In the family of point-support foundations, the columnar structure looks like a black sheep. Unlike pile-screw schemes or variants 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 base.
How to install a column foundation
But in fact, the columnar version has two remarkable features. The construction of a columnar foundation with your own hands is available even to 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 site, near a pine forest or on hard limestone soils, the easiest way to solve the problem of arranging the foundation is in one of the following ways:
From the above list, the first two options will require the use of construction equipment and handling equipment, for a brick scheme, a bricklayer skill is needed. The last method from the listed list requires only time and a little patience in doing it yourself and following the recommendations of the practical guide.
Important! A cast columnar foundation can be safely called universal, if there is drainage and drainage on the site, it can be placed even on small slopes without the need for a grader to level the horizon on the site plan.
In fact, a columnar foundation is the best option for building a small do-it-yourself foundation. summer kitchen, gazebos or bathhouses on suburban area. 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 dirty work with mixing cement mortar, installing and strengthening columnar formwork, leveling and cleaning work surfaces. Can go over simple way and buy ready-made blocks with a length of 40 cm and a section of 20x20 cm. A foam concrete block of the D1200 structural grade or heavy expanded clay concrete grades are best suited.
For heavier house options, granite blocks can be made. To do this, the blocks are cast on a manual machine for pressing cinder blocks with a filler of heavy rock. Such a block can withstand a load of 300-400 kg, which corresponds to the weight of the walls log house. If you have experience with do-it-yourself work 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 are cast on the machine in the form of a truncated pyramid with a reinforcing frame. A pin or threaded pin is laid in the upper base of the pyramidal columnar support, which makes it possible to tie the installed columns with a wooden bar or steel profile. It is enough to tamp and pour out a horizontal platform in order to install a finished foundation field of columnar supports along the stretched cords.
Do-it-yourself column foundation 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 do-it-yourself columnar support. From practice, it turns out that the next two columnar supports take as much time as one previous one. The whole technology for arranging a columnar foundation comes down to five simple operations:
- Preparation of a pillow and a pit at the place of marking a columnar support;
- Assembling the formwork to be poured with concrete;
- Installation of reinforcement into the formwork and pouring the form with concrete;
- Assembly and binding of the foundation.
Advice! It will take at least three days and three or four sets of detachable formwork to make the foundation field. If we proceed from the calculation that for one columnar support it will take three days 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 sole of a columnar block
The most serious problem of columnar foundations is not the weak bearing capacity of the supports, but their tendency to tip over when the lateral component of the load increases. Strong wind and uneven subsidence of the foundation, when some supports sink into the ground, while others are torn off by beams from the pillow, leads to a heel and overturning 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 gravel, soil. For columnar supports installed on the surface or in a slight recess, it is recommended to reinforce the base by expanding the support spot or using 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 concrete pad, buried 10-15 cm into the ground, and a vertical support of a round or rectangular section, connected to the pad by one reinforcing cage.
In any case, to install the supports of the columnar foundation, it will be necessary to dig a pit to a depth of immersion plus 20 cm of sand and gravel cushion and 20-25 cm of a layer of large rubble or crushed stone material. The dumping mass is laid on the bottom of the pit in layers of no more than 10 cm, with each layer compacted with a hand or electric tool.
It is clear that for the manufacture of supports, formwork boxes of the same size are most often used. This allows you to get the pillars of the column foundation of the same height, but only under one condition - if the crushed stone pillow has the same height in all the pits. So the correct thing to do would be:
- open required amount mini-pits for foundation supports, cut and level the walls so that the earth and the fertile layer do not fall on the gravel pad;
- Drive a reinforcement bar into the center of the bottom part of the excavation of the future column, align it with the stretched marking cords of the foundation;
- Pour the gravel-sand mixture of the pillow with the tamper of the mass. Sealing the cushion must be done with the utmost care, the main thing is to prevent 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 cage
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 glued with a plastic film, or materials with a laminated surface are used. Thus, a support with smooth and even walls is obtained. In addition, the internal coating of the formwork significantly reduces swelling. wooden structure and contributes to the preservation of the original shape of the foundation pillars.
Before installing the formwork, it is recommended to stretch the dimensional cords, along which you can align and fix the wooden frame of the form with a minimum error. In addition to the horizontal supports of the walls, it will be necessary to install additional fixing wedges that prevent the formwork from floating under the influence of concrete pressure on the lower part of the wooden form.
At the next stage, a reinforcing frame is installed inside the wooden form, welded from 4 or 6 rods with a diameter of 8-10 mm, photo. Like the formwork, the reinforcement is leveled inside the mold and fixed in a vertical position, after which it is possible to proceed to pouring the concrete mix inside the support.
Leveling and pouring concrete
Filling the formwork with concrete must be carried out as carefully as possible to prevent displacement of the installed support elements. The long columns of the foundation are poured in several portions, with the "punching" of each layer inside the support with a vibrator or manual rammer for 10-15 minutes. In total, it will take 35-40 minutes to fill out one support form. 2-4 studs are embedded in the concrete surface of the upper part of the post, allowing you to further fix the strapping beam on concrete surface supports. The poured formwork is covered with a plastic bag to reduce moisture loss and prevent rainwater from washing out the foundation concrete.
Important! If you have made the formwork box high, but not rigid enough and strong enough, especially in the central or bottom part, then 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 increases, and the level of concrete falls, which means that the height of the foundation column will decrease. Therefore, the shape of the formwork has to be poured a few millimeters higher than 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 bituminous 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 upper surface. After about a couple of days, until the concrete is of design strength, the plane of each support must be cut with a grinder or grinder along the horizon and height. Before starting the tying of the support of the columnar foundation, treat it with mastic and lay the rolled waterproofing. Then you can lay a wooden beam and knit it with the supports of the columnar foundation, but the erection of walls and further construction is allowed no earlier than a month later.
At first glance, it may seem that building a columnar foundation for a house with your own hands is an almost impossible task. However, this statement is not true.
Features of the column foundation
Initially, you need to understand the definition of a columnar foundation. To put it simply, it is a complex of supports that carry the weight of the structure under construction. Racks are installed in places maximum load- these are the corner points of the building, the connection points of the walls and spans longer than 2.5 meters.
The distance between the racks, as well as the shape of the pillars, are calculated values \u200b\u200bdepending on a number of factors:
- type of racks;
- material of manufacture;
- building structure;
- the planned mass of the structure;
The standard distance is 1.5 - 2.5 m, the cross-sectional diameter for round supports is from 20 to 25 cm. The size for rectangular supports is from 25 by 25 to 40 by 40 cm. It is desirable that the ground part be at least 50 cm in height, length underground part depends on the depth of the bookmark.
The top points of the supports should be at the same level, which must be carefully checked after installing the racks and adjusted if necessary.
Disadvantages and advantages
Before building a columnar foundation with your own hands for frame house, you need to understand in which cases its use is suitable and in which it does not make sense, as well as its pros and cons.
Flaws:
- it is impossible to equip the basement of the future house;
- can not be used on floating and water-saturated soils
Advantages:
- quick drying and;
- insignificant costs;
- construction in any season;
- separate installation of each support;
- ease of installation;
- affordable replacement and repair.
Types of columnar foundations
There are different foundations depending on the parameters, the shape of the supports in the section, the materials and processes for the production of pillars and the depth of laying the foundation. In the context of the rack are round, square, rectangular. It is possible to make supports in a monolithic form of concrete, or in a prefabricated form of bricks, blocks, buta.
The classification by bookmark depth is as follows:
- for heaving soil, buried pillars are laid below the freezing point;
- for non-rocky and low-rock soils with a sandy-gravel air embankment, shallow racks are used with a laying of up to 70% of the freezing point of the soil;
- for non-buried soils with low or non-rocky soils using a dense sand cushion.
Base device
In order to competently build a columnar foundation with your own hands for a frame house, it is important to clearly understand the device and the process of its construction.
Ground work
- To start work, it is necessary to prepare the site for the construction of the foundation.
- Complete removal of debris and removal of sod by about 15-20 cm.
- Leveling the surface of the earth.
- Marking the site with pegs according to the plan. The pegs are installed at the corner points of the future foundation, connected with a cord, after which the marking accuracy is checked along the perimeter.
- The marking of the installation points of the pillars is carried out.
- Digging holes.
Support device
1. brick supports . Separate situations make it possible to make support posts from bricks, which is advisable to do on stable soils and in places of deep occurrence ground water.
Laying is possible in two ways:
- laying on a pillow of sand;
- the construction of a concrete shoe, then the laying of bricks on a hardened base.
Most often, supports are prepared 25 by 25 cm (a row of 2 bricks). If you plan to build a large building, then you can lay 4 bricks - 38 by 38 cm with additional installation of reinforcement inside the column.
It is important to observe the exclusively vertical position of the supports with regular checks with a plumb or level.
2. Block . An alternative option is wall or shoe (pillow) rectangular concrete blocks measuring 20 by 20 by 40 cm. The second ones should be mounted on top of a sand cushion at the base of the supports, the shape of the racks is trapezoidal. Most often erected as shallow or shallow supports.
3. Monolithic . Such supports are made by pouring concrete mortar into a pre-installed formwork, round or rectangular in cross section, additionally reinforced with steel rods.
4. Rectangular supports . The formwork for such supports is constructed from plywood or edged boards. If the construction takes place on stable ground, then the formwork is created naturally from the walls of the recesses. Before pouring the solution, it is necessary to cover the walls of the pit with waterproofing material.
When mounting racks in loose soils, it is necessary to erect formwork along the entire height of the future pillar, the recesses are dug out in such a way that it can be installed and fixed without problems.
5. Round poles . It is allowed to erect supports round in section. For manufacturing, wells are drilled 20 - 25 cm in diameter. The construction technology coincides with the manufacture of rectangular supports, roofing material, plastic or asbestos pipes serve instead of formwork.
In some cases, TISE technology is acceptable when specialized drills are used with a plow for wells with an extension at the bottom in order to increase the footprint.
6. Combined supports. In some cases, a do-it-yourself columnar foundation for a frame house is built not from one material, but from two. For example, first, the buried part of the support is concreted, after which the ground part is erected, but already with the use of bricks.
formwork
Before the formwork is erected for both installation options, it is necessary to create a bed of a mixture of sand and gravel 30 - 50 cm high for shallow and non-embedded props and 10 - 20 cm for buried props.
Formwork is mounted strictly vertically on the pillow, fixed with stops. Inside the walls are covered with waterproofing.
Supports can be of uniform thickness along the entire length or with a thickened bottom - a “shoe”. In this case, the width of the pit for the support must correspond to its dimensions. The "shoe" can be installed separately with the release of reinforcement from it, after its hardening, the formwork of the support is installed from above.
Four ribbed reinforcing bars with a diameter of 10 - 12 mm make up the frame, connected by clamps 6 - 10 mm in diameter from ribbed or smooth reinforcement. The distance between the reinforcement and the formwork is more than 3 mm, the same gap from the cushion in order to corrosion protection metal. You can ensure the distance by means of plastic supports, which will also prevent the reinforcement from moving.
When erecting supports with a "shoe", the rods are installed before mounting the formwork.
If a grillage is not planned, then the upper end point of the reinforcement is 5 - 6 cm down relative to the level of pouring the mortar. Installation of embedded studs with a diameter of 14 - 16 mm is envisaged for connecting the supports with the bottom trim.
For foundations where the grillage is planned to be erected, the frame protrudes 15-25 cm above the fill level in order to link it with the frame of the latter.
Next, a concrete solution is poured, made independently or purchased with a brand of at least . Portion pouring with tamping with a vibrator or other means. Removal of the formwork is permissible after the final hardening.
Grillage
You can install a grillage, you can do without its construction. This is a one-piece cast concrete structure, which serves to ensure uniformity of the load on the supports. The lower surface of a high grillage is located at a distance of 10 - 20 cm from the soil surface, a low one is laid on a sand and gravel pillow buried 15 - 10 cm deep in the ground.
Formwork for grillage
To install a hanging grillage, it is necessary to build a formwork. Two installation methods are allowed here: place the bottom at the level of the supports' heads, or build it to its full length to the ground level, and then fill the space between the soil and the grillage with sand. The formwork must be closed with waterproofing.
The height of the formwork is important, its top should end flush with the level of pouring the concrete mortar, or exceed it by 5–6 cm. , and width from 25 to 40 cm.
Reinforcement
The frame is made up of 1 - 2 rows of longitudinally located reinforcement, which is connected by transverse rods or clamps. The connection is made with a soft wire. The gap between the frame and the formwork is not less than 3 - 5 cm, the same rule applies to the upper surface of the grillage.
The reinforcement must be linked to the releases of the reinforcing cages of the supports. If the length of the reinforcement bars of the supports exceeds the height of the grillage, they must be bent at the highest points of the grillage surface at 90 °.
Mortgages for blowers are mounted at the stage of fixing the formwork together with studs for fixing the bottom trim. The diameter of the latter is 14 - 16 mm, and they are placed strictly parallel to the supports along the line where the lower trim beam is located.
Concrete grillage
Concrete is poured carefully, with full coverage of the reinforcement and without the formation of cavities. It is recommended to use tools for compacting the solution. At the end of the pouring process, it is necessary to level the top layer so that the surface is even over the entire area. The formwork can only be removed after the concrete has completely hardened.
Use of waterproofing
For those parts that are the above-ground component of the supports, waterproofing is necessary, as they are vulnerable to environmental influences and the weight of the building. In order to protect against external sources of moisture (rain, snow), wind, physical and chemical effects, roofing material or solutions designed for such tasks can be used.
Conclusion
In general, it is obvious that a do-it-yourself columnar foundation for a frame house is a completely feasible task. In addition, the installation of such a foundation makes it possible to build a truly reliable foundation for the future home.
Only a professional builder can design and implement a support-column foundation according to the recommendations of SP 50.100, 22.13330, 32.13330, 45.13330, 27.13330. These grounds are too unreliable; the results of geological surveys should be studied in as much detail as possible.
The technology of the grillage on the pillars depends on the construction technology of the building for which the foundation is being built. Columnar bases are made of structural materials:
- reinforced concrete - pouring into the formwork in place, installation of the finished product in a glass 1F or 2F;
- tree - logs with a widening sole;
- brick - clinker, full-bodied ceramics;
- blocks - wall, only with dense fillers, hollow;
- rubble concrete - a stone is introduced into the formwork after partial filling with ready-mixed concrete.
In addition to the tape grillage, it can be used slab construction. This is the only option for a columnar foundation suitable for a brick cottage on sandy soils with a groundwater level (GWL) below 1 m. In all other cases, columnar foundations are created for log cabins, half-timbered houses, buildings from SIP panels, panel, frame buildings.
Types of columnar foundations according to the depth of laying
Depending on the geological characteristics in the building spot, wall materials, columnar foundations are:
- buried - below the freezing mark, GWL, but may not reach the bearing layer;
- shallow - 40 - 70 cm below ground level;
- not deepened - instead of the removed fertile layer, non-metallic material is filled up, the underground part is absent.
The height of the pillars above the zero mark depends on the design of the grillage and the technological solutions used in the project. The head is embedded in a monolithic grillage by 20 cm, the beams of the prefabricated grillage are installed on top of the piles. Therefore, the height above the surface is always individual. The construction of buried pillars is justified if there is a bearing layer at this mark. A shallow foundation of this type is stabilized by soil against lateral shear. Unburied has a minimum construction budget.
Column foundation design
The fundamental difference between columnar foundations and piles is the occurrence of the sole, as a rule, above the freezing mark, the level of groundwater level, layers with a bearing capacity. Therefore, in any case, the supporting-columnar foundation is protected from heaving forces and movements in several ways:
- sand cushion under the base plate, if the base of the foundation is located below the freezing depth, a sand cushion is not required;
- draining the soil with a drainage system;
- insulation of the blind area and basement.
For the last two activities, open excavation is required in the building spot.
Even with a slight deepening of the pillar itself, it will be necessary to take into account the thickness of the broadening (20 - 40 cm plate), the underlying layer (pillow of 20 cm sand + 20 cm crushed stone). In addition, you will need an annular ditch for laying drains, access for workers to the lower level. Therefore, the size of the well and trench increases several times, it is inconvenient to work from the ground at a depth.
The manufacture of columnar foundations, by analogy with bored piles, is a gross violation of technology. The sole is difficult to widen, there are heaving forces under it. The tangential forces of the same processes act on the side walls without backfilling with sand.
Thus, the correct design of the columnar foundation is:
- preparation - sand (layer thickness 20-40 cm) with layer-by-layer compaction with a vibrating plate, pouring;
- footing - serves exclusively for laying waterproofing, is a 5 cm screed;
- stepped plate (sole) - distributes the load due to the increased surface of the sole;
- column - a vertical stand made of monolithic or prefabricated concrete;
- grillage - reinforced concrete products, monolithic structure, timber or rolled metal (channel, I-beam).
Unlike piles, pillars do not have spatial rigidity, therefore grillage beams must not only rest on their heads, but be attached to each pillar for tying into a single structure.
Step-by-step instruction
Due to the variety of operations for the construction of the grillage on the pillars step-by-step instruction necessary for an individual developer as a benefit. If you skip a stage, you will have to redo the work later or return to it, spending more effort and money.
For example, the instruction recommends laying drains at the excavation stage. If you forget about them at the beginning, remember when landscaping the territory, the trenches will have to be dug again, the construction will be delayed, the site will again be clogged with soil. The height of the pillars is selected 20 cm above the bottom of the grillage for immuring in concrete.
Below we will tell you how to make a columnar foundation correctly.
Geological surveys and calculation
The technology for constructing a columnar foundation depends on the results of geotechnical surveys, wall material, building technology. For example, it is forbidden to leave unloaded poles in the winter even when tied with a grillage.
Prefabricated loads (the weight of the building, residents, furniture, belongings, wind, snow loads) may not be enough to compensate for the extrusion forces, or the building will gradually sink into unstable ground with excess weight.
In contrast to the test screwing of screw piles in the technology of the same name to find the depth of the bearing layer, full-scale surveys are required here, costing at least 30 thousand rubles. The designer needs the following information:
- layered arrangement of layers;
- composition and characteristics of the top three layers;
- GWL level;
- freezing mark.
The cross section of the pillars should be more than 40 x 40 cm with concrete or brickwork, 20 x 20 cm or 20 cm in diameter for a monolithic reinforced structure.
Marking and earthworks
Unlike bored piles that reach the bearing layers, it is much more difficult to pour the pillars into the wells. The main problem will be the lack of sand backfilling of the sinuses:
- after a few years, the soil near the pile body will self-compact;
- pick up moisture, freeze in winter;
- heaving forces will pull out the pillar, like a carrot from a garden;
- in the presence of a lower broadening, the column will rise up by heaving forces, the soil will crumble under the sole;
- the plate will not allow you to pull out the entire column, but it will no longer be able to stand in place.
We dig holes for the widening of the columnar foundation.
Therefore, the only correct way would be to mark the trenches, taking into account the width of the sole, the drainage contour, and the work on the construction of the formwork. Instead of a square shaft of 40 x 40 cm, you will have to take out much more soil of 1 x 1 m at least. This takes into account the thickness of all layers of the foundation cake, the height of the groundwater level. If last feature just below a meter, you need to go deep by 0.6 m, no more.
Preparation
The construction of a monolithic foundation of a dwelling by default should provide protection against corrosion and destruction. In the absence of oxygen, the only aggressive environment underground remains moisture, which should be removed from the sole by drains, stopped at the surface concrete structures over the entire height with a waterproofing carpet.
Construction is carried out in stages:
- layered backfill - 20 cm of sand with moisture, vibrocompaction twice (total height 40 cm);
- footing - screed height 5 cm, no reinforcement;
- waterproofing - 2-3-layer carpet of rolled material on a fiberglass basis;
Reinforcement
The technology of the armo-belt device of a column with an expanded sole has the form:
- knitting a reinforcing mesh to the size of the slab, taking into account the side protective layers (40 mm from the formwork to the metal) with a cell of 15 x 15 cm or 20 x 20 cm with a thickness of 12 - 16 mm;
- docking to the grid of rods bent at a right angle 12 - 16 mm, protruding above the sole of the grillage by 20 - 30 cm (usually 4 pieces in the corners, one in the middle of each side);
- vertical bars are reinforced with horizontal square clamps from reinforcement 6 - 8 mm;
- the design is installed on a waterproofing carpet, which is produced beyond the dimensions of the sole by 10-15 cm, for subsequent bending onto the side edges of the sole.
It is forbidden to lift the reinforcing structure with metal scraps, bricks, crushed stone to provide a protective layer.
Post widening
The construction of the sole is the pouring of the slab into the formwork. The broadening area is twice the section of the column, the height of all elements is a multiple of 30 cm. The formwork is simple - four boards fastened with screws, corners or bars at the bottom of the pit, trench.
Reinforcement of broadening and column.
The sides of the formwork should be slightly above the design level in order to qualitatively level the surface of the concrete. Permissible error in horizontal plane is 1 cm. pouring is carried out after installation of the reinforcing structure.
formwork
We install and strengthen the formwork for the columnar foundation.
Drainage and waterproofing
From the perimeter of the building can be made at any stage, from the pit to the backfill. For the installation of drains, an annular trench is required with a single slope to the underground tank. Dornite or geotextiles are spread at the bottom, 10 cm of crushed stone are backfilled. Perforated pipes in the filter are laid in it, manholes are installed. After that, the communication is covered with another 10 cm of rubble, covered with the remains of geotextiles.
Waterproofing device - several technologies with different materials:
- impregnations - contain penetrating additives, change the molecular structure of concrete, making it waterproof throughout the depth;
- rolled materials - Bikrost, TechnoNIKOL and other analogues on a fiberglass basis, laid in two layers;
- coatings - mastics on an epoxy, bituminous basis;
- paints - enamels based on bitumen resins.
Most often, combined methods are used to achieve a 50-70 year resource. Roll, coating materials will have to be updated every 15 years.
Ready columnar foundation with reinforced concrete grillage.
backfilling
After the drainage device, a continuous waterproofing layer on the concrete surface, it is necessary to protect the side surfaces from heaving forces. The sinuses are covered with sand, compaction is necessary, since loose soils are extremely unstable. The chernozem of the fertile layer is saturated with organic matter, sits down after it rots. In the rest of the soils there is clay that swells in frost. Therefore, only non-metallic materials are used, in which heaving is less.
For light small buildings, a columnar foundation is being built. This is one of the cheapest types of foundation, which, in addition to minimal financial costs, does not require the involvement of specialists. It is easy to build with basic construction skills. How to make a columnar foundation with your own hands? More on this later, first consider what structures it is intended for.
Types of buildings
This type of foundation is established for the following buildings:
- gazebos;
- terraces;
- hozblokov;
- garden houses;
- summer kitchens;
- garages and other similar structures.
The pillar foundation is able to withstand even frame one-story houses. As for high-rise buildings or buildings made of heavy materials, it is not suitable for them.
Advantages and disadvantages
The advantages of a columnar foundation include ease of construction, no need to use special equipment. It is suitable for any type of soil, except for soil where groundwater is close. The construction of such a foundation does not require complex landscape work and high material costs. The advantages include the high speed of construction, as well as the strength of the structure.
The disadvantages are the inability to withstand heavy loads and the impossibility of creating a basement.
To build a pillar foundation with your own hands, you can use several different options building materials, which is also a nice plus. Among them it is worth highlighting:
- asbestos pipes - a convenient material, easy to use;
- brick - durable and strong, but expensive, has the difficulty of laying in a pit and is able to deform as a result of heaving soils;
- wood is an economical option, easy to install, but has a short service life and the need for a complex waterproofing system;
- reinforced concrete is strong and durable, but there are difficulties in the construction of the removable formwork required for the posts.
Thus, the columnar foundation is prefabricated and monolithic. Experts recommend giving preference to a monolithic basis. During its construction, reinforcement is necessarily used, which allows it to withstand heavy loads.
When using brick (prefabricated base type), repeated freezing and thawing of the soil will cause the posts to be pushed out. As a result, the seams will diverge, cracks and distortion will appear. Based on this, it is recommended to build a columnar foundation using asbestos pipes and reinforced concrete.
Calculations
When calculating the pillar foundation, such indicators as the type of soil, the depth of soil freezing, and the weight of the structure are taken as the basis. They affect the strength of the future building.
Depending on the type of soil on which it is planned to erect the structure, the design of the columns is selected. With the close placement of groundwater to the surface of the earth, additional measures are taken with the involvement of specialists. If the groundwater is deep, you can not undertake preliminary preparation, but safely proceed to the construction process.
A lot also depends on the level of freezing of the earth. The columns are deepened below it. If you do not follow this recommendation, the foundation will be deformed in winter during the frost period. Thus, if the level of soil freezing is at a depth of 1 meter, the pillars are buried by 1.2 or 1.5 meters.
The distance between the columns and their deepening also depends on the type of foundation and the weight of the future structure. Under normal conditions, a distance of 2 meters should be observed between them.
There is one more nuance. Columns must be installed on the most important nodes, which include external corners, junctions internal walls and various intersections. This will increase the strength of the entire structure. The average installation depth of pillars in places of important nodes is 1.5–2 meters, but this value may vary depending on the site.
Preparatory work
No matter what material is used, preparatory work provide almost the same actions. It is necessary to create a drawing diagram, which indicates the exact distance between the pillars, the shape of the base.
Before starting construction, it is necessary to prepare the area. Do-it-yourself marking of the columnar foundation is done using a rope and several pegs. A turf layer up to 30 cm thick is removed from the area of land allotted for construction. Thanks to this, it will be possible to make a pillow of crushed stone and sand for drainage and protection against vegetation germination. Then you need to dig the required number of holes, for which a hand drill is used.
It is also worth considering another nuance. The cross section of the pits is 10–15 cm larger than that of the columns themselves. This is done to provide space for various technological activities (bricklaying, waterproofing).
The use of asbestos pipes: instructions for the construction of the foundation
After the preparatory measures, it is worth starting the installation of the columns. Sand and gravel are poured into the pits, which are subsequently compacted. Then asbestos pipes are used, the diameter of which is from 20 cm. They are installed at the bottom of the dug holes. 2-3 metal rods are necessarily placed in each pipe. They are pressed tightly into the ground by 15 cm. Ribbed rods with a diameter of 12–14 cm are used. This will ensure reliable grip with concrete mix. Every 50 cm of reinforcement should be tied with wire.
You should also indicate the required wire length. When calculating, you need to take into account 20 cm of reinforcement, add the depth of the pit and provide an additional 20 cm (for connecting vertical rods with horizontal ones installed around the perimeter of the base). These activities are performed before pouring the columnar foundation with your own hands.
Then a concrete solution is poured inside the pipes, as well as around them.
Until the moment when he had time to grab, it is necessary to correct the evenness of the base with the help of the building level. During solidification, the columns should not be touched. When the concrete hardens, you can begin to create a horizontal component called grillage. For it, prefabricated concrete blocks or solid structures made of reinforcement and concrete, as well as contoured with a removable formwork (made of wood) are used.
Monolithic pillar foundation: instructions
This method of erecting a pillar foundation differs little from the previous version. The difference is that vertical formwork should be provided in dug pits.
They are removable type and burst between the walls. And only after that you can start making columns, for which a concrete solution is used. It is advisable to use cement grade not lower than M200. A mandatory requirement is the creation of reinforcement strapping inside the formwork. After that, the concrete solution is poured. It is necessary to remind once again that the length of the rods above the ground should be at least 20 cm.
When the concrete solution hardens, the formwork is knocked down, measures are taken to waterproof the supports. In this case, it is desirable to use roofing material, with the help of which the columns are wrapped in 2 or 3 layers.
As mentioned above, the second component of this type of foundation is the grillage. After the formwork is installed, the horizontal and vertical bars are tied together, then the concrete solution is poured. When the grillages harden, it is worth starting to create waterproofing using roofing material. Floor slabs are installed on top.
In the end, it is worth pointing out some of the nuances that you need to know before you make a do-it-yourself columnar foundation:
- to obtain a uniform consistency of the concrete solution and ensure greater structural strength, it is recommended to knead it in a concrete mixer;
- the foundation must be equipped with a fence that can provide protection from gusty winds and snow drifts under the structure (it is created from rubble stone or brick);
formwork is made of planed boards, the thickness of which is 3 cm or more.
A durable and inexpensive columnar foundation is usually built under buildings whose walls can be called lightweight - and these are wooden and panel baths, framed and made of foam blocks. But it happens that a zero level of this type is also laid under a heavy brick bath - when a deep foundation is needed and the strip foundation in this case can ruin. After all, columnar ones cost at least one and a half times cheaper than the last option, which, in fact, are good.
For a usually light and small bath massive strip foundations often akin to unnecessary luxury - but columnar is much more suitable for such construction: both in price and in strength. Yes, the traditional arrangement of a columnar foundation does not imply the presence of a basement - but the Russian steam room just does not need it.
Budget columnar foundation with grillage
If you build a columnar foundation with your own hands, then the first step is to make its exact calculation. Why is it necessary to calculate the mass of the bath, and here it is important to take into account its snow load - in the Moscow region it is about 100 kg for each square meter area. As well as the weight of the internal filling of the bath: furniture, stove and people - that is another 100 kg per meter.
By the way, if it is difficult to calculate the bearing capacity of the soil in a certain area, then it is better to proceed from this calculation: 0.5-0.6 kg per cm2. In fact, these are the parameters of a peat bog or an old drained swamp. In all other cases, things are much better.
Stage I. Making pits
The easiest way is to take a drill with a diameter of 25 cm and drill small holes in the ground with it - 15-20 cm. This will be the basis for making the lower part of the pillars. It is necessarily reinforced with a fine mesh and covered with sand concrete of the 200th grade.
In the central part of the pit, you need to insert several bars of reinforcement so that they peek out of the pit no more than 10 cm. These can be old and unnecessary pieces of pipes, pieces of iron and debris.
And so that the cement milk is not absorbed into the soil, pieces of roofing material or even ordinary plastic bags will help.
Stage II. Pole installation
A piece of asbestos-cement pipe is taken, with a diameter of 10 cm, two reinforcing bars with a diameter of 1.2 cm are placed in it, and all this is placed on the “shoe”. You need to fill it with the same sand concrete, simultaneously tamping everything with another rod. From above - either a bolt, or another piece of reinforcement.
Stage III. Second drilling
It takes about 4-5 days for the concrete to harden after the last steps. Next, you can start the second drilling. To do this, you need a drill - they make a hole with a diameter of 30 cm and always below the estimated freezing depth. In this opening, you need to quickly insert the resulting pillar - so that it does not crumble. Its strength can reach up to 11 tons of load.
Stage IV. Construction of a grillage
A grillage for such a columnar foundation can be made of metal, concrete and even wood - here is what anyone likes more. The main thing is only that the grillage itself hangs above the ground by more than 10 cm.
The main advantage of this type of foundation is that it is suitable for almost any baths that do not have a strong weight - log, timber and frame. And he serves for a long time - at least a hundred years, and even when he stands in a swamp.
Solid support-columnar foundation
Of course, the foundation pillars can be of very different materials - concrete, brick or stone. But the most popular today for individual construction is affordable and practical reinforced concrete.
So, this is how a standard columnar foundation for a bath is built:
Stage I. Site preparation
It all starts with cleaning the site - for this, the entire top layer of soil is cut off, right along with the plants. Its thickness is usually a little over 30 cm, and it cannot be left under the foundation.
If there is clay on the site, then you need to make additional gravel-sand bedding. Its thickness depends on the geological features of the soil.
Now all irregularities are removed on the landscape, soil is poured into the pits, and with the help of pegs and ropes, you can start marking for the future foundation.
Stage II. foundation plan
Further from the drawings to land plot you need to transfer the plan for the future bath - where and what will be. This can be done with standard materials, fixing the axes and noting the main dimensions of the future foundation. How accurately everything will be marked up - it will be so much easier to work later.
Stage III. Pit preparation
Pits for reinforced concrete columnar foundations are dug either manually or with the help of an excavator - which, of course, is both easier and more expensive. They will be located along the axes.
If the depth of the pit does not exceed a meter, its walls can not be strengthened. If more, you will have to dig with slopes and install fasteners from boards with special spacers.
The pits should turn out 30 cm more than the calculated depth of the foundation - so that gravel-sand bedding can be done. The width is taken a little more than it will be - so that the formwork and spacers become free.
Stage IV. Formwork installation
To make a good formwork for the columnar foundation of the bath, you will need planed boards up to 40 mm thick and 150 mm wide. Alternatively, chipboard, metal sheets and moisture-resistant plywood can be used instead of wood. You need to put the boards to the concrete.
Stage V. Foundation reinforcement
It is necessary to reinforce the foundation pillars in the longitudinal direction with A3 rods and a diameter of 12-14 mm. Horizontal jumpers should be placed in increments of 20 cm - a wire of 6 mm in diameter is quite suitable for this.
In order to later connect the pillars with the grillage through the reinforcing cage, it is necessary that the rods go out above the edge of the foundation by at least 10-15 cm. By the way, something more solid can also serve as a grillage - this is how the column-strip foundation is built, which has its advantages, but, however, not always justified for a bath.
Stage VI. Pouring foundation pillars
Concrete must be poured in installed pipes, which will then remain in the ground with a foundation.
It is necessary to lay it in layers - 20-30 cm each, using manual vibrators for the convenience of the process. This will ensure the homogeneity of the mixture and all the air will leave the solution.
Stage V. Waterproofing of the columnar foundation
You can protect the future foundation from moisture with the same materials as the tape one. These are mastics of cold and hot preparation, gluing membranes, roofing material on bitumen - and all new and well-proven materials.
Stage VI. Construction of a grillage
A monolithic belt makes both a solid and a columnar foundation made of blocks more rigid and stable. And you can make it from prefabricated reinforced concrete rand beams or immediately monolithic.
So, if a prefabricated belt is being made, then the jumpers must be well connected to each other with trimmings of reinforcement - welding them by welding with mounting loops. Further, the formwork, the reinforcing cage are already installed and everything is poured with concrete of the M200 brand.
As soon as the concrete hardens and becomes strong, and waterproofing is carried out, the sinuses of the pits can be covered with soil and the installation of floor slabs can begin.
By the way, in order to protect the underground space under such a bath from snow and cold air, a fence is usually made between the pillars - a special wall, most often made of brick. It is not necessary to tie it to the poles - after all, the bath will still settle, and so cracks may appear. And already in the pick-up itself, technological holes are made for communications. Outwardly, all this is beautifully decorated with false panels and siding - that's all.
