How to make a strip foundation with your own hands. Guide to self-pouring the foundation of the house

Description

Already on the basis of the name, it can be understood that this type of foundation will be somewhat reminiscent of a tape under the contour of the building.

Like other types of foundation, it can be:

• monolithic - poured entirely at once at the construction site;
• prefabricated - consist of individual prefabricated elements (foundation blocks and slabs, for small buildings - bricks, in mining sites -).

Specifications

It is a closed circuit for load-bearing and self-supporting walls of buildings and structures. The width of this tape is slightly larger than the planned wall thickness.

Must be buried in the ground with a sufficiently strong bearing capacity, because. transfers only the vertical load to the underlying soil, unlike, say, hanging piles, which provide the bearing capacity due to lateral friction forces.

Necessary building materials

In the case of a prefabricated type, the foundation elements themselves will be needed - foundation blocks and foundation pillows, as well as cement mortar to connect the fragments into a single object.

For a monolithic version, you will need. It can be removable or remain in the body of the foundation, further strengthening and waterproofing it. Well, actually for the foundation itself, reinforcement and concrete mixture are needed.

Advantages and disadvantages

Advantages:

• Allows you to arrange a basement in the building - the side surface of the foundation in this case will play the role of the basement walls.
• Relatively economical.
• Applicable for a variety of structures that have a complex shape in plan, different number of storeys, large and small loads.
• Allows you to make different depths of laying under walls with different loads, which saves materials.
• Requires less excavation compared to.

Flaws:

• Not suitable for heaving and weak soils.
• Relative pile and columnar are more material-intensive, labor-intensive, and more expensive.
• Unfavorable in conditions of great depth of soil freezing.

Stages of construction of a strip foundation

Step-by-step instruction

1. Before proceeding directly to work on the foundation, it is necessary to determine the depth of its foundation. To do this, it is important to clearly understand what will be the loads from the own weight of the building, the people and things located there.
2. In addition, it is necessary to analyze the soil at the construction site, because the bearing capacity depends on its type and other characteristics. A detailed laboratory study would be optimal, but if this is not possible, you should at least determine its type, density, and humidity. The methods of these studies are described in detail in regulatory documents; they do not require sophisticated equipment and special knowledge, i.e. under the power of almost everyone.
3. Next, earthworks begin - a fragment of a trench or pit is 30-50 cm deeper than the depth of the foundation. These centimeters will be occupied by a sand or sand and gravel cushion. Its role is to level the bottom of the pit, to give the foundation additional hydro and thermal insulation. The pillow should be well sealed.
4. Also, in some cases, concrete preparation or the so-called concrete preparation is poured over the pillow. "footing" of lean concrete (usually B -7.5) 10-15 cm thick.
5. If a prefabricated foundation is selected, then you can start laying the elements. A brick foundation can be laid out by hand, but heavy blocks and slabs require specialized equipment.
6. Between themselves, the components of the foundation are connected with a cement-sand mortar. For strong adhesion, it should not be made too liquid. For the strength of the connection, you can add another thin reinforcing mesh.
7. Blocks laid flat may be used instead.
8. The prefabricated strip foundation can be loaded after 1-2 days. However, in comparison with the similar one, it will have about a quarter less strength and will cost 30 percent more.
9. The device of a monolithic foundation begins with the installation of formwork. Already at this stage, it is necessary to take care of the holes for laying various communications. In the right places, sections of strong pipes of the required diameter are installed, filled with earth or sand, so that the solution does not subsequently flow there.
10. Next, the reinforcement cage is installed. Between themselves, individual reinforcement bars are usually connected with a knitting wire. The use of welding in this case is undesirable, because. it significantly reduces the corrosion resistance of steel reinforcement.
11. If further construction will also be monolithic, then releases of 5-10 cm are made at the foundation reinforcement. They will subsequently be connected to the reinforcement of walls or columns.
12. It is important that the reinforcement is completely inside the concrete stone, nowhere in contact with the external environment, otherwise corrosion will soon render it unusable. The protective layer should be at least 4-5 cm.
13. Now fiberglass reinforcement is becoming quite popular. Its advantages include low weight and price. However, there are significantly more disadvantages - fiberglass is combustible, which means that in the event of a fire, a structure with such reinforcement will collapse much faster and stronger than with traditional steel. Moreover, this material is not resistant to concrete components. To protect it from destruction, a special coating is needed, which impairs the adhesion of concrete to reinforcement. Accordingly, the bearing capacity of the structure becomes worse. In addition, the plastic fittings bend slightly.
14. After the installation of the reinforcement, the concrete mixture is laid. It can also be made independently directly at the facility under construction. However, the use of prefabricated concrete is preferable. Manufacturers constantly monitor the quality of the components and the resulting mixture, optimize the compositions, and have the opportunity to use various additives. As a result, you can be sure that the concrete used will meet the requirements of strength, frost resistance, water permeability, etc.
15. The strength of concrete is ensured by the exact proportions of its components - cement, sand, crushed stone and water. In order not to violate these proportions, in hot and dry weather, the drying structure must be additionally watered. In damp and rain, the foundation will have to be covered with plastic wrap.
16. After the foundation is laid, it should be protected from moisture in the ground. There are various types of coating, roll, sheet and spray waterproofing, which are often combined.
17. Along the perimeter of the building under a slight slope, concrete slabs, paving slabs or other suitable materials are required. Its role is to divert atmospheric precipitation from the foundation.

Common Mistakes to Avoid and Their Consequences

too much haste

If the foundation is monolithic, then it is necessary to allow the concrete stone to gain a significant part of the strength. If hardening accelerators were not added to the mixture, then under normal conditions it will gain almost one hundred percent strength on the 28th day.

Ideally, before continuing construction work, it is better to wait this time. If you need to build much faster, then you should wait at least a week. On the 7th day, concrete already has about 75% of its final strength.

Otherwise, the foundation may be deformed, nullifying all the work on its construction. And it’s good if this happens at the construction stage, and not when tenants move into the house.

Ignoring waterproofing

Waterproofing should not be neglected. Even if the construction area has a fairly dry climate, and groundwater does not pass near the construction, some liquid in the soil will be necessary. Through the pores in the concrete stone, it will seep into the room, causing dampness and fungus there.

As you know, when freezing, water expands, so in winter it will literally break concrete from the inside. If chemically aggressive substances are present in it, then the destruction process will even accelerate.

In a destroyed concrete stone, reinforcement will quickly become unusable.

Large breaks in pouring concrete

Do not pour a monolithic foundation at intervals of more than 12 hours. Otherwise, the connection between the previously and later poured parts of the structure will be weak, which means that the strength of the entire foundation will also decrease.

There are many types of foundations for the construction of private low-rise buildings. But most often, under domestic cottages, an option is set up in the form of reinforced concrete tape under load-bearing walls. After all, to make a strip foundation with your own hands, you only need to have minimal skills in mixing concrete and follow the instructions. The technology for arranging such a foundation is simple, which is why it is chosen so often for independent execution.

What it is?

Structurally, a strip foundation is a reinforced concrete structure created along the perimeter of the future structure to redistribute the load on the ground. A similar support is used for the construction of residential buildings, garages, outbuildings, baths, garages and even fences. It's not difficult to make it yourself.

This is how he looks

However, when building such a foundation, it is extremely important to adhere to certain rules and recommendations. If the technology for manufacturing the strip foundation is not followed, the durability of the supporting structure itself and the building on it can be forgotten. They won't last long.

Seasonal heaving of soils, the effect of moisture on concrete without waterproofing, incorrectly calculated loads - there are many reasons for the destruction of the strip base on which the house already stands. All of them must be foreseen and taken into account in advance, otherwise a damaged or completely destroyed structure will have to be rebuilt.

Types and types of foundation

According to the depth of laying, it is MZLF (shallow) and simply buried. In the first case, the concrete belt for a low-rise building is buried only 200–400 mm into the ground, and in the second case, it is buried up to one and a half meters (below the ground freezing level).

If the soils at the construction site are rocky, and the groundwater is deep, then it is better to choose a cheap and shallow concrete option, small in volume. On heaving, high groundwater levels and sandy areas for the house, you will have to make a more powerful and expensive support. Often the estimate for a similar basis for a dwelling is such that you generally have to choose a different type of foundation.

Scheme of walls with MZLF

Structurally, the tape reinforced concrete base is:

Monolithic;

The first type is performed by pouring a reinforced concrete belt. The second option is laid out from special factory-made foundation blocks (FBS) or bricks.

Pros and cons of strip foundation

It has three undoubted advantages

Extreme simplicity of the device - any novice builder can handle pouring concrete and laying blocks (there is a step-by-step instruction - to build everything correctly, you just need to follow it step by step);

The ability to withstand heavy loads both from below the ground and from above from the weight of the cottage and everything in it.

A reinforced concrete strip base will last for many years, even if not light aerated concrete blocks are taken for the construction of the walls of the house, but a heavy solid brick. In terms of cost, it is second only to screw piles, but in most cases it surpasses them in reliability.

Among the disadvantages of such a foundation are:

Mandatory thorough analysis of soils at the construction site;

The need to use lifting equipment (in the case of using FBS);

Long-term curing of concrete for at least 3 weeks (when choosing a monolithic option);

The impossibility of bookmarking on strongly heaving and watered soils.

Step-by-step instructions - do-it-yourself foundation

The thickness and height of the tape of the base under consideration, as well as the depth of its laying, are selected based on the analysis of the soil, the climatic conditions of the area and the number of storeys of the house being built. Without knowledge in this area, it is better to entrust this design stage to a professional. There are many nuances and requirements of GOSTs that must be observed.

But it is quite possible to create a support for your house according to an already finished project on your own. But in order to avoid mistakes, it is best to make the strip foundation yourself with the step-by-step instructions given below. It describes all the details of building a similar design for a typical one-story cottage.

Stages of work

The first stage is marking and earthworks. Regardless of the depth of laying, the sole must rest on solid layers of soil. It can be clays, sandy loams, stony layers or loams. Usually they are hidden under the turf and layers of ordinary earth. All this will have to be torn down and removed before starting to build the foundation of the house.



We prepare the site, distribute the main materials: fittings, insulation, formwork boards

To mark the site, you will need pegs, a tape measure and twine. If the soil is dense, then excellent formwork will be obtained from the walls of the dug trench. It will only be necessary to increase it then from above. If the soil is loose and constantly crumbling, then the trench will have to be dug a little more in width so that formwork boards can be placed inside the pit.

The second stage is the preparation of the pillow. The bottom of the excavated trench is leveled with sand and fine gravel. This sand and gravel layer should be carefully compacted, pouring water as it is filled. In height, it should turn out to be within 10–30 cm. This pillow serves to redistribute and reduce point loads on the strip foundation from below during seasonal swelling of the soil.



On top of the pillow, you can put a heater - this will avoid heaving from freezing of the soil

The third stage is the setting of the formwork. Here you will need bars with a cross section of 30 to 40 mm and boards 15–20 mm thick or laminated chipboard. The formwork created for the concrete foundation of the house will subsequently have to withstand a considerable mass of concrete poured into it. Make it strong and reliable. If, after filling with a concrete mixture, it collapses, then everything will have to be started anew.



We expose the formwork from the boards

If the groundwater at the construction site is high, then reinforced concrete will require waterproofing. From above, at the level of the basement of the house, it is usually coated. And to protect that part of the base that remains in the ground, a roofing material should be laid in a trench on the sides and at the bottom. It will reliably protect concrete from excess moisture in the soil at the stage of its solidification and after.

The fourth stage is the laying of reinforcement. For reinforcement, steel rods with a cross section of 14–16 mm and a thin dressing wire are usually used. You can also fasten the reinforcement by electric welding. But in this case, experience with a welding machine and he himself is necessary. Plus, when performing welding, one must be prepared for the appearance of metal corrosion in the future.



We knit reinforcement






Inside the trench, as a result, a frame of reinforcement with cells of 25–30 cm should be formed. Moreover, it is laid so that the steel is covered from all sides with poured concrete. Otherwise, the metal will inevitably begin to rust, then the house will definitely not stand idle for a long time.








The fifth stage is pouring concrete or laying out FBS. If it is decided to equip the foundation for the house being built using block technology, then this greatly speeds up the process of its construction. Here you do not have to make formwork and wait almost a month until the concrete setting is completed.

However, reliance on foundation blocks will cost more than a monolithic counterpart. Plus, they will have to dig a larger trench in width. To distribute loads for the bottom row, FBS masonry is made with an expanding base.

If a monolithic option is chosen for the support device, concrete should be poured immediately over the entire surface. No breaks in length and no layers in height. A monolith is a monolith. The house must be on a solid foundation.



Nails can mark the border of the pour in the formwork

When self-preparing the concrete mix, it is necessary to mix cement, sand and crushed stone in proportions of 1: 3: 3. But it is better to initially order a ready-made solution with the M300 brand and higher.



We fill











When pouring concrete, it is extremely important to ensure that no voids form inside it. There are special vibrators for compaction. However, you can also use a piece of reinforcement to pierce the filled mass and release air from it.








The sixth stage is waterproofing and blind area. It is allowed to start waterproofing work 3-4 days after pouring concrete. It takes about three weeks to complete its setting. But you can already begin to process with mastic, even if not completely frozen, the strip foundation for the house.



We are waiting for solidification

Also, around the entire perimeter of the building, you will need to make a blind area to drain rainwater away from its walls.



Finished foundation with basement rows of bricks

Use for building a house

Such a support can easily withstand private houses two or three floors high. To build a cottage on it, you can choose glued beams, logs, foam blocks or ceramic blocks. It is only necessary to correctly examine the soil and correctly calculate all the loads. At the end, the foundation will not hurt to veneer for additional protection from the weather. For this, natural stone or clinker tiles for the facade are ideal. But you can also choose an easier-to-install and inexpensive corrugated board or siding.

The strip foundation has a lot of advantages, its technology has long been worked out, it is not a difficult task to arrange a strip foundation with your own hands, the main thing is to follow all the stages of technology. This is the only option that allows you to lay in the project a full-fledged underground / basement floor.

According to the SNiP standards of 1987, strip foundations are classified according to the following criteria:

• construction - prefabricated from factory reinforced concrete blocks FBS on FL slabs; monolithic (filling in place into the formwork), laying the tape with bricks or rubble;
• laying depth - shallow strip foundation (MZLF - 0.4 - 0.7 m), deep occurrence (below the freezing mark in the region).

In the individual construction of low-rise buildings, a monolithic type of this foundation is usually used.

Step-by-step instructions for arranging a strip foundation

To ensure the maximum resource of the structure, it is not enough to pour the strip foundation into the formwork. It is necessary to lean it on non-porous soil, remove moisture, and compensate for the forces of frost heaving. For this, a pillow, drainage, hydro and thermal insulation are made, respectively. To do all the operations correctly, you must follow the technology below:

Preparation

Soil samples before construction

In order for the strip foundation to serve for a long time, it is necessary to order surveys from a specialized company. This will make it possible to identify the possibility of seam movement, the composition of the soil and the depth of groundwater. Only in this case, the foundation of the house can be done correctly. Survey data are necessary to calculate the cross section of the reinforcement, the number of belts and the cross section of the tape.

markup

At this stage, it is necessary to remove the fertile layer from the entire development area (usually 0.4 - 0.6 m), mark up:

• cords on pegs along each wall;
• lime mortar scheme on the ground.

Marking trenches for strip foundations.

The stakes are mounted a little further than the axes of the walls so that the cords do not sag when the soil is sampled with a shovel. In the projects of rectangular and square cottages, the diagonals must match, with an accuracy of 2 cm. If there are pilasters, porches or verandas, the geometry of each architectural element is controlled additionally.

For heavy equipment (pumps, emergency generators), heating appliances (boilers, furnaces weighing more than 0.4 tons), independent foundations not connected with the tape are marked. The distance between the reinforced concrete structures should be more than 10 cm, after pouring the concrete, it is covered with non-combustible material (crushed stone or sand).

Excavation

Depending on the depth of the tape, different heaving forces act on it:

• tangents - they try to move the structure to the side or squeeze it tangentially up;
• push-out - only for MZLF, not reaching layers that do not swell in winter.

Therefore, in addition to the sand cushion under the sole of the tape, it is necessary to provide lateral backfilling of the foundation with non-metallic material (sand, crushed stone, ASG mixture).

Digging a trench for a strip foundation. In the future, the fertile layer of soil inside the foundation must be removed.

To compensate for heaving forces and create normal operating conditions for the underground floor, the walls of which in 60% of cases are strip foundations, the outer surface of the concrete structure is insulated with XPS expanded polystyrene sheets along the waterproofing layer. The heat insulator layer is continued in a horizontal plane along the bottom of the trench by 0.6 - 0.8 m, spreading sheets of the same material.

To do hydro-thermal insulation properly, builders need access to these surfaces below ground level. This requires an increase in the width of each trench along the perimeter of the house by 0.8 - 1 m. Doing a strip foundation with your own hands will take four times as long as using special equipment. For a shallow MZLF tape, work can be done manually; for depths below the freezing mark, it is better to use an excavator.

At the last stage, it is necessary to level the bottom of all trenches at a single level. However, earthworks do not end there, since the tape must be protected from moisture in another way.

Drainage

Most manufacturers of expanded polystyrene have flow charts for insulated MZLF and deep tapes. They provide step-by-step instructions for arranging drainage:

• along the outer perimeter of the trench expanded at the previous stage, a recess is created 30 cm below the sole of the tape;
• a general slope of the system is created in one direction (3 - 4 degrees for gravity movement of drains);
• at the collection point, a sealed container is buried in the ground with a neck that goes to the surface;
• the bottom of the recess is covered with crushed stone, if the soil is muddy, it is necessary to lay geotextiles (a margin of 30 cm on each side for subsequent wrapping of the pipe), compacting the pillow with a vibrator or rammer is mandatory;
• drainage pipes (smooth or corrugated, with slotted or round perforation) are laid on the pillow, they are launched into the wells, leaving free space into which, in case of blockages, it will be possible to lower the hose to purge the system with high pressure;
• manholes are mounted in the corners from a corrugated or smooth pipe with plugs on top;
• the mini-trench is covered with rubble to the level of the bottom of the trench.

To make drains correctly, all of the above conditions must be met. This will keep the reinforced concrete structures of the house buried in the ground dry. The drains should be under the planned blind area so that the runoff from it does not fall into the drainage, but into the surface storm drain, which will relieve the tank from overflow.

It is worth noting that drainage is not always provided for, if you are in doubt about whether or not to do underground drainage, then only the geology of the soil, which is worth ordering, can say for sure.

Sand substrate

To make the foundation cushion correctly, it is necessary to compact 15–20 cm of sand and the same amount of rubble in layers. Only in combination with drainage and insulation of the tape, the construction will provide a century-old resource of the house without destruction. At the time of compaction, non-metallic material must be wetted for better shrinkage.

• crushed stone and sand have drainage properties, that is, water can only seep through them down;
• there is no capillary rise from lower levels in these materials.

With a sudden increase in GWL, the roofing material will not protect the concrete, since it is not associated with the lateral waterproofing of the structure. Moisture from concrete does not go down when vibrotampering, cement milk rises up, large fractions go down. Therefore, it is better to make normal hydro- and thermal insulation of the base of the house after stripping the structure.

formwork

The formwork must be securely fastened with braces and wired through the holes drilled in the shields.

Step-by-step installation instructions for classic removable formwork are as follows:

• manufacturing - shields are knocked together from plywood, edged boards, chipboard or OSB (height from the bottom of the trench to ground level + 40 - 50 cm of the base);
• installation - the shields are fastened with jumpers for stable geometry when bursting from the inside with concrete, from the outside they are fixed with inclined bars resting on pegs;
• holes - in the basement, pipes of suitable diameter are passed through the shields for ventilation ducts, similar sleeves are mounted underground for the input of engineering systems (if floors are planned on the ground, ventilation ducts are not needed);
• processing - to facilitate stripping and improve the quality of the side surfaces of the concrete tape from the inside, the shields are sheathed with roofing felt or PVC film.

It is not recommended to pour concrete along the upper edge of the formwork, it is better that the level is 2–5 cm below it. This will prevent splashing during the vibration compaction of the mixture, and will allow to better level the surface. Marking the horizon with a marker or cord on the inner surface of the shields will allow you to control the filling of the form with concrete.

Do not forget to lay plastic mortgages for products and communications in the formwork.

The technology of fixed formwork is somewhat different from the previous version:

• instead of lumber, polystyrene blocks are used (the assembly is similar to the designer);
• there are no external supports, plastic ties are mounted from the inside;
• thanks to the corrugated surface of polystyrene, internal screeds, the insulation reliably adheres to concrete.

The fixed formwork is always narrower than the classic formwork, which makes it difficult to place the internal vibrator. When pouring MZLF, the formwork is filled with concrete at a time. If the depth of the foundation is below the freezing mark, 40 - 60 cm of formwork is assembled in height, the concrete is poured, compacted. Then the formwork is built up to the same height, the operations are repeated.

Reinforcement

To make the armo-belt of the base of the house without errors, it is necessary to make a calculation (section, number of longitudinal bars, jumper pitch), take into account the nuances:

• it is forbidden to join the bars in the corners, T-junctions, one whip is bent at a right angle (50 reinforcement diameters minimum), the second is attached to it on a straight section of the adjacent wall;
• it is not recommended to have a diameter of longitudinal bars of a periodic section (corrugation) less than 12 mm, distribution clamps or jumpers less than 6 mm (smooth reinforcement);
• longitudinal rods are usually laid 4 - 6 pcs. in each frame (2-3 from below, 2-3 from above);
• in junctions and corners, the spacing of the jumpers is reduced by a factor of three (20 cm instead of 60 cm);
• overlap recommended 40 - 60 cm with double wire tying.

The scheme of reinforcing the corners of the strip foundation with U-shaped clamps.

Knowing the volume of formwork for ordering concrete, you can roughly estimate the consumption of reinforcement - 80 kg per cubic meter of mortar. It is forbidden to touch the armored belt to the formwork panels, from metal elements to them there should be at least 2 cm, preferably 5 cm.

When using clamps (a closed element bent from a bar, repeating the shape of the formwork), the performance of the installation of the armored belt increases.

fill

The basic rules for professional do-it-yourself pouring of a tape base are:

• filling the formwork in one day with breaks within 1 - 2 hours (the beginning of setting, depending on the weather);
• moving the mixer along the perimeter, and not dispersing liquid concrete from one place along all walls (the mixture loses its properties);
• the horizontal of the upper plane of the tape is below the sides of the formwork panels, and do not look with them;
• it is forbidden to drop the solution from a height (maximum 2 m from the bottom of the trench);
• it is necessary to compact the concrete mixture with a vibrator.

Pouring concrete into formwork.

For high-quality filling of the formwork, it is necessary to rearrange the mixer several times around the building spot in order to fill the height of 60 cm. Then go through all the sections with a deep vibrator, repeat the operations until the design mark is reached. The norm for a vibrating tool is a compaction depth equal to 1.25 of the tip length.

Curing

To avoid wasting the construction budget at the excavation stage, the developer must know how much the concrete in the formwork settles and how to care for it. The main troubles that can happen with a reinforced concrete structure are:

• damage - chemical or mechanical;
• drying to complete hydration - fragile structure, broken internal bonds, possibly in the heat;
• cracking from temperature changes - relevant in late summer, autumn;
• shells on the surface - shrinkage due to the lack of plasticizers.

After pouring, the foundation is poured with water for a week and covered with a film on top to prevent moisture from evaporating.

Until the concrete has gained 2/3 of the design strength (you can recognize it by the brand), it cannot be stripped and must be protected from the indicated influences. To do this, the building spot or the perimeter of the base is covered with PVC film, burlap or tarpaulin, after 8 hours watering begins. The tape covered with loose materials retains moisture longer, it is recommended to sprinkle it with sand, sawdust, cover with burlap and moisten these materials.

Stripping

When using fixed formwork technology, this structural element remains on the belt. In other cases, shields are removed at 70% of the design strength of concrete, which is a week in summer. It is better to work together, holding the formwork elements to be removed from the canopy.

A home master, when building a strip foundation with his own hands, will avoid serious mistakes when following these recommendations and save money. The foundation is too important element of the building to risk its integrity and resource.

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Most often, with the independent construction of a country house, a bathhouse, a garage or a country house, tape-type foundations are used as a foundation. The thing is that the construction of a strip foundation is easy to do with your own hands because of the simplicity and availability of technology. In addition, this is a universal solution suitable for use on any type of soil and with any material of the walls of the house, as well as a very affordable design. Before making such a foundation, it is necessary to decide whether it will be shallow or deep, as well as to choose the right materials and think over the future design. Installation instructions, photos and videos from our article will help you understand the process and equip the strip foundation for your home.

Selecting the type of foundation

All tape-type foundations can be divided into shallow and deep, monolithic and prefabricated:

1. If the house will be made of lightweight material - wood or foam blocks, then you can equip shallow base
   . This option is suitable for frame buildings, as well as brick buildings with a small thickness of external walls and small sizes (sheds, outbuildings). They can be done on weakly heaving soils. The height of such a tape is no more than 50-70 cm.
2. buried foundation
   suitable for a house with massive heavy load-bearing walls made of brick, stone or concrete. It can be built on any type of soil, as well as for a house with a basement. The depth of laying such a foundation depends on the freezing mark of the soil - the structure should be 200-300 mm lower than this mark.
3. Monolithic structures
   represent a continuous tape from monolithic reinforced concrete. The structure is made using formwork and poured directly on the construction site. This option is suitable for slightly heaving and heaving soils. To make such a foundation, you do not need lifting equipment. Everything can be done manually, so this option is more suitable for self-production. The execution technology can be studied in detail in the video instructions at the end of the article.
4. Prefabricated bases
   slightly inferior in strength to monolithic structures, but are assembled faster due to the use of factory foundation pads and concrete blocks. However, in order to build such a foundation, it is necessary to attract construction lifting equipment. In the photo below you can see the design of the prefabricated base.

In our article, we will consider in detail the technology for performing a monolithic foundation of a tape type.

Monolithic strip base technology

Before starting to make a foundation for a house, it is necessary to examine the soil in order to establish its composition and the height of the groundwater. This will help you choose the right foundation design, as well as determine the depth of its foundation. After completing the drawings and calculating the volumes of materials, work can begin.

Site preparation and marking

The construction site must be cleared of debris and green spaces that will interfere with construction. After that, you can begin marking the foundation of the house on the site. This can be done with a rope and pegs, or you can use a construction level and a theodolite.

To properly mark the future home, you must:

• First of all, the breakdown of the axes of the structure is carried out on the site.
• Further from the border of the site, the extreme corner of the structure is tied and a peg is hammered. A rope is pulled from it at a right angle to the next corner of the house.
• Then, using a theodolite or a square, the next corner of the building is found.
• After that, the corners are checked along the diagonals.
• If the result of the check is positive, then all the corner pegs are connected with a rope.
• Now you can start marking the inner face of the foundation. To do this, from a stretched rope, you need to retreat deep into a distance equal to the width of the future base.

After marking, it is worth checking the elevation differences on the site. Then you need to find a low point and from it to read the depth of the foundation. This will eliminate differences in the height of the structure.

Now you can start digging a trench or pit. Work can be done manually with a shovel or using construction equipment. In any case, the final leveling of the walls and bottom of the trench is done manually with a shovel. To ensure that the depth of the trench is the same, a building water level is used.

Pillow arrangement

After the trench is completed, they begin to prepare the base for pouring the foundation:

1. After laying, the sand is spilled with water and carefully rammed.
2. Sometimes it is recommended to waterproof the sand bed, although this is not required. For insulation, you can use a strong film or make a layer of concrete M 150 100 mm high. Such a concrete layer will increase the strength of the base, protect it from shrinkage and cracking. It is especially recommended to carry out such a concrete footing on sandy and sandy loamy soils, as well as at high standing groundwater.

Important: do not use geotextiles as insulation. This material can backfire and reduce the bearing capacity of the foundation.

Formwork device

A week later, when the mortar of the footing has set, you can begin to make formwork from planed boards 40-50 mm thick. Instead of boards, you can take moisture-resistant plywood or OSB. When erecting formwork, it is necessary to strictly control its verticality.

Above the ground, the formwork should rise to the height of the basement according to the design of the house. Before pouring concrete, the inner surface of the formwork can be lined with plastic wrap. This will reduce the adhesion of the concrete to the wooden elements and facilitate the removal of the formwork. In addition, boards protected from contamination can be reused.

Attention: when installing formwork, it is necessary to provide a hole for an asbestos-cement pipe, which will act as a sleeve for passing engineering networks through the foundation into the house.

Formwork can be removed after the concrete has gained initial strength. This usually happens within a week.

Reinforcement tab

After assembling the formwork, you can begin to make a reinforcing cage. Usually, for a residential building with a height of no more than 2-3 floors, it is enough to make a frame from AIII reinforcement with a cross section of 10-12 mm. In this case, a thicker bar is used as longitudinal guides of the frame, and transverse bars of reinforcement with a diameter of 10 mm are laid in increments of 200 mm.

Important: it is better to make a spatial frame, that is, to connect two flat reinforcing meshes with vertical bars. Their height depends on the design of the base.

To protect the reinforcing cage from corrosion, it must be buried in the thickness of concrete by at least 5 cm. Take this into account when calculating the width of the cage, as well as when laying it at the bottom of the trench with formwork. Spacers can be placed underneath to provide the required distance from the edge of the concrete.

Communications and ventilation

Before pouring the concrete mixture, it is necessary to make structures that will allow ventilating the space under the house, if a basement is not provided, as well as bringing engineering communications into the house - water supply networks and sewerage.

To do this, it is better to use plastic or asbestos-cement pipes, which are laid in a reinforcing cage between the walls of the formwork and tied with wire to the reinforcement. To prevent mortar from entering the pipes during concrete pouring, pour sand into them.

When laying a sleeve for the input of engineering networks, it is worth considering the mark of soil freezing, because the input is performed below it. Thus, when arranging a shallow foundation, the entry will be below the entire structure, and when arranging a buried foundation, the sleeve should be laid 200 mm above the bottom of the foundation.

pouring concrete

Concrete pouring should be done, adhering to the following recommendations:

1. As you can see in the video below, the pouring is done in layers 150-200 mm high. After pouring each layer, the concrete is rammed with a manual rammer or a special internal vibrator. This will get rid of air bubbles and increase the strength of the structure.
2. For pouring, you can use prefabricated concrete, as in the proposed video, or prepare the mixture yourself. To do this, cement, sand and crushed stone are mixed in a ratio of 1-3-5.
3. To avoid delamination of concrete, do not pour the solution from a height of more than 150 cm. Otherwise, the final strength of the structure will decrease.
4. When performing work in winter, frost-resistant concrete additives, such as table salt or calcium chloride, are required.

After pouring, the concrete foundation is covered with a plastic film for uniform evaporation of moisture and protection from precipitation. The film can be removed after 4-5 days. Concrete gains initial strength after 14 days, and complete hardening occurs after 28 days.

Important: in the heat, concrete must first be moistened with water to protect it from rapid evaporation of moisture and cracking.

Waterproofing

After the concrete has set and the formwork has been removed, the walls must be waterproofed. To do this, you can use bitumen or bituminous mastic. The composition used is applied in two layers to the outer walls of the foundation.

For the foundations of houses with basements, which are built in conditions of a high level of groundwater, in addition to coating waterproofing, it is worth using covering the outer surfaces of the foundation with roofing material. Particular care must be taken to seal the place where utilities enter the house. If your house does not have a basement and the groundwater level is low, then vertical waterproofing of the base can be abandoned.

Warming

Foundation insulation can be done using one of three methods:

1. Expanded clay can be used to fill the space around the foundation in the trench. However, the backfill should be made at least 50-100 cm wide. With a smaller backfill thickness, the insulation efficiency will be insufficient. However, this is not a very good method, since expanded clay can absorb moisture, from which its thermal insulation qualities will decrease.
2. Effective insulation of the base is achieved using extruded polystyrene foam. In this case, plates with a thickness of at least 50-100 mm are needed. This is the best option for insulation, which is also suitable for a house with a fall. Expanded polystyrene plates are mounted on the basement of the house above the ground level, as well as on the foundation wall to the level of soil freezing.

Tip: an effective and economical solution would be the manufacture of fixed formwork from expanded polystyrene. However, in this case, it is necessary to thoroughly fix the slabs from the outside so that they are not torn apart by concrete.

1. Insulation can also be performed by spraying polyurethane foam on the walls of the base. However, the price of this method is rather big, because for this you have to turn to specialists. In addition, this material quickly collapses under the action of ultraviolet radiation.

Completion of work

After completion of work, you can backfill the trench. To do this, it is better to use not previously excavated soil, but clay or sand. At the same time, sand is poured in layers with water and rammed, and clay is simply rammed in layers.

To protect the foundation from destruction by melt water and rain, a blind area is necessarily made with a slope from the house. Its width must be at least 1 m. Concrete or asphalt concrete can be used for it.

Do-it-yourself monolithic strip foundation: step-by-step video instruction

The construction of buildings begins with a load-bearing foundation, which determines not only the service life of the building itself, but also forms the comfort and microclimate inside the premises. The strip foundation is one of the most popular types of foundations used both for the construction of private housing and for the construction of technical buildings.

Features of the strip foundation

A strip foundation is a load-bearing base, which is a closed loop in the form of a strip of reinforced concrete, brick and block building materials. The tape is erected under the bearing walls of the building, which contributes to the uniform distribution of the load and its further transfer to the underlying soil layers.

For the manufacture of a monolithic strip foundation, high-strength concrete grades are used

The design of the strip foundation allows you to build structures both from wood and foam concrete, and from brick and concrete blocks. When building a foundation, a large amount of land and construction work is required. Despite this, the strip foundation is popular both among summer residents and owners of suburban areas, and among professionals.

The arrangement of the foundation is carried out on a pre-compacted pillow of sand and gravel. After hardening, the carrier tape is covered with an insulating material that will protect the integrity of the reinforced concrete surface. If the total weight of the building being erected is small (up to 50 tons), then the preparation of the underlying cushion can be neglected.

The configuration of the carrier tape depends on the shape of the walls of the building under construction

The competitive advantages of the strip foundation include:

• technology proven and refined over the years. A properly executed base will evenly distribute the load exerted on it without the risk of collapse of the supporting structures of the building;
• strength. The monolithic construction of the foundation ensures high reliability and durability. Subject to technology, the service life of the foundation can reach 100 years or more;
• versatility. The strip foundation can be used both for heaving and moving soil types, and for loamy and clay soil types. To improve performance, it can be combined with vertical piles and supports.

The disadvantages include the fact that the construction of a strip foundation is a very time-consuming process, requiring the investment of a considerable amount of finance. On average, the cost of a supporting foundation is 15-20% of the total budget allocated for the construction of a house.

The foundation construction technology assumes that the tape will be poured in a work shift, and it is problematic to prepare such a volume of concrete mix even with a concrete mixer. Because of this, it becomes necessary to purchase concrete from the manufacturer, which is also a significant waste.

Types of strip foundation according to the depth of laying

According to SNiP 3.02.01-87 "Earth structures, foundations and foundations", tape bearing foundations are classified according to two criteria:

• by depth;
• according to the method of the device.

The depth of the foundation depends on the bearing capacity of the soil and the calculated load that will be placed on the foundation being built. The bearing capacity of the soil is determined based on its type, the depth of freezing and the presence of groundwater in the area where the building is planned to be built. Read about the design and method of strip foundation construction in the next section.

Shallow strip foundation

A shallow strip foundation is a strip of concrete and a reinforcing frame, located at a shallow depth in the ground. The minimum level of laying depends on the depth of soil freezing, its heaving and the height of groundwater.

A shallow strip foundation can be made of reinforced concrete, brick or foam blocks

For example, if the groundwater is high and the depth of soil freezing is large, then both lateral and tangential heaving forces will act on the foundation, which will compress and displace the shallow carrier tape. And vice versa - the lower the groundwater level and the higher the level of soil freezing, the less the impact of heaving forces.

The recommended minimum depth of the strip foundation can be found in SNiP II–B.1–62. For reference, we offer a table compiled on the basis of data from this document. On average in Russia, the depth of laying varies from 0.4 to 0.75 m. Additionally, you can consider the depth of seasonal freezing of the soil in the region where it is planned to lay the bearing foundation.

Table: foundation depth depending on the level of soil freezing

The depth of laying a shallow strip foundation in the central region of Russia should not be less than 0.5 m

The construction of shallow strip foundations is recommended in the following cases:

• in regions with high average annual temperature and shallow depth of soil freezing;
• in the construction of private houses using frame technology, as well as buildings made of aerated concrete, foam concrete and other materials with low weight;
• when warming the supporting base from the outside, coupled with the arrangement of a blind area made of crushed stone, sand and concrete.

The construction of a shallow strip foundation on soil consisting of peat, sapropel, silt and other organic deposits is strictly prohibited. It is not recommended to build this type of strip base on mixed and heaving types of soil that are oversaturated with moisture.

Buried strip foundation

A buried foundation or a deep foundation is a load-bearing reinforced concrete or prefabricated strip, which is 20–30 cm lower than the level of soil freezing.

The depth of the carrier tape can reach 1.5–2 m, depending on the level of soil freezing

The main idea behind the deep laying of the carrier tape is to rely on dense soil layers with a higher bearing capacity. This type of foundation implies even greater volumes of excavation and concrete mix costs.

The construction of a deep strip foundation is recommended:

• in regions with low temperatures in winter and freezing of the soil to a great depth;
• if it is planned to build a two- or three-story house made of bricks, reinforced concrete blocks and slabs;
• in the presence of fine-grained soil types supersaturated with moisture.

In addition, the recessed foundation allows you to equip the basement. With high-quality insulation and sufficient insulation, it is possible to equip a basement floor intended for living or storing things.

Types of strip foundation according to the device method

Depending on the design features, strip foundations are monolithic and prefabricated. They, in turn, can be divided into monolithic foundations with vertical supports and precast tapes made of brick or foam block.

Monolithic strip foundation

When constructing a monolithic strip base, reinforcement and pouring of the foundation are carried out directly at the construction site. As a result, the overall integrity and continuity of the carrier tape is achieved.

A monolithic strip foundation is an inextricable reinforced concrete strip around the entire perimeter of the building

Depending on the geology of the site, the depth of laying a monolithic foundation varies from 80 to 250 cm. When building private houses, the laying depth rarely exceeds 150 cm.

Monolithic types of foundations, regardless of technology, are used to build objects for various purposes on heaving and moving types of soil. Monolithic design provides high strength and reliability of the bearing base.

Pile and column-strip foundation

Pile-tape and column-tape types of foundations are a monolithic reinforced concrete strip located on supports buried in the ground. In fact, these types of foundations - nothing more than a modernized version of pile or columnar foundations with a grillage.

Pillars or piles are located along the perimeter of the foundation with a step of 2 m

In the first case, steel products in the form of piles of various lengths are used as supports, which are screwed into the ground manually or automatically. In the second, the supports are made from the same concrete mixture that is used to fill the carrier tape.

The arrangement of pile and columnar foundations of the tape type is justified only in the construction of facilities in areas with a large depth of soil freezing. Steel piles or reinforced concrete poles buried below the freezing level of the soil will distribute the load that is transferred from the reinforced concrete strip.

Prefabricated strip foundation

The main material for the construction of a prefabricated strip foundation are reinforced concrete foundation blocks (FBS), made of heavy grades of concrete. The foundation carrier tape is formed from the blocks, which is located along the perimeter and area of ​​\u200b\u200bthe future building. To connect the blocks to each other, concrete grade M350 and steel reinforcement Ø15 mm are used.

After assembling the foundation, the outer surface of the bearing base is treated with waterproofing materials. The most commonly used bituminous mastic and special bituminous membranes, which have a self-adhesive base.

Prefabricated strip foundation consists of reinforced concrete foundation blocks connected with concrete

The main advantage of the prefabricated strip foundation is the short construction time. Unlike a monolithic base, you do not have to wait for the minimum strength of the concrete mixture to set. You can start building a house within a few days from the moment the tape is assembled.

Despite this advantage, a prefabricated strip foundation is used for the construction of private houses a little less often than a monolithic concrete foundation. This is largely due to the fact that the prefabricated structure is not suitable for use on moving types of soil. With the same thickness, the strength indicators of a prefabricated structure are 20–30% lower than a monolithic one.

Brick strip foundations are a prefabricated structure and are often used for the construction of one-story houses using frame technology. For the manufacture of the tape, burnt solid brick is used. Depth of laying - 40–50 cm.

The strip foundation made of bricks is highly maintainable, but requires the arrangement of high-quality waterproofing

After assembly, as in the case of blocks, it is necessary to equip a full-fledged waterproofing layer. The benefits of this foundation include:

• structural rigidity;
• high maintainability;
• ease of arrangement.

If we make a more detailed comparison of bricks with reinforced concrete blocks, then the foundations of the blocks are less hygroscopic and higher strength. The brick is more fragile, which affects not only the frequency of repairs, but also the life of the structure as a whole. With this in mind, it is recommended to build a brick strip foundation in areas with dry and hard soil, as well as with low groundwater.

How to make a strip foundation for a house

In order to start the construction of a strip foundation, it will be necessary to perform calculation operations, during which it is necessary to find out the depth of the foundation and the width of the carrier tape. If possible, these works can be delegated and contacted by a design and construction organization, where all the necessary parameters will be calculated for you, on the basis of which a project for the future foundation will be drawn up.

Calculation of the strip foundation

If you decide to survey the soil and draw up a project yourself, then be prepared that even a small mistake made can lead to the destruction of the house. Especially if you are planning to build a two- or three-story building.

Table: the depth of the strip foundation, depending on the type of soil

Type of building	Depth of the strip foundation (cm) depending on the type of soil
		Rocky ground, flask	Dense clay, soft loam	Packed dry sand, sandy loam	Soft sand, muddy ground	Very soft sand, sandy loam, silt	peat bog
Barn, bathhouse, household the buildings	20	20	30	40	45	65
One-story cottage with an attic	30	30	35	60	65	85	Requires a different type of foundation
Two-storey cottage	50	50	60		Requires calculation of specialists	Requires calculation of specialists	Requires a different type of foundation
Multi-storey cottage	70	65	85	Requires calculation of specialists	Requires calculation of specialists	Requires calculation of specialists	Requires a different type of foundation

For low-rise buildings made of wood, garages, bathhouses, chicken coops and technical buildings, you can perform a calculation taking into account the recommendations given in SNiP II–B.1–62 “Foundations of buildings and structures”.

The simplest option is to check the known parameters with a special table that allows you to determine the depth of the strip base. The referenced table is shown above. For reference: 1 kN = 101.9 kg. The table has been compiled on the basis of European standards adopted in 2010.

To level the site, improvised means, hand tools and special equipment are used.

As an example, we will calculate the parameters of the strip foundation required for the construction of a one-story cottage from a bar, the length of which is 8 m and the width is 6 m. The height of the cottage, not including the roof, is 2.5 m. The structure will be built on the ground of dry fine sand. The depth of soil freezing is 1.4 m, which corresponds to the central part of Russia.

The sequence for calculating the strip foundation is as follows:

1. Building weight - to calculate the total weight of a building, you must have a building design that describes what materials will be used to build it. On average, the weight of a one-story structure made of timber with an attic is no more than 70 tons. To this value should be added the weight of heat-insulating materials, ceilings and partitions, as well as snow load (160–240 kg / m 2). As a result, it turns out that on average a one-story dacha with the parameters announced above will weigh about 100 tons.
2. Foundation area - length of the carrier tape: (6 + 8) * 2 + 6 = 34 m. The width of the tape is selected depending on the weight, but not less than 20 cm. As a result, it turns out that the surface area of ​​\u200b\u200bthe foundation is: 28 * 0.2 m \u003d 6.8 m 2. This value may be adjusted later.
3. Depth of laying - the soil consists of dry sand, the freezing depth of which is 1.4 m. From this we can conclude that the soil in the area is non-porous. Therefore, for the construction of a one-story cottage, you can use a shallow foundation with a laying depth of 0.6 m.
4. The load on the carrier tape - according to SNiP 2.02.01-83 "Foundations of buildings and structures", the formula is used to calculate the load: P = total weight of the structure / foundation area. For fine sandy soil, the resulting value should be less than 20 tons (value taken from DBN V.2.1-10-2009). In our case, P \u003d 100 / 6.8 \u003d 14.7 t / m 2.

Based on this, we can conclude that the previously indicated width of the carrier tape (0.2 m) is ideal for a one-story cottage weighing no more than 100 tons. As a result, it turns out that for the construction of a timber cottage with an area of ​​​​48 m 2, a strip foundation 0.2 m wide is required, which will be buried in the ground by 0.6 m.

Using the tables given in this article and SNiP 2.02.01–83, you can perform a calculation for any strip base that will be built on non-rocky soil types. Data on the weight of building materials can be taken from open sources, and for an approximate calculation, use online calculators.

Site preparation

After all the design operations have been completed, the project of the foundation and the future building has been received, you can proceed to the preparation of the land. During preparation, it is necessary to clean and mark the surface of the site using improvised means.

The marking of the site for the strip foundation is carried out using wooden pegs and a strong rope that is stretched between them.

To prepare, you will need to do the following:

For the final check, it is necessary to measure the diagonals of the platform under the foundation. To do this, the thread is stretched crosswise. If everything is done correctly, then the diagonals will be equal. Otherwise, it is necessary to double-check the corners with the device and rearrange the pegs.

trench digging

During earthworks, it will be necessary to dig trenches to the design depth, which is calculated taking into account the type of soil and the foundation being built. To do this, you can use both special equipment and hand tools in the form of shovels and scrap.

The trench for the strip foundation is dug to the design depth of the bearing base and the underlying cushion

To equip trenches around the perimeter of the foundation, you will need to perform the following activities:

Formwork device

For the manufacture of formwork, an edged board 20 × 150, 20 × 175 or 20 × 299 mm is used, which is fastened with wooden bars 50 × 50 mm. If possible, you can use moisture-resistant plywood, which is mounted on a pre-assembled frame from a bar. The principle of the arrangement of formwork panels is shown in the photo below.

The formwork is installed in the following sequence:

If the foundation provides for the laying of pipes for communications and the creation of ventilation gaps, then special holes of the desired section are sawn in the formwork. For this, an electric drill with a crown nozzle is used.

Video: formwork installation

Reinforcing frame installation

To reinforce the strip foundation, a frame made of steel reinforcement Ø12–15 mm is used. The frame is assembled by welding or using steel wire.

The knitting of the reinforcing frame is as follows:

When knitting, it should be remembered that the frame must be hidden under a layer of concrete to a depth of 5–6 cm. The maximum length of the jumper with a tape width of 40 cm should not exceed 30 cm.

To speed up the knitting process, you can purchase a special construction gun that works on the principle of a stapler, but instead of the usual staples, it uses steel wire of the desired section.

Video: how to knit a reinforcing cage

Pouring concrete mixture

When erecting strip foundations for private housing, a concrete mix of the M200, M250, M300 or M350 brand is used. Concrete brand M200, as a rule, is used only for small frame baths and utility rooms. Concrete of higher grades - for pouring foundations for the construction of two- and three-story houses, and M350 concrete - only for overall buildings.

The foundation is poured strictly in one step, so it is important to ensure the required volume of concrete mix, which is calculated based on the size of the foundation. If it is not possible to prepare the required amount of concrete, then the foundation is poured in layers with the obligatory tamping of each layer.

The proportions of the solution for independent mixing of the mixture are 1 part of cement, 2 parts of sifted sand and 4 parts of crushed stone of fraction 20–40. When changing the proportions of the solution, it should be remembered that there should be 1.5–2 times more crushed stone than sand.

Automated supply of concrete mix will greatly speed up the process of pouring the strip base

You can start pouring the mixture from any convenient place in the trench. Concrete is fed in portions so that it can be evenly distributed over the volume of the trench. To compact the mixture, a reinforcement rod or a wooden lath is used.

The last portion of concrete is leveled along a stretched guideline. To do this, raw concrete is covered with dry cement and rubbed with a wooden grater. After that, the foundation is covered with a plastic film and moistened 2-3 times a day with a small amount of water.

The concrete strip foundation will gain full strength no earlier than after 27 days, but after 14–17 days it is already possible to dismantle the formwork. After 27–30 days, the foundation is waterproofed and backfilled.

Despite the relatively high cost, the strip foundation is one of the most durable types of load-bearing bases. In addition, many owners of summer cottages prefer this type of foundation, as it allows you to equip a basement or even an entire basement.