the groundwater level. If it is below the soil freezing level, then you can also build a shallow foundation on clay soil and loam.

A shallow strip foundation is perfect as a foundation for light frame structures, garages, extensions, fences, and wooden houses. Although for a one-story brick house it is also possible to make a non-buried foundation.

The technology for arranging a shallow foundation can be described as follows::

A trench is dug 70 - 80 cm deep and 50 - 60 cm wide.
The bottom of the trench is compacted.
A 30 cm layer of crushed stone is poured onto the bottom and compacted, and then a 10 cm layer of sand is also compacted.
Formwork is installed inside the trench, the top of which should rise 30 - 50 cm above ground level.
The walls of the future foundation must be protected from the influence of water, so a waterproofing material - roofing felt, glass insulation or any other rolled material - is attached to the bottom of the trench and to the walls of the formwork.

A reinforcement frame made of 8 mm thick rod is placed inside the formwork.
Concrete solution is poured on top.
The concrete is compacted using a vibrator.

The crushed stone layer should not be neglected, as it serves as a kind of shock absorber. A well-prepared cushion of crushed stone and sand will eliminate the occurrence of local subsidence.

Important! This foundation option is not suitable if the site is uneven and has height differences, as well as for heavy stone buildings.

A shallow brick strip foundation is a conventional brickwork made of baked bricks that does not absorb moisture. It can be equipped for wooden houses, extensions, garages and other light structures.

The depth of the so-called buried foundation is below the freezing level of the soil. This depth differs in different regions and ranges from 70 cm to 1.5 m or more. It can be built on any solid soil, if the groundwater level is below the freezing level of the soil.

Recessed strip foundations can be made on such soils:

Sand.
Clay.
Loam.
Sandy loam.
Rocky soil.

You cannot make a strip foundation if:

Groundwater is high. The foundation will freeze and collapse.
Large elevation changes.
Swampy soil. There is an exception here though. If the peat layer is not too large, up to 1 m, then it is removed to the full depth to a solid bedding base.
Loose, fragile soil.
The soil freezes too deeply. It is not practical to spend money on building such a deep foundation. For example, if the freezing depth exceeds 2 m, it makes sense to choose a different type of foundation.

On insufficiently strong soils, you can make the tape wider and deeper. But this is only if the soil is of average fluidity and there is still strong soil at the bottom of the trench.

The technology for constructing a buried strip foundation is no different from constructing a shallow foundation. The only difference is the depth of the trench and the fact that the material consumption is much greater: more reinforcement and more concrete will be required. Technological openings for pipelines and vents are also provided in the foundation walls.

The buried foundation is strong enough to withstand heavy stone buildings: brick, concrete, etc. That is why it is so popular among the residents of our country.

Columnar foundations are used in cases where the construction of a heavier strip foundation is impractical. For example, if the building is light and the load on the foundation is less than the standard. The columnar foundation consists of pillars with a pitch of 2.5 - 3 m, located along the entire perimeter of the building under the load-bearing walls and under the internal partitions and the intersections of the walls. A grillage must be placed on top of the pillars, which can be made of concrete, timber or channels.

The pillars themselves can be concrete, rubble, rubble concrete, brick and wood. The depth of the pillars is usually taken equal to the depth of soil freezing.

Columnar foundations can be used for:

Wooden houses.
Frame and panel houses.
Extensions.
Lightweight houses made of aerated concrete.

Important! A columnar base is not suitable if you plan to make a basement, ground floor or garage in the house. But this is an ideal option if the site has a slope. Then the pillars are buried to dense soil.

Also note that a columnar foundation can be used in cases where laying a strip foundation is not economically feasible. For example, if the depth of soil freezing is 4 - 5 m. In such cases, a columnar foundation with a reinforced concrete grillage is installed.

Wooden pillars are used for the construction of foundations extremely rarely, since they are short-lived. Before installing them in a well, the wood is treated with various waterproofing materials and anti-mold impregnations. Once treated, wooden poles can last a maximum of 30 years. Typically, a wooden base is equipped for light wooden structures, such as bathhouses, sheds, and gazebos.

The technology for constructing a columnar foundation can be described as follows::

Wells are drilled under the pillars to the required depth plus 20 - 30 cm. The diameter of the well is 25 cm.
A 20 cm layer of crushed stone and a 10 cm layer of sand are poured onto the bottom.
After that, rolled roofing material is lowered into the well, which will serve as both formwork and waterproofing for the pillars. Also sometimes used are blanks in the form of steel or asbestos-cement pipes. The upper edge of such formwork should rise above the ground by at least 30 cm.
A reinforcement cage made of rods 10 - 12 mm for vertical load-bearing and 6 mm for horizontal ones is lowered inside the well. The reinforcement should rise 20 - 30 cm above the formwork if you plan to make a reinforced concrete grillage.
Then concrete is poured into the wells and compacted with a vibrator.

On top of the pillars you can build a grillage made of concrete, wooden beams or steel channels. In the technology of arranging a columnar foundation, it is extremely important to ensure that the upper edges of the pillars are horizontal so that they form a flat plane.

The dimensions of a columnar foundation depend on the material from which they are made. For brick, the width of the pillars should be 50 - 55 cm. For reinforced concrete, 25 cm is enough. Wooden logs are taken 25 - 28 cm in diameter. When arranging a rubble concrete columnar foundation, a width of 50 - 60 cm is taken.

A type of columnar foundation, or rather a combined type of foundation, is a columnar-strip foundation using TISE technology. It is also called a pile-grillage or pile-column foundation.

Recently, this type of foundation has gained widespread popularity; it is even installed for heavy stone houses in regions with cold winters and deep freezing of the soil. Time will tell how durable they are. In the meantime, they are recommended to be used in cases where the arrangement of a strip foundation is too expensive.

The essence of a columnar strip foundation is that the pillars are lowered below the freezing depth of the soil, and a grillage in the form of a strip foundation is built in the top layer of soil.

The correct foundation using TISE technology is built like this::

The top fertile soil is removed, then a trench is dug as for a strip foundation with a depth of 50 cm.

At a distance of 1.5 - 2 m from each other, holes with a diameter of 25 cm are drilled for the pillars. Depth 1.5 m or equal to the depth of soil freezing in the region. The pillars must be located at all corners of the building and at the junction of walls.
At the bottom of each well, an expanded heel with a diameter of 40 cm is made.
The heel is filled with concrete solution.
Then formwork in the form of a roll of roofing material or asbestos pipe is lowered into the well.

A reinforcing frame is inserted inside, its upper edge should rise above the ground to the entire height of the future foundation.
Along the perimeter of the trenches, wooden formwork is installed, in which technological openings are provided for pipes and communications.
A reinforcing frame is inserted inside and connected to the frame protruding from the wells.
After all the reinforcement elements are connected to each other, you can begin to pour the concrete solution.

First, the pillars are poured and the concrete is thoroughly compacted using deep-hole vibrators.
Then the tape is poured without interruption and the concrete is also compacted.

After pouring, concrete gains strength within 28 - 30 days. After this time, construction can continue.

It is not recommended to install a column-and-strip foundation in swampy areas or on peat bogs.. During operation, it is possible that concrete pillars will separate from the foundation strip or the entire support will become distorted. But if the soil is dense, a foundation of this type can save a lot of money.

If the site has weak, easily compressible soil, a pile foundation is installed. Also, if reaching hard soils of a natural basis under peat bogs is impractical due to their large depth - 4 - 6 m, a pile foundation is driven as the foundation for the building.

Among other things, pile foundations are allowed to be installed for buildings on solid soils, if it is economically justified.

According to the method of transferring and distributing loads on the ground, two types of piles are distinguished:

Hanging piles do not reach the hard soil of the natural base. They seem to hang in light compressible rock and transfer loads to it along their entire vertical surface. Typically the end is a screw thread that holds well in the ground.
Standing piles or riser piles pass through soft soils to a solid foundation and rest on it with their ends.

According to the construction method, screw piles are divided into driven and driven ones. Driven piles“hammered” into the ground using special heavy equipment; simultaneously with driving the pile, the soil around it is compacted, which ensures greater reliability.

Driven piles are installed on the construction site using the same technology as pillars for a columnar foundation.

Piles can be concrete, reinforced concrete, metal and wood.

A screw foundation is usually made of steel piles with a thread at the end; they are screwed into light soil. A grillage is installed on top, the material of which depends on the weight of the structure and the material of the walls. For a wooden house, a grillage in the form of an embedded beam is sufficient.

Pile and pile-screw foundations can be constructed on peat soils, in cases where the site has a strong slope, on quicksand, swamps, and subsidence soils. Indicators for using piles as a support are low strength, porosity and excessive soil moisture on the site.

Slab foundation for a house

A solid or slab foundation consists of slabs under the entire area of the building. It is installed in cases where the load from the building is significant, and the foundation soil is weak and cannot withstand it. For example, if a site on a drained swamp, soft porous peat is not able to support the weight of a house, it will shrink and move under its weight. If you build a strip foundation, there is a high probability that it will simply break or skew, and part of the house may fail.

The good thing about a slab foundation is that it will move and “travel” along with the foundation soil. The house will remain intact.

The technology for arranging a slab foundation can be described as follows::

A pit is dug across the entire area of the building. The depth of the pit depends on whether you plan to make a ground floor and basement. Let's consider the option without a basement. In this case, the depth of the pit should be 50 cm.
The bottom of the pit is carefully compacted.
Then pour a 20 cm layer of crushed stone and compact it.
Then a 10 cm layer of sand is also compacted.
A layer of waterproofing material is spread on top, the edges of which are placed on the walls of the pit.
Formwork is installed around the perimeter of the pit. The height is usually no more than 20 cm above ground level.
A reinforcing frame made of 12 - 16 mm rod is installed inside the pit. It takes a lot of material to make it.

The reinforcement frame must be located in the thickness of the concrete, so chairs 3 cm high are placed under it.
Concrete is poured. There must be no interruptions, so a mixer with ready-made concrete is ordered to the site.
The concrete is compacted using vibrators.

Slab foundations are sometimes called floating foundations, as they are able to move with the soil. They can be built on the following foundations: clay, subsidence soils, marshy areas, quicksand, peat soils, heaving soils. On solid foundations, a slab foundation is unprofitable.

In conclusion, I would like to give a few recommendations. If there is high groundwater in the area, it is better to equip a slab foundation, a shallow strip foundation or a pile foundation. If the water level is so high that even a shallow foundation is likely to get wet, then it is necessary to provide high-quality drainage around the house and drain the water into a drain or well. It is highly undesirable for a reinforced concrete foundation to get wet. Soil is considered dry if the groundwater level is below the soil freezing level. As a rule, in such cases you can equip any foundation.

Construction of a house begins with the foundation. Building materials for its construction are often selected taking into account regional availability. In some areas, the cost of a strip foundation is comparable to a reliable foundation structure built from granite. Such a foundation firmly holds a house of any size, even built on black soil and other unstable soil. Taking into account modern construction requirements, the main purpose of the review is to talk about innovative approaches and how to make a strip foundation guaranteed to be reliable.

If there is no possibility of constructing an “airbag” for a house made of high-strength material, craftsmen recommend that novice builders use ready-made foundation blocks. This construction option will help to avoid a number of mistakes, which for a number of reasons are not taken into account in cases where the strip foundation is built with your own hands.

Classic mistakes when building strip foundations

The strip foundation remains the most affordable option for constructing the foundation of a house with your own hands and is recommended for the construction of light houses. Meanwhile, the strength of the foundation depends not only on the conditions of its construction, but also on the territorial features of the area. Let's look at the main mistakes when constructing strip foundations, as well as how to avoid them.

Geological and hydrological works

Before starting work, it is recommended to obtain geological and hydrological survey data, which, when developing a project, will allow making calculations based on the location. Most standard projects, as expected, were made without taking into account the characteristics of the soil, so in some regions one can observe abnormal behavior of the foundation.

Strip foundations installed on black soil are not considered a solid foundation for any residential building. Typically, areas of black soil under the foundation are selected, covered in layers with sand, carefully compacted using water and covered with a bed of crushed granite stone.

Features of Extreme Design

When building a house yourself, you can conduct a soil analysis on your own. To do this, you need to drill the area in 2-3 places and check the depth of the fertile layer, water, clay and sand. It will be useful to ask your neighbors about the features of foundations that have stood for several decades:

to what depth the foundations were buried;
types and materials used for the device;
about the presence of a drainage system near the house;
about cases of soil sliding on slopes.

Errors during work and installation

Construction of foundations in autumn-winter

Foundations are not installed on waterlogged and frozen soil, or on snow. The construction of a concrete foundation in winter is undesirable or must be carried out using strict technology using construction equipment. When concrete is laid in a trench on snow, voids filled with water are formed.

Heaving soils and their features

A standard error is the lack of soil when digging a trench under the foundation to the design level. According to SNiP, in heaving soils it is allowed to deepen the base of the foundation below the calculated freezing depth.

On heaving soils, pile and strip-buried (strip-pile type) foundations are not installed. Piles hold the foundation in place, and heaving forces push it to the surface, as a result of which the concrete strip is very likely to crack or the pile to break off.

Reducing the likelihood of soil heaving on any soil

To prevent heaving, drainage is laid under the base of the foundation, clay is selected and the foundation pit is filled with sand and crushed stone, eliminating the source of heaving. On such soils, the blind area must be insulated, which prevents the foundation from freezing and eliminates the possibility of heaving.

Pasting and thermal insulation of the outer side allows you to shift the dew point beyond the boundaries of the foundation, which eliminates the influence of tangential heaving forces.

Foundation protection includes:

gluing waterproofing film;
installation of XPS polystyrene foam (high density);
cover with 2 layers of dense polyethylene;
Additionally, sheets of polystyrene PSB 25 are pressed to the foundation by backfilling with soil.

Principle: soil heaving forces crush PSB 25, which moves up the polyethylene without damaging the main thermal insulation. After thawing, the structure restores its sandwich structure.

Do-it-yourself strip foundation photo: step-by-step instructions

Basic strip foundation structures: their appearance and design diagrams

Depending on the characteristics of the soil and the type of construction, choose the design of the future concrete foundation of the house. When building houses on black soil, buried and deep-buried modifications are used. When building on black soil, the depth of the foundation depends on the thickness of the black soil layer. In some cases it reaches 2 m.

Trench and sub-concrete waterproofing

Communications

Simultaneously with the removal of soil for the foundation, the preparation of communications that must be connected to the house is carried out. At this stage, special attention should be paid to the house sewer pit and the waste drainage device. If water will be supplied from a well, it is necessary to make simultaneous preparation of communications, since the laying of water supply pipes is carried out at a depth of 1.5-2 m.

After removing the soil to the design level, sand is poured in layers of 10 cm with water. In some cases, the cushion can reach 40-80 cm; with high groundwater or a desire to make a safety cushion at low cost, the thickness of the backfill is 40-80 cm, of which up to 2/3 of the height can be crushed stone.

Next, formwork is laid 10 cm deep; it should be twice as wide as the base of the tape and filled with “lean” concrete (B7.5 mixture). After the mixture reaches 70 strength, a waterproofing membrane or polyethylene 0.15 mm thick is laid with a margin of 20-30 cm from the edge of the tape - drains.

A reinforcing belt made of reinforcing wire 10-12 mm (on moving soils up to 16 mm, grade A400) is laid on top and bottom of the trench, fastening it with a spatial wire frame (grade A240, 6-8 mm). Laying is done on plastic spacers 2-4 cm wide. The upper level of the frame should be located close to the surface, no deeper than 5 cm, under the fastening layer of concrete.

The reinforcement is usually overlapped with a size of 50 diameters of reinforcing wire according to the new SNiP requirements (with 12 mm wire the overlap is 60 cm, previously the requirements assumed an overlap of 20-30 cm). At the corners, the reinforcement cannot be installed end-to-end; in the corners, L-shaped and U-shaped shapes are used and fastened according to the scheme shown in the photo.

install sleeves in the reinforcing belt to enter communications into the cottage or carry out simultaneous installation of pipes;
40 cm from the blind area in the formwork of houses with beamed floors, it is necessary to provide for the installation of void formers to ensure ventilation of the subfloor, prevent corrosion, rotting and ensure the removal of harmful radon. The dimensions of the ventilation openings should be a total of 1/400 from the basement of the house.

To fill the foundation, use ready-made or home-made formwork. Shields can be made of OSB boards, plywood or boards. The shields are secured using internal ties, as shown in the photo. Ready-made formwork allows you to concrete structures with complex shapes.

Pouring the foundation

It is advisable to use ready-mixed concrete for foundations. In this case, it is possible to carry out winter work, since for these purposes a special brand of solution is used that hardens in the cold. The brand is selected depending on the type of structure:

M100 – for wooden houses and outbuildings;
M150 – for buildings made of foam concrete;
M200 – for one- and two-story cottages with light floors;
M250 and M300 - for buildings up to 5 floors, as well as for monolithic floors;
M400 – for multi-storey buildings (up to 20 floors).

It is not recommended to fill a layer of no more than 60 cm at a time. Deep foundations are poured in several stages, with a break between them of no more than 2 hours. Concrete can be poured after 12 hours, but the surface film must be cleaned off with brushes or removed with water pressure. Concrete must be placed in the trench with a vibratory compactor. Loose concrete does not gain the declared brand strength.

The formwork is removed no earlier than after 3 days. During this period, the upper part of the tape is moistened with sawdust or rags moistened with water, which will provide the required level of strength and also avoid the formation of craters and cracks.

When laying a concrete foundation, it is not advisable to neglect vertical waterproofing (of the base walls), this will help protect it from damage and ensure long-term operation. This is especially important for those areas that are characterized by winter thaws, during which the foundation is moistened and goes through several freezing cycles.

Do not neglect horizontal insulation, the absence of which can lead to the appearance of fungus on the walls and increased humidity, since moisture from a moistened foundation will be absorbed into the walls of the first floor.

DIY strip foundation video

How to make a strip foundation with your own hands video: monolithic slab

In conclusion, we present one of the modern solutions. As you know, one of the types of strip foundation is a monolithic slab. The technology for constructing a monolithic insulated Swedish slab (USP) is an innovative development that is becoming increasingly popular. And it can also be made with your own hands.

The base of the house is a reliable sandwich structure, which provides the necessary strength to the base of the house and its insulation. This technological solution is used for the construction of passive houses, in which the internal heat of the building is retained to reduce energy costs. Above we showed how to make a foundation with your own hands, video, now we offer technology for constructing USP.

The construction issue is covered in detail in the video.

New requirements for housing construction, including private housing, are pushing developers to use innovative technologies, for example, building a foundation using Tise technology - which means ensuring the reliability of the building, savings on construction, a solid foundation and easier installation of the foundation of the house.

The abbreviation TISE stands for “technology of individual construction and ecology”, and its principles are implemented in the countries of the former CIS. First of all, the technological process concerns specifically individual construction, since all construction operations are designed to be performed with one’s own hands, but with the help of specialized tools and equipment, the authorship of which is confirmed in the name of Yakovlev R.

Construction technology of a TISE columnar foundation with a grillage

The main principle when using TISE is the construction of a grillage resting on the supporting pillars of the foundation with an expansion of the lower end (sole). The pillars for such a foundation cannot be considered full-fledged piles, although wells for them are drilled according to the same principle - the supports for the TISE foundation base are immersed to a shallower depth, and the usual piles do not have a widening in the lower part.

A distinctive feature of TISE is a columnar grillage. In practice, the foundation of the tise provides complete leveling of heaving forces that try to put pressure on the foundation in the off-season and during freezing/thawing of the soil. What else makes this structure stand out among foundations with similar functionality:

Piles (pillars, supports) are immersed below the soil freezing level in the region;
Minimum area of contact between the support and the ground along the side surfaces;
Heaving soils are replaced with gravel or crushed stone on the house construction area and beyond it by 1.5-2 meters (at the distance of drainage and blind area);

Another advantage that the chise pile foundation has: supports with an extension at the lower end (heel) can be made using traditional technology, and when deepening the pile (support) it is much easier to drill a well wider than the diameter of the support. A heel is poured into the well, onto which a tubular formwork with a diameter smaller than the sole is installed.

The free space in the well is filled with bulk materials to create drainage around the support. If you use ordinary piles (without an expanded base), then the drilling depth will have to be increased, plunging the pillars below the freezing level of the soil by at least 1 meter, so that the pushing forces of heaving soil cannot affect the base of the pile.

The support must be reinforced from the inside, which will give the foundation additional strength. Thus, a DIY TISE foundation for a one-story frame house can have only 2-3 TISE piles instead of 10-15 conventional submersible piles, which are driven in every 1-1.5 on all lines of load-bearing walls.

For an individual developer, the construction of such an innovative foundation presents one difficulty: how to expand the bottom of the well? Buying one specially designed for this purpose is very expensive for a one-time job, and this is the only drawback of the author’s method, since you will have to build a homemade drill from available building materials.

Construction site preparation

Even on an uneven or sloping site, it is not necessary to carry out work to level and clear the site, and this is the great advantage of all individual pile or columnar foundations. Also, to install columnar supports, you will not need to install drainage next to the foundation walls or insulate the blind area and base. When supporting a building on a suspended columnar grillage, the structure area must have at least three load axes for each of the load-bearing walls of the house:

In the center of the support pillars for drilling a well;
Along the outer border of the concrete grillage for arranging the formwork;
On the inside of the grillage.

For step-by-step marking of the site you need:

Make pegs with a strip nailed on top - cast-offs. You need two of them for each side of the foundation;
Place the cast-offs at a distance of 1.5 m from the corners of the house perimeter and stretch the cords between them.

Important! The pegs should be such a length that the horizontal planks extend 2-5 cm above the level of the grillage, and the total length of all planks is 10 cm greater than the width of the grillage tape. This condition is met so that the cord can be pulled over the same pegs many times.

The sequence of drilling and placement of wells and piles is as follows:

According to the author's technology, the universal foundation of the Tise technology should have so-called leader holes - these are small depressions (10-20 cm) made with a shovel at the site of drilling wells for supports;
Manual drilling is a simple process: the plow needs to be removed from the drill, or fixed vertically using a special stopper so that it does not interfere with soil excavation. After a few turns of the drill, it must be removed and the soil receptacle freed from the soil;
The expansion (widening) of the heel is done in this way: when the drill plunges to the designed depth, there is no longer any need to put pressure on it, and then the freed or installed plow will loosen the soil with the expansion of the dome. Also, after several turns of the drill, the soil must be removed from the receiver.

The drilling of each well should be controlled by level; when drilling hard ground rocks, the well should be watered, large fragments of stones should be crushed with a crowbar to a size of 5 cm so that they fit into the soil receiver.

When calculating the Tise foundation, one should not forget about the reinforcement of the supports. Subsequently, the piles are reinforced according to the requirements of SP 52.105. When arranging a reinforced frame inside a pile, you cannot use scraps of pipes and other rolled products, you cannot embed metal mesh and pieces of steel sheets into the frame - only reinforcing bars Ø 8-12 mm are allowed to be used:

Piles (supports, pillars) must have reinforcement protruding above the surface of the formwork up to 40 cm high;
Piles must also be reinforced in the transverse direction with smooth reinforcement Ø 6-8 mm. Transverse frames can be made square or round, the step between the belts is up to 0.6 m.

In the future, the vertical reinforcement will need to be connected to the grillage reinforcement. To do this, the pile rods are bent at an angle of 90 0 at the level of the grillage reinforcement and connected to its reinforcement with knitting wire. Before pouring concrete, the internal reinforcement of the support is protected from contact with the walls of the pile by placing special plastic washers on the rods. The supports themselves can be cast using inexpensive materials:

You need to measure a piece of tape from a roll of roofing felt and roll it into a cylinder, fasten it with wire or a stapler, then tie it with wire;
An asbestos cement pipe will be stiffer, but it allows moisture to pass through, so it needs to be waterproofed (bitumen, tar, mastics);
PVC pipes are not afraid of moisture and corrosion, but their thickness must be at least 0.5 cm.

Due to the small diameter of the formwork, it is inconvenient to lay the mortar into it, and the reinforcement inside the pile does not add convenience. Therefore, it is recommended to pour the solution through a homemade funnel, for example, from the same roofing material or thick waterproof cardboard. When building a universal foundation, Tise technology takes into account the following features of this stage:

The formwork is only half filled with mortar so that the concrete can be compacted and the air released from it;
You can compact concrete manually (with a crowbar or a thick rod), or using an electric deep vibrator;
After compaction, the support is completely filled and compacted again;
Exposed concrete must be protected from rapid drying with film, sawdust, or simply covered with a thin layer of soil for 2-3 days;
During these 2-3 days, water the support every 5-6 hours so that the concrete sets and hardens evenly throughout the entire depth of the pile.

If there is a basement in the house project, the distance between the supports is allowed to be increased so that doors or gates can be installed. A foundation with a grillage must always be covered with factory-made reinforced concrete slabs or reinforced concrete beams, so it is impossible to install a floor on the ground.

How the grillage formwork is arranged

The zero cycle (excavation work) can be significantly reduced if you start making grillage formwork after pouring concrete inside the piles. To do this quickly and without loss of quality, two cords are pulled on the pegs without a middle one. The following operations:

Deck panels are made from available materials (boards, thick plywood, chipboard, OSB) and protected with a layer of waterproofing, for example, polyethylene or tarpaulin. This is necessary for possible reusable use of the formwork;
The formwork is mounted as follows: first, holes are made in the panels for supports, the panels are put on piles and secured with H-shaped cross members at a distance of 0.5-0.7 m;
The side formwork is mounted as follows: wooden panels are installed at the level of the stretched cords and attached to the bottom panel with nails or self-tapping screws.

In order not to complicate the design of the formwork by making a wooden bottom panel, it can be replaced with a sand cushion with a layer of up to 40 cm (depending on the characteristics of the soil). The pillow is moistened and compacted. Also, the lower formwork shield can be made from extruded polystyrene foam, although this will be a little more expensive;

If a sand cushion is being made, then the sand must be covered with waterproofing material (polyethylene, tarpaulin, roofing felt) so that the solution does not leak onto the ground. The waterproofing material will need to be removed from under the grillage as soon as the concrete reaches its design strength. The easiest way to do this is with shovels. If you leave the waterproofing material inside, then possible heaving of the soil can tear the grillage away from the pile supports; heaving forces cannot be resisted due to the fact that the area of contact with the soil is too small.

Extruded polystyrene foam is a non-removable formwork; the brand can be chosen with the lowest density, for example, PSB. Even if the soil swells, the heaving force will deform such insulation, but will not crush the grillage. And after the increased soil moisture subsides, the heaving is leveled out, and the polystyrene foam will be restored. This process can happen as many times as you like.

It is impossible to evenly distribute local loads from load-bearing walls, partitions, heavy equipment or furniture concentrated in one place over a grillage arranged on a columnar-pile foundation. This grillage should not be in contact with the ground, so that during heaving it will be separated from the piles. Therefore, it is necessary to reinforce the grillage, and it is also necessary to strengthen the reinforced frame at the points of connection with the walls using anchors or other connections. For this:

Vertical reinforcing bars are bent at an angle of 90 0, while the rods are distributed between the levels of the lower and upper chords;
The grillage formwork inside is also reinforced with a reinforcing belt consisting of longitudinal corrugated rods Ø 8-12 mm, and vertical transverse rods Ø 6-8 mm. The fittings can be replaced with metal clamps;
From the outside, the corners of the reinforced frame are attached to the grillage with metal clamps or plates;
The lower deck of the formwork must be protected from moisture penetration.

It is much easier to build a pile-column grillage for a foundation using TISE technology than to build it for a strip foundation, so to strengthen the structure you need to fill the entire formwork along the perimeter of the base with mortar. Then the concrete is compacted, and all that remains is to wait 21-28 days until it completely hardens.

Do-it-yourself chise foundation updated: February 26, 2018 by: zoomfund

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

Device and types

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

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

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

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

Types of grillage

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

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

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

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

Extensions and their foundations

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

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

How to close the gaps between the pillars

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

installation of a fence - stone or brickwork between pillars;
by attaching pieces of sheet material or finishing materials.

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

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

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

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

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

What is the difference between a pile and columnar foundation?

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

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

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

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

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

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

Application area

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

They are suitable for the following cases:

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

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

In other cases they can be used.

Laying depth

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

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

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

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

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

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

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

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

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

Pole sizes

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

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

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

Construction stages

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

Marking

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

How to mark a foundation

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

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

Digging holes for poles

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

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

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

Installation of sand and gravel cushion

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

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

Heel device

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

Two types of heel - monolithic from concrete block

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

Construction of pillars

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

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

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

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

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

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

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

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

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

Grillage arrangement

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

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

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

Waterproofing

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

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

At the bottom of the strip foundation, where it comes into contact with the ground, a stepped expansion is made, which is called the support base. This technology is used if the house is heavy enough and is built on weak-bearing soils of a heterogeneous type.

The additional contact area that is obtained when using a support sole makes it possible to more evenly distribute the weight of the structure and reduce pressure on the ground. The foundation is of a strip type and can have from one to three stages. This is determined by the total weight of the structure, its shape and the technical characteristics of the soil.

Construction method. The construction of such foundations is not a very complex technical task. All walls of the structure under construction are located on a foundation strip, which is poured into a trench dug in the ground. The tape is supplied under all walls of the building, both external and internal. At the same time, the geometric dimensions of the base remain unchanged. This allows the weight of the structure to be distributed fairly evenly.

The foundation strip must be buried at least 30 cm below the level to which the soil freezes in your region. In the Moscow region, this value is 140 cm.

A strip foundation can be erected using the following materials:

Brick.
Stone.
Reinforced concrete blocks.
Monolithic concrete.

Most often, strip foundations are made using monolithic concrete. Foundations for buildings and structures using brick and stone are now quite rarely used. Foundations made of reinforced concrete blocks are most often used in large-scale construction. Because working with them requires special equipment.

What advantages does such a foundation have?

What are the disadvantages of this type of foundation?

This type of foundation cannot be used in areas where the soil is highly swelling and freezes to great depths.
Construction requires a large amount of time and labor.
A large number of different materials are required.
Special construction equipment is required.
The cost of constructing a deep strip foundation is quite high.

But, despite all the listed disadvantages, a strip foundation with a supporting base is the most commonly used in construction.

What do we include in the price when building a strip foundation with a support base?

Preparatory work, including locating the object on the ground.
Excavation work associated with digging a trench for the foundation.
Filling of a sand cushion up to 20 cm high, followed by thrombosis.
Welding frames made of metal reinforcement.
Installation of formwork.
Pouring the foundation using concrete grade M250.

At the request of the client, concrete can be replaced with grades M300-M400, it is possible to use reinforcement of a larger diameter, and change the dimensions of the foundation.