Do-it-yourself columnar foundation step-by-step instructions. Columnar foundation for a bath - do-it-yourself manufacturing technology. Column foundation with grillage
Now frame houses are being created in almost all climatic zones. Due to the low weight of the structure, a base with a small bearing capacity... A simple option is a columnar foundation.
Advantages and possible disadvantages of a columnar foundation
Columnar base is a simplified version pile foundation... The structure is a network of supports installed along the perimeter of the walls and in places of greatest stress. The maximum pitch between the supports is 2.5 m. All the pillars are joined together by a grillage (horizontal strapping). Columnar foundations for frame buildings are used of 2 types: monolithic concrete (made by pouring into supports) and prefabricated (built from ready-made blocks or stones). Despite the fact that the structure is constructed without continuous pouring of concrete throughout the entire perimeter, such foundations have a number of advantages that make the structure reliable and durable.
Column foundation for frame house
Benefits of a columnar foundation:
- Costs less than tape counterparts;
- You can make it yourself;
- Erected quickly;
- No heavy equipment is needed for its construction;
- Easy to repair;
- Poles can be installed at any time of the year, including winter.
The disadvantages of the design include a large number of self made(if there is no drilling equipment) and the need for additional insulation of floors, since the frame structure practically hangs in the air.
Preparation for manufacturing
At the preparatory stage, it is necessary to find out the dimensions of the future structure, the load on the foundation of the higher structures and the bearing capacity of the soil. Before erecting a frame house, you can independently carry out a soil study. To do this, you need to drill several holes in the area. The depth of the well is below 50 cm of the basement base. In this way, the type of soil and the absence of aquifers are determined.
Characteristics of soils:
- Rocky - soils with a high content of stone or gravel, are distinguished by a strong base, hold the load well, do not collect water.
- Coarse sands - represent a strong base with low heaving.
- Fine sand - poorly suited for construction, as they are highly heaving. They collect water in the upper layers and act in a pushing manner on the foundation.
Calculating the depth and number of posts
Columnar bases are buried (for water-saturated and clay soils) and shallow (for rocky and sandy soils with low level occurrence groundwater). The height of the buried foundation depends on the average depth of soil freezing in your area. The sole of such a foundation should be located below this level by 30-50 cm. Before starting work, the load of the house should be calculated, for this, the weight of the walls, floors, roofs and the mass of the foundation are summed up.
If the slope is more than 60 degrees, the snow load is 0.
To determine the weight of a reinforced concrete columnar foundation, its volume must be multiplied by the specific weight of reinforced concrete (2500 kg / m³). To calculate the weight of one column, the following formula is used: V = 3.14 * G² * h. V - column volume, G - column radius, h - column height. All values are in meters. The resulting value must be multiplied by the number of pillars, and we get the total volume of the foundation.
Bearing capacity of different soils (in kg / cm²):
If the load on the soil exceeds the bearing capacity of the soil on the site, you need to increase the number of posts.
Material selection and quantity calculation
Different materials are used for the construction of a columnar foundation:
- Wood is a very short-lived material; even when treated with protective compounds, it will last no more than 20 years.
- Stone pillars - usually erected from quarrystone or granite stones. They are distinguished by their durability and reliability. The disadvantage is massiveness and laboriousness during construction.
- Monolithic concrete pillars.
The number from the table must be multiplied by the length of the post (in meters) and the number of supports.
The reinforcement for the columnar base is corrugated, class A, with a diameter of 10–12 mm. The metal rods are needed the same length as the supports. For a column with a diameter of 10-14 mm, you will need 4 bars of reinforcement. They are placed at a distance of 10 cm from each other and tied across half a meter with a smooth and thinner reinforcement with a diameter of 6 mm. Thus, for a two-meter post, you will need 8 m thick and 1.2 m thin reinforcement. The resulting figures are multiplied by the number of supports and we get the footage of the reinforcement required for the columnar base.
Required tools
Before starting construction, the following tools must be prepared:
- Concrete mixer;
- Shovel;
- Roulette;
- Level;
- Nails and screws;
- Hammer;
- Cord;
- Pegs;
- Hand drill;
- Master OK;
- Formwork pipes or boards.
Step-by-step instructions for creating a foundation with your own hands
Site marking
Before starting work, marking is done - pegs are driven in the corners of the future building and a cord is pulled. At this stage, it is imperative to check the diagonals. They must be the same. Further, on the entire area, debris and vegetation are removed and the locations for the installation of pillars are outlined.
Digging holes and waterproofing
Drilling holes for a columnar foundation
For a foundation made of monolithic concrete or asbestos pipes, it is convenient to use a motor drill. The pits can be either straight or with an extension at the bottom. A wider outsole will increase the bearing capacity of the base and improve heaving resistance. Now you need to waterproof the foundation. To do this, a pipe made of roofing material or polyethylene should be lowered into each pit. The upper edges of the waterproofing must be pressed against the soil with stones or covered with earth.
Formwork creation and reinforcement installation
Opalbum from pipes for a columnar foundation
In the finished wells, the formwork of their asbestos or metal pipes (fixed) or boards (removable) is installed. Then, reinforcement with a diameter of 10–14 mm (at least 4 pcs.) Is inserted into each foundation pit. Horizontal lintels are made from thinner rods of 6 mm.
Installation of reinforcement in wells for pillars
All posts must be installed in such a way that the grillage turns out to be strictly horizontal. To do this, select the starting point and then use the level to mark the height of each support.
Concrete pouring and grillage
Installation of formwork for grillage
For the construction of columnar foundations, concrete M200 can be used. Filling is done in layers of 20-30 cm, each area is carefully compacted. The concrete is poured without interruption to prevent the formation of transverse seams. After the pillars have dried, the grillage is installed. For its manufacture, a horizontal formwork is installed on top of the pillars along the entire perimeter of the foundation. Then the reinforcement frame is laid and concrete is poured. The standard dimensions of the grillage are 2.5–2.5 m (width and height).
Video: pouring a columnar foundation with concrete
A columnar foundation is one of the simplest and most economical solutions for frame structures, which is quite feasible to implement on your own. Use our advice and good luck with your work!
Main advantages:
- Reliability, strength, durability, long service life;
- A versatile material suitable for any type of construction, on any landscape;
- Cost savings - considered one of the cheapest;
- No large preparatory work, waterproofing is minimal;
- Installation can be carried out by one person;
- The speed of work.
Columnar foundations are economically justified - much cheaper than strip foundations. But the geological features of the soil should allow it to be set.
- it is impossible to make a cellar, or a basement;
- only suitable for simple, light structures.
Foundation types
Before starting to build a columnar foundation for a frame house, we decide on the material for the pillars: bricks, wood, concrete, stone, flagstone. The choice depends on the budget of the construction site and the type of construction:
- Lightweight structures on the frame;
- Buildings with 1-2 floors;
- Outbuildings, sauna, terrace.
Wood is a durable, but capricious material, it needs to be burned and treated with antiseptics from decay. The tree requires additional application waterproofing materials.
- The main types of columnar foundation
A monolithic columnar foundation has maximum compressive strength, and with a reinforced base it has maximum tensile strength. The best foundation material, therefore popular. It is durable, durable and easy to install.
Brick is considered one of the most affordable and durable. Unlike wood, it is stable, has the simplest technology, and will last about a century. This type can be used to build a two-story building.
Among the disadvantages of a brick base are high labor costs, earthworks, poor resistance to moving soil. As a result: displacement of the structure. The main disadvantage: a special burnt brick is needed for masonry, which is expensive. Minimum size brick pillars - 500x500 mm.
The foundation is also made of limestone and rubble stones. The minimum size of the posts is 600x600 mm.
A column foundation with a grillage is created to evenly distribute the load. An even distribution of efforts by a grillage is the basis of construction.
We carry out calculations
The calculation of the columnar foundation can be performed independently under the supervision of specialists. We take into account the type of house, the weight of the structure and materials. We take into account the waste on the grillage for bundling materials and the correct distribution of loads. The technology ensures the safety and reliability of the frame.
There are 2 types of depth:
- Shallow deepening (40-70 cm) - used on the territory of rocky, sandy soil with low groundwater.
- Recessed (below half a meter - the depth of soil freezing) - it can be installed at a depth of up to 2 meters, below the groundwater level. Applied on clayey soil saturated with water.
The exact calculation of the pillar parameters depends on the characteristics of the soil and the construction features, but a reliable support foundation cannot be less than 500x500 mm. If the starting material is flagstone or stone, we make a foundation of at least 600x600 mm. When drawing up the drawings, we take into account the loading - the wall between the columns. The zabirka protects the house from cold, rain and snow.
Phased construction of a reliable foundation
The first stage is the preparation of the site for construction. We do not just clean up the site (remove the debris, fill up the irregularities), but also do the backfill if the soil is clayey and wet. The second stage is marking: we fix the axis according to the drawings, control the angle and diagonal. Work on the ground can be done manually, as well as with an excavator. The main thing is to accurately position the pits along the axes.
- Digging holes for a columnar foundation
If the depth of the pillar is less than 1 m, then the strengthening of the walls is not needed, if it is more, we dig a pit with slopes, we put fortifications with board slopes. We make the pits wider than the pillars, since it is possible to install supports and formwork. We make a reinforced concrete pillow under the post to protect it from subsidence.
- Formwork
We arrange the formwork. We take boards 10-15 cm, 4 cm wide and about. Particleboard, plywood, iron sheets are suitable. If needed fixed formwork, we use pipes made of asbestos, concrete, iron, 100 mm wide.
We reinforce the columnar foundation with rods 10-15 cm longitudinally. We make wire horizontal bridges of 6 cm. The rods should rise 15 cm on the foundation to connect the grillage with the frame.
- Reinforcement
We pour concrete in layers of 20 cm. The finished mixture is rammed with a manual deep vibrator and waterproofing is performed. If the soil is wet, we make a double layer, for the rest - a single layer of roofing material.
We mount the grillage. We connect the lintels with scraps of reinforcement, cook mounting loops, mount the formwork and make a reinforcing base. We make a monolithic belt, or using reinforced concrete beams. After the concrete is poured, we take a break so that it settles and becomes strong, acquires its main characteristics, then we make waterproofing and fill the hole.
A concrete columnar foundation made of blocks is another popular option.
Block foundation
The main advantage is ease of assembly: the base is made of crushed stone, a sand cushion is poured, blocks are placed and tied with a cement mortar. There are limitations when choosing blocks:
- Do not use on horizontal soil prone to mobility;
- Not used to construct large buildings;
- Do not use on a weakly bearing surface - peat, water-permeable.
During the selection, we fix concrete blocks with a rigid reinforced concrete grillage, which makes the construction process expensive, and if we take into account the plinth plating, it is even laborious and complicated
If we are planning a pipe with pushed foundation, then we make holes in the ground, ram the base, insert the pillars and sprinkle on the outside. Next, pour concrete by a third, raise the pipe and fill it again, leave 15 centimeters at the top unfilled. We ram the concrete and install a reinforcement rod in the center, leave it for grasping, immerse metal anchors into the left cavity to tie the foundation to the wall, then we concrete it to the end.
Calculation of the cost of building a foundation
The main elements for the construction of a columnar foundation do not differ from the tape option: concrete, reinforcement, sand, gravel and waterproofing are required. For the construction of industrial facilities, a special reinforced concrete foundation made by professionals is used. All types differ only in construction technology. The cost of materials differs across the country and below are the average figures:
Cost of materials:
- Heavy concrete of class B15-B20 - from 800 to 1500 rubles per cubic meter. m.
- River sand - from 80 to 200 rubles per ton
- Expanded clay - from 800 to 1000 rubles per ton
- Glass type of industrial columnar foundations - costs from 1000 rubles apiece. It all depends on the purpose, state and class
- Fittings with a diameter of 6 - 14 class A400 from 10 to 15 thousand rubles per ton
- Cement 50 - 100 rubles a bag.
Cost of work:
- Digging soil - 250 rubles cubic meter
- Installation of a monolithic foundation - 2700 - 4000 rubles per cubic meter. m.
- Waterproofing of a columnar foundation - 40 - 60 rubles per square meter
- Automobile crane (rent for assembling the main parts and supplying concrete) - from 3000 rubles per day
- Rent of equipment for the delivery of elements and materials - from 270 rubles per hour.
How to avoid mistakes during construction
During construction, it is important to ensure the operation of all pillars at the same time by distributing the load using a grillage. A professional design engineer will be required to draw up the correct project based on engineering and geological calculations. The project is the drawings and bill of materials.
The main mistakes in the construction and design of columnar foundations:
- Incorrect assessment of the geological features of the soil. If during the design it was not taken into account that the soil can freeze and settle, then this will lead to cracks in the grillage;
- Poor quality concreting. For concrete to set the main characteristics and strength, it must be kept for almost a month and moistened on hot days;
- Excessive savings in materials. To save money, the wrong grade of concrete was used during construction. Savings can lead to collapse and high slump;
- During the device, the engineers did not take into account the differences in the relief (during construction on the slope) and did not withstand the depth;
- The main documents - the Project and the Work Agreement - were not viewed - with their help it is easy to control the correctness of the work, the savings in materials, the deadline.
The foundation of the columnar type is most suitable for the construction of small and light buildings - garden or country houses, outbuildings, utility blocks, etc. This type of foundation is most suitable for self-erection and saving construction costs, because compared to a strip foundation, columnar supports are several times cheaper. The advantage of this design is that there is no need to rent special equipment for carrying out earthworks... Meanwhile, it even requires much more labor and financial investments... Also, columnar pile foundation can be equipped on any type of soil, including rocky, highly damp or weak.
Concrete, as in the case of mortar for brick supports, must gain strength within 2-3 weeks before the grillage and walls can be built on the posts. A pure concrete support is poured into the formwork installed in the well and pre-reinforced. On difficult ground or for a heavy building, the support is equipped with a widening - a concrete "sole" or "heel".
Advantages and disadvantages of columnar bases
Advantages:
- The cost of materials and construction is cheaper than MZLF or other types of foundations by 50-75%;
- Practical guidelines for the arrangement of a columnar foundation provide almost no excavation, with the exception of a few shallow wells;
- Everything construction works can be carried out by one person - without assistants and special equipment;
- In terms of time, the arrangement of the supports can be carried out separately: all the pillars do not have to be erected at the same time, and even one support can be built in parts;
- The columnar foundation puts much less pressure on the ground - the pressure occurs only at the points of deepening of the supports, and this property is actively used in areas with complex soil.
Disadvantages:
- The main disadvantage is that a basement cannot be made in the house;
- The columnar type of base can only be used for small and / or lightweight buildings;
- For a brick house, such a foundation can only be built when the pillars are deeply immersed - more than 1.5 meters. However, at such a depth of immersion, it is easier to lay a pile foundation from ready-made piles, since the piles can simply be driven into the soil, even the most moist or heaving, to any depth. Also safer on difficult terrain strip foundation, with the use of which it is possible to equip a basement in the house;
- It is not recommended to build houses from foam or aerated concrete on columnar supports, since it is lightweight aerated concrete does not withstand bending loads, and even in the first years, cracks and other deformations may appear on the walls of the house.
The main advantage that the do-it-yourself columnar foundation has step-by-step instructions and the technology for making supports are described above is the construction of housing on heaving soils, which is unacceptable for MZLF. Heaving forces act only on the heel of the support, which is much smaller in area than the sole of a concrete tape, and cannot affect shrinkage and other deformations building structure... An ideal columnar foundation is one in which the supports sink to a depth below the freezing point of the soil in the region.
To facilitate the immersion of poles to such a depth, TISE technology is often used, which consists in minimizing labor and financial costs. When using this environmentally friendly technology, columnar supports are built deep in the soil, and a monolithic concrete tape serves as a grillage, which is built according to the technology of erecting a conventional strip base, and has only one difference: all construction operations are carried out not in a trench, but on the ground. Such an original approach to solving the problem with a reliable foundation provides the required protection against the effects of heaving.
But also when using TISE technologies the properties and characteristics of the soil on the site are taken into account: if the relief has significant differences in height (≥ 1.5-2 meters), then the columnar base is considered ineffective and unreliable even for light buildings, since the stability of the building as a whole decreases.
Calculation of columnar foundations
Of course, it is better to entrust design work to specialists. But perform calculations, for example, for the construction of a light building on summer cottage, it is quite possible and independently.
But for this you need to know several important data:
- the average depth of soil freezing in the climatic zone in which construction is planned;
- hydrological situation: groundwater level and the likelihood of flood or seasonal fluctuations;
- climatic features of the region and, above all, the amount of winter precipitation, which creates an additional load on the structure of the house;
The results will depend on:
- at what depth should the supports be laid - it should be borne in mind that it is preferable to place the lower edge below the freezing level, and the pillars should rise above the surface to a height of 0.2-0.5 m;
- the size of the section, which is also determined by the material selected for construction;
- the number of supports and the distance between them. It is imperative that the pillars be arranged under each corner joint. load-bearing walls: external and internal, as well as under the structures of the house, the length of which exceeds 3-4 m. Under the terraces, stoves, porch, local supports should be installed, which are independent of the main structure, that is, they are not combined with them by one grillage.
Step-by-step instructions for the construction of a columnar foundation updated: February 26, 2018 by: zoomfund
In the family of point-bearing foundations, the columnar structure looks like a black sheep. Unlike pile-screw schemes or options on bored piles, a columnar foundation cannot ensure the stability of a building on a slope or on decrepit peat soil. Even the most desperate heads of amateur housing construction do not try to install columnar structures on a swamp or heaving foundation.
How to install a columnar foundation
But in fact, the columnar version has two remarkable features. The construction of a columnar foundation with your own hands is available even for beginners in construction, and the cost is about half the estimate for a shallow tape. If you have a need to build a hut on a sandy area, near a pine forest or on solid limestone soils, the easiest way is to solve the problem of arranging the foundation in one of the following ways:
From the above list, the first two options will require the use of construction equipment and material handling equipment; a brick scheme requires the skill of a bricklayer. The last method from the above list requires only time and a little patience in doing it yourself and following the recommendations of the practical guide.
Important! The cast columnar foundation can be safely called universal, if there is drainage and drainage on the site, it can be installed even on small slopes without the need for a grader to level the horizon on the site plan.
In fact, a columnar foundation is the best option bases for building a small summer kitchen, gazebo or bathhouse in a suburban area with your own hands. For large and heavy buildings, the columnar foundation is weak and dangerous.
How to make a columnar foundation with your own hands quickly and easily
Casting concrete columnar structures will require a long and rather messy work with mixing cement mortar, installing and strengthening the column formwork, leveling and cleaning the working surfaces. You can go the simpler way and buy ready-made blocks 40 cm long and 20x20 cm cross-section. foam concrete block structural grade D1200 or heavy claydite-concrete grades.
For heavier versions of the house, granite blocks can be made. For this, the blocks are cast on a manual machine for pressing a cinder block filled with heavy rock. Such a block will be able to withstand a load of 300-400 kg, which corresponds to the weight of the walls of a log house. If you have experience with your own hands with laying stone on cement mortar, then you can build 6-8 columnar supports in half a work shift.
In addition to standard rectangular blocks, hollow massive blocks in the form of a truncated pyramid with a reinforcing frame are cast on the machine. A pin or threaded rod is placed in the upper base of the pyramidal columnar support, allowing the installed posts to be tied with a wooden beam or steel profile. It is enough to tamp and fill the horizontal platform in order to install a ready-made foundation field made of columnar supports along the stretched cords.
Column foundation do it yourself step by step instructions
Casting foundation supports from cement is no more difficult than working with a shallow tape, but at the same time the volume of concrete and earthworks is three times less. Most of the time is spent on the first self-made columnar support. From practice, it turns out that the next two columnar supports take the same amount of time as the previous one. The entire technology for arranging a columnar foundation is reduced to five simple operations:
- Preparation of the cushion and foundation pit at the site of the marking of the columnar support;
- Assembling the formwork to be poured with concrete;
- Installation of reinforcement in the formwork and pouring the form with concrete;
- Assembly and strapping of the foundation.
Advice! It will take at least three days and three to four sets of split formwork to make the foundation field. If we proceed from the calculation that it will take three days for one columnar support to cure the concrete, then in a week you can make a columnar foundation of 8 supports with your own hands.
The best option for arranging the soles of the columnar block
The most serious problem of columnar foundations is not the weak bearing capacity of the supports, but their tendency to overturn when the lateral component of the load increases. Strong wind and uneven subsidence of the foundation, when some supports are immersed in the ground, and others are torn off by beams from the pillow, leads to a roll and overturn of the foundation pillars, as in the photo.
Therefore, when preparing a pillow for a columnar foundation, it is necessary to pay attention to the presence of reinforcement in the form of a bed of gravel and soil. For columnar supports installed on the surface or on a slight depression, it is recommended to strengthen the base by expanding the support spot or use fungal types of columns. In the latter case, the foundation structure can be made in the form of two independent elements: in the form of a round concreted platform, buried 10-15 cm in the ground, and a vertical support of a circular or rectangular section, connected to the platform by one reinforcing cage.
In any case, to install the supports of the columnar foundation, you will need to dig a pit to the immersion depth plus 20 cm of sand and gravel cushion and 20-25 cm of a layer of coarse rubble or crushed stone material. The filling mass is placed on the bottom of the excavation in layers of no more than 10 cm, with each layer tamped with a hand or electric tool.
It is clear that for the manufacture of supports, formwork boxes of exactly the same size are most often used. This makes it possible to obtain the supports of the columnar foundation of the same height, but only under one condition - if in all the pits the crushed stone pillow has the same height. Therefore, it would be correct to proceed as follows:
- Open the required number of mini-pits for the foundation supports, cut and level the walls so that the earth and fertile layer did not hit the gravel pad;
- Drive the reinforcement rod into the center of the bottom part of the pit of the future column, align it along the stretched foundation marking cords;
- Pour the gravel-sand mixture of the pad with compaction of the mass. Sealing the pad must be done with the utmost care, the main thing is not to allow displacement or deflection of the centering rod. We constantly check the height of the pillow by the distance from the cord to the plane of the filling along the clogged piece of reinforcement.
Installation of formwork and reinforcing frame
To obtain a homogeneous defect-free concrete casting, it will be necessary to make a collapsible reusable box-shaped or tubular formwork. The inner surface of such a box is pasted over with plastic wrap, or materials with a laminated surface are used. Thus, a support with smooth and even walls is obtained. In addition, the inner coating of the formwork significantly reduces swelling. wooden structure and helps to preserve the original shape of the foundation pillars.
Before installing the formwork, it is recommended to tighten the dimensional cords, along which you can align and fix the wooden frame of the mold with a minimum error. In addition to the horizontal supports of the walls, it will be necessary to install additional fixing wedges to prevent the formwork from floating up under the influence of concrete pressure on the lower part of the wooden form.
At the next stage, a reinforcing frame is installed inside the wooden form, welded from 4 or 6 rods with a diameter of 8-10 mm, photo. Like the formwork, the reinforcement is leveled inside the mold and fixed in a vertical position, after which you can proceed to pouring concrete mix inside the support.
Leveling and pouring concrete
The filling of the formwork with concrete must be carried out as carefully as possible in order to prevent displacement of the installed support elements. Long-length foundation columns are poured in several portions, with "punching" each layer inside the support with a vibrator or manual ramming for 10-15 minutes. In total, it will take 35-40 minutes to fill out one support form. In the concrete surface of the upper part of the post, 2-4 pins are embedded, allowing in the future to fix the strapping bar on the concrete surface of the support. The poured formwork is covered with a plastic bag to reduce moisture loss and prevent rainwater from eroding the concrete foundation.
Important! If you made the formwork box high, but not rigid and strong enough, especially in the central or bottom part, in this case a situation may arise when the concrete mass crushes and expands the lower part of the foundation form.
The result is not rectangular shape supports, but barrel-shaped. Everything would be fine, but the volume of the form at the same time increases, and the level of concrete falls, which means that the height of the foundation pillar will decrease. Therefore, the formwork must be poured several millimeters above the calculated one. After about a couple of hours, the surface can be sprinkled with wet sand to reduce cracking and shrinkage of the foundation columns.
After the concrete mass has set, the formwork is disassembled and removed, after which that part of the support surface that will be under the soil layer must be treated with a waterproofing bitumen coating. After 7-8 hours, the space around the columnar base can be covered with layers of a mixture of gravel, expanded clay and sand.
Conclusion
No matter how hard you try, a columnar base does not have a perfectly flat and horizontal top surface. After about a couple of days, until the concrete has the design strength, the plane of each support must be cut with a grinder or grinder along the horizon and height. Before starting the strapping of the support of the columnar foundation, treat it with mastic and lay roll waterproofing. Next, you can lay a wooden beam and knit it with the supports of a columnar foundation, but the construction of walls and further construction is allowed no earlier than in a month.
We will send the material to you by e-mail
D wooden and panel houses make noticeably less requirements for the foundation (base) than brick, stone, block or concrete. This is due to the lower weight of the structure, which also reduces the load on the ground. If you decide to make a columnar foundation with your own hands, the step-by-step instructions that you will find in this article will help you correctly determine the procedure and calculate the cost of materials and work.
Columnar base example
The main advantage of this type of base is its low cost. After all, there is no need to dig a deep long ditch around the entire perimeter of the house, which is done when building a normal strip base. You also do not have to fill in a huge thick concrete pad, as they do for a slab base. The columnar foundation is a heavily trimmed version of the strip base, so all the advantages and disadvantages of the parent are fully inherent in it. The advantages of a columnar base include:
- low cost even at maximum depth;
- high resistance to soil heaving;
- ease of installation (no powerful construction equipment required).
The disadvantages include:
- low resistance to ground movement;
- inability to use on swampy or mobile soils.
Types of columnar foundations
There are three main types of these bases:
- not buried;
- shallow;
- installed below the depth of soil freezing.
Shallow columnar foundation
This type of foundation is used in regions where positive winter temperatures and low rainfall are combined. They can also be used in other regions, but only for one-story frame houses. This is due to the lower load-bearing capacity.
Useful information! Most often, such a foundation is used for various wooden outbuildings.
Columnar unburied foundation
This type of foundation is tried on in the same way as non-deepened. The difference is that on this basis it is possible to build from a log or a bar, as well as frame structures with a height of 2-3 floors.
Foundation installed below the depth of soil freezing
This type of base has maximum strength and bearing capacity, and is also not affected by soil heaving. Therefore, it is used for any wooden houses and buildings.
Heaving of soil above the freezing depth
How is the columnar foundation
The columnar base consists of:
Pillow and reinforced concrete slab
A cushion of sand and crushed stone and a reinforced concrete base plate ensure that the weight of the building is evenly distributed over the ground. The smaller the slab area, the greater the pressure on the soil. When creating a pillow, it is imperative to use rasklinzovka - a special order of laying crushed stone, in which each upper layer is stacked with a material of a smaller fraction than it went to the lower one. If you don’t do the splitting or use only a sand cushion, then the pressure on the ground will become uneven and in some places the soil may sink. On hard soils, you can place the pipe for pouring the post directly on the crushed stone pad.
Pillar
The pillars are made from various materials. The most popular are brick, cinder block and reinforced concrete. According to their characteristics, they are the same, however, pouring a reinforced concrete pillar will require slightly less time than laying a block and even more so a brick. As formwork for concrete, wooden or plastic boxes, foam structures, asbestos pipes of large diameter are used. If you decide to make a columnar foundation from asbestos pipes with your own hands, the video will help you understand the basic principles of this work.
Video: reinforcement and concreting of asbestos-cement pipes
Grillage
A large distance between the posts (1.5–4.5 meters) reduces the cost and labor intensity of the work, but negatively affects the wall, leading to subsidence of individual sections. To avoid this, a grillage is mounted on the pillars - load-bearing beam increased rigidity, which provides support for the wall at the entire distance between the individual foundation elements. The grillage is made of reinforced concrete, wood or steel. The characteristics of the grillage and the maximum allowable distance depend on the material used. For wooden houses, these distances are equal:
Calculation of the foundation
The correct calculation of the foundation takes into account the following points:
- determination of the type of soil;
- determination of the depth of freezing;
- calculation of the depth of the base;
- choice of materials for the pillar;
- determination of the optimal distance between the posts (depending on the type of grillage).
Determination of soil type
For those who decide to build a columnar foundation with their own hands, step-by-step instructions begin with checking the soil, is it suitable for this type of foundation? This type of foundation should not be built on mountain slopes or any inclined surfaces because its horizontal stability is minimal. It is also undesirable to build it where the average annual rainfall is high or where swamps and rivers are located nearby. In such places, the soil is saturated with water to a depth of several meters, therefore it is unable to withstand such loads. In all other places, it is quite possible to build a house on such a basis.
Calculation of the depth of freezing and deepening of the foundation
Winter frosts lead to freezing of water that fills the ground. The lower the air temperature, the deeper the frost penetrates into the soil. The depth of freezing depends on the temperature outside, the structure of the soil and the level of groundwater. That's why shallow foundation they are used only in those regions where the winter temperature does not drop below minus 5 degrees. If you do not know what the freezing depth is in your area, use the table or contact the builders.
Useful information! After calculating the depth of freezing, add to it the thickness of the sand-crushed stone cushion (30–40 cm). The resulting value is the value of the foundation deepening.
