Do-it-yourself columnar foundation - step by step instructions. Do-it-yourself column-strip foundation How to fill the columns under the foundation
In the article we will consider the columnar foundation of the house, we will describe the columnar strip foundation (columnar foundation with a grillage). We will tell you in which cases the construction of a columnar foundation is most applicable. Separate parts describe the device of the column foundation, recommendations and errors when installing the column foundation.
General information about columnar foundations.
The stages of preparation and manufacturing technology of a columnar foundation and a strip foundation are in many ways similar. Therefore, the general provisions characteristic for the manufacture of foundations (evaluation of soils, freezing depth, the presence of groundwater and communications, preparatory work, installation of formwork, pouring concrete, possible errors in design and construction) in this article should not be repeated. To get acquainted with them, just refer to the article.
Along with an overview of all options for columnar foundations, we will focus on foundations made of prefabricated concrete and reinforced concrete blocks.
The columnar foundation is a system of pillars located at the corners and at the intersections of the walls, as well as under heavy and load-bearing walls, beams and other places of concentrated load of the building. To create conditions for the joint operation of the pillars as a single structure, and to increase the stability of the columnar foundations, to avoid their horizontal displacement and overturning, as well as to arrange the supporting part of the base between the pillars, a grillage is made (strapping beams, rand beams).
The main type of columnar foundations used in mass construction is monolithic reinforced concrete foundations.
As a rule, the distance between the posts is 1.5-2.5 m, but it can be more.
With a distance between the pillars of 1.5-2.5 m. The grillage is an ordinary reinforced jumper. At the same time, it is impossible to connect the attached terrace, veranda, porch into a single constructive solution. These rooms must have their own foundation, that is, they must be separated by an expansion joint, since the load from the porch is not comparable to the load from the walls of the house, and, accordingly, their settlement will be different.
You can read more about the device of such a seam in the topic .
With a distance between the foundation pillars of more than 2.5-3 m, the grillage is made of a more powerful, so-called rand beam. Randbalka is made in the form of a monolithic or prefabricated reinforced concrete beam. It can also be metal (I-beam, channel, profile).
- under houses without basements with light walls (wooden, panel, frame);
- under brick walls, when deep laying is required (1.6-2.0 meters, i.e. 20-30 cm below the depth of seasonal freezing of the soil) and the strip foundation is uneconomical;
- when the soils during the operation of the building provide the settlement of the columnar foundation (at equal pressures of the columns on the soil) is much less than that of the strip foundation;
- when it is necessary to exclude as much as possible the negative impact on the foundation of frost heaving, because columnar foundations are less susceptible to this phenomenon.
a - prefabricated-monolithic with the location of groundwater at the time of work below the base of the foundations;
b - prefabricated at any location of groundwater;
1. prefabricated reinforced concrete support column with a rod reinforcement cage;
2. the same, with a steel pipe core;
3. the same, with a reinforcing bar cage and an asbestos-cement pipe sheath;
4. the same, with a steel pipe core and an asbestos-cement pipe sheath;
5. prefabricated support column made of steel pipe;
6. backfilling with excavated soil;
7. base plate made of monolithic reinforced concrete;
8. base plate of prefabricated reinforced concrete foundation;
9. sand cushion.
Consider a few points in favor of using a columnar foundation:
- If the cost of foundations of other types is 15-30% of the cost of the entire house, then the cost of a columnar foundation will be no more than 15-18%.
- Pillar foundations are 1.5-2 times more economical than strip foundations in terms of material consumption and labor costs.
- 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 soil by 20-25% and, consequently, reduce the total area of the foundation.
- The most dangerous forces acting on the foundation of low-rise individual houses are the forces of frost heaving. Therefore, almost all of the given options for 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 or shallow foundations. Let's explain their differences.
- Shallow consider foundations with a laying depth of 0.5-0.7 of the standard freezing depth. For example, with a standard freezing depth of 140 cm, the depth of a shallow foundation will be 140x0.5 = 70 cm.
- Unburied foundations- such foundations are considered, the laying depth of which is 40-50 cm, and averages half or a third of the freezing depth.
With a large freezing depth in heaving soils, anchor columnar reinforced concrete monolithic or prefabricated foundations are effective. On such foundations, the influence of frost heaving forces acting on the side surface is insignificant, since the pillars are made with a minimum cross section. If the foundation is erected from stone, brick, small blocks, monolithic concrete without reinforcement, its walls must be made tapering upwards, this will save material and evenly distribute the load from the walls.
Additional measures to reduce the influence of frost heaving forces can be: covering the side surfaces of the foundation with materials that reduce soil friction, such materials are bituminous mastic, plastic lubricants (synthetic grease “C”, TsIATIM-201, BAM-3, BAM-4), organosilicon compounds , epoxy resins, furan-epoxy composition, polymer films as well as insulation of the surface layer of soil around the foundation. The feasibility and options for such insulation are set out in the question.
Conditions under which columnar foundations are not recommended:
- in horizontally moving soils and soft soils, as their design is characterized by insufficient resistance to overturning. To compensate for the lateral shift, a rigid reinforced concrete grillage is required (its device will negate the cost savings on the difference between columnar and tape).
- Their use is limited on weakly bearing soils (peat, subsiding rocks, water-saturated clay, etc.) and in the construction of houses with heavy walls (massive brick with a thickness of more than 510 mm, reinforced concrete standard slabs and blocks);
- If you have limited financial opportunities or a time period for installing a basement. If with a strip foundation the plinth is formed as if by itself, then with a columnar filling of the space between the pillars with a wall (pick-up) is a difficult and time-consuming task;
- It is not recommended to arrange columnar foundations also in areas with a sharp difference in height (height difference in the area under the foundation of 2.0 m or more).
Let's consider what materials a slab foundation can be made of, depending on the design of the house (primarily its mass and number of storeys):
- The stone foundation is made of rubble stone or flagstone of medium size. It is advisable to select a stone of the same size, and the flatter it is, the better.
- It is advisable to make brick foundations from well-burnt red brick (black), preferably iron ore. Poorly fired brick quickly collapses.
- Concrete foundations are made of heavy concrete grades B15-B25;
- rubble concrete;
- Monolithic reinforced concrete (a monolithic foundation has increased strength, has the highest service life - up to 150 years);
- Ready prefabricated concrete and reinforced concrete blocks. In the prefabricated version, the poles are made separately and mounted during installation.
- asbestos-cement or metal pipes filled with concrete mix.
- concrete and rubble concrete - 400 mm;
- masonry - 600 mm;
- brickwork above ground level - 380 mm, and when dressing with a pick-up - 250 mm;
- from buta - 400 mm;
Photo of a columnar foundation for a small private (country) house.
Information about the depth of laying the supports of the columnar foundation
It is necessary to pay attention to three main points when determining the depth of laying a columnar foundation:
- the depth of soil freezing in your area in which the house is being built; (The best option is to lay the pillars below the freezing depth of the soil, thus eliminating foundation deformations)..
- determination of the type and composition of the soil (Stationary soil or mobile, clay or sandy. Sand can serve as the best soil, since water leaves through it instantly and it has a high bearing capacity, it is impossible to build on silty and peaty soils, it is necessary to arrange partial or complete replacement of the soil on sandy);
- the level of groundwater location (is there a reservoir nearby, a river, if there is, this indicates the presence of a high level of groundwater, it is necessary to do waterproofing or drainage)
These factors must be taken into account in the house project you ordered.
Also, when calculating the depth of laying the foundation, the designer should take into account not only natural influences on the foundation, but also the following indicators:
- weight of the future home;
- the weight of the foundation supports;
- the weight of the furniture in the house and the number of people who will live in this house;
- seasonal, temporary loads (snow).
It is advisable to contact a designer who has all the necessary data to carry out such calculations (groundwater level in your area, freezing depth, soil structure, etc.). The value of the designer's participation in the design process lies in the fact that he will calculate the depth of the foundation with absolute accuracy (without an extra margin of depth). This will allow you to save building materials, financial resources without compromising the quality and safety of your home.
Column foundation device
In this section, we will consider the technology of building a monolithic reinforced concrete column foundation as the most common type in private construction.
1. Preparatory work
Work must begin with cleaning the construction site. To do this, it is necessary to cut off the vegetation layer, preferably at least 2.0-5.0 meters in each direction from the planned location of the foundation. Its thickness is 10-30 cm, and it is not suitable for the base of the foundation. This soil must be cut and transferred to the garden or garden.
If under the cut layer the soil consists of sand mixed with small stone (gravelly sand, coarse or medium grained sand), then it is used as a foundation base, regardless of humidity, groundwater level or freezing depth.
If there are clay soils (clays, loams, sandy loams), then a sand and gravel cushion is necessary. The thickness of the cushion depends on the geological characteristics of the soil.
If you find peat or silty soils under the cut layer, then a complete replacement of the base is necessary, in which case a geologist's consultation on the composition and arrangement of the artificial base is necessary.
Debris and all foreign objects are removed from the construction site.
After the construction site is cleared, its horizontal layout is made. The mounds are removed, the soil is poured into the existing pits. The control of the horizontalness of the site is carried out by a level that is installed on a 2-2.5 meter flat board or rail. The preparation ends with the delivery and storage of building materials to the site.
2. Foundation breakdown
The breakdown of the plan of the house on the site consists in the fact that it is transferred from the drawings to the land plot and the axes and main dimensions of the foundation are fixed.
Before breaking down the foundation of the house, pillars (cast-off) are installed along its perimeter, at a distance of 1-2 m from the building. To the pillars from the side of the future walls of the house and parallel to them, wooden boards or slats are nailed to the level, on which the dimensions of the individual parts of the pit (trenches and pits) and the foundation itself and future walls are marked. The accuracy of stakeout of centerlines is controlled by accurate measurement of distances with a tape measure. Be sure to check the corners of a rectangular or square foundation, they must be strictly straight at 90 degrees. Be sure to check the bottom of the trench with a theodolite, at least at the corners of the house and at the points of intersection of the tapes. It must correspond to the design (that is, if you decide to deepen the foundations by 1.4 m, then the bottom of the trench should be 1.4 m below the zero mark of the house).
Check the correct alignment of the axes, their intersections, the angles must be strictly the same as on the plan of the house.
As mentioned above, the pillars should be under each crosshair of the walls.
The pillow is plentifully watered and rammed with a manual rammer. In order to prevent water from pouring out of the poured concrete, polyethylene or roofing felt is laid on the pillow.
4. Formwork installation
For the manufacture of formwork, planed on one side (the planed part is installed facing concrete) boards of any kind of wood, 25 ... 40 mm thick and 120 ... 150 mm wide, are used. Formwork lumber must have a moisture content of up to 25%. Wide boards for formwork, as a rule, are not suitable, since gaps appear during their installation. You can also use chipboard, metal structures, waterproof plywood.
Wooden formwork is preferred over metal formwork as it is lighter and has less bonding force to concrete. The disadvantages of wooden formwork include the possibility of its deformation, hygroscopicity. The formwork is installed close to the walls of the pit, strictly perpendicular to the base of the foundation, checking this with a plumb line.
In some cases, if the walls of the pit are dry and do not collapse, concrete can be poured without formwork. At the same time, polyethylene is laid around the perimeter so that water does not leave the concrete.
Also, asbestos, ceramic, iron pipes can be used in the form of formwork. Depending on the design of the building, pipes with an internal diameter of 100 mm or more can be used. Concrete is poured directly into the pipes, and they remain in the ground along with the foundation.
When installing wooden formwork, it must be remembered that the boards must be damp, for which they are well moistened. Otherwise (dry boards) will absorb water, which adversely affects the strength properties of concrete.
If it is possible to use ready-made panel formwork, then this is a plus. Such formworks have a large number of options for their installation, which is very convenient when building foundations with a large number of corners. Inventory formwork panels are rigid and flexible, their length can be from 0.5 to 3 m.
5. Reinforcement installation
The pillars are reinforced with longitudinal reinforcement with a diameter of 10-12 mm with a mandatory device, after 20-25 cm of clamps with a diameter of 6 mm. They are installed vertically and wrapped around with clamps or annealed wire to prevent their divergence to the side. It is desirable to ensure the outlet of the reinforcement above the top of the foundation (as shown in the figure) by 10-20 cm, so that later the reinforcement of a monolithic grillage can be welded to them.
Photo of reinforcement of a columnar foundation.
6. Concrete supply
Here everything is the same as in strip foundations, concrete is laid in layers of 20-30 cm with vibration by hand vibrators.
Photo of pouring concrete into the column formwork.
7. grillage device
The grillage can be made in the form of a monolithic or prefabricated reinforced concrete rand beam.
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, precast-monolithic or monolithic reinforced concrete belt (grillage).
The device of a monolithic belt will ensure proper longitudinal rigidity and stability of the foundation. Prior to the beginning of the installation of the 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 along the top of the lintels and a reinforcing cage is installed, the M200 concrete mixture is laid.
Photo of the grillage device of the columnar foundation.
The surface of the concrete is leveled and covered with any waterproofing material to protect it from atmospheric influences. After gaining strength and waterproofing, you can proceed with the installation of floor slabs.
8. Pickup device
When constructing columnar foundations for warming the underground space and protecting it from debris, snow, moisture, dust, cold air, etc. a fence is set up, a fencing wall between the pillars. The fence can be made of various materials, most often of stone or brick.
To arrange a pick-up between the supports of a columnar foundation, it is necessary to make a concrete screed, which will serve as a basis for it. The concrete screed does not have a recess, it is placed on a sand cushion, which has a depth of 15 to 20 cm.
Lay the pick-up on a concrete screed. As in the basement, technological windows are made in the pick-up for the supply of various communications. The pick-up is not connected with the supports, since uneven settlement can lead to the formation of cracks.
The height of the pick-up must be at least 40 cm. The degree of moisture exposure to the walls of the house depends on the height of the pick-up, the higher the pick-up, the less the effect of moisture on the walls of the house. Also, a house with a low base looks squat, visually it may seem that such a house has no foundation and is built right on the ground, but houses with a high base look much more attractive and reliable. In this case, the height of the supports must correspond to the height of the plinth. For more information about the device of the base can be found in the article.
9. Foundation waterproofing
Foundation waterproofing can be done in one of the following ways:
- apply a layer of bitumen on the top of the supports and pick-ups. Lay a strip of roofing material on this layer and apply a layer of bitumen again, after which you lay another strip of roofing material;
- on the top of the posts and fences, apply a layer of cement mortar in which the ratio of cement to sand is 1:2. After you have leveled the mortar, sprinkle it on top with dry cement - a layer thickness of 2 mm to 3 mm. After letting the cement "grab", lay a strip of roll material (roofing material or roofing felt).
How to perform such waterproofing, and with what materials, you can read in the article .
Important points in the construction of a columnar foundation
- 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 unloaded for the winter (without walls, ceilings and roofs) can be deformed. This is true for all types of foundations, but it is especially important for column foundations, since each pillar behaves like a separate foundation (due to the lack of a single rigid core, unlike strip or slab foundations). Each pillar gives its own draft, which in the future (after frost - in the spring) can complicate the construction of the grillage and walls.
- Unforeseen deformations can also occur in the case when the built house is not used and not heated in winter, and the depth of the foundation was calculated for the thermal regime of the heated house. A favorable time period for laying the foundation is considered to be that period of time when the soil “departed” from frost and groundwater descended to the lower layers. It can be the summer months and the beginning of autumn.
- In the event that you made the supports of the column foundation from monolithic concrete, then you should know that the “readiness” of the concrete is achieved after 30 days. The entire period of "ripening" on concrete supports should not be subjected to any loads, and it is also worth taking care that the top layer of concrete does not dry out. To do this, you can cover it with a film or roofing material. For uniform setting of concrete, from time to time the supports should be moistened with water (two or three times a week, depending on weather conditions).
- For the preparation of concrete, it is best for you to use cement grade M400. Fine gravel and coarse sand can be used for concrete filler.
An example of calculating the components for the preparation of a concrete mixture:
- cement 20 kg;
- sand 50-55 kg;
- gravel* (crushed stone) 80-85 kg.
- If the composition of the concrete mixture is too liquid or, on the contrary, too thick, then the strength of the concrete structure is reduced by 25% of the strength of the same structure, in the manufacture of which all the requirements for the proportionality of the components were met.
What mistakes can occur when laying the foundation and how to avoid them
Many developers who decide to build a house on their own often make a number of mistakes when laying the foundation, which lead to varying degrees of damage to the foundation and walls of the house. These errors can be classified as follows:
- An insidious defect in the foundation is the unevenness of its subsidence. This can occur for a number of reasons, which include:
- the calculation of the depth of laying the foundation was not correctly performed;
- supports have different depths.
- The load on the foundation supports is uneven.
To exclude this phenomenon, it is necessary to perform an accurate calculation of the systematic distribution of the load on the foundation. Do not forget to take into account the load on the foundation when adding a second level to the house (for example, building an attic);
- Low quality material was used - the wrong brand of cement, sand that contained an admixture of clay, etc. Or a material, such as cement, has a long shelf life (it should be recalled that when stored for six months, its brand is reduced by 25%, and when stored for a year or more by 35-50%);
- The bearing properties of the soil were not correctly assessed.
A correctly completed project by specialists and constant monitoring of construction by you or an independent expert will help to avoid these mistakes.
Estimated cost of a columnar foundation
Editor's note: Prices in this article are for May 2009. Be careful.
The cost of a columnar foundation is determined by the technology of laying the foundation and the depth of its laying and consists of the following components:
Foundation prices:
- installation of a sand base 100 mm thick - 80-100 UAH / m2 (or 10-13 US dollars);
- crushed stone foundation (depending on the fraction) - 80-100 UAH / m2 (or 10-13 US dollars);
- device for concrete preparation (with a thickness of 10 cm); - 100-120 UAH / m3 (or 13-16 US dollars);
- laying of reinforced concrete pillows or blocks - 160-180 UAH/piece (or 21-24 US dollars);
- installation of monolithic reinforced concrete walls of foundations - 1300-1500 UAH / m3 (or 179-198 US dollars).
Prices for masonry work:
- rubble foundation masonry - 300 UAH / m3 (or 40 US dollars);
- laying of brick pillars - 250 UAH/m3 (or 33 USD);
- walls - 600 UAH/m3 (or 80 USD).
Floor covering prices:
- installation of a monolithic reinforced concrete floor (formwork, reinforcement, concreting) - 1300-1500 UAH / m3 (or 170-198 US dollars).
Relationship between contractor and customer.
It would not be superfluous to recall that if a construction organization (contractor) is involved in the construction of a house, then the relationship between you should be built only on a contractual basis.
A construction contract is the main document of relations, which specifies the terms of cooperation, the cost of work, the timing of the start and completion of construction, etc.
The estimate is an integral part of the Construction Contract. It lists all types and costs of work and materials.
The schedule for the performance of work should provide for the timing of the performance of work and the timing of payment for the stages of work.
The contract must also provide for design documents: the architectural design of the facility, structural sections of the project and other documents necessary for construction.
Read an overview of the types of foundation for a house in the article.
The foundation is the most important element of any structure: from a light garden gazebo to a capital multi-storey country mansion. This is the beginning of the construction and its foundation in the literal sense. The strength, durability and safety of the operation of the building depends on how correctly the foundation is chosen, calculated and executed. The question of what type of foundation to choose arises even at the stage of construction planning. Its optimal solution in many cases will be the decision to build a columnar foundation with your own hands: a step-by-step instruction for performing work can give a complete picture of the principles of its design and the intricacies of the arrangement process.
Advantages and disadvantages of a columnar foundation
Self-calculated and do-it-yourself columnar foundations for frame houses and buildings without basements that do not exert strong pressure on the ground are easy to perform and relatively cheap.
According to reviews, columnar foundations have a fairly impressive list of advantages:
At the same time, there are only two disadvantages of columnar foundations:
Types of columnar foundation
Before proceeding with the detailed design and calculation of the columnar foundation, it is necessary to decide on which site, what type and by what technology the building will be erected on it. The choice of material for the columnar bases of the foundation and the depth of their laying depend on these factors.
Foundation materials
The following materials can be used for foundation foundations:
- reinforced concrete;
- rubble concrete;
- blocks;
- brick;
- a natural stone;
- tree;
- pipes: asbestos or plastic.
Foundation depth
The depth of the columnar foundation is determined by its design, technological parameters of the structure and the geological characteristics of the soil in the building spot.
According to the depth of laying, columnar foundations are divided into three main types:
For a do-it-yourself columnar foundation, step-by-step instructions are needed as the most detailed and visual aid.
In the general case, the design of a support-columnar foundation is a system of supports of the smallest possible cross-section located at the points of load concentration: at the corners of the building, at the intersection of walls, under load-bearing beams, piers, under the furnace. To determine the number of stand-alone columns, the distance between them is assumed to be 1.5–2.5 m. To connect the foundation supports into a single structure, a grillage is made between them.
The height of the pillars above the zero mark is individual and depends on the design features of the grillage.
Calculation of the column foundation
The construction of a columnar foundation begins with a calculation. Most likely, to independently perform calculations, you will need a program like "Foundation" or some other program that can be found on the Internet and downloaded for free. To work with such programs, you will need the following parameters:
The technology for building a foundation with columnar supports also requires additional data:
As a result of the calculations, the following values \u200b\u200bare required for the installation of a columnar foundation will be obtained:
Columnar non-buried foundation
A columnar, non-buried foundation on supports spaced in 1.5-2.5 m increments is used quite often. Such foundations can be erected on non-rocky and slightly heaving soils, despite the fact that the building (wooden or panel house, bathhouse, utility block, annex or summer kitchen) has a small area and, accordingly, light weight. Moreover, if construction is carried out on rocky, coarse-grained or non-movable soil, this type of foundation can also be arranged under a fairly large house made of logs or timber. It is also possible to build a foundation on non-buried supports, provided that the effect of heaving forces on the structure is reduced. To do this, the soil under the supports is replaced with a sand cushion.
As a material for pillars, it is possible to use concrete, rubble concrete, sand concrete or concrete blocks for the foundation, the sizes and prices of which are very diverse. However, most often they take foundation blocks with dimensions of 20x20x40. The price of such a foundation, as well as the number of blocks required for its construction, can be calculated independently or using the "fundamental" online calculator. You can also make a columnar foundation of bricks with your own hands, but it must be taken into account that the use of silicate or ceramic bricks with low frost resistance is unacceptable.
Work on the construction of an unburied columnar foundation from prefabricated blocks can be divided into several main stages:
When building a foundation from 20x20x40 blocks with your own hands, video clips and step-by-step instructions will help you understand the technology of work, understand the process and more accurately assess financial costs.
Shallow columnar foundation
Shallow foundation is one of the most popular types of columnar foundation. The means and efforts required by its device are minimal, and the range of application for frame-type buildings is very wide.
As a basis for a frame house or a light bath, a columnar foundation is often made using pipes as formwork for the concrete mixture. Since the reinforced concrete pillar will take on the entire load, the material of the pipes does not really matter: both plastic and asbestos pipes, usually used for sewer networks, are suitable.
The diameter of the pipes depends on the load. For light buildings such as gazebos or outbuildings, 10 cm is enough; for buildings made of logs, pipes of 25-30 cm are needed. The amount of concrete in the end is determined precisely by the diameter of the pipe. For 10 m of a pipe 10 cm in diameter, 0.1 m3 of concrete will be needed, a pipe of 20 cm will require 0.5 cubic meters, and 30 cm - 1 cubic meter. The calculation is made taking into account the concrete cushion of the base.
The scheme for carrying out work on the installation of a columnar foundation from asbestos pipes with your own hands (a video of the process can be found on the Internet) is in general terms as follows:
- preparation of the construction site - garbage collection, removal of foreign objects, removal of sod and leveling. Marking the perimeter of the future building, corners, internal walls and their intersections. The installation sites of the foundation supports are marked with pegs;
- then, holes are made in the ground with a hand drill for pillars. The depth of the well should be 20 cm more than calculated: for the installation of a sand cushion;
- arrangement of a sand cushion with obligatory tamping and spilling sand with water. After the final absorption of water, pieces of roofing material should be laid on the bottom in order to prevent moisture from leaving the concrete mix in the sand;
- installation of pipes in wells with a height margin of at least 10 cm. Alignment of pipes according to the level and fixing them in wells using wooden blocks. With a close occurrence of groundwater, the pipes must be smeared with bituminous mastic to the ground level for waterproofing;
- then the base of the pipe by 40-50 cm is poured with a thoroughly mixed concrete-gravel mixture (1 part of cement and 2 parts of sand, diluted with water to a batter state, are combined with 2 parts of fine gravel). Immediately after pouring, the pipe is raised to a height of 15-20 cm and left in this position until the cement has completely solidified. This is necessary to create a base that resists extrusion during heaving of the soil;
- after the concrete has hardened, it is necessary to waterproof the pipe from the outside with roofing material and fill the well with sand with gradual pouring and tamping;
- fittings are placed inside the pipes, after which the rest of the pipe is poured with concrete;
- after the final hardening of the concrete - after 2-3 weeks - continue construction work. It should be added that it would be useful to waterproof the foundation with polymer or bituminous solutions.
According to the same scheme, do-it-yourself installation of a columnar foundation made of plastic pipes is possible. Videos and photos will help you navigate the intricacies of the workflow, which is generally simple.
Pillar foundation with grillage
The grillage is a system of rand beams and strapping beams. It rigidly fixes the foundation, excluding its displacement in the horizontal plane or overturning of the entire structure. In the presence of a grillage, the load from the structure is distributed evenly over all installed columnar supports, as a result of which stability and resistance to destruction increase.
To facilitate understanding of the process, the necessary work is outlined in stages.
Preparation and installation of supports:
- in any case, the initial stage of preparation for the construction of the foundation is the arrangement of the construction site. After removing debris, etc. along the perimeter of the future foundation, the turf and the topsoil are removed;
- for supports, it is necessary to dig holes with a depth of 20 cm more than the level of soil freezing. The width of the pit should be 40 cm more than the width of the wall, since 20 cm are added on each side for formwork and spacers;
- at the bottom of each pit, a well-compacted and spilled pillow of sand-gravel mixture 20 cm high is made. The pillow is lined with roofing material or polyethylene so that moisture from the concrete poured into the pit does not go into the ground;
- formwork boxes are assembled from boards 20 mm thick;
- it is recommended to thoroughly moisten the formwork installed in the pits to prevent the absorption of moisture from the cement mortar and facilitate removal;
- after the formwork is installed, a reinforcement frame is placed in the pits. The frame is assembled separately, from a bar 10-14 mm in diameter. The length of the bars is selected in such a way that when the concrete hardens, their ends stick out 30-40 cm above the ground level;
- the concrete mixture is poured continuously, in layers of 20-30 cm, leveling with a vibrator to avoid the formation of air bubbles;
- the formwork is removed after 3-4 days, the surface of the supports is treated with any suitable waterproofing mixture, and the rest of the pit is covered with sand. Before backfilling, it is also possible to insulate the foundation with extruded polystyrene foam.
Grill device:
There are two options for mounting the grillage: laying it on the ground or lifting it above its surface. The advantage of the second method is the exclusion of the effect of heaving forces:
The cost of works on the device of the columnar foundation
The total cost of a columnar foundation is the sum of the cost of materials and the cost of the actual work. In most cases, it is significantly lower than the cost of other types of foundations, since almost all types of columnar foundations can be built with your own hands. Videos and photos, instructions and manuals found on the Internet are also usually cheap or free.
The calculation of the cost of most types of columnar foundations can be done independently using special online calculators or programs. Many of them are quite easy to find on the Internet, are free and have an intuitive interface.
A variety of bases for light and ultra-light buildings is a columnar foundation. This foundation design is one of the cheapest, so it is often used in the construction of small outbuildings and suburban buildings.
The columnar foundation is characterized by maximum simplicity of design Source konopatka.org.ua
Application, advantages and disadvantages of a columnar base
In some situations, a foundation on pillars is preferable to other structures:
The construction of a building with walls made of light building materials and without a basement.
During the construction of temporary sheds and other outbuildings.
The need to save as much as possible on the foundation.
All of the above, plus, the inexpediency of building a strip foundation.
In addition, the popularity of the column base is characterized by the following design advantages:
for the installation of poles requires a minimum of time;
low labor costs
availability of building materials;
usually there is no need for special construction equipment;
a minimum of materials for heat and moisture insulation is required;
long period of operation;
the possibility of mounting the structure on soils subject to significant freezing;
ease of maintenance and repair of the structure;
the cost of a columnar base is much lower compared to other foundations.
In some cases, you can get by with a minimum of excavation and without concreting. Source ruspskrf.ru
the presence of weak or moving soils at the construction site;
the soil contains a significant part of peat or clay;
high level of groundwater occurrence;
the use of heavy building materials and the construction of several floors;
height difference at the construction site is more than two meters.
Also, the columnar foundation will have to be abandoned if, for some reason, a basement is needed under the building.
Device designs and varieties
The columnar foundation is a set of pillars installed in a certain order, holding the structure and transferring the load from it to the soil.
Usually, in a columnar foundation, the distance between the pillars is from 1.5 to 2.5 meters from each other. Less is simply impractical - then the main trump card of the foundation - cheapness, will be doubtful. No more is done due to the possible sagging of the lag and loosening of the entire structure in the future.
Without fail, the pillars are mounted at corners, at the intersection of walls, along the line of installation of load-bearing walls and beams of the future structure.
An example of a "pile field" - a drawing showing the number and location of pillars Source mauro-gianvanni.ru
In the section, the cross section of the support can be round or rectangular. The material for the manufacture can be used different:
Monolithic reinforced concrete. The most durable and stable structure, which is made of concrete reinforced with a reinforcing mesh.
concrete blocks. Slightly inferior to monolithic reinforced concrete. But for their installation it is necessary to use special equipment, since the blocks have a significant dead weight.
Booth or rubble concrete. A mixture of rubble stone with concrete. It is applicable for light outbuildings, but will significantly "weight" the estimate. Careful selection of stones will be required here, since the density of the support depends on the degree of their fit to each other.
Tree. Recently, wooden pillars for the foundation are used only for temporary and lightest buildings. In any case, solid woods are used: oak, pine or larch.
Combining the pillars into a monolithic structure is carried out using a grillage.
Monolithic columnar foundation with grillage Source nur.kz
Types of grillage
In order for the load from the structure to be evenly transferred to the ground, a grillage is installed on the pillars. It connects the columnar structural elements into a single system and minimizes the difference in shrinkage of the base legs. At the stage of mounting the columnar bases, a special pin or bolt is installed in them, on which the grillage will subsequently be mounted.
Grill equipment options:
Wooden beams with a large section. They are used for wooden structures of low weight.
I-beam or tee structures. Can be used as a separate element, or serve as a base for wooden logs.
Concrete beams - can be prefabricated or monolithic. They are installed if necessary to ensure maximum stability and strength of the building, if dense wood or relatively heavy building materials are used for construction.
Online foundation calculator
To find out the approximate cost of a columnar foundation, use the following calculator:
construction of small architectural forms (arbors, utility blocks, grill houses) on a turnkey basis
Calculations for the installation of column poles
Before installing the structure, it is necessary to perform mandatory calculations and prepare the construction site.
Even for an unpretentious columnar foundation, it is desirable to level the site Source perevozka-24.by
Before starting the calculations, it is necessary to take a soil sample at a depth of 0.5 meters below the installation level of the pillars. The analysis will allow you to understand whether the soil is suitable for the installation of a columnar foundation.
The necessary calculations include:
Determination of weight future building. This will allow you to determine the total pressure on the ground: the total mass of walls, ceilings, roofs, wind load, planned furniture.
Calculation of the number of supports. The perimeter of the building is divided into two meters (the step of mounting the supports). In addition, you need to add poles that will be installed under the internal supporting walls and crosshairs.
Support pillar area. Table value. For example, the area of a support with a diameter of 40 cm is 1250 cm2.
Their number directly depends on the area of \u200b\u200bthe supporting pillars. The smaller the area of the support, the more their number must be installed.
For each material, the minimum size of the support section is set. For monolithic reinforced concrete, this value is 0.3 meters, brick - 0.38 meters, concrete - 0.4 meters, rubble and rubble concrete - 0.6 meters.
The calculation of the base of the pillars should be carried out in such a way that the size of the support exceeds the thickness of the wall by 10 centimeters - 5 centimeters on each side.
Preparation for work
The beginning of the robot begins in the preparation of the construction site and materials. To ensure construction, it is necessary:
Clear the site of debris.
Remove the plant layer of soil to a depth of 15-20 cm and two to three meters away from the construction site.
Carry out the alignment of the construction site, check the evenness of the site. To do this, use the building level, installed on the board, about two meters long.
If clay soil is found under the cut of fertile soil, then it is necessary to equip a sand-gravel cushion.
After the site is ready, you can start building.
Execution of construction works
Base breakdown
The essence of the work lies in the fact that the mounting scheme of the supports is transferred from the drawing to the construction site.
Before breaking down the foundation, along the perimeter of the future building, at a distance of one or two meters from it, a so-called cast-off is made. These are ordinary posts on which wooden planks are stuffed. A rope is stretched between the planks, which will mark the construction site.
Even with all the triumph of technology, without a cast-off at a construction site, there is nowhere yet ... Source stroychik.ru
Further, the details of the foundation are noted: pits and trenches, their dimensions and depth. Along the perimeter and inside the base, stretch marks are made from the rope, indicating the place where wells are drilled for the supports. Axial lines, building angles are controlled by measuring instruments. Their location to each other should be strictly at an angle of 90 °.
Theodolid check the bottom of the site, the corners of the future structure and the joints of the walls. The mark after verification should be similar to the design indicator.
Good to know! Theodolite is a measuring device for determining horizontal and vertical angles in topographic surveys, geodetic measurements, in construction and other works.
Pits for supports
Under reinforced concrete or prefabricated foundations, pits are dug using special equipment or manually. The holes must be vertical.
If the soil is not loose and the depth of the pit does not exceed one meter, then its walls can be straight. With a pit depth of more than one meter or in the presence of loose soil, the walls of the pit are made inclined outward. If necessary, strengthen with boards or spacers.
The depth of the pit under the pole should exceed the design value by 0.2-0.3 meters.
Now you can make a sand and gravel pillow. Source dm-st.ru
The width of the pit should differ from the design width by 0.2-0.4 meters in each direction. This will make it possible to freely mount the formwork and install spacers.
Under the round poles, pits are made with a special automatic or manual drill. To broaden the base, a drill equipped with special folding knives (TISE) is used. At a given depth, the knives open and perform the design widening of the base.
In any case, the width of the columnar base must exceed the width of the walls of the future building.
On our website you can find contacts of construction companies that offer the service of auditing construction works. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".
Pillow construction
Under each pillar, a sand-gravel or simply crushed stone pillow is equipped - this will eliminate frost heaving. The pillow should exceed the dimensions of the base of the column by 0.1-0.2 meters on all sides.
The bottom of the pit to a height of 0.1-0.15 meters is covered with crushed stone, which is rammed after backfilling. A layer of coarse-grained sand, about 0.1 meters high, is laid on the compacted gravel, watered and rammed. The total height of the layer should be such that, after laying it, it is possible to reach the zero level of the installation of the base of the column. So that water does not leave the concrete that will be poured, the pillow is covered with polyethylene or roofing material.
Waterproofing is laid on the sand cushion Source zen.yandex.ru
When equipping pits for round poles, the principle of installing a pillow is similar. Tampering is done with a long pole.
Formwork installation
For the manufacture of concrete monolithic columnar supports, reusable, or disposable, non-removable formwork can be used.
Reusable formwork is a structure that is made of various materials and can be assembled in different ways. It can be:
Boards that are knocked into shields of different sizes.
Plywood sheets, 1-1.5 cm thick.
Metal removable formwork.
Plastic prefabricated formwork.
Metal and plastic formwork are more often used in industrial construction.
For wooden formwork, a planed one-sided board is used, with a thickness of two to four centimeters and a width of 12-15 cm, with a moisture content of not more than 20%. Installation of boards is carried out with the planed side inward. Formwork boards or plywood must be damp. Otherwise, they will absorb moisture from the concrete.
As a disposable formwork, pipes made of hard cardboard or plastic are used, with a thickness of 0.5 to 2.5 cm. The diameter of the pipes and their length can be of various sizes. The inner surface of the pipes is treated with a water-repellent solution. The role of a disposable formwork can be performed by an ordinary roofing material.
Ruberoid as a one-time formwork Source fundamentdomov.ru
Brickwork, asbestos or plastic pipe, the same roofing material can be used as fixed formwork. After filling with concrete mortar, such formwork is not removed.
Reinforcing glass
It is formed from reinforcing bars with a diameter of 1.0-1.2 cm. The number of bars in one column can reach from 4 to 6 pieces. They can be arranged in a square or in a circle. Along the entire length, every 15-20 cm, the reinforcing bars are twisted with a wire frame or ring, for which reinforcing wire is used, with a diameter of 0.6-0.8 cm. Such a connection will give stability to the reinforcing bars, rigidity of the reinforcing structure and the columnar base as a whole. The distance from the reinforcing bars to the formwork should not be less than five centimeters.
If it is planned to subsequently erect a monolithic concrete grillage, then it is recommended to bring the reinforcing bars out - this will simplify the adhesion of the pillars to the grillage. If it is planned to install a wooden, I-beam or T-beam, it is advisable to provide for the installation of a mounting rod or bolt into the hardening concrete.
A concrete monolithic grillage will be installed on the pillars Source stroy-dom-pravilno.ru
Pouring solution
For a conventional reinforced concrete base, the solution is poured in parts of 0.3 meters high. Each such part is separately vibrated so that air bubbles come out. This procedure is repeated until the inner container of the formwork is filled to the design height.
If brickwork is used under the pillars, then the mortar is made from Portland cement, at least M300. The best option is the M500 brand. The solution can be made in several ways:
Cement - 1 part, sand - 3 parts.
Cement - 1 part, sand - 10 parts, limestone - 3 parts.
Cement - 1 part, sand - 10 parts, clay - 1 part.
For rubble masonry, stones with a thickness of more than 25 cm are used. Laying is carried out on a mortar with maximum adjustment of the stones to each other. The voids are filled with medium or small gravel, followed by tamping. To increase the strength, the reinforcing mesh for rubble masonry can be installed in any position.
The supports of the columnar foundation must be of the same height. To do this, you must constantly monitor the vertical plane and "beat off" the extra value. The frozen top is difficult to remove and requires extra costs.
Video description
How the installation of the armoframe and pouring concrete is done, see the video:
Underground decoration
When erecting a building on a columnar foundation, a ventilated space is obtained between the ground level and the grillage (subfloor). This has a positive effect on maintaining a constant level of moisture content of materials, but negatively affects the thermal insulation of the room. In addition, animals can live in an empty space. Therefore, in most cases, they try to sew up the empty space. For this, one of the options is used:
Upholstery around the perimeter with sheet or finishing material. Bearing rails are attached to the foundation pillars. To them, with the help of self-tapping screws or galvanized nails, a finishing material is attached.
Pickup manufacturing. Between pillars of brick or stone, laying is carried out in one row. At the same time, it is possible to mount decorative elements for cylindrical foundation pillars.
Both options can have their own designer beauty, but the pickup option will cost a little more.
You can also install panels with imitation masonry. Source bouw.ru
Attached structures
Often, an additional structure can be added to an already built building. In the case of a columnar foundation, when the “box” does not stand on the ground, at least a porch can become such a structure. Also, another room can be attached, which in its mass will be lighter than the existing one.
In any case, for attached structures, its own contour and its own foundation are made. This is done due to the fact that the structures have different masses and if they are rigidly connected, then in the event of shrinkage of the main “box”, the extensions will deform and collapse.
Video description
The consequences of such an error are shown in the following video:
The foundations of the "box" and extensions should not touch. An expansion joint is installed between them. For the seam, dense materials with good absorbing ability are used. For example, roofing material folded in several rows, mineral wool, rubber gaskets.
On our website you can find contacts of construction companies that offer installation and repair of foundations. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".
Conclusion
The biggest plus of a columnar foundation is its price, because such a foundation does not require specific building materials or highly qualified workers. But you must always remember that columnar foundations are designed exclusively for light buildings. Not a single specialist who concludes an agreement with you, where warranty obligations will be written, will undertake to build a residential building on such a basis.
Among all the varieties of concrete foundations used today, the columnar-strip foundation deserves special attention. Most often, this design is used in the arrangement of heavy and massive construction projects.
Subject to competent construction, the column-and-strip structure will have the highest performance. At the same time, relatively little time and money are spent on arranging such a foundation, and all the required work can be done on its own.
Read the general information about the column-strip bases, study the guide for arranging such structures and get to work.
The use of such a design will be justified when performing construction work in areas with a large depth of soil freezing.
In such situations, the construction of an ordinary buried strip foundation will require irrational financial investments, and a shallow structure simply cannot cope with the tasks assigned to it.
In such conditions, a column-strip foundation is an excellent option. Even a beginner can cope with the arrangement of such a design.
An additional advantage of the base under consideration is the possibility of its arrangement on inclined sections. But if the underground aquifer is located too close to the soil surface, it is recommended to refrain from such a decision.
In the considered design, the largest part of the load falls on the base of the pillars. In this case, the pillars must be placed in the ground at least 200 mm below the freezing point of the soil. Thanks to this, maximum indicators of durability and reliability of the structure will be ensured.
So that in the future the tape does not rise under the influence of natural changes in the structure of the soil, its lower part must be made somewhat expanded.
In the construction of the column-tape type, the tape performs the functions of only the upper grillage, which is necessary for connecting the pillars into a single structure and additionally increasing the strength of the base. In this case, the tape does not exert any load on the ground.
With the help of the tape, the most even distribution of the load on the main foundation pillars is ensured.
The foundation must be designed so that after the construction is completed, at least 150-200 mm of free space remains between the lower edge of the grillage and the top layer of soil. Due to the presence of such a gap, the foundation will not receive any significant damage even with strong swelling of the earth.
What are the poles made of?
Before proceeding with the independent arrangement of the column-strip base, you must choose the optimal material for the manufacture of supports. Available solutions include: wood, concrete blocks, bricks, as well as pipes made of asbestos cement and metal. Check out the features of each option and choose the solution that best suits your situation.
They are rarely used due to their relatively low durability. Pillars made of wood are only suitable for arranging a foundation intended for installing a terrace or other similar structure.
The optimal diameter of wooden poles is 150-200 cm.
Before deepening the pillars of the material in question into the ground, they must be treated with antiseptic and flame retardant impregnation. Thanks to this treatment, the resistance of the material to decay, pest damage and fire will be significantly increased.
For waterproofing wood, bitumen-based mastics are best suited.
Brick-iron ore is well suited for arranging a columnar-ribbon structure. With its use, shallow-depth columnar foundations are also erected.
Supports in the form of concrete pillars, additionally reinforced with reinforcement, are considered the most reliable. In view of this, it is these supports that are most popular.
Concrete pillars can have either a solid (monolithic) structure or consist of several blocks.
It is important that the width of the pillars is at least 40 cm.
Pipes made of asbestos cement or metal are very easy to install. Installation is reduced to the placement of hollow pipes in pre-prepared recesses, the installation of reinforcement bars inside the pipes and the final filling of the cavity with concrete mortar.
The work is done extremely quickly and simply. The optimal pipe diameter is selected individually, taking into account the expected load on the base being built.
Stages of arranging the foundation
The construction of the foundation of this type is carried out in two stages. First you will need to create the base of the structure from the pillars, and then equip the shallow concrete strip.
pillars
Before starting work, determine the optimal depth of the column-strip base. At this stage, consider the following options:
- type and features of the soil structure;
- ground freezing level;
- depth of groundwater passage.
There are shallow and deep foundation structures. When arranging a shallow foundation, the pillars are usually immersed in the ground by 40 cm, while in the case of building a buried foundation, the supports are deepened 10-50 cm below the freezing point of the soil.
Keep the installation step of the supports within 100-250 cm in accordance with the future load. The higher the loads on the base, the smaller the space between the installed supports. Professional builders strongly do not recommend placing supports with a step of more than 250 cm, because. this will lead to a significant decrease in the strength of the finished structure.
Proceed with the installation of support pillars. This is a fairly simple job done in a few steps.
First step. Prepare the site for upcoming events. To do this, remove the fertile ball of soil and level the site. If the top layer of soil in your area is clayey, remove a larger volume of it and cover the resulting base with a small layer of sand.
Second step. Mark up the area. For this, any suitable pegs and a noticeable rope will do. Pull the thread at a distance corresponding to the width of the future concrete tape.
Watch the angle of intersection of the cords. It is important that the threads intersect strictly perpendicular.
Mark the intersections and junctions of the internal partitions and external walls of the building, the corners of the future structure and the areas that will be subjected to the most serious loads.
Third step. Dig a trench in the place where the strip part of the foundation is arranged. A hole with a depth of about 400 mm will suffice. The width of the trench should be 70-100 mm greater than the width of the tape. Such a gap is necessary for the installation of formwork boards.
Fourth step. Make recesses in the places of future installation of support pillars. A drill or other suitable device will help you with this. Select the diameter of the recesses individually in accordance with the expected loads on the foundation. The higher the load, the larger the diameter of the support pillars should be.
If, according to the project, the pillars will lie more than 100 cm, be sure to install supports made of durable boards. They will prevent soil erosion. If the pits have a depth of up to 100 cm, the installation of props can be abandoned.
Fifth step. Backfill the bottom of each recess with a 100mm layer of sifted sand.
Sixth step. Start arranging the pillars. In this example, the supports are made of asbestos-cement pipes.
Preliminary perform waterproofing of the supports. To do this, paste over them with a double layer of roofing material or other similar material. Insert the waterproofing pipe into the recess until it stops.
Tie a reinforcing frame of steel bars and tie wire. Use rods with a diameter of 12-14 mm. The fittings should have such a length that its upper ends protrude from the pipes by 150-250 mm.
Start filling. First you need to pour concrete in the free space in the pits around the supports to about 20 cm of the height of the recesses, and then pour the pipes directly.
Leave the finished posts to dry and gain strength.
Ribbon
Proceed to the arrangement of the tape part of the structure.
First step. Tie a frame of reinforcing bars and steel tie wire. Weld the structure and screw it to the rebars protruding from the concreted support posts.
Second step. Perform the installation of the formwork for pouring the tape. Collect the formwork from boards 40 mm thick and about 150 mm wide. Boards can be replaced with chipboard, plywood or sheet metal.
Third step. Cover the inner surface of the formwork with moisture-proof material. Polyethylene is suitable for waterproofing, and more modern membrane materials can also be used.
Fourth step. Fill the formwork with concrete mortar. To save time and effort, you can order ready-made concrete. If desired, the solution can be prepared by hand. Fill in one pass. Pour the solution horizontally. Vertical joints are strictly prohibited - they will crack even before the concrete has completely hardened.
Treat the poured concrete with a special vibrator. This treatment will eliminate voids and excess air. If you don't have a vibrator, at least pierce the concrete with rebar in several places, and then carefully seal the holes with concrete.
The fill will dry for a month. It is recommended to dismantle the formwork only after the casting has completely hardened. For some time (usually 1-1.5 weeks), the poured concrete must be additionally moistened, otherwise it will crack.
Determine the frequency and duration of dampening individually in accordance with the "behavior" of concrete and weather conditions.
Waterproof the hardened and cured concrete, backfill the remaining trenches with earth, and proceed with the planned construction activities.
Successful work!
Video - Do-it-yourself column-strip foundation
Depending on what kind of soil is on the construction site, you have to choose the right foundation structure. If the soil is soft, mobile, with flooding or with a high level of groundwater, then a columnar foundation is indispensable. With the seeming simplicity of installation work, the process of building a columnar structure requires an accurate calculation of the bearing capacity of each support post.
But among all types of foundations for a house, this one is the cheapest in terms of material consumption, moreover, it is possible to use various building materials for it. Let's look at step-by-step instructions for building a columnar foundation with your own hands.
Advantages and disadvantages
One of the advantages has already been mentioned, this is low-cost construction. You can also add to the benefits:
- quick construction of the foundation;
- there is no need to use construction equipment;
- the simplicity of the work carried out, so making a columnar foundation with your own hands is not a problem;
- the absence of additional measures related to the thermal insulation of the foundation;
- columnar foundation is easy to repair;
- you can build this species on frozen soils;
- the service life of the poles with strict adherence to technology is up to 100 years.
As for the shortcomings, there are not so many of them:
- not very high bearing capacity, so it is recommended to build light buildings on the pillars: wooden, frame, panel;
- the stability of supports is reduced if they are erected on moving soils;
- there is no possibility to organize a basement or underground.
Before you start making a columnar foundation with your own hands, you need to familiarize yourself with its classification, materials and carry out a calculation.
General scheme of the device
The general scheme of construction work can be identified by several main stages. They, in principle, do not differ from the construction of any type of foundation.
- The bearing capacity is calculated taking into account the number of supporting pillars and the weight of the building.
- A general drawing of a columnar foundation is made with an exact indication of the distance between the posts, the cross section of the supports and the height of the protrusion above the ground.
- Preparatory work is underway. This is marking exactly according to the plan, earthen with digging holes - wells, making reinforcing frames, pouring pillows into holes, waterproofing and installing frames. If there is a need, then the formwork of the basement is assembled.
- Making a concrete solution and pouring it into prepared wells, followed by the removal of air by baying the mixture. If bricks or blocks are used as the material for the columnar foundation, then they are laid.
The entire node of the columnar foundation is the union of the columns with a horizontal tape, which is called a grillage. It can be concrete, metal, wood or be the lower crown of a log cabin.
As you can see, there are not so many positions according to the scheme, which is why it is believed that it is not difficult to build a columnar foundation with your own hands.
Material classification
Like any foundation for a house, a columnar foundation must be strong and reliable. Therefore, building materials are used for its construction, which can provide the necessary strength and reliability. These include concrete, concrete blocks, bricks, stone, metal, and some types of wood, which are used in the form of logs or timber, installed vertically.
The choice of material is actually a crucial moment, on which the quality of the end result depends. And if the task is to build a columnar foundation with your own hands, then you need to choose the right material for its construction. For example, it is believed that it is better to erect monolithic structures on water-unsaturated soils, and prefabricated structures on damp ones.
Monolithic reinforced concrete pillars
This is the strongest and most reliable design. Such a foundation for pillars has high tensile and compressive strength. Of course, if you take into account the correct reinforcement.
At the same time, if you correctly distribute the racks around the entire perimeter of the house, taking into account the required section of the supports, then multi-storey buildings can be erected on such a foundation.
We add that the columnar reinforced concrete foundation is constructed in cases where it is necessary to fill it to a sufficient depth, and more often below the level of soil freezing. It perfectly withstands heaving of the soil, but is afraid of contact with groundwater. Therefore, it is necessary to take care of the waterproofing of the supports.
Asbestos cement pipes for the construction of pillars for the foundation are not often used. Although they feel great in any soil.
Their bearing capacity is not high, but it is not required, because the pipes in the foundation structure act as formwork.
Pillars made of plastic pipes
Here the situation is the same as with asbestos-cement. That is, plastic pipes act as formwork. They do not corrode, do not collapse under the influence of water, so they do not need waterproofing. The only thing is that it is necessary to correctly pour the supports under the foundation. Namely: install a reinforcing frame in them and pour concrete mortar.
Of bricks or blocks
Brick pillars for the foundation should be treated as the most long-known structures. From the history of European and Russian architecture, they are "long-livers".
Until now, brick pillars stand under huge buildings, and, apparently, they will stand for more than one century.
Because the attitude towards the choice of bricks in those ancient times was serious. Be sure to use burnt bricks of the highest quality. Therefore, when building a house on a columnar foundation, this requirement must be taken into account.
As for the block pillars, they are not inferior in strength to brick ones, of course, depending on the material from which the blocks are made. It is better to give preference to concrete blocks, the cinder block in this regard cannot carry heavy loads, although they are used for light buildings such as a veranda, a bathhouse, and so on.
Pillars built of stone can be attributed to block structures. A good option, strong enough, but such supports cannot withstand the exploits of the soil. Therefore, when a house is being built on a slope, it is better to refuse stone pillars. As a replacement for them - the foundations of rubble concrete. This is when stones are poured into the prepared formwork, and then they are poured with concrete mortar.
Such a columnar foundation, like a brick one, has been used in Russia for a long time.
Today it is not so in demand, but, for example, under baths installed by a river or lake, they are often found.
We must pay tribute to the correct choice of wood. The stronger it is, the longer the life of the pillars. At the same time, protective measures must be taken very carefully.
- Treatment of the entire column with antiseptic compounds.
- Processing of the part deepened into the ground with bituminous mastics with gluing a layer or two roofing material.
Doing all this yourself is not a problem. The main thing is not only to make protection, but also to install wooden supports under the pillars. They are made of a board with a thickness of at least 50 mm and a width over the entire area twice as large as the section of the column. Support boards also need to be protected from moisture and the negative effects of the soil.
Mostly wooden racks are used for light structures, although even a hundred years ago, boyar mansions of several floors were built on them.
Frost heaving is the force that is taken into account in the first place when designing a columnar foundation.
This is a very dangerous pressure, which, if not laid correctly, can break the foundation of the house.
Therefore, a large number of options for the construction of buildings are considered from the point of view of the impact on the foundation structure of frost heaving.
The basic design rule says that the foundation should be laid below the freezing depth of the soil by 30 - 50 cm. And if this indicator is, for example, 1.2 m, then, accordingly, the laying depth will be 1.5 - 1.8 m.
But often a light structure cannot exert enough pressure on the piers to contain the forces of frost heaving. That is, even when laying to a great depth, the foundation will be subjected to deformations. Therefore, when building a columnar foundation with your own hands, it must be borne in mind that there are two more positions: shallow and superficial.
Unburied
Non-buried columnar foundation or surface - these are all the same racks, only their laying depth does not exceed 30 - 40 cm. Often they are simply built on the surface of the soil, having previously made a pillow and waterproofing. Designers refer this variety to those foundations, the laying depth of which does not exceed a third of the level of soil freezing. From our example: 120: 3 = 40 cm.
The device of the columnar foundation of this type belongs to the category of the cheapest and prefabricated structures. As practice shows, they usually use block modification using blocks, stones or bricks. But since the height of the pillars is not very large, which means that their bearing capacity is also low, therefore it is recommended to increase the cross-sectional area of the supports. The minimum size is 40 x 40 cm.
Shallow
The shallow foundation from its name suggests that it is buried in the ground, but not to a great depth. In any case, not below the level of its freezing. Designers are laying the depth at the rate of 0.5 - 0.7 of the depth of freezing of the earth. Again - from our example: 120 x 0.5 \u003d 60 cm.The main requirement for this design is not to touch groundwater.
The node of the columnar foundation - the grillage has one single task - to distribute the load from the house to all the pillars evenly. As mentioned above, the grillage can be built of concrete, metal (channel or I-beam), wood (beam with a section of 150 x 200 or 200 x 200 mm) or be a log of the first crown of the log house.
Do-it-yourself step-by-step construction instructions
We turn to the main question, how to properly make a columnar foundation with your own hands. The scheme of work has already been described above, where the first stage was to carry out calculations and draw up a project. If a house is being built on a columnar foundation, then this stage of construction is best left to specialists. Indeed, in order to accurately make all the calculations, it is necessary to take into account a large number of different indicators and nuances. Eg:
- type of soil on the site;
- groundwater level;
- the level of soil freezing;
- type of building, its number of storeys, what materials it is constructed from;
- materials from which it is supposed to build the foundation itself;
- additional loads.
Of course, you can use online calculators, but not for solid houses. For baths, verandas, sheds it can be used. And then no one gives a guarantee of one hundred percent correctness of the calculations.
Video
Video on how to make a columnar foundation yourself.
Marking and earthworks
So, if the project of the building is in hand, then the designers must have made the binding of the foundation to the terrain in it. This makes it easier to find its location on the plane. Usually, the binding is carried out to the boundaries of the site, indicating the distance from the foundation structure to these very boundaries. Therefore, before marking the pillars, it is necessary to postpone these same dimensions from the borders and determine the perimeter of the building.
To do this, two rows of twine are stretched along the boundaries of the building, which immediately determine the width of the foundation pillars. The rest is simple:
- sod is removed to a depth of 20 cm;
- the installation sites of the pillars are marked: at the corners of the building and between them with the necessary distance, which is determined by the project;
- wells are made in the ground with a garden or electric drill, the depth and section of which are also determined by the project.
We must pay tribute to the fact that the drawing of the columnar foundation helps a lot in marking. Because it clearly indicates all the parameters of the future design.
A pillow is a layer of sand 20–30 cm thick. It is poured into wells and rammed with improvised means. It can be a beam, a wooden lath, a log of a small section. Often a pipe is used, to the end of which a metal plate is welded.
The purpose of the sand cushion is to divert some of the water from the supports that enters the ground. Next, a concrete solution is poured onto the sand, which will subsequently become a support for columnar structures. The thickness of the concrete layer is 10 - 30 cm.
Formwork must be dealt with carefully. After all, much will depend on what kind of soil is located on the construction site.
- If the soil is clayey, that is, strong, then there is no need to make formwork as such. Clay itself, like a monolith, does not collapse or collapse.
- If the soil is weak sandy, then formwork will have to be installed in the well. At the same time, it is necessary to take into account what kind of section the designers have determined in terms of shape: rectangular or round. If the second, then pipes are used as formwork: plastic, asbestos-cement or metal. If the first option, then the well will have to be expanded, made of a rectangular section, and formwork made of boards or other flat materials should be installed in them. This is a large amount of earthworks, so this form for buried structures is rarely used.
As for the first position, usually a roofing material rolled into a tube is laid inside the shaft. It forms the walls of the foundation and will continue to perform the functions of waterproofing. Roofing material formwork is a must.
Regardless of whether the formwork will be installed in the well or not, it is imperative to form a pillar in the basement. So, here the formwork is going to be sure.
Reinforcement of pillars is carried out without fail, after all, it is the reinforcement laid in concrete that makes it possible to restrain loads from the forces of frost heaving.
In the project, the number of reinforcing bars, their form of connection to the frame and diameter must be indicated. Therefore, the reinforcement is simply cut into pieces of the desired length and into the frame.
Its cross section in shape can be triangular, square or round. The main task is to correctly fold the reinforcing bars relative to each other at the required distance. Then clearly tie them together with wire.
After that, the frame is lowered into the prepared well exactly in the middle. Then you can start pouring concrete.
The length of the reinforcement bars is cut, taking into account that their ends will be attached to the grillage reinforcement cage. Therefore, the rods are cut 10 - 30 cm longer. So that they stick out this size above the basement of the pillars.
The pouring of a columnar foundation must be approached from the standpoint of standard technology. A concrete solution is made according to the classical technology:
- one part of cement brand M 400;
- two parts of washed sand, without a large amount of clay impurities;
- three parts of crushed stone with granules 5 - 40 mm.
The most interesting thing is that for a columnar foundation there is no need to prepare a large batch. And there is no need to fill all the pillars at once in one day, as is usually done when constructing a tape or slab structure. It is enough to calculate the volume for one column, make a batch and pour it.
For example, a pipe with a diameter of 150 mm is used as formwork, and it is installed at a depth of 1.2 m. It turns out that the volume of an empty pipe is equal to:
V = SxH, where S is the area of the pipe and H is its length or installation depth. The area can be found using the formula: S \u003d πD² / 4 \u003d (3.14 × 0.15²) / 4 \u003d 0.018 m³. If converted to liters, it will be 18 liters. In fact, these are two buckets of solution.
Pipes are filled with concrete, tapping on the formwork, punched to remove air. In this state, the poles must stand for 28 days. During this time, concrete will gain its branded strength.
grillage device
We will assume that the grillage will be monolithic according to the project. This means that under it it will be necessary to build a formwork from any flat materials.
It is made on weight, therefore, supports made of bricks, blocks, boards, logs and other materials are installed under the lower shields. The formwork is assembled into a rectangle with a complete and strong fastening of the panels to each other.
A reinforcing frame is placed in it. Usually these are two vertical gratings connected with 6 mm wire rod or 6 - 8 mm reinforcement. Be sure to fasten the reinforcing cage of the grillage with pieces of reinforcement sticking out of the pillars.
This node of the columnar foundation is subjected to serious loads. Therefore, the fastening of two reinforcing structures must be approached carefully. Concrete solution is poured with ramming and bayonet. After 7 days, the formwork is dismantled, after 28 days the foundation can be loaded.
Summarizing
As you can see, it is necessary to approach the construction of a columnar foundation with your own hands with a thorough analysis of all stages of the ongoing construction processes. You can't make mistakes in the first place.
You can not apply to the markup in large allowances. It is necessary to accurately drill wells to the required depth. Even a few centimeters can play a bearing role in extreme situations. The device of the foundation is an integrated approach to its construction, where there is no place for mistakes and miscalculations.
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