We make a light foundation with our own hands. How to choose and pour a foundation for a house Columnar foundation for light buildings

As you know, a wide variety of foundations are used in construction, corresponding to the dimensions and other characteristics of the future structure. It is no secret that the characteristics of the foundation must meet a number of requirements; otherwise, problems during operation are almost impossible to avoid.

In this article we will talk about lightweight foundations for small buildings. It should be noted that in modern conditions this basis is the most practical and truly relevant. Of course, a lightweight foundation also has its own characteristics, as well as important details related to the selected materials. Moreover, we cannot exclude the properties of the soil, on which a lot actually depends.

I would like to note in advance that lightweight foundations are built only for small houses and other structures, so otherwise there is no need to take risks. Again, these are important construction projects, so it is best to seek help from specialists who will do all the work efficiently and also provide a guarantee, which means a lot these days.

Features of a lightweight foundation for a house

According to experts, now there is actually an increased interest in lightweight foundations, but it must be borne in mind that only houses of light weight are built on such a basis. Most often we are talking about wooden structures. It should be understood that in modern conditions wood is not used very often, so it is advisable to conduct additional consultations with specialists before choosing a lightweight foundation.

It must be borne in mind that a light foundation means a structure that is quite easy to erect, but all its features must be taken into account. Despite the fact that the house may be made of wood, equipment or furniture can be placed inside it, which will have an impressive weight and negatively affect the condition of the foundation.

If you understand that in the future you will expand your building, then it makes sense to immediately equip a strong and durable foundation, but not a light one. If in the future it is still planned to expand the space, then you will have to start with modernizing the foundation, or you will need to start construction from the very beginning. Thus, a lightweight foundation is far from the most correct solution in many modern conditions.

Risks when installing a lightweight foundation

It becomes clear that there are definitely risks when creating a lightweight foundation. For example, there may be serious problems if we use the premises for a small warehouse. As already mentioned, when the house expands, the load will definitely increase; accordingly, at one point the foundation may not be able to withstand it and will begin to deform (or even collapse).

It is especially bad if the owners decide to add one or more floors to the house. In this situation, an emergency is almost guaranteed. If we are talking about the most ordinary extensions, then it is quite possible to get out of this situation by creating an additional foundation. However, even in this case, it is advisable to strengthen the main foundation if it is really necessary.
If it turns out that the strength of the light foundation is not enough for the safe operation of the home, the foundation will need to be reconstructed. Accordingly, it will be necessary to spend a lot of money to carry out the full scope of construction work. And here it is no longer possible to do without specialists.
If we have a small gazebo or a small garden or country house, then we can safely choose a lightweight foundation, since large loads on the foundation are not expected. However, consultation is still necessary. A specialist will quickly analyze even the most basic parameters of the future structure and draw some conclusions.

Choosing a foundation type

If we talk about a light foundation, then we mean a structure that is quite modest in weight. Accordingly, it is from this information that you need to start when choosing the type of foundation.

It should be noted that in this situation almost all types of foundations can be used, however, their designs may have some features related to the specifics of construction.

Thus, you need to analyze all the factors associated with the future construction, and only after that make a choice in favor of one type of foundation or another.

Columnar foundation

Most often, a columnar foundation is erected for those structures that need to be strengthened as reliably as possible. The thing is that pillars can cope with many features of a specific soil. Moreover, thanks to some tricks, a columnar foundation can easily withstand the effects of moisture and water.

But at the same time, the columnar base has a fairly low price. Moreover, it is often used to strengthen wooden structures, so this would be an excellent option for lightweight houses.

This option is also economical for the reason that a wide variety of building materials can be used to create pillars:

bricks;
concrete pillars;
stones.

The most difficult part of constructing such a foundation can be called transporting the pillars. For example, if these are concrete pillars, then you may need a truck. If the pillars are small, then you can limit yourself to an ordinary passenger car with a trailer.

The pillars are installed along the entire perimeter of the future structure (the distance between them should be about 1.5-2 m), and deepen by 1.5 m (depending on the existing construction project, the values may vary). In this matter, the most important thing is to maintain the vertical position of the pillars, since any distortions can mean further deformation of the entire structure.

If the construction takes place on the basis of heaving soil, then it will not be superfluous to arrange a sand cushion, the thickness of which should be about 20 cm.

Shallow foundation

The shallow foundation is lightweight and easy to carry out construction work. Of course, such a foundation is far from the most reliable, but for a small wooden structure it is an excellent option.

There are many requirements, as well as important features related to this type of foundation:

Waterproofing. The foundation itself has a small area, so it will not be difficult to ensure reliable and durable waterproofing. To do this, use a special coating, which is best applied in two layers.
Avoiding foundation freezing. Experts recommend avoiding freezing of the shallow foundation in winter. The whole point is that such a foundation may gradually lose its most important properties. It will also not hurt to create a load on the foundation throughout the winter, and then the base will be sufficiently submerged so that after a cool period there will be no problems in terms of operation.
Basement dimensions. If we want to additionally create a basement, then we should definitely know about its dimensions. Indeed, the height of the cellar will be small, but at the same time we should not forget that this is a light foundation for a small wooden house.
Carrying out construction work. Again, returning to soil freezing, it must be said that in winter it is better not to carry out the construction process. All this concerns the slight depth of the foundation, which is why, when the warm season comes, the foundation may turn out to be unadapted to existing conditions (deformations, problems with deepening).

Pile foundation

Piles are the best solution for small-scale construction, where there is a need for a truly reliable foundation with a small amount of building materials, as well as modest financial costs.

The main part of such a foundation is pillars with pointed ends. The good news is that there are now a huge number of pile options used in construction, all of which can form the basis for concrete, wood or metal frames.

Strong piles must go deep into the soil and provide maximum foundation strength. Accordingly, the pointed post breaks through strong and loose soil, but in the end the base is highly durable.

In many ways, such a foundation is similar to a columnar foundation, but metal piles definitely inspire more confidence.

Experts say that one metal pile can withstand colossal loads that exceed 5 tons. When creating the foundation, we use several piles, so almost any one-story private house can have such a foundation.

To install piles, special installations are often used that do their job as efficiently as possible. Such a foundation turns out to be quite light and also relatively inexpensive.

Strip foundation

This type of foundation is often used for lightweight buildings, but it should be understood that a huge amount of building materials will have to be spent on this foundation. Accordingly, the strip foundation is characterized by enormous weight and high labor intensity during construction.

At the same time, builders note that this particular foundation has the simplest technology, which means that even beginners can figure it out.

The foundation itself consists of a reinforced concrete strip located around the entire perimeter of the building. At the same time, it is necessary to focus on the fact that it is on the basis of this foundation that a basement or cellar is created, which is incredibly important for many owners of private houses.

The strip base must be laid to a depth of 20 cm (below the freezing depth). As for the thickness of the strip foundation, this value depends directly on the thickness of the walls of the future home.

For wooden structures, it is customary to use a shallow version of a strip foundation. Moreover, experts recommend using this particular base when building on slightly heaving soils.

Slab foundation

Despite the fact that a slab foundation involves the use of a large amount of concrete resources, this foundation also has its positive aspects. Quite often, a slab foundation is used for small houses, while the concrete base can act as a floor.

The main feature of a slab foundation is its versatility. This foundation can be safely used on various soils, and groundwater often does not pose any threat to the slab foundation.

As for the structure, this type of foundation consists of a continuous concrete layer along with reinforcement. Additional waterproofing wouldn't hurt either.

As already mentioned, for this foundation you need to use a lot of building materials, and not everyone will risk large financial expenses if we are talking about a small suburban building.

Other features of creating lightweight foundations

To make a choice in favor of a lightweight foundation, you should pay attention to the following factors:

Building height. Even if we have a wooden house, it should consist of no more than two floors. Otherwise, it is categorically not recommended to skimp on the strength of the foundation. If the house is brick, then even a one-story building may turn out to be too massive.
Specifics of structures. Most often, lightweight foundations are used for small gazebos, bathhouses, and also for modest-sized outbuildings. As for a residential building, everything should be carefully analyzed together with specialists.
Price question. Even when creating a light foundation, you need to pay attention to the financial component of construction work. Perhaps the owner already has some building materials, so construction will take place on their basis. The cheapest option is a columnar base, which, moreover, is highly reliable.

Kirill Sysoev

Calloused hands never get bored!

Content

In housing construction, one of the main structures is the foundation for the house, which can only be selected taking into account the soil and the load from the object itself. These are the main factors influencing the choice of one option or another. Several types of foundations are suitable for a private house. They all differ in the type of construction, materials used and their price, installation technology. The foundation design is the basis of the entire future home, so choosing a specific type must be taken seriously. The information with photos and videos below will help you with this.

Types of foundations for a private house

The main classification that describes what types of foundations there are for building a house takes into account their design and the weight for which they are designed. In their pure form, there are strip, columnar, monolithic and pile. In some cases, combinations of these are used. For example, a ribbon around the perimeter of a building with pillars or piles in the center. It all depends on the amount of load that the foundation experiences from the private house itself.

Tape

The strip foundation owes its name to its appearance. These are ribbons dug into the ground that rest on slabs. They take the weight from the structures lying above and transfer it to the ground. More often, such tapes are made along the perimeter of the building and at the location of load-bearing walls. There are two options for how to properly build a foundation - monolithic and prefabricated. In the first case, formwork is constructed, after which concrete mortar must be poured into it, and in the second, individual elements are used, for example, foam blocks, rubble concrete, rubble stone or foam concrete.

Columnar

The cheapest option is columnar. A minimum of materials is required here. The structure itself consists of pillars immersed to a certain depth or a concrete mixture. The latter is immersed in advance into a drilled well. For one-story cottages, this option is considered optimal, especially if it is light wooden. An inexpensive columnar foundation for a house can also be monolithic or prefabricated. In the first option, you need to dig wells into which concrete is poured, in the second, pillars are assembled from blocks or brickwork.

Monolithic slab

The most expensive and reliable is a slab foundation for a house. It is a monolithic surface, slightly buried in the ground or lying on it. The thickness of the slab can vary from 0.3 to 1 m. For stability, it is reinforced with metal rods with a diameter of 12-25 mm. The slab is used for very heavy loads from the number of floors (usually more than 2 floors) or weak soils. The plate distributes forces evenly over its entire surface. It happens:

Monolithic. The most common option is when the entire area under the building is filled with concrete mortar up to 50 cm thick, depending on the calculated mass.
Caisson. Suitable for light buildings - wooden or metal frames or gas blocks. This is a lightweight and economical option.
Swedish stove. Used in construction from SIP panels or frame panels. Suitable only for well-drained soil.

On stilts

A bit similar to a columnar pile foundation for a house, but it is more expensive. It is used on unstable soil or when strong soil is located very deep - sand, quicksand, with close groundwater. Even significant weights are easily transferred to the piles, which are connected on the surface by a grillage. They can be wooden, metal, concrete with reinforcement. According to the principle of deepening the piles can be:

screw - screw into the ground;
driven - hammered with a special hydraulic hammer to failure;
poured - concrete is poured into a pre-drilled well;
pressed – pressed by hydraulic pumps.

Which foundation is better

It is difficult to determine exactly which house foundation is better. It all depends on the mass, i.e. number of floors of the building, soil type and budget. The most common and frequently used is tape. It is also suitable for buildings with a basement and will withstand even heavy loads. It is better to use slab in case of large volumes. Piling is mainly used when the soils on a construction site are insufficiently strong. Columnar is best used for lightweight structures, for example, small wooden country houses.

How to choose the right one

It has already been said above what the choice of foundation for a house depends on. There are a number of factors, each of which is important to consider. The presence of groundwater and its level, the depth of soil freezing, and whether a basement is planned for the project are affected. For some, you even have to make calculations. Others can often be found on the Internet - freezing depth for a specific region. You can also find them out from organizations involved in construction. This is especially true for soil types and groundwater locations.

Availability of groundwater

One of the first factors influencing the laying of foundation structures is the groundwater level (GWL). To determine it, at least 4 wells are drilled in the corners of the proposed structure. Their depth should be 50 cm lower than the expected level of the sole. The choice will be difficult only if the water level is high. This will require bedding, waterproofing material, drainage and insulation. The basis itself is chosen as follows:

when the groundwater level is below 1.5 m - a shallow slab or tape;
above 0.5 m - only piles, and it is better from screw piles, because they are cheaper;
below 0.5 m - a non-buried slab, columnar, is suitable.

Soil freezing depth

It is equally important to determine soil freezing. The foundation base must lie below this level. This will help avoid lifting of structures due to frost heaving of the earth. Moreover, for unheated premises the freezing value increases by 10%, and for heated premises it decreases by 20-30%. It is measured from the ground level or the basement floor, if such is provided.

Foundation and soil types

Only a geotechnical professional can tell you exactly how to determine the type of soil. But this can also be done based on the characteristic features of the soil at the construction site. In any place there are almost always several types of soil. The main ones are the following:

Rocky or clastic. This is a rock mass that does not swell or freeze, but it is difficult to build a structure on it, but it can be shallow.
Sandy. Sand particles of different sizes are not prone to heaving and are easily compacted, but require preparation to strengthen the walls of trenches and pits.
Clayey. The most difficult due to the high heaving index. In most cases, only piles are suitable here.
Dusty-clayey. The bases are not at all suitable for pouring, as they freeze very much and swell.

Foundation calculation

To build the foundation correctly, you will have to make several calculations. The first one is called collecting scales. Necessary to determine the mass of all structures that will be located above the ground. Based on this value, the optimal base is selected. Next, you need to define a few more values. This is the area and depth. The latter is determined depending on freezing. These are the basic recommendations that describe how to calculate the foundation for a house.

Calculation of house weight

The first priority is to determine the weight of the house. It takes into account many values, so it is better to use a special online service. That’s what it’s called – a house weight calculator. There you will only need to enter the characteristics of the future building that you will find in the project. In addition to quickly calculating values, the calculator will offer you a sequence of calculations with a detailed explanation of all stages.

Calculation of foundation area

Instructions on how to calculate the area of the foundation depend on the type of structure chosen. For a tape, you need to calculate the length of the entire tape - this is the perimeter of the building. This value is then multiplied by the width of the base, resulting in the area. In general, it is calculated as follows: S = yn*F / y с*R 0. The values used in the formula are:

S – required area (cm2);
yn = 1.2 – reliability coefficient;
F – design load on the base, i.e. weight of the structure (kg);
R 0 – design soil resistance at a depth of 1.5-2 m.
Another value in the y c formula is the operating conditions coefficient:
1.0 – for plastic clay, stone walls of a building;
1.1 – for plastic clay, but under wooden or frame walls;
1.2 – weakly plastic clay, soil – silty sand;
1.2 – coarse sand, long structure;
1.3 – fine sand, any structures;
1.4 – coarse sand, non-rigid structures or hard but long ones.

How deep should the foundation be?

Taking into account the freezing of the ground, the depth of the foundation for the house is determined. The soil has a high or low heaving index. In the first case, the base is located below the calculated freezing mark of the ground. In the second option, it can have a height of 0.5-1 m. On coarse sand or rocky soil, a depth of about half a meter is allowed.

How to calculate materials

The construction of a foundation is a calculation of the materials themselves. It will be necessary to determine the amount of concrete mixture, reinforcement and piles. In some cases, the volume of required bricks is also calculated, for example, for a columnar foundation. The data obtained will help you avoid unnecessary expenses. Including transport. In addition, this generally reduces the construction time of the structure.

Quantity of concrete

It makes no difference whether you decide to order work on the construction of the foundation or install it yourself; it will not be superfluous to estimate the required volume of concrete. This is very easy to do. The calculation is carried out using one simple formula. You need to take the area value already calculated above, multiply this number by its height. The result will be the volume of the structure. This is how much concrete is needed for the foundation.

Rebar and wire

It is somewhat more difficult to calculate the amount of reinforcement. It all depends on the type of foundation, the type of soil and the weight of the building. The greater the last factor, the thicker the reinforcement should be. It must occupy at least 0.001% of the cross-section of the base of any type of structure. This applies to ribbed reinforcement. Smooth is only a binder, so it will be required 1.5-2 times less. The wire for tying reinforcement is taken at the rate of 20-30 cm per connection.

Calculation of the number of piles

To calculate a pile foundation, you will need the required area calculated above. In the formula it is the main quantity. It must be divided by the cross-sectional area of one pile. The result will be their number. For example, the required area is 6 m2, and the cross-section of the piles is 0.3 m2, then the following is obtained: 6/0.3 = 20. Result: 20 piles are required.

How to make a foundation

To properly build a foundation for a house, it is important to mark it step by step, then build the formwork, after which it will be possible to pour the concrete mixture. These steps are also suitable for a prefabricated structure. Only instead of pouring the solution, you will need to lay all the elements in a certain order. Formwork is required only for columnar, strip and slab types. The pile is mounted without it.

Marking

Even before the start of excavation work, the corners and sides of the building are marked according to the drawn diagram. To do this, you will need simple materials and tools - rope, cord or fishing line that would be visible against the background of the ground. You also need to stock up on a tape measure and pegs to mark the corners. Step-by-step instructions on how to mark the foundation:

Drive one peg into the base corner of the building, any one of your choice.
Next, measure 4 m in the direction of one of the walls. Drive in another peg and connect it to the previous one with a rope.
Then move to the adjacent wall. From the first peg, measure 3 m in its direction, drive in another peg, connect them.
Measure the distance between unconnected pegs - it should be 5 m (golden triangle rule, or Pythagoras).
Adjust the position of the pegs so that the sides are 3, 4 and 5 m.
Next, stretch the rope to the required length of the walls. Make other right angles in the same way.

How to fill

The next stage after marking is pouring the foundation. It is better to place the concrete mixer in close proximity to the place where it is installed. It is necessary to pour everything at once or so that the number of layers of concrete does not exceed two. Each of them must be compacted, for example, with a reinforcement rod or a special vibrator. Upon completion of the work, the finished structure is covered over the entire area with a layer of film or roofing felt to protect it from weather factors. Concrete reaches its design strength after 28 days.

Formwork

In private construction, the installation of temporary formwork is more often used. It acts as a plinth when constructing a strip, slab or columnar structure. For its installation, you can use second-rate wooden blocks and boards. They make special shields that are installed around the perimeter of the trenches. Nails or self-tapping screws are used for connections. After installing the panels, you need to make clamps that give rigidity to the formwork. The shields themselves are additionally supported by slopes.

Foundation price

The cost consists of the price of all materials used. They can only be clarified with the manufacturers. Costs will also apply to preliminary work - soil excavation, delivery of materials and possible additional labor. Approximate prices for the Moscow region are shown in the table:

Name of work or materials	Price, rubles
Mechanized digging of a trench 50 cm wide per linear meter
Filling a cushion of crushed stone and sand per linear meter
Imported concrete mixture (M300), 1 m3
Concrete laying work, 30% of its cost
Reinforcement, 1 rod with a diameter of 14 mm
Work on installing one reinforcement bar
Formwork
particle board 12 mm, per 1 m2;
block 50x50 mm;
self-tapping screws;
installation work, per linear meter.
Total for 1 linear meter
	5142*L, where L is the length of the foundation

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Very often, the construction of residential buildings, bathhouses, sheds and other objects is carried out with one’s own hands. The foundations that support the entire building should be constructed with particular care. When erecting a support for a building, you want to build a structure that is highly durable and reliable, but at the same time not complicated in execution. In this article we will consider such a topic as a lightweight foundation option.

Strip foundation

Strip foundations for houses and baths are by far the most common type of support foundation, which is erected during the construction of individual objects with one’s own hands.

The basis of a strip foundation is a support erected along the entire perimeter of the building, having internal lintels under the main walls and partitions. Ribbon supports can be constructed in monolithic form or from prefabricated reinforced concrete elements.

Finished foundations made from a monolith or prefabricated products practically do not differ in strength, but have different construction technologies and labor intensity, which we will discuss below.

It is easier to make a monolithic strip foundation with your own hands; this option does not require the use of heavy lifting equipment, which is necessary at the construction site from the beginning to the end of installation work.

Technology for constructing a strip monolithic base

The construction of a lightweight version of the foundation is the construction of a monolithic strip foundation, which is easy to do with your own hands in a short summer period. Monolithic structures should be erected in the warm season so that the structure is not exposed to low temperatures at the time of pouring the concrete mixture and gaining strength.

Preparation and marking of the site

The first stage of work is preparatory activities that must be carried out very carefully:

Clear the construction site of various debris, grass, bushes, and trees. If necessary, old stumps should be uprooted.
All holes and recesses on the building site should be filled with soil, and raised mounds should be leveled.
Carry out leveling work on the site, storing the fertile topsoil separately.
Mark the building on the planned territory, for which you should determine the perimeter by driving in pegs. You can make the pegs yourself from wood, or use scraps of reinforcing rod. If the building has a complex shape, pegs are driven in all corners and in places of protrusions.
A cord is pulled over the driven pegs, which will help more accurately determine the location of the future foundation.

Excavation and formwork construction

Trenches for pouring the foundation (belt type) can be dug with your own hands or using earth-moving equipment. It should be remembered that the walls and bottom of the trenches must have a flat surface, so after working with the excavator you will have to level the trench manually.

Trenches will have to be made not only around the perimeter of the building, internal load-bearing walls and partitions must also be supported on the foundation. The bottom and walls of the trench for the strip foundation are compared and compacted.

At the bottom of the trench under the strip foundation, a sand cushion is placed in a layer of approximately 10 cm; the sand must be thoroughly compacted, pouring water over the layers. A layer of fine gravel is laid on top of the sand bedding, constantly compacting the bedding. The construction of the sand and gravel cushion must be done with special care; to increase the density, the backfill layers must be watered.

The formwork is installed in the trench very carefully, propping up the panels with supports and braces. It is very important that the strip foundation made of monolithic reinforced concrete has perfectly even shapes. You can make formwork yourself from wooden boards, plywood sheets or chipboard.

It is allowed to use reusable metal formwork, but before placing the panels in the trench, the reusable formwork structures should be thoroughly cleaned of concrete stains, dirt, oil and dust.

Reinforcement frame and concreting

To increase the strength of the foundation base, its rigidity and load-bearing capacity, the structure is strengthened with a spatial frame made of reinforcing steel, which is laid in the formwork before concreting. Do you own a welding machine? Do you have welding skills? This means that the frame can be made with your own hands. The main structure uses reinforcing steel with a diameter of 10 to 12 mm, the spatial connecting frame is made of wire with a diameter of 6-8 mm.

The second option for connecting the reinforcement is using a binding wire. In this way, it is easy to make a frame for the foundation with your own hands, even without certain construction skills.

The finished frame is placed in the formwork in such a way that the metal does not touch the formwork walls anywhere.

The foundation strip is concreted with concrete mortar, which is best poured into the formwork within one day, thus avoiding the appearance of cold bridges during the operation of the foundation. It is best to fill the formwork with concrete on both sides at the same time, constantly leveling the concrete.

Compaction of the mortar in the formwork is carried out using deep vibrators, trying to carefully process all joints of the reinforcement frame. The presence of cavities and shells in the body of the foundation should not be allowed.

Concrete care and backfilling of sinuses

The foundation support must gain sufficient strength before the construction of walls can begin. Strengthening continues for at least 28 days, so during this time work on the construction site is suspended. The surface of the foundation must be moistened frequently, covered from the sun and wind with plastic film.

Gaps between prefabricated foundation blocks require careful sealing; poorly sealed seams significantly weaken the foundation structure.

A belt made from prefabricated elements cannot be used on heaving soils.

You can easily make the simplest foundation yourself. Of course, you should strictly monitor the quality of work, because the durability of your construction project will depend on it. So, let's look at what options there are for a simple foundation.

Simple foundations are:

tape;
columnar (pile);
ribbon-columnar.

Let us consider only simple variants of columnar and strip foundations as the most frequently used and well-proven ones over a considerable period of time in the history of the construction of light buildings such as dachas, bathhouses, garages, and others.

Choosing the right foundation for construction

When choosing, you should first of all be guided by the type of future structure, whether it will be a house or a light country house, a bathhouse or a gazebo.

Accordingly, the greater the total mass of the building, the larger the foundation required for it. If you plan to build a light frame structure such as a country house, a gazebo, then the foundation in the usual sense may not be built. It will be enough to confine yourself to installing your house or gazebo on vertically dug pillars, which can be concrete pillars or blocks. In some cases, it is even possible to install the building on wooden piles burned and treated with waterproofing material or on pre-dug holes filled with concrete with a depth of at least 60 cm (not less than the freezing depth of the soil in your region). If the foundation needs to be built for a permanent house, then it would be more advisable to choose the traditional strip option.

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Calculation of the foundation for the structure

It is advisable to calculate any foundation, even the simplest one, before starting work. When calculating the foundation for construction, various aspects are taken into account, such as the seismicity of the soil, the structure of the soil, the weight and dimensions of the future structure, and building materials. As a rule, specialists are involved in the calculation of complex foundations due to the complexity of all calculations due to the high degree of responsibility for the quality of the future structure. In the case of a simple foundation, the calculation can be carried out independently, having basic knowledge in the field of house construction.

The foundation must support the maximum weight of elements such as walls and ceilings. To do this, you need to make the following calculations. As a sample, let’s take a simple house with dimensions of 6m by 9m, one-story, with a wall height of 3 m. We calculate the perimeter of the building, for which we add up the length of all the walls: 6+6+9+9=30 m. Add to this figure the length of the interior partitions: 30 +15=45 m. The area of the floor will be (6+9+6)*3=63 m. The basement floor is equal to the area of the attic and will be 6*9=54 m. In accordance with the mass of materials used for load-bearing structures and partitions, we calculate the total mass structures. In most cases, the weight of the roof is omitted, since it will be significantly less than the weight of the main structures. Typically, to account for the mass of the roof, another 20% of the total weight of the structures is added.

A simple one, suitable for calculating the foundations of country cottages and houses, but not suitable for calculating the foundations of multi-story buildings, looks like this: So = (Md/Ks)x1.1. Designations:

So is the area of the base of the future foundation;
Md - the total mass of the house and all its elements;
Kc is the coefficient of soil resistance.

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Composition and preparation of concrete for pouring the foundation

Concrete is a multi-component building material. Includes the following components:

sand;
crushed stone;
cement;
water.

Most often, cement of grade 300 or 400 is used to prepare concrete. The concrete produced is of a design grade that is half the grade of cement used. Conventionally, the composition of concrete can be divided into cement and ballast - filler, crushed stone and sand. In percentage terms, the optimal concrete composition is 1/3, where 1 is cement, and 3 is filler. There should not be more sand than crushed stone; their ratio in concrete should be approximately 1/1. First, all components are mixed dry until thoroughly mixed and a homogeneous dry mixture is obtained. Then water is added in the amount necessary to obtain the mixture of the desired consistency.

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The simplest columnar foundation

The simplest foundation for light construction is, of course, a columnar foundation. The undoubted advantages of this type of foundation are ease of construction and low cost, in comparison with other options, as well as versatility. Such a foundation can be erected on any type of soil and any terrain; it will not require complex heat and waterproofing work. Building it yourself is as easy as shelling pears; no serious experience in construction is required.

You should decide on the material from which the pillars will be built. It could be:

brick;
concrete;
concrete blocks;
rubble concrete;
natural stone;
quarry flagstone.

Before starting work, it is necessary to prepare the site. It is cleared of debris and excess vegetation. If necessary, individual areas are covered with soil and leveled. Next, you should mark the area in accordance with the project. Mark the perimeter of the future foundation with pegs, and stretch the cord along the pegs. Carefully check the correctness of the geometric shape of the future foundation, in particular the diagonals.

Dig holes. Depending on the chosen material, the pits will be of different widths. If the foundation will be built from bricks or blocks by laying them on mortar, it is necessary to dig holes of such a width that it is convenient to carry out the laying. Subsequently, the resulting pillars are treated with waterproofing material, such as bitumen, and backfilled. from materials such as brick, concrete blocks, rubble stone is very similar and differs only in the methods of laying materials on the mortar. In the center of the future pillar, it is necessary to install a reinforcement rod vertically, which will give the pillar greater strength and solidity. The rod is installed on the first rows of the masonry and then lined on all sides with brick or other material. In height, it should not exceed the height of the pillar itself, or at the end of the masonry, the excess part of the reinforcement is cut off with a grinder.

A columnar concrete foundation can be poured without the use of formwork. To do this, you need to carefully dig holes as wide as the pillar should be. A prerequisite for the construction of such a foundation is that the soil should not crumble. Fill the resulting holes with concrete. The top of the foundation will be at soil level, so it is advisable to build it up with a row of concrete blocks or several rows of bricks. The disadvantage of such a foundation is the lack of waterproofing, and, therefore, less durability.

The construction of any house, bathhouse, or even just a barn always begins with preparing the foundation. But it’s quite difficult to do it; there are many potential problems that every builder, be it a professional or an amateur, must eliminate. First, it’s worth understanding what the foundation for a house actually is.

What it is?

A foundation is an underground, much less often underwater, part of any structure that transmits static and dynamic stresses to the soil foundation. Proper design implies such a transmission of impulses in which it is impossible to exceed shrinkage standards and accelerate the destruction of the house.

There are a number of techniques by which this effect is achieved:

dispersal of operating forces over a large territory;
removal of soil to a solid mass;
overcoming the loose layer in some places using piles;
increasing the strength of the surface mass.

The easiest option is to build on completely rocky soil, there is no shrinkage there, or it is too small. It is much more difficult to create and design foundations where the soil is highly compressible. It’s even worse for architects and developers of areas with changing soil properties.

The type of substrate determines the preferred options for the foundation for the house. The contact space is calculated based on the generated load and the predicted response from the soil.

Varieties

In domestic low-rise construction, a much smaller range of foundation options is used than in the industrial sector. That is why it is possible and necessary to study each type most closely in order to prevent errors from occurring. Along with monolithic strips and slabs, glass-type bases are also in wide demand. The name is no coincidence - a point structure takes on the excess load, then this force is distributed exactly where the pressure can be very high. Under large buildings of small height, it is “glasses” that are installed in many cases.

Important: do not take the name of this foundation literally. In geometric terms, it most closely resembles steps in the form of trapezoids, the tops of which are narrower in comparison with the base.

It should be noted that, in principle, glasses should not be placed under low-rise buildings.

It is preferable to place them under:

bridges over bodies of water;
transitions and crossings over railway tracks;
underground garages, parking lots;
single-tier warehouse, sports, entertainment and retail establishments;
workshops and auxiliary facilities at energy enterprises.

Glass foundations are formed strictly within the framework of technical specifications and GOSTs; in principle, there can be no amateur initiative here. Determining the properties of soil and material, drawing up a picture of geological strata is carried out through careful testing. For each specific case, design institutes develop special series of glass foundations, the features of which are fixed as strictly as possible.

The key components are:

the slab, which acts as a support, is installed on a cushion of sand and crushed stone occupying the bottom of the pit;
Column;
the column sill, which is what looks most like a glass;
a concrete pillar supporting support beams under walls.

The heavy reinforced “glass” is made point-like, and therefore the load on the ground is minimal. The speed of work impresses even those who are fairly familiar with construction. Moreover, the need for special machines when lifting heavy parts does not negatively affect the completion time of the work. The low level of contact with the ground allows water absorption to be reduced to a minimum. Under buildings of significant size, the “glass” is very good, but under a private house it does not justify itself.

A glass foundation cannot be made unless the surface is thoroughly cleaned to a perfectly level state. It is forbidden to lay a slab higher than 1 m. During the work, the geometry is constantly monitored using levels and levels. After delivery to the construction site, the glasses are cleaned of any debris, and they are lifted and installed using a crane. You need to work slowly, carefully checking the positions of the marks.

A mesh of thread will help tie together the individual elements. The excavated soil cannot be removed; it will be useful for backfilling the pit to the top of the mounted block. Next, they place the support beams on the glasses themselves or on the posts.

The use of wedges under the columns of industrial buildings is strictly necessary. In private and individual construction, the “floating” type of foundation is of particular importance.

Of course, there shouldn't be any liquid in it or around it. On the contrary, the structure being created is a rigid, reinforced slab of reinforced concrete, located under the entire volume of the future house. “Swimming” comes down to adapting support to emerging loads. This solution almost does not change under the influence of soil movements, unlike metal pipes (piles), they are not deformed by cold heaving forces. In most cases, slabs 25-30 cm thick are used, under which there is a layer of sand and gravel of comparable sizes.

A serious problem with any floating foundations is the significant consumption of building materials. It is impossible to pour a slab where the area has at least a slope different from the measurement error. And even in the most favorable cases, it is not possible to organize a basement or basement. Requirements for communications are becoming more stringent, their wiring and planning are becoming a filigree art. Moreover, if errors are made with the infrastructure, the complexity and cost of correcting them is unacceptably high.

Materials

Much when choosing the type of foundation and its optimal organization depends on the type of building materials used above. So, a brick wall is heavier than a comparable (or even slightly larger) wooden structure, so you will need to create a strong, stable foundation underneath it. A building with deep support is considered by most experts to be the most reliable and stable, but the complexity of preparing such an element makes it acceptable only for a large brick house.

In addition to concrete strips, three types of piles are often installed:

bored;
screw;
clogged.

Even without special geological and geophysical studies, it is obvious that the properties of the soil in different places are not the same. Its composition and mechanical parameters directly affect the choice of the optimal and acceptable type of material.

It is also worth taking into account the freezing zone, the characteristics of the above-ground structure, climate, groundwater, and the funds available to the developer.

reinforced concrete;
asbestos pipes;
metal constructions.

But wood, even especially durable and treated according to all the rules of protection, cannot be considered a completely effective solution. In most cases, independent developers choose reinforced concrete because this material is universal and suitable for all known types of soil. It can be prepared using cement, sand of various fractions, crushed stone and reinforcing rods. The installation of steel strips is done in the formwork; after connecting them, mortar is poured inside.

By changing the proportions of its components, consistency and adding special additives, you can flexibly adjust the properties of the finished casting.

When erecting a building on strong soil composed of rocks, natural stone and light grades of rubble concrete can be used for laying the foundation. The same materials are recommended for use on most soils that are not subject to heaving in winter. But we must pay attention to the fact that compliance with the work methodology becomes critically important. The irregularity of the contours of natural stones makes it difficult to lay them out in a dense, uniform manner. It is very difficult to correct detected deficiencies; to do this, you almost always have to call in lifting equipment.

Therefore, simple concrete is much more often chosen (even without reinforcing reinforcing inserts). In addition to cement, polymers of a special composition and a combination of silica and lime are sometimes used as a binder for the production of concrete. But the latter type, which makes it possible to make silicate concrete, performs very poorly where the soil is abundantly saturated with moisture or is subject to freezing to great depths.

Instead of pouring it yourself, you can install ready-made blocks, but this is a less accurate and reliable method. Semi-finished industrial products are needed for pillar and strip foundations.

Much attention should, of course, be paid to sand. In addition to being part of the concrete mortar, it is “noted” in one more role - the underlying cushion. It is recommended to create such linings if the rocks below are loose and cannot bear the resulting load on their own. Both cases, when sand is used in the construction of the foundation, require mainly its quarry variety with a large fraction. Special rods are used as reinforcement, the geometry of which is designed for ideal adhesion to the concrete mass.

Wood is used as supports in formwork structures. The cheapness and availability of this material, unfortunately, does not allow us to ignore its main problem, that is, its short service life. When choosing a natural stone, you should carefully consider not only its characteristics and cost, but also transportation costs. Quarry stone is cheaper and more practical than granite or sandstone; it can be obtained without excessive expenses. Expanded clay is traditionally used to insulate foundations, but it makes sense to think about other, more modern and practical insulating materials.

Peculiarities

The structure of a particular foundation depends to a very large extent on the type to which it belongs. Low-rise private buildings are characterized by the whole range of classical foundations and their combinations. The slabs are invariably cast only inside the formwork; they cannot be used on a steep slope or on subsiding soil. Assembling pillars from concrete posts and glasses does not exhaust all possible options; It is quite possible to cast the solution into tubular or panel formwork. This formwork has a particularly wide lower part, but its load-bearing capacity is less than that of piles.

The strip base can be assembled from FBS foundation blocks, lined with rubble, decorated with bricks or poured into formwork.

If the soil is prone to heaving, the tape requires:

drainage works;
backfilling of non-metallic materials;
thermal protection of the most problematic parts of the structure.

As for piles, each subtype has its own specifics. Thus, the drilled version works well in areas with complex terrain or weak soil. But at the same time, the lack of waterproofing makes it impossible to use such supports at medium and high levels of soil water. Screw supports have no technological limitations, but it is recommended to use them only under wooden buildings.

All pile and pillar foundations must be equipped with a grillage; it can be made in different ways, but in any case it is intended to become a support for the walls and increase spatial rigidity. Under the stairs, emergency power generators, stoves, capital fireplaces and so on located in the house, it is necessary to organize autonomous foundations.

When an extension is being built, it is advisable to give preference to solutions on stilts and poles. Regardless of whether these or any other types of foundations are chosen, it is very important to leave a technological gap between the main and secondary foundations.

Please note: the rafter systems of roofing blocks must also be autonomous. The pole system is attractive due to its exceptional simplicity and the ability to perform almost all work without assistants. The column is supposed to be poured in one go.

The constituent structures of a foundation assembled from pillars are:

slabs 0.3 m thick;
reinforced concrete racks;
reinforcing vertical frame;
grillage made of various materials.

Despite all the advantages, the pillar option will not cope with the load from heavy walls. It will not work well on wet soil, on soil prone to subsidence and sliding. It is not recommended to use this approach where there are steep slopes. But heaving is not too dangerous; a typical set of measures to prevent it is quite enough.

Pillars are better than piles in the sense that they allow for additional formwork and waterproofing after construction is completed.

Private developers highly value strip foundations with shallow depth. Arranging them is much more difficult than any pillars. For reinforcement, frames are used, the connecting points of which are reinforced with anchors. To make the outer layer of concrete last longer, use pads and side rings.

Additional cover is provided by:

waterproofing layer;
insulating materials on the outer edge;
blind area (preventing swelling);
non-metallic materials (for the same purpose);
backfilling of trench sinuses (so that the tape does not pull out to the surface).

It is necessary to bury the tape only if there are basement floors. In any case, it is not used on subsiding and wet soils. If construction is carried out on a slope, stepped concreting often helps out, but even this does not allow confident installation of heavy walls. The undoubted advantage of the tape is the ease of working with utility entry points and the absence of restrictions on the height of the house. Floors can be built on the ground; installation of floors on beams is also acceptable. In the most difficult cases, when tape, pillars and piles are ineffective, it is recommended to use slabs.

It should be noted that even this very reliable technology has objective limits. If the soil has low resistance, the slab base may sag. Under the influence of heaving forces arising on an overhanging slope, the block can move to the side. The floating slab has an identical perimeter thickness and requires significant consumption of building materials.

The ribbed option allows you to reduce the thickness of the central area; There are also solutions with built-in heated floors and with a built-in cellar.

Regardless of the option used, all foundations must have vents. The underground continuously accumulates moisture evaporating from the ground. Water vapor is very dangerous for any building structure, for any finishing material. Increased attention should be paid to wooden buildings and all kinds of houses in areas where radon accumulation is likely. The lack of soil freezing causes moisture to seep into the underground even in winter.

If you do not take care of the vents, water will collect and freeze on various parts of the foundation, on the back side of the floors of the first floors. SNiP stipulates that even in ideal cases, the total area of ventilation ducts should be at least 0.25% of the space of the basement or technical subfloor. And when work is carried out in areas with high levels of radon concentration, this figure increases by 2-3 times. Additionally, it is worth considering that installing vents smaller than 0.05 square meters. It just doesn't make sense. Their maximum value is 0.85 square meters. m, since if this size is exceeded, the structure will have to be carefully reinforced.

What shape the vents should be made is decided by the house owners themselves. Most often, a rectangle is chosen; this configuration is not only simple, but also the most aesthetically pleasing in appearance. But the location of the holes on the outside should be uniform in area. It is possible to eliminate the formation of “bags” without ventilation if you do not move the vents away from the corners by more than 90 cm (measurements are taken along the inner edges). The most effective solution is a symmetrical arrangement of an even number of holes.

How high the vents should be placed is determined according to the height of the first floor above the ground. But their lowest point should not be closer to the ground than 20-30 cm. If this rule is not followed, you may encounter underground flooding in the spring and autumn months.

Important: when a house is equipped with internal load-bearing walls, vents should be made for each underground space. If the calculations indicate an excessively large number of holes, which can weaken the foundation structure, you need to get around this problem by increasing the size of a separate channel.

In addition to ventilation, rational arrangement of the foundation also involves backfilling. Houses of permanent residence, heated year-round, do not allow the underlying soil to freeze. Therefore, under such buildings it is allowed to use any type of backfill, even clay. Projects in which it is planned to cover beams are recommended to be filled from the inside with clay as the cheapest material. Sand will have to be used under floating floors in a layer of at least 100 mm.

Significant volumes of construction work make it completely justified to backfill with soil from the construction site, removed from the trenches. Only the upper part can be covered with sand to fill the footing. In areas with high groundwater levels, crushed stone is used. If the aquifer lies relatively deep, it is possible to save money by using sand.

For your information, the organization of external clay castles described in the building codes of outdated editions is now prohibited.

Compaction of the backfilled soil is mandatory every 0.2 m. The presence of large stones (over 0.25 m in size) in the backfill is unacceptable. Drainage, if necessary, is formed in the form of longitudinal channels connected to a single circuit running along the entire perimeter of the building. The foundation needs to be covered with non-metallic materials to different depths. So, for occasional heating of a house, 0.2 m of sand next to the internal walls is enough.

If there is no heating, and the soil can freeze to a depth of 100 cm, it is necessary to form a 200 mm cavity, saturated with inert materials. But when the freezing depth reaches 2 m, you will have to install 50 cm of a protective layer.

Important: this backfill depth is usually measured from planning marks, most often from blind areas. It cannot exceed ¾ of the recess of the soles of the tapes. Only when forming floors along joists is it permissible not to compact the buried materials; in all other cases this is extremely important.

Under the screed, it is always necessary to compact the backfill to a level of 0.95 m. Completing the compaction, whether manually or mechanized, must be completed after it is impossible to leave a mark on the ground. Watering sand, loam and sandy loam is impractical; this can lead to excessive saturation of soil horizons with water. Heavy soil can be moistened to no more than 23%, and light sandy loam to a maximum of 14%. In any case, installing the screed before the soil is completely dry is unacceptable.

Footing must be used under all monolithic foundations.

Its role is threefold:

reducing the height of protective layers;
preventing the breakthrough of laitance into the lower layers;
covering the waterproofing of the foundation base.

The soil located along the outer edges of the foundation is not protected from the cold in any way. This means that it will swell, non-uniformly throughout the entire volume, and a force will arise that pulls the concrete base upward. There are three main options for solving this problem, one of which is backfilling. You can also insulate the blind area by forming a tape 0.6-1.2 m wide around the entire house. Another method is to create sliding-crumpled thermal insulation.

Its essence is that rigidly dense extruded polystyrene foam is attached to the outer walls. Next, the base, fixed in the ground, is covered with a couple of layers of polyethylene. PSB-25 sheets are mounted; they must be placed strictly vertically and pressed tightly against the wall. Sand powder can hold these sheets in place, so no additional fastening is required. Heaving forces invariably crush polystyrene, but its rise over the layer of smoothed film does not damage the key level of thermal protection.

Returning to the sole under the foundation, it is worth noting that most often it is twice the width of the base itself. In order for the sole to rest steadily along its entire length, a so-called concrete footing is equipped (the other functions of which have already been discussed). In industrialized countries, this support structure is required by all building standards and technology regulations. Double-checking all the distances between the milestones placed by surveyors helps eliminate errors. Only then are all the installation lines shown using cords.

Crushed stone footing allows you to save on construction work. The thickness of the created layer cannot be less than 200 mm. But the problem may be related to the low rigidity of the substrate being formed. Therefore, there is no point in pouring crushed stone under the foundations of serious, important buildings. But under utility blocks and sheds, such a solution is completely justified.

Concrete preparation layer is widely used under slabs and strips. In addition to the increased load-bearing capacity, this is also due to the convenience of organizing these types of foundations on rigid underlying surfaces. This advantage is especially important in the winter months, when soil characteristics deteriorate sharply.

According to standard rules, preliminary concreting is carried out strictly with solutions of M-350 and higher.

How to choose?

No matter how carefully the footing and drainage are done, if the type of main foundation is chosen incorrectly, all this work and construction will be almost useless. When the construction site is composed of easily moving wet clay or dusty sand that is prone to deep freezing, you should not choose a strip foundation. As soon as spring arrives, frost heaving will be replaced by subsidence. This will inevitably lead to the occurrence of cracks and even faults. Worst of all, even immediate repairs according to all the rules using adequate tools and materials will be powerless.

But if there are no such problems with soils, the tape has a clear advantage - accelerated installation even without the help of professionals. Therefore, it is recommended to consider it primarily for a residential building, courtyard buildings and baths. A monolithic strip foundation made of concrete can last up to 150 years, and everyone can install it, even without spending money on renting powerful construction machines. The fee for the tape is very high, and it cannot be installed during the cold months.

Problematic soils, which occur quite often, especially in areas of new development, can be easily “defeated” using a slab. The speed of its installation, with the same level of preparation, is the same as that of a strip base. Slab substrates are confidently poured in 1-2 months using our own resources. More precisely, pouring occurs faster, but the mixture takes a lot of time to harden. When ascending and descending, the buildings on the slab move evenly, and this eliminates the danger of their destruction.

The monolithic structure can be mounted both on the surface and with some depth; the benefits are largely offset by increased costs.

The solution to the problem of difficult soil is also possible through piles. The bored type is installed exclusively with the help of special equipment, and it is very diverse - you will need concrete pumping systems, lifters, and drilling machines. If you plan to build a clay castle around the pile supports, it will have to be supplied with special pumps. Of course, using a whole fleet of machines and involving several professionals significantly increases the cost of construction work.

If the goal is to reduce costs and labor intensity, screw structures can be used.

Calculations

The foundation drawing is prepared only after all the necessary calculations, calculations of linear and strength parameters have been completed. External images are written separately, general scales are from 1: 100 to 1: 400. To make it easier to transfer the diagram to the terrain, axial markings are used. The gap from the outer axes to the center axes should definitely be noted in the documentation. Another essential element of any well-thought-out scheme is a coordinate grid.