Water heaters

The designation of the strip foundation in the drawing. Reinforcement of the strip foundation according to the drawings

It is he who must take on the entire load and “carefully” transfer it to the layers of soil. The construction of a strip foundation implies the laying of a reinforced concrete strip completely around the perimeter of the object. A reinforced concrete strip is laid under the walls from the inside and outside of the building along the perimeter.

It is used in houses with walls made of brick, stone and high-density concrete (over 1250-1300 kg / m3). If it is laid correctly, then it is able to correctly “redistribute” the load on the walls and permanently eliminate the appearance of cracks.

Before construction, you need to choose a suitable foundation. At the same time, the lowest prices for a strip foundation should not “play” a decisive role, since an incorrect foundation design and excessive savings on everything can lead to skew, cracks, or even uneven shrinkage and breakage of the building.

What is the relationship between the process of building a strip foundation and the service life of the future structure?

The service life of the future structure directly depends on the quality of the materials that you use in its construction:

base - on cement can last about 150 years;
"brick" tape - from 40 to 50 years;
prefabricated concrete structure - from 60 to 75 years.

Drawing of a strip intermittent prefabricated monolithic foundation
drawing of a shallow strip reinforced concrete foundation

If we consider the design feature of the base, then they can be divided into 2 types:

monolithic, which is being built on the construction site itself;
prefabricated from massive and non-lifting blocks-packs of reinforced concrete, which are mounted directly on the construction site by a crane.

A competent and clear drawing of a strip foundation is the success of a durable and reliable construction

Before starting laying the slabs, it is extremely important to correctly and thoroughly draw up a drawing of the strip foundation. There will be few "fuzzy" calculations for its compilation, it is extremely important to observe all the accuracy in the calculations and take into account possible resistance to future loads.

For such a foundation, reinforced concrete, a foundation slab and a block, as well as brick and rubble concrete, are suitable.

strip foundation drawing
recessed strip foundation

strip foundation drawing
strip foundation

The width of the "sole" of the base must be calculated based on the composition of the soil, as well as from its pressure on the foundation. To find the width of the "sole", you need to clearly calculate the base. For example, with excellent bearing capacity the width will be 40 cm, while with the same load on subsiding soil, it increases by 2 times.

If it is not provided for in the future house, and the slabs will be laid no more than 1.5 meters, then when building a tape support, the mills must be made of concrete (without reinforcement). When building a house with a basement, monolithic walls must be reinforced, while the reinforcement and the thickness of the wall itself directly depend on the deepening of the basement.

It is simply impossible to do without during the construction, regardless of the chosen walls. This is necessary then to avoid the dampness of the walls and the appearance of mold with fungus.

What is the price of a strip foundation?

As for the price of a tape support, it ranges from 3000 rubles. ($85) per sq. meter, the base of cement blocks with tape will cost 2 times cheaper than 1500 rubles. ($42) for one sq. meter.

To lay this foundation, you will need:

concrete B15 - from 4300 rubles. ($120) /m3;
concrete B7.5 - from 3800 rubles. ($105) / m3;
fittings 10 and 12 - from 35,000 rubles. ($980) / t;
masonry - 130 rubles. ($3-4)/bag;
FBS 24-5-6 - from 3500 rubles. (95-99 $)/ for 1 block.

When drawing up a drawing of a strip base, it is necessary to calculate the future expected load, which consists of the weight of the floors, the roof and bearing walls. When accounting, it is necessary to take into account the estimated weight of the snow cover, which lingers on the roof of the building in winter. Accurate calculations will help you calculate the required volume of mortar required for pouring, the cubic capacity of earthworks and the footage of rolled metal required for reinforcement.

You can save on laying slabs only with the right materials. It is not worth saving on the materials themselves, choosing analogues cheaper, since such “savings” can cause cracks on the walls over time and you just have to do a major overhaul or a complete restructuring of the foundation.

Any building, regardless of its purpose, is unthinkable without a reliable foundation. The construction of the foundation is one of the most important and natural tasks of the entire construction cycle as a whole, and this stage, by the way, is often one of the most time-consuming and costly - often up to a third of the estimate is spent on it. But at the same time, any simplifications, unreasonable savings on quality and quantity should be absolutely excluded here. necessary materials, neglect of the current rules and technological recommendations.

Of all the variety of foundation structures, it is most popular as the most versatile, suitable for most houses and outbuildings being built in the field of private construction. Such a base is highly reliable, but, of course, with its high-quality performance. And the key condition for strength and durability is the well-planned and properly carried out reinforcement of the strip foundation, the drawings and the basic principles of the device of which will be considered in this publication.

In addition to the diagrams, the article will provide several calculators that will help the novice builder in this rather difficult task of creating a strip foundation.

Important features of the strip foundation

General concepts. Advantages of strip foundation

So, in short, a few general concepts about the device of the strip foundation. By itself, it is a continuous concrete strip, without gaps for door or gate openings, which becomes the basis for the construction of all external walls and capital internal partitions. The tape itself is buried to a certain calculated distance into the ground and at the same time protrudes from above with its basement. The width of the tape and the depth of its laying, as a rule, is maintained the same throughout the entire length of the foundation. This form contributes to the most uniform distribution of all loads falling on the base of the building.

Strip foundations can also be divided into several varieties. So, they are not only poured from concrete, but also made prefabricated, using, for example, special reinforced concrete foundation blocks, or using rubble filling. However, since our article is devoted to reinforcement, in the future only a monolithic version of the foundation tape will be considered.

The strip foundation can be attributed to the universal type of foundations. This scheme is usually preferred in the following cases:

When building houses from heavy materials - stone, brick, reinforced concrete, building blocks and the like. In a word, when it is required to evenly distribute a very significant load on the ground.
When the developer plans to get a full-fledged basement or even a basement at his disposal, only a tape scheme can allow this.
During the construction of multi-level buildings, with the use of heavy interfloor ceilings.
When a building plot is characterized by heterogeneity of the upper layers of the soil. The only exceptions are completely unstable soils, when the creation of a strip foundation becomes impossible or unprofitable, and it makes sense to turn to another scheme. A strip foundation is also impossible in regions with permafrost.

A monolithic strip foundation has a considerable number of other advantages, which include durability, estimated for many decades, the relative simplicity and clarity of construction, wide opportunities in terms of laying engineering communications and organizing insulated floors on the first floor. In terms of its strength properties, it is not inferior monolithic slabs, and even surpasses them, while requiring less material costs.

However, one should not think that the strip foundation is an absolutely invulnerable structure. All of the above advantages will be valid only if the parameters of the foundation being built for the house correspond to the conditions of the construction area, the design load, and have a built-in safety margin. And this, in turn, means that special requirements are always imposed on the design of the foundation (any, by the way). And the reinforcement of the tape in a series of these problems occupies one of the key positions.

The width of the foundation tape and the depth of its laying

These are two key parameters on which the very scheme of reinforcing the future foundation tape will depend.

Rebar prices

fittings

But the degree of penetration into the ground strip foundations can be divided into two main categories:

A shallow strip foundation is suitable for the construction of frame structures, small country houses and outbuildings, provided that there is sufficiently stable, dense soil on the site. The sole of the tape is located above the soil freezing limit, that is, it usually does not fall below 500 mm, excluding the basement.
For buildings constructed from heavy materials, as well as in areas where the condition of the soil is not stable, deep tape is required. Its sole is already falling below the freezing level of the soil, at least 300÷400 mm, and if there is also a (basement) in the construction plans, even lower.

It is clear that the height of the foundation strip as a whole, including the depth of its occurrence, is by no means arbitrary values, but parameters that are obtained as a result of carefully performed calculations. When designing, a whole array of initial data is taken into account: the type of soils on the site, the degree of their stability both in the surface layers, and the change in structure as they deepen; climatic features of the region; availability, location and other features ground water bearing horizons; seismic characteristics of the area. Plus, the specificity of the building planned for construction is superimposed - the total load, both static, created only by the mass of the structure (naturally, taking into account all its constituent elements), and dynamic, caused by operational loads, and all kinds of external influences, including wind, snow and others.

Based on the foregoing, it would be appropriate to make one important remark. The fundamental position of the author of these lines is that the calculation of the basic parameters of the foundation tape does not tolerate an amateurish approach.

Despite the fact that on the Internet you can find many online applications for carrying out such calculations, it would still be more correct to entrust the issue of designing the foundation to specialists. At the same time, the correctness of the proposed calculation programs is not in the least disputed - many of them fully comply with the current SNiP and are capable of really producing accurate results. The problem lies in a slightly different plane.

The bottom line is that any, even the most advanced calculation program, requires accurate input data. But in this matter, it is impossible to do without special training. Agree that it is correct to assess the geological features of the site for construction, to take into account all the loads that fall on the foundation tape, and - with their expansion along the axes, to provide for all possible dynamic changes - a non-professional simply cannot do it. But each initial parameter matters, and underestimating it may well then "play a cruel joke."

True, if it is planned to build a small country house or an outbuilding, then inviting a specialist designer may seem like an excessive measure. Well, at your own peril and risk, the owner can build a shallow strip foundation, using, for example, the approximate parameters that are shown in the table below. For light buildings, a heavily buried tape is not required (a large depth can even play a negative role, due to the application of tangential forces during frosty swelling of the soil). As a rule, in such cases it is limited maximum depth the location of the sole in 500 mm.

Type of building under construction	barn, bath, outbuildings, small garage	Single storey country house, including - with an attic	One- or two-story cottage, designed for permanent residence	Two or three story mansion
Average soil load, kN/m²	20	30	50	70
SOIL TYPES	RECOMMENDED DEPTH	TAPE INSTALLATIONS	(EXCLUDING THE GROUND	FOUNDATION PARTS)
Pronounced stony ground, flask	200	300	500	650
Dense clay, loam that does not disintegrate after being compressed by the force of the palm	300	350	600	850
Packed dry sand, sandy loam	400	600		Professional foundation calculation required
Soft sand, silt or sandy loam	450	650	Professional foundation calculation required	Professional foundation calculation required
Very soft sand, silt or sandy loam	650	850	Professional foundation calculation required	Professional foundation calculation required
peat bog		Requires a different type of foundation	Requires a different type of foundation	Requires a different type of foundation

We emphasize once again that these are only average values that cannot be considered as the ultimate truth. In any case, if an amateur builder uses such sources, he takes a certain risk on his own responsibility.

Now - about the width of the foundation tape.

It also has its own characteristics. Firstly, to ensure the rigidity of the foundation structure, it is customary to adhere to the rule that the total height of the tape should be at least twice its width - but this rule is not difficult to follow. And the second - the width of the tape in the sole area should be such that the distributed load is less than the calculated parameters of soil resistance, of course, also with a certain design margin. In a word, the foundation tape with a full load should stand stably, without sinking into the ground. In order to save materials, often to increase the area of \u200b\u200bsupport, the sole of the strip foundation is made with a broadening.

Probably, it makes no sense to give here formulas and tabular values of soil resistance for independent calculations. The reason is the same: not so much the difficulty in performing calculations, but the problems with the correct determination of the initial parameters. That is, again, it is better to turn to professionals on such issues.

Well, if a light structure or a country house is being built, then you can be guided by the fact that the width of the tape should be at least 100 mm more than the thickness of the walls being built. As a rule, when planning the foundation independently, they take round values that are multiples of 100 mm, usually starting from 300 mm and above.

Foundation tape reinforcement

If a specialist is engaged in the design of a strip foundation, then the finished drawing will, of course, include not only the linear parameters of the concrete belt itself, but also the characteristics of the reinforcement - the diameter of the reinforcing bars, their number and spatial arrangement. But in the case when a decision is made to independently erect a foundation for a building, when planning the structure, it is necessary to take into account certain rules established by the current SNiP.

cement prices

What fittings are suitable for these purposes?

For proper planning, you need at least a little understanding of the assortment of reinforcement.

There are several criteria for classifying reinforcement. These include:

Production technology. So, the fittings are wire (cold-rolled) and rod (hot-rolled).
According to the type of surface, reinforcing bars are distinguished into smooth and having a periodic profile (corrugation). The profiled surface of the reinforcement provides maximum contact with the poured

Reinforcement can be designed for conventional or prestressed concrete structures.

To create a reinforcing structure for a strip foundation, as a rule, reinforcement is used that is produced in accordance with GOST 5781. This standard includes hot-rolled products intended for reinforcing conventional and preloaded structures.

In turn, these fittings are distributed into classes, from A-I to A-VI. The difference mainly lies in the grades of steel used for the production and, therefore, in the physical and mechanical properties of the products. If in the armature primary school low-carbon steel is used, then in high-class products, the parameters of the metal approach those of alloyed steels.

Know all the characteristics of reinforcement classes when self construction not necessary. And the most important indicators that will affect the creation of the reinforcing cage are shown in the table. The first column shows the reinforcement classes according to the two designation standards. So, in brackets there is a designation of classes, the digital designation of which shows the yield strength of the steel used for the production of reinforcement - when purchasing material, such indicators may appear in the price list.

Reinforcement class according to GOST 5781	steel grade	Rod diameters, mm	Permissible cold bending angle and minimum bending radius when bending (d - rod diameter, D - bending mandrel diameter)
A-I (A240)	St3kp, St3sp, St3ps	6÷40	180º; D=d
A-II (A300)	St5sp, St5ps	10÷40	180º; D=3d
-"-	18G2S	40÷80	180º; D=3d
AC-II (AC300)	10GT	10÷32	180º; D=d
A-III (A400)	35GS, 25G2S	6÷40	90º; D=3d
-"-	32G2Rps	6÷22	90º; D=3d
A-IV (A600)	80С	10÷18	45º; D=5d
-"-	20HG2C, 20HG2T	10÷32	45º; D=5d
A-V (A800)	23X2G2T, 23X2G2C	10÷32	45º; D=5d
A-VI (A1000)	22H2G2AYU, 20H2G2SR, 22H2G2R	10÷22	45º; D=5d

Pay attention to the last column, which indicates the allowable bending angles and curvature diameters. This is important from the point of view that when creating a reinforcing structure, you come to manufacture bent elements - clamps, inserts, paws, etc. In the manufacture of conductors, mandrels or other devices for bending, it is necessary to focus on these values, since a decrease in the bending radius or exceeding the angle can lead to a loss of strength properties by the reinforcement.

rods class A-I are produced in a smooth version. All other classes (with some exceptions, which, however, are more dependent on the individual requirements of the customer) are with a periodic profile.

Specify the requested values and click "Calculate the minimum number of rebars"

Estimated height of the tape (taking into account the depth and base), meters

Estimated tape thickness, meters

Reinforcing bar diameter

After the calculation, it may turn out that even two or three rods are enough for reinforcement. However, with a width of the foundation tape of more than 150 mm and a height of more than 300 mm, it is still recommended to place two belts of longitudinal reinforcement, two rods each, as shown in the diagram. At the same time, the calculator will help determine the minimum diameter value - perhaps by increasing the number of rods to 4 pieces, you can use thinner reinforcement in order to save money. True, we do not forget the recommendations of the table above.

If you get an even value that exceeds 4 rods, then it is recommended to distribute the reinforcement into three belts, placing the middle one in the center between the top and bottom. If an odd number is obtained, five or more pieces, then it makes sense to strengthen the lower tier of reinforcement with an unpaired rod - it is there that the highest bending loads are applied to the foundation tape.

Another rule: the requirements of SNiP established that the distance between adjacent elements of longitudinal reinforcement should not exceed 400 mm.

The binding of longitudinal reinforcement rods into a three-dimensional structure is carried out using prepared clamps. For their manufacture, a special device is usually constructed - it is easy to assemble it on a workbench or on a separate stand.

The installation step of the clamps also obeys certain rules. So, it should not be more than ¾ of the height of the foundation tape, and at the same time - not exceed 500 mm. In areas of reinforcement - at the corners and junctions of walls, clamps are installed even more often - this will be discussed below.

If on a straight section there is a need to connect two reinforcement bars located along the same line, then an overlap of at least 50d is made between them (d is the diameter of the reinforcing bar). When applied to the most commonly used diameters, 10 and 12 mm, this overlap will be from 500 to 600 mm. In addition, it is desirable to install an additional clamp in this area.

The fittings and clamps are connected into a single structure by tying using galvanized steel wire.

Even if there is a personal welding machine, and the owner himself considers himself a fairly experienced welder, all the same, the reinforcing structure must be made by wire twists. A poorly welded joint, and even worse - overheating of the reinforcement will lead to a sharp decrease in the strength characteristics of the structure being created. Not without reason, only highly qualified specialists are allowed to weld reinforcing structures in industrial construction. And besides, it is also necessary to use specialized fittings, in the class designation of which there is an index "C" - welding.

We will not dwell on the issues of practical knitting of the reinforcing cage in this publication - this topic deserves separate consideration.

Reinforcement of complex sections of the frame structure

If everything is quite clear with the installation of the frame on straight sections of the reinforcing belt of the strip foundation, then in difficult areas very often many make mistakes. Evidence of this is the numerous photographs published on the Internet, which clearly show that two frames converging in a corner or adjoining each other are simply connected with wire twists at the points of intersection of the reinforcement.

Incorrectly mounted joints or junctions of reinforcing chords lead to the fact that the uniform distribution along the axes of the load falling on the foundation is disturbed, which in the future may well result in the appearance of cracks or even destruction of the tape in these areas. There are certain schemes for reinforcing such nodes - they will be discussed in the table below.

Basic schemes for reinforcing corners and junction areas

(In the diagrams, the border of the foundation tape is shown in burgundy, dark gray - bars of longitudinal reinforcement, blue - clamps of the frame structure. Additionally different colors individual specific elements of the reinforcement node will be highlighted, which is specified in the text part. All illustrations are in miniature, which can be enlarged by clicking the mouse).

Reinforcement scheme for corners and junctions	Brief description of the scheme
STRENGTHENING IN AREAS OF OBTE-ANGLE CHANGE IN THE DIRECTION OF THE FOUNDATION TAPE
	If it is necessary to perform an obtuse-angle change in the direction of the foundation tape, provided that the angle exceeds 160 degrees, no special reinforcement can be provided. Longitudinal reinforcement is bent at the desired angle. The installation step of the clamps (S) practically does not change. The only feature is that two clamps are placed side by side at the bending point of the reinforcement located on the inner contour of the belt.
	It would seem that the situation is similar, but the angle of change of direction, although obtuse, is less than 160 degrees. The amplification scheme is already different. The reinforcing bar running along the outer contour of the frame simply bends in accordance with the desired direction. The rods converging to the inner contour to the corner are made longer, so that they intersect each other, reach the opposite side of the reinforcement belt, and end on it with paws bent at the desired angle (highlighted in red). The length of this curved part-paw is at least 50d (d is the diameter of the longitudinal reinforcing bar). The paws are tied to an external reinforcement rod, and the installation step of the clamps in this area is halved. At the top of the corner on the outer contour, a vertical piece of reinforcement is additionally installed (shown by an orange arrow).
REINFORCEMENT AT RIGHT ANGLES OF THE REINFORCING FRAME
	Scheme with one large overlap and two "legs". The longitudinal reinforcements converging along the inner contour of the frame intersect each other, reach the opposite walls of the formwork, where they bend with the formation of "legs" (shown in red), located in divergent directions. The minimum length of the "legs" is from 35 to 50d. One reinforcement on the outer contour is cut off at the corner, and the second, perpendicular to it, is bent with the formation of a large overlap (shown in purple), which should be of such a length as to at least completely cover the "foot". The whole structure is linked with clamps, the pitch of which should not exceed half of the calculated one - 1 / 2S. The top of the bending angle is additionally reinforced with vertical reinforcement.
	Scheme similar to the previous one. Longitudinal reinforcements are also wound up and bent with “legs”, and instead of overlapping, an L-shaped insert is installed along the outer reinforcement contour (shown in green). The length of each side of this insert is at least 50d. Linking the knot - using clamps installed with a half-step. The rest is clear from the diagram.
	A scheme that is convenient when the frames on each side are knitted separately, and then placed in the formwork. In this case, the intersection and linking of frames in general design made using U-shaped inserts (shown in dark blue). The length of the "horns" of each of these overlays is not less than 50d. Traditionally, in the reinforcement section, the installation step of the clamps is reduced by half from the calculated one. Pay attention to the additional reinforcement of the intersection of the U-shaped inserts with vertical reinforcement.
REINFORCEMENT IN THE SITES OF THE LATERAL CONNECTION OF THE FOUNDATION TAPE
	Longitudinal reinforcement of the main foundation strip at the junction is not interrupted. The longitudinal reinforcement of the adjoining tape intersect with the internal contour of the reinforcement, reach outside formwork and are bent with "legs" (red color), which are located in converging directions. Linking with clamps with a step reduced by half, and plus, the intersection of the converging "legs" is additionally linked to the external longitudinal reinforcement of the main tape. The length of the "legs" is at least 50d.
	A scheme that is convenient for the separate assembly of adjacent reinforcing cages. The frame of the main tape is not interrupted, and the frame of the adjoining one ends along the intersection line. Linking into a single structure is carried out using L-inserts (green), which connect the longitudinal reinforcement of the adjacent tape with the outer contours of the main one. The side length of such an insert is at least 50d. All clamp connections are installed and linked with a halved pitch.
	Scheme of reinforcement of the junction area using a U-shaped insert. As in other cases, the frame of the main foundation tape is not interrupted. The longitudinal reinforcement of the adjoining frame is brought to the outer contour and bent with "legs" (red) that are located in divergent directions. The length of the side of such a foot is from 30 to 50d. The main reinforcement is performed by a U-shaped insert (dark blue) with a length of each of the "horns" of at least 50d. Linking - with a traditionally halved installation step of the clamps. Additional linkage with the installation of vertical reinforcement - in the area where the lower part of the U-shaped insert fits to the outer contour of the reinforcement of the main tape.

Another nuance should be correctly understood. The schemes proposed in the table show the linkage of the upper tier of the reinforcing belt. But exactly the same reinforcement should be provided for in the lower belt, especially since on lower part the foundation tape usually drops out the maximum loads.

Useful applications for calculating the amount of materials needed

Below, the reader will be offered three calculators that will help in calculating the amount of material required to implement the selected strip foundation reinforcement scheme.

Calculator for calculating the number of main reinforcement

To calculate the required amount of the main longitudinal reinforcement of the strip foundation frame, you need to know several initial values:

First of all, this is the total length of the foundation tape being created. Of course, this should include not only the outer perimeter, but also all internal jumpers, if they are provided for by the project.
The second parameter is the number of longitudinal reinforcement bars. How to determine this amount was described above in this publication, with the application of the appropriate calculator.
The third parameter is the number of gain sections, also discussed above. This includes all corners and junctions of foundation strips. Naturally, in these areas, the consumption of reinforcement increases.

The accounting program, in addition, will take into account the need for overlapping reinforcing bars on straight sections of the tape. The overlap length is taken equal to 50d, that is, for the most commonly used reinforcement diameters, it will be from 500 to 600 mm.

The calculator will give the result in a piece quantity of a standard length reinforcing bar (11.7 meters). Sometimes the difficulties of transporting "long lengths" force buyers to purchase rods cut in two (5.85 meters). On the one hand, transportation is simplified, but on the other hand, the number of reinforcement overlaps during the installation of the frame inevitably increases, that is, the total required footage. The calculation program also provides for a second final value, expressed in the number of “halfed” rods. This will allow you to make a comparison and make a subsequent choice in favor of the first or second option.

The foundation tape prefabricated has become widespread in civil, industrial, as well as individual construction. Externally, strip foundations are a closed structure in the form of a strip, which is installed around the entire perimeter of the building, under all the walls of the structure.

The main task of such a foundation is to evenly distribute the weight of the building over the entire support, as well as throughout the soil that is located under the building. In addition, the foundation must maintain the structure and geometry of the building, no matter what external forces, shocks from the ground or other conditions will affect the building.

What are prefabricated bases?

The prefabricated foundation is a base that is equipped with individual structural elements produced on an industrial scale. Such products include:

Foundation pads. This part of the foundation is one of the most significant. Since it is from it that the load is transferred - from the structure to the ground. In its appearance and design features, this product is a reinforced concrete slab, which has a trapezoidal section. You can find pillows for the foundation in various dimensional options. Considering that the pillow plays a very important role in the structure of the building, increased requirements are imposed on the manufacture of this element, for example, the pillow is made using a strong reinforcing cage.
foundation blocks. In the construction industry, this product is often referred to as FBS. Appearance the foundation block is an elongated parallelepiped, which is also made of reinforced concrete. At the ends of the block there is a place for filling its liquids during installation. Reinforced concrete block can have different sizes.

Precast concrete foundation is most often used in construction, because it has some advantages:

It is much faster to erect the base of the building due to the use of ready-made products in this process. After the foundation is assembled, you can almost immediately begin to erect the walls of the structure, which cannot be done when arranging monolithic foundations.
Prefabricated foundation tapes are of high quality, since their construction is carried out from finished parts, the quality of which is confirmed by the GOST standard. Such products are produced at industrial-scale enterprises, where quality control is carried out quite strictly.

However, despite the great popularity, it is still necessary to take into account some of the disadvantages inherent in reinforced concrete products and prefabricated foundation generally:

Tape-prefabricated foundations are less durable than monolithic foundations.
Strip-prefabricated foundations include seams that remain between the products. Due to this feature, it is much more difficult to provide thermal insulation, as well as protection of the building from moisture, than with the arrangement of a monolithic base.
Sometimes the arrangement of prefabricated structures is more expensive for builders, since the delivery of products to the construction site requires quite a lot of expenses. In addition, when installing a precast strip foundation, the services of a crane may be required to place heavy structures in the right places. Therefore, experts recommend making calculations at the stage when a drawing of a building is drawn up and the type of foundation is selected.

Today, in construction practice, variants of a combined base are widely used, when the sole of the structure itself is made in the form of a monolith, and the walls are in the form of a prefabricated strip foundation. You can consider in more detail this option for building a support in the photo. It should be noted that the combination of a monolith with a strip-prefabricated structure is more durable than the use of conventional prefabricated strip foundations.

Design from reinforced concrete blocks

A foundation drawing must be drawn up when creating a project for the entire structure. It is worth noting that this type of work should in any case be carried out only by specialists, since the drawing must also comply with the construction standards set out in normative documents. These include not only GOST rules, but also other state-issued documents.

When a drawing of a strip-prefabricated base is drawn up, the following parameters must be taken into account:

The distance the soil freezes. This figure is for reference only and varies by region. For example, within the Moscow region, the freezing depth is 120 centimeters, and in the Krasnodar Territory it is much less - 60 centimeters. An important point is that the sole of prefabricated strip foundations or any other type of foundation should be located slightly below the freezing depth of the soil. This is necessary to avoid adverse effects that may arise due to heaving forces that occur when the soil freezes or thaws.
Location of groundwater. The foundation drawing must necessarily take into account the depth of ground flows. In construction practice, a well is usually drilled, through which the depth of water flows is measured.
Construction dimensions. In this case, the building scheme must necessarily include not only the length and width of the base, but also the width of the walls, the materials that will be used to build the walls, as well as the number of storeys of the building and the total load on the foundation and soil.
The relief of the construction site and the location of the structure as a whole.
The structure and condition of the soil at the construction site. It is important to take into account in this case the degree of subsidence of the soil, its heaving and other indicators.
Features during the construction of the building. In this case, such a parameter as the seismicity of the region is taken into account. In areas with an increased risk of earthquakes, the foundations are equipped with the most durable ones.
The design of the prefabricated strip foundation.

After all the work of the designer is completed, the customer receives a ready-made construction plan, with which he applies to special organizations to obtain a building permit. The drawing necessarily includes a plan for the foundation of a strip prefabricated from reinforced concrete products.

Block foundation scheme

The base plan of the building in the drawing represents the entire structure in a section at the level of the foundation, so that it can be seen quite well and understand all the features of the structure. The plan of the supporting structure must necessarily include the following indicators:

Parameters and dimensions of support pads or monolithic soles.
The depth of the location of absolutely all elements of the foundation relative to the zero mark, which is considered to be the floor level of the first floor of the building.
The drawing must contain an image cross section the base, on which the backfill is displayed in detail, its type and thickness, the depth of the sole and other elements, the height of the foundation above ground level, the type of waterproofing and the use of insulation.
The plan must necessarily show the location of all types of communications, whether it be water supply, gas pipes, electrical cables, sewers and more. The scheme should contain all the holes through which this or that communication will be laid. In addition, an explanatory note should be attached to the plan, in which the method of organizing all types of communications should be described in detail.
The foundation drawing must necessarily contain the location of all foundation blocks, as well as pillows. If a monolithic structure is used as the sole, its location and structure should also be indicated.
The foundation plan necessarily contains an explanatory note, to which all the design features of the foundation, as well as the technology for erecting and installing all elements, will be described in detail.

The finished foundation plan is a complete document, according to which you can immediately begin to calculate the cost of all building materials, as well as the necessary construction works, and then start buying everything you need for construction.

Construction of prefabricated foundation

Work on the installation and construction of the foundation begins with a carefully carried out markup. Marking is carried out using special construction equipment and strictly by professionals. At the same time, the markup includes determining the axes of the future building, as well as determining trenches or a place for a foundation pit, if it is planned to build a basement floor.
Most often, when preparing a construction site for the construction of a foundation, an excavator is used, since prefabricated strip foundations are generally always located below the freezing level of the soil. After the front of the work of the excavator is over, the area is cleaned manually. In addition, it is important to check the density and structure of the soil so that the foundation of the house is placed on solid and stable soil.
Before installing the base cushions, a layer of gravel and sand is made with a layer of at least 10 centimeters. All layers of backfill are carefully compacted and spilled with water. It is these materials that are used as backfill, since when moisture appears, neither sand nor gravel absorb water into themselves and do not increase in size.
Along the axes of the future building, trenches or a foundation pit are pulled out. Be sure to check the squareness of the shape under the base, as well as exact compliance with all dimensions indicated in the plan. Further, special identifiers are set up, where reinforced concrete pillows are laid.
After all the pillows are laid, you can start laying the reinforced concrete blocks. Products are installed using special equipment on a pre-laid building mixture. A solution is also poured between the blocks. At the same time, do not forget about the holes that are necessary for the installation of communications. Be sure to level the surface of the base so that the rest of the structural elements stand upright. At the end of the installation of all blocks, only small work remains to fill the empty space with concrete or using brickwork as well as providing waterproofing.

As you can see, the process of erecting a prefabricated strip foundation is quite simple, however, do not forget about all its features. This type of foundation is quite versatile and allows you to cope with construction work much faster.

In private and public housing construction, a tape-type bearing base is often used. It is considered the most practical and does not require large financial costs, as well as the use of heavy special equipment. But first it is necessary to properly plan the strip foundation, drawing, project and miscalculation - this is what any foundation requires in order to be really strong and ensure the stability of the entire structure.

Calculation of the depth and width of the strip foundation

Design works with basic parameters, so before creating a house plan, you need to know the characteristics of the soil, the dimensions of the future building. For a large residential facility, the foundation should be buried below the freezing point of the soil up to 0.6 m, while the total depth of occurrence can reach 2-3 m, especially on soft and moving soils. A light secondary structure or wooden structure can be deepened up to half a meter. Homogeneous and strong soils allow deepening of the foundation by 0.45 m.

The project takes into account the layout, dimensions and width of the external, internal load-bearing walls, under which a monolithic or block foundation is arranged. The minimum width of the supporting base must be no less than the width of the walls. It is permissible to hang a wall element over the foundation, but not more than 13 cm, and when arranging only one type of bearing base - this is a reinforced concrete foundation. It has greater strength in comparison with the materials of the wall structure, therefore it has the ability to withstand massive loads. A narrowed foundation will save on the cost of materials and fittings.

Depending on how wide the foundation will be, its sole, the total width of the supporting structure is calculated. To do this, the project reflects all the loads (sum) that put pressure on the foundation. Therefore, the preliminary plan of the house will come in handy, as well as the conclusion of the geologists, which indicates the main points: soil properties, freezing level and the height of aquifer soil layers.

Advice! If there are reference books on geological exploration data, then the freezing point of the soil and the heaving, the severity of the soil can be found from there. In this case, it is not necessary to order geological exploration. But in heaving soils there is a possibility of a change in the level of groundwater, so it is better to play it safe so as not to redo not only the project, but also the foundation of the house itself.

Do not forget that a sand or gravel fine-grained cushion up to 10-20 cm wide is necessarily arranged under the supporting base, so the trench is dug out taking into account this depth. You can take a sand-gravel mixture in a ratio of 40:6.

The width of the bearing base is calculated from the total load wall panels, floors, roofs and net weight of materials. To this mass is added the weight of the furniture and everything that will be in the premises, so the plan of the house should also provide for such nuances.

Important! The dimensions of the base of the foundation are calculated so that the magnitude of the loads does not exceed the allowable weight on the soil layers of the construction site! The design resistance of the soil should not be less than the specific gravity of the pressure of the building mass.

If the house plan involves a construction in the form of a rectangle or square, then calculating the required volume and size is quite simple, another thing is pouring complex bases. Here you will have to divide each node into basic elements and calculate the volumes and sizes from them, then adding the resulting values. After calculations, it is easy to think over the amount of materials needed for the construction of the foundation, concrete mix, reinforcement, formwork and other things.

Calculation of the bearing capacity of the foundation

Bearing capacity is the maximum possible load on the foundation, which it can withstand without loss of quality and strength characteristics. As a rule, the indicator includes certain times for the formation of deflections, the level of stiffness and the width of the crack opening.

Ground masses consist of particles filled with water and air. Under the influence of the load, the particles are compressed, changing their shape, so the soil in total mass also changes and can even sometimes protrude from under the carrier base. This is called shifts, as a result of which even a monolithic foundation can warp, the house settles, loses its stability. Therefore, when starting to think over a project or building plan, it is important to take into account such factors.

Important! Knowing the maximum load on the ground is necessary to calculate the mass of the building. If the indicators are exceeded, the soils are displaced by an unacceptable amount. The settlement of a monolithic, block or piled strip foundation is determined by the ratio of deformation and stress calculations - this is the average value of the pressure that has its effect on the soil masses.

Features of a shallow foundation

This type of carrier base does not need to be made high so as not to exceed the allowable stiffness standards. A sufficient height is considered to be 40-50 cm. In addition to imparting unnecessary qualities, a high foundation entails an overrun of reinforcement and concrete mix. A low load-bearing base is a more economical and fairly durable structure.

Thermal, waterproofing materials will help improve the performance and reliability of the building. Therefore, when designing a house plan, it is worthwhile to thoroughly consider each node based on actual values, indications and characteristics.

An example of planning, calculating materials and the size of the foundation of a house

Building materials required for work:

Pure sand of fine-grained fraction;
Crushed stone, fine gravel;
Cement;
Reinforcing rod, wire, steel rods;
The basis of the underground part of the foundation: rubble stone, wire, metal pieces.

Any bearing base consists of ground and underground parts. Measurements of length, width, height are necessary for calculating the dimensions of a monolithic reinforced concrete foundation. In order to determine the volume of the flooded area of the above-ground part, the length of the trench along the perimeter is summed up, multiplied by the width and planned height, it is better to reflect this in the plan of the house. Example: if the total length of the supporting base is 30 m, the width is not more than 30 cm, and the total depth is 1 m, then the volume of the foundation is 9 m3.

The same data will help you buy the right amount of sand and cement, but you need enough reinforcement to lay 2 times around the entire perimeter of the foundation, that is, the length bearing base multiplied by 2 and it turns out 60 m. Here are 60 meters of reinforcement and you need it. But at the same time, the reinforcing bars pass in a vertical position in a cut of 1 meter (height). The pitch of the rod is 50 cm, which means that you will have to buy 60 reinforcement rods of 1 meter in length. Bottom line: 60 m + 60 m = 120 meters of reinforcing bar is necessary for the foundation of our building. And all this should be taken into account in the project.

In addition, it is necessary to calculate the number of formwork boards. This is not difficult: multiply the height of the above-ground part of the supporting base by the length of the formwork and another 2. Thus, an estimate is calculated according to the plan of the future structure, where each node, connection is indicated and trifles and nuances are taken into account.

Today, a strip foundation is often used as a foundation for residential and industrial buildings. It is quite simple to perform and does not require the creation of complex drawings. In addition, it is important to note that the most important advantage of this type of foundation is the affordable cost.

Everything you need to know about strip foundation

Specialists in the construction industry attribute the tape type of foundation to monolithic foundations, but only with the exception of one, but very significant difference - efficiency and availability. Despite the fact that the amount of concrete mortar required for the work is reduced, the foundation does not lose its strength characteristics and is distinguished by a special degree of reliability. Today it is used to build high-rise buildings, industrial and public facilities, as well as, of course, in the construction of country cottages of any number of storeys.

Supports for strip base

The supporting structures that are used for this type of foundation are of 2 varieties, namely:

Tape monolithic foundation. The concrete mixture is gradually and evenly poured into the pit;
Prefabricated strip foundation. In addition to the solution, ready-made reinforced concrete structures are also used.

In order to determine how deep the trench should be in this case, it is necessary to be guided by a map of soil freezing. It is different for each locality, and if an inaccurate indicator is used during the work, then such an oversight can be fraught with shrinkage of the structure or even destruction of the entire foundation. The width of the pit depends on what load will be placed on the foundation during the direct operation of the house.

What should be taken into account during calculations?

In order to make calculations correctly, it is important to consider the following characteristics:

weight of the future structure. To calculate this indicator, you should be guided by the total weight of the materials that will be used for construction. An important factor is the number of storeys of the building.
soil type. It has a direct effect on the degree of shrinkage.
the degree of load on the foundation during the period of operation.

Making a plan right

When creating supports for a strip foundation, the drawing must meet the following requirements.

When determining the most appropriate scale, it is highly recommended to choose either 1 in 100 or 1 in 400.
Before starting construction work, the site should be marked.
If you plan to create a house or a public structure with columns, be sure to indicate this designation and section in the drawing.
All lines on paper must be clear and precise, the thickness of each of them is 0.5-0.8 millimeters.

In the general scheme, there must certainly be a designation of the sole, as well as places in which there will be various bulges or recesses. This is important in order to calculate the location of communications from the central highways.

Such holes and protrusions must be displayed on the diagram in contour and broken lines. If necessary, you can make explanatory notes and footnotes.

Complex sections of the circuit

If you plan to build a capital and large-scale structure, then it will certainly require the creation of a complex prefabricated or monolithic base. As a rule, such schemes cannot fit on one drawing. Therefore, experts in the construction industry strongly recommend developing separate schemes for complex sites. Alternatively, you can apply additional centerlines and a section designation (if necessary) to the main plan, as well as create large cuts on the sheet, after making a note about it. In addition, depending on the degree of the section, it is recommended to choose a scale of 1 to 20, 1 to 25, or 1 to 50, in order to bring the section and complex structural elements as close as possible.

Additions to the scheme

In the event that you are going to create a monolithic or prefabricated type of strip base, then, to clarify the drawings, they should be accompanied by the following technical documents:

Scheme of reinforcing the site based on the future load of the structure on the foundation;
An application that displays the design features of the building;
Recommendations regarding preparatory work Location on;
Tables and diagrams that are necessary for waterproofing and thermal insulation of foundations.
Data on the norms of load on the base supports.

Determination of the degree of deepening

As already mentioned, the depth of the trench to create a tape type base is calculated depending on the scope of the supports. Today, 2 main types of structures are popular - deep and shallow. After you decide which of the options should be preferred, an appropriate designation should be made on the plan.

The first type of base is characterized by reinforced reinforcement and is an excellent choice for large structures, the design of which involves the creation basements, attic or heavy partitions. It is believed that the most optimal indicator of the degree of deepening of the trench for the tape is an indicator that is 20-25 meters higher than the level of a particular region.
The drawings certainly contain information about how deep the tape will be buried. It is important to remember that the amount Supplies for the formation of buried supports, an order of magnitude more.

Fundamental differences between support schemes

Above, we tried to describe in as much detail as possible the process of creating a structure plan, for which a strip foundation drawing is used. But at the same time, one should not forget that the drawings containing information about the prefabricated type of supports differ radically from monolithic ones in that it has a section, as well as the designation of straight and corner reinforced concrete structures.

We do our own calculations

We assure you that today enough information has been provided on the network in order to make the most of all necessary calculations. To do this, it is absolutely not necessary to be an engineer and have a technical education. With a responsible approach to the issue, as well as being an observant and attentive person, you can easily calculate all the criteria necessary to create, for example, a strip base for a non-residential structure or a building envelope. It is important to consider the following:

Vertical impact on the ground;
The weight load of the main structure on the base;
roof weight and truss system(but only if you are going to build a barn or non-residential outbuilding);
When creating a foundation drawing, in order to eliminate errors, the results must be multiplied by "2%". This will help to insure against possible shortcomings in the process of independent design.

Will the services of professional specialists be required to create a drawing?

Of course, a strip foundation plan for a residential building needs much more accurate and detailed calculations, which are best left to a specialist. Turning to the master of your craft, you can be sure that the drawing will be:

easy to read;
as accurate as possible;
meeting all the requirements of SNiP;
containing comprehensive information about the preparatory work;
having, in addition to the main drawing, technical applications in the form of various tables, diagrams, etc.

In this article, we tried to provide comprehensive information about the process and principle of creating a drawing of a strip foundation for a residential as well as non-residential structure. And remember that if you are not confident in your abilities, then do not try on your own or with the help of unlicensed programs to carry out the calculations necessary for such a basis. Savings in this case can be fraught with huge losses or even the destruction of the entire building or fence.